$NTRS
NORTHERN TRUST CORP Stock $ntrs

$ntrs Overview Financials Valuation SEC Filings Company Website

2021 Q4 Form 10-K Financial Statement

#000007312422000071 Filed on February 28, 2022

Income Statement

Concept	2021 Q4	2021	2020 Q4
Revenue	$1.650B	$6.465B	$1.523B
YoY Change	8.39%	5.96%	-7.1%
Cost Of Revenue	-$16.60M	-$59.80M	$700.0K
YoY Change	-2471.43%	-207.17%	-99.23%
Gross Profit	$1.667B	$6.465B	$1.522B
YoY Change	9.53%	5.96%	-1.67%
Gross Profit Margin	101.01%	100.0%	99.95%
Selling, General & Admin	$866.6M	$3.459B	$888.8M
YoY Change	-2.5%	3.96%	8.59%
% of Gross Profit	51.99%	53.51%	58.4%
Research & Development
YoY Change
% of Gross Profit
Depreciation & Amortization	$132.8M	$515.6M	$414.4M
YoY Change	-67.95%	3.06%	253.28%
% of Gross Profit	7.97%	7.98%	27.23%
Operating Expenses	$1.129B	$4.427B	$1.149B
YoY Change	-1.65%	-1.04%	7.21%
Operating Profit	$537.5M	$2.038B	$373.4M
YoY Change	43.95%	25.22%	-21.62%
Interest Expense		$23.80M
YoY Change		-88.12%
% of Operating Profit		1.17%
Other Income/Expense, Net
YoY Change
Pretax Income	$509.6M	$2.010B	$373.4M
YoY Change	36.48%	23.5%	-21.62%
Income Tax	$103.2M	$464.8M	$132.5M
% Of Pretax Income	20.25%	23.12%	35.48%
Net Earnings	$406.4M	$1.545B	$240.9M
YoY Change	68.7%	27.78%	-35.08%
Net Earnings / Revenue	24.62%	23.9%	15.82%
Basic Earnings Per Share		$7.16
Diluted Earnings Per Share	$1.948M	$7.14	$1.153M
COMMON SHARES
Basic Shares Outstanding		208.1M shares
Diluted Shares Outstanding		208.9M shares

Balance Sheet

Concept	2021 Q4	2021	2020 Q4
SHORT-TERM ASSETS
Cash & Short-Term Investments	$64.63B	$3.057B	$64.20B
YoY Change	0.67%	-30.37%	15.43%
Cash & Equivalents	$3.057B		$4.390B
Short-Term Investments	$61.58B		$59.81B
Other Short-Term Assets
YoY Change
Inventory
Prepaid Expenses
Receivables
Other Receivables
Total Short-Term Assets	$3.057B	$3.057B	$4.390B
YoY Change	-30.37%	-30.37%	-1.55%
LONG-TERM ASSETS
Property, Plant & Equipment	$488.7M	$1.020B	$514.9M
YoY Change	-5.09%	-5.13%	6.54%
Goodwill	$706.2M		$707.2M
YoY Change	-0.14%		1.49%
Intangibles
YoY Change
Long-Term Investments	$128.8B	$128.8B	$121.3B
YoY Change	6.19%	6.19%	33.82%
Other Assets
YoY Change
Total Long-Term Assets	$180.8B	$180.8B	$165.6B
YoY Change	9.19%	9.19%	25.11%
TOTAL ASSETS
Total Short-Term Assets	$3.057B	$3.057B	$4.390B
Total Long-Term Assets	$180.8B	$180.8B	$165.6B
Total Assets	$183.9B	$183.9B	$170.0B
YoY Change	8.17%	8.17%	24.25%
SHORT-TERM LIABILITIES
YoY Change
Accounts Payable
YoY Change
Accrued Expenses	$663.1M	$663.1M	$701.0M
YoY Change	-5.41%	-5.41%	16.25%
Deferred Revenue
YoY Change
Short-Term Debt	$160.5B	$160.5B	$144.2B
YoY Change	11.29%	11.29%	30.88%
Long-Term Debt Due	$3.584B	$3.584B	$4.012B
YoY Change	-10.67%	-10.67%	-40.52%
Total Short-Term Liabilities	$164.7B	$164.7B	$148.9B
YoY Change	10.62%	10.62%	26.7%
LONG-TERM LIABILITIES
Long-Term Debt	$3.651B	$3.651B	$4.590B
YoY Change	-20.45%	-20.45%	14.78%
Other Long-Term Liabilities	$3.514B	$3.514B	$4.836B
YoY Change	-27.33%	-27.33%	14.38%
Total Long-Term Liabilities	$7.166B	$7.166B	$9.426B
YoY Change	-23.98%	-23.98%	14.57%
TOTAL LIABILITIES
Total Short-Term Liabilities	$164.7B	$164.7B	$148.9B
Total Long-Term Liabilities	$7.166B	$7.166B	$9.426B
Total Liabilities	$171.9B	$171.9B	$158.3B
YoY Change	8.56%	8.56%	25.91%
SHAREHOLDERS EQUITY
Retained Earnings	$13.12B		$12.21B
YoY Change	7.45%		4.73%
Common Stock	$408.6M		$408.6M
YoY Change	0.0%		0.0%
Preferred Stock
YoY Change
Treasury Stock (at cost)	$3.298B		$3.205B
YoY Change	2.91%		4.51%
Treasury Stock Shares	37.41M shares		36.88M shares
Shareholders Equity	$12.02B	$12.02B	$11.69B
YoY Change
Total Liabilities & Shareholders Equity	$183.9B	$183.9B	$170.0B
YoY Change	8.17%	8.17%	24.25%

Cashflow Statement

Concept	2021 Q4	2021	2020 Q4
OPERATING ACTIVITIES
Net Income	$406.4M	$1.545B	$240.9M
YoY Change	68.7%	27.78%	-35.08%
Depreciation, Depletion And Amortization	$132.8M	$515.6M	$414.4M
YoY Change	-67.95%	3.06%	253.28%
Cash From Operating Activities	$2.042B	$1.356B	$1.476B
YoY Change	38.31%	-28.51%	206.03%
INVESTING ACTIVITIES
Capital Expenditures	-$171.4M	$95.50M	-$170.3M
YoY Change	0.65%	-29.68%	-30.57%
Acquisitions
YoY Change
Other Investing Activities	-$18.62B	$163.7M	-$16.64B
YoY Change	11.91%	-49.27%	36.85%
Cash From Investing Activities	-$18.79B	-$18.60B	-$16.81B
YoY Change	11.79%	-37.83%	35.52%
FINANCING ACTIVITIES
Cash Dividend Paid
YoY Change
Common Stock Issuance & Retirement, Net		$267.6M
YoY Change		-10.74%
Debt Paid & Issued, Net
YoY Change
Cash From Financing Activities	15.64B	$16.07B	14.84B
YoY Change	5.42%	-42.33%	46.71%
NET CHANGE
Cash From Operating Activities	2.042B	$1.356B	1.476B
Cash From Investing Activities	-18.79B	-$18.60B	-16.81B
Cash From Financing Activities	15.64B	$16.07B	14.84B
Net Change In Cash	-1.106B	-$1.333B	-492.6M
YoY Change	124.44%	1812.05%	-72.73%
FREE CASH FLOW
Cash From Operating Activities	$2.042B	$1.356B	$1.476B
Capital Expenditures	-$171.4M	$95.50M	-$170.3M
Free Cash Flow	$2.213B	$1.261B	$1.647B
YoY Change	34.42%	-28.42%	126.27%

Facts In Submission

Frame	Concept Type	Concept / XBRL Key	Value	Unit
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CY2021	dei	Document Fiscal Year Focus DocumentFiscalYearFocus	2021
CY2021	dei	Document Fiscal Period Focus DocumentFiscalPeriodFocus	FY
CY2021	dei	Entity Central Index Key EntityCentralIndexKey	0000073124
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CY2021	dei	Document Type DocumentType	10-K
CY2021	dei	Document Annual Report DocumentAnnualReport	true
CY2021	dei	Document Period End Date DocumentPeriodEndDate	2021-12-31
CY2021	dei	Current Fiscal Year End Date CurrentFiscalYearEndDate	--12-31
CY2021	dei	Document Transition Report DocumentTransitionReport	false
CY2021	dei	Entity File Number EntityFileNumber	001-36609
CY2021	dei	Entity Registrant Name EntityRegistrantName	NORTHERN TRUST CORPORATION
CY2021	dei	Entity Incorporation State Country Code EntityIncorporationStateCountryCode	DE
CY2021	dei	Entity Tax Identification Number EntityTaxIdentificationNumber	36-2723087
CY2021	dei	Entity Address Address Line1 EntityAddressAddressLine1	50 South La Salle Street
CY2021	dei	Entity Address City Or Town EntityAddressCityOrTown	Chicago,
CY2021	dei	Entity Address State Or Province EntityAddressStateOrProvince	IL
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CY2021	dei	City Area Code CityAreaCode	312
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CY2021	us-gaap	Other Noninterest Expense OtherNoninterestExpense	299100000	USD
CY2020	us-gaap	Other Noninterest Expense OtherNoninterestExpense	346700000	USD
CY2019	us-gaap	Other Noninterest Expense OtherNoninterestExpense	329800000	USD
CY2021	us-gaap	Noninterest Expense NoninterestExpense	4535900000	USD
CY2020	us-gaap	Noninterest Expense NoninterestExpense	4348200000	USD
CY2019	us-gaap	Noninterest Expense NoninterestExpense	4143500000	USD
CY2021	us-gaap	Income Loss From Continuing Operations Before Income Taxes Extraordinary Items Noncontrolling Interest IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest	2010100000	USD
CY2020	us-gaap	Income Loss From Continuing Operations Before Income Taxes Extraordinary Items Noncontrolling Interest IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest	1627600000	USD
CY2019	us-gaap	Income Loss From Continuing Operations Before Income Taxes Extraordinary Items Noncontrolling Interest IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest	1944100000	USD
CY2021	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	464800000	USD
CY2020	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	418300000	USD
CY2019	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	451900000	USD
CY2021	us-gaap	Net Income Loss NetIncomeLoss	1545300000	USD
CY2020	us-gaap	Net Income Loss NetIncomeLoss	1209300000	USD
CY2019	us-gaap	Net Income Loss NetIncomeLoss	1492200000	USD
CY2021	us-gaap	Preferred Stock Dividends Income Statement Impact PreferredStockDividendsIncomeStatementImpact	41800000	USD
CY2020	us-gaap	Preferred Stock Dividends Income Statement Impact PreferredStockDividendsIncomeStatementImpact	56200000	USD
CY2019	us-gaap	Preferred Stock Dividends Income Statement Impact PreferredStockDividendsIncomeStatementImpact	46400000	USD
CY2021	us-gaap	Net Income Loss Available To Common Stockholders Basic NetIncomeLossAvailableToCommonStockholdersBasic	1503500000	USD
CY2020	us-gaap	Net Income Loss Available To Common Stockholders Basic NetIncomeLossAvailableToCommonStockholdersBasic	1153100000	USD
CY2019	us-gaap	Net Income Loss Available To Common Stockholders Basic NetIncomeLossAvailableToCommonStockholdersBasic	1445800000	USD
CY2021	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	7.16
CY2020	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	5.48
CY2019	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	6.66
CY2021	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	7.14
CY2020	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	5.46
CY2019	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	6.63
CY2021	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	208075522	shares
CY2020	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	208319412	shares
CY2019	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	214525547	shares
CY2021	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	208899230	shares
CY2020	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	209007986	shares
CY2019	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	215601149	shares
CY2021	us-gaap	Net Income Loss NetIncomeLoss	1545300000	USD
CY2020	us-gaap	Net Income Loss NetIncomeLoss	1209300000	USD
CY2019	us-gaap	Net Income Loss NetIncomeLoss	1492200000	USD
CY2021	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Net Of Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodNetOfTax	-534700000	USD
CY2020	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Net Of Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodNetOfTax	527800000	USD
CY2019	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Net Of Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodNetOfTax	228900000	USD
CY2021	us-gaap	Other Comprehensive Income Loss Cash Flow Hedge Gain Loss After Reclassification And Tax Parent OtherComprehensiveIncomeLossCashFlowHedgeGainLossAfterReclassificationAndTaxParent	800000	USD
CY2020	us-gaap	Other Comprehensive Income Loss Cash Flow Hedge Gain Loss After Reclassification And Tax Parent OtherComprehensiveIncomeLossCashFlowHedgeGainLossAfterReclassificationAndTaxParent	500000	USD
CY2019	us-gaap	Other Comprehensive Income Loss Cash Flow Hedge Gain Loss After Reclassification And Tax Parent OtherComprehensiveIncomeLossCashFlowHedgeGainLossAfterReclassificationAndTaxParent	-7700000	USD
CY2021	us-gaap	Other Comprehensive Income Loss Foreign Currency Transaction And Translation Adjustment Net Of Tax OtherComprehensiveIncomeLossForeignCurrencyTransactionAndTranslationAdjustmentNetOfTax	10500000	USD
CY2020	us-gaap	Other Comprehensive Income Loss Foreign Currency Transaction And Translation Adjustment Net Of Tax OtherComprehensiveIncomeLossForeignCurrencyTransactionAndTranslationAdjustmentNetOfTax	26900000	USD
CY2019	us-gaap	Other Comprehensive Income Loss Foreign Currency Transaction And Translation Adjustment Net Of Tax OtherComprehensiveIncomeLossForeignCurrencyTransactionAndTranslationAdjustmentNetOfTax	49900000	USD
CY2021	us-gaap	Other Comprehensive Income Loss Pension And Other Postretirement Benefit Plans Adjustment Net Of Tax OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansAdjustmentNetOfTax	-59800000	USD
CY2020	us-gaap	Other Comprehensive Income Loss Pension And Other Postretirement Benefit Plans Adjustment Net Of Tax OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansAdjustmentNetOfTax	-67500000	USD
CY2019	us-gaap	Other Comprehensive Income Loss Pension And Other Postretirement Benefit Plans Adjustment Net Of Tax OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansAdjustmentNetOfTax	12100000	USD
CY2021	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	-463600000	USD
CY2020	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	622700000	USD
CY2019	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	259000000.0	USD
CY2021	us-gaap	Comprehensive Income Net Of Tax ComprehensiveIncomeNetOfTax	1081700000	USD
CY2020	us-gaap	Comprehensive Income Net Of Tax ComprehensiveIncomeNetOfTax	1832000000	USD
CY2019	us-gaap	Comprehensive Income Net Of Tax ComprehensiveIncomeNetOfTax	1751200000	USD
CY2018Q4	us-gaap	Stockholders Equity StockholdersEquity	10508300000	USD
CY2019	us-gaap	Net Income Loss NetIncomeLoss	1492200000	USD
CY2019	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	259000000.0	USD
CY2019	us-gaap	Common Stock Dividends Per Share Declared CommonStockDividendsPerShareDeclared	2.60
CY2019	us-gaap	Dividends Common Stock DividendsCommonStock	565900000	USD
CY2019	us-gaap	Dividends Preferred Stock DividendsPreferredStock	46400000	USD
CY2019	us-gaap	Stock Issued During Period Value New Issues StockIssuedDuringPeriodValueNewIssues	391400000	USD
CY2019	us-gaap	Stock Issued During Period Value Share Based Compensation StockIssuedDuringPeriodValueShareBasedCompensation	152600000	USD
CY2019	us-gaap	Treasury Stock Value Acquired Cost Method TreasuryStockValueAcquiredCostMethod	1100200000	USD
CY2019Q4	us-gaap	Stockholders Equity StockholdersEquity	11091000000	USD
CY2020	us-gaap	Net Income Loss NetIncomeLoss	1209300000	USD
CY2020	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	622700000	USD
CY2020	us-gaap	Common Stock Dividends Per Share Declared CommonStockDividendsPerShareDeclared	2.80
CY2020	us-gaap	Dividends Common Stock DividendsCommonStock	592000000.0	USD
CY2020	us-gaap	Dividends Preferred Stock DividendsPreferredStock	44700000	USD
CY2020	us-gaap	Stock Redeemed Or Called During Period Value StockRedeemedOrCalledDuringPeriodValue	400000000.0	USD
CY2020	us-gaap	Stock Issued During Period Value Share Based Compensation StockIssuedDuringPeriodValueShareBasedCompensation	111900000	USD
CY2020	us-gaap	Treasury Stock Value Acquired Cost Method TreasuryStockValueAcquiredCostMethod	299800000	USD
CY2020Q4	us-gaap	Stockholders Equity StockholdersEquity	11688300000	USD
CY2021	us-gaap	Net Income Loss NetIncomeLoss	1545300000	USD
CY2021	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	-463600000	USD
CY2021	us-gaap	Common Stock Dividends Per Share Declared CommonStockDividendsPerShareDeclared	2.80
CY2021	us-gaap	Dividends Common Stock DividendsCommonStock	593900000	USD
CY2021	us-gaap	Dividends Preferred Stock DividendsPreferredStock	41800000	USD
CY2021	us-gaap	Stock Issued During Period Value Share Based Compensation StockIssuedDuringPeriodValueShareBasedCompensation	150100000	USD
CY2021	us-gaap	Treasury Stock Value Acquired Cost Method TreasuryStockValueAcquiredCostMethod	267600000	USD
CY2021Q4	us-gaap	Stockholders Equity StockholdersEquity	12016800000	USD
CY2021	us-gaap	Net Income Loss NetIncomeLoss	1545300000	USD
CY2020	us-gaap	Net Income Loss NetIncomeLoss	1209300000	USD
CY2019	us-gaap	Net Income Loss NetIncomeLoss	1492200000	USD
CY2021	us-gaap	Marketable Securities Gain Loss MarketableSecuritiesGainLoss	-300000	USD
CY2020	us-gaap	Marketable Securities Gain Loss MarketableSecuritiesGainLoss	-400000	USD
CY2019	us-gaap	Marketable Securities Gain Loss MarketableSecuritiesGainLoss	-1400000	USD
CY2021	us-gaap	Accretion Amortization Of Discounts And Premiums Investments AccretionAmortizationOfDiscountsAndPremiumsInvestments	-99700000	USD
CY2020	us-gaap	Accretion Amortization Of Discounts And Premiums Investments AccretionAmortizationOfDiscountsAndPremiumsInvestments	-88900000	USD
CY2019	us-gaap	Accretion Amortization Of Discounts And Premiums Investments AccretionAmortizationOfDiscountsAndPremiumsInvestments	-64600000	USD
CY2021	ntrs	Credit Loss Expense Reversal And Available For Sale Allowance For Credit Loss CreditLossExpenseReversalAndAvailableForSaleAllowanceForCreditLoss	-81500000	USD
CY2020	ntrs	Credit Loss Expense Reversal And Available For Sale Allowance For Credit Loss CreditLossExpenseReversalAndAvailableForSaleAllowanceForCreditLoss	125000000.0	USD
CY2019	ntrs	Credit Loss Expense Reversal And Available For Sale Allowance For Credit Loss CreditLossExpenseReversalAndAvailableForSaleAllowanceForCreditLoss	-14500000	USD
CY2021	us-gaap	Depreciation Amortization And Accretion Net DepreciationAmortizationAndAccretionNet	515600000	USD
CY2020	us-gaap	Depreciation Amortization And Accretion Net DepreciationAmortizationAndAccretionNet	500300000	USD
CY2019	us-gaap	Depreciation Amortization And Accretion Net DepreciationAmortizationAndAccretionNet	458900000	USD
CY2021	us-gaap	Increase Decrease In Accrued Income Taxes Payable IncreaseDecreaseInAccruedIncomeTaxesPayable	37200000	USD
CY2020	us-gaap	Increase Decrease In Accrued Income Taxes Payable IncreaseDecreaseInAccruedIncomeTaxesPayable	25400000	USD
CY2019	us-gaap	Increase Decrease In Accrued Income Taxes Payable IncreaseDecreaseInAccruedIncomeTaxesPayable	-70700000	USD
CY2021	us-gaap	Pension Contributions PensionContributions	11200000	USD
CY2020	us-gaap	Pension Contributions PensionContributions	15600000	USD
CY2019	us-gaap	Pension Contributions PensionContributions	6100000	USD
CY2021	us-gaap	Deferred Income Tax Expense Benefit DeferredIncomeTaxExpenseBenefit	2000000.0	USD
CY2020	us-gaap	Deferred Income Tax Expense Benefit DeferredIncomeTaxExpenseBenefit	16400000	USD
CY2019	us-gaap	Deferred Income Tax Expense Benefit DeferredIncomeTaxExpenseBenefit	34300000	USD
CY2021	us-gaap	Increase Decrease In Receivables IncreaseDecreaseInReceivables	460900000	USD
CY2020	us-gaap	Increase Decrease In Receivables IncreaseDecreaseInReceivables	-4500000	USD
CY2019	us-gaap	Increase Decrease In Receivables IncreaseDecreaseInReceivables	50300000	USD
CY2021	us-gaap	Increase Decrease In Interest Payable Net IncreaseDecreaseInInterestPayableNet	-7800000	USD
CY2020	us-gaap	Increase Decrease In Interest Payable Net IncreaseDecreaseInInterestPayableNet	-23600000	USD
CY2019	us-gaap	Increase Decrease In Interest Payable Net IncreaseDecreaseInInterestPayableNet	-23600000	USD
CY2021	us-gaap	Increase Decrease In Derivative Assets IncreaseDecreaseInDerivativeAssets	466500000	USD
CY2020	us-gaap	Increase Decrease In Derivative Assets IncreaseDecreaseInDerivativeAssets	17800000	USD
CY2019	us-gaap	Increase Decrease In Derivative Assets IncreaseDecreaseInDerivativeAssets	-1154000000	USD
CY2021	us-gaap	Increase Decrease In Other Operating Capital Net IncreaseDecreaseInOtherOperatingCapitalNet	-183800000	USD
CY2020	us-gaap	Increase Decrease In Other Operating Capital Net IncreaseDecreaseInOtherOperatingCapitalNet	16400000	USD
CY2019	us-gaap	Increase Decrease In Other Operating Capital Net IncreaseDecreaseInOtherOperatingCapitalNet	448200000	USD
CY2021	us-gaap	Net Cash Provided By Used In Operating Activities NetCashProvidedByUsedInOperatingActivities	1356000000	USD
CY2020	us-gaap	Net Cash Provided By Used In Operating Activities NetCashProvidedByUsedInOperatingActivities	1896800000	USD
CY2019	us-gaap	Net Cash Provided By Used In Operating Activities NetCashProvidedByUsedInOperatingActivities	2592000000	USD
CY2021	ntrs	Proceeds From Payments For Federal Funds Sold ProceedsFromPaymentsForFederalFundsSold	0	USD
CY2020	ntrs	Proceeds From Payments For Federal Funds Sold ProceedsFromPaymentsForFederalFundsSold	5000000.0	USD
CY2019	ntrs	Proceeds From Payments For Federal Funds Sold ProceedsFromPaymentsForFederalFundsSold	129000000.0	USD
CY2019	ntrs	Net Change In Client Security Settlement Receivables NetChangeInClientSecuritySettlementReceivables	-821000000.0	USD
CY2021	us-gaap	Proceeds From Payments For Securities Purchased Under Agreements To Resell ProceedsFromPaymentsForSecuritiesPurchasedUnderAgreementsToResell	897700000	USD
CY2020	us-gaap	Proceeds From Payments For Securities Purchased Under Agreements To Resell ProceedsFromPaymentsForSecuritiesPurchasedUnderAgreementsToResell	-700900000	USD
CY2019	us-gaap	Proceeds From Payments For Securities Purchased Under Agreements To Resell ProceedsFromPaymentsForSecuritiesPurchasedUnderAgreementsToResell	357300000	USD
CY2021	us-gaap	Proceeds From Payments For In Interest Bearing Deposits In Banks ProceedsFromPaymentsForInInterestBearingDepositsInBanks	2344500000	USD
CY2020	us-gaap	Proceeds From Payments For In Interest Bearing Deposits In Banks ProceedsFromPaymentsForInInterestBearingDepositsInBanks	712600000	USD
CY2019	us-gaap	Proceeds From Payments For In Interest Bearing Deposits In Banks ProceedsFromPaymentsForInInterestBearingDepositsInBanks	-614600000	USD
CY2021	ntrs	Payments For Proceeds From Federal Reserve And Foreign Central Bank Deposits PaymentsForProceedsFromFederalReserveAndForeignCentralBankDeposits	9970400000	USD
CY2020	ntrs	Payments For Proceeds From Federal Reserve And Foreign Central Bank Deposits PaymentsForProceedsFromFederalReserveAndForeignCentralBankDeposits	19845200000	USD
CY2019	ntrs	Payments For Proceeds From Federal Reserve And Foreign Central Bank Deposits PaymentsForProceedsFromFederalReserveAndForeignCentralBankDeposits	3683200000	USD
CY2021	us-gaap	Payments To Acquire Held To Maturity Securities PaymentsToAcquireHeldToMaturitySecurities	54734900000	USD
CY2020	us-gaap	Payments To Acquire Held To Maturity Securities PaymentsToAcquireHeldToMaturitySecurities	40187900000	USD
CY2019	us-gaap	Payments To Acquire Held To Maturity Securities PaymentsToAcquireHeldToMaturitySecurities	14154300000	USD
CY2021	us-gaap	Proceeds From Maturities Prepayments And Calls Of Held To Maturity Securities ProceedsFromMaturitiesPrepaymentsAndCallsOfHeldToMaturitySecurities	54902600000	USD
CY2020	us-gaap	Proceeds From Maturities Prepayments And Calls Of Held To Maturity Securities ProceedsFromMaturitiesPrepaymentsAndCallsOfHeldToMaturitySecurities	35658600000	USD
CY2019	us-gaap	Proceeds From Maturities Prepayments And Calls Of Held To Maturity Securities ProceedsFromMaturitiesPrepaymentsAndCallsOfHeldToMaturitySecurities	16290900000	USD
CY2021	us-gaap	Payments To Acquire Available For Sale Securities Debt PaymentsToAcquireAvailableForSaleSecuritiesDebt	13896200000	USD
CY2020	us-gaap	Payments To Acquire Available For Sale Securities Debt PaymentsToAcquireAvailableForSaleSecuritiesDebt	10886800000	USD
CY2019	us-gaap	Payments To Acquire Available For Sale Securities Debt PaymentsToAcquireAvailableForSaleSecuritiesDebt	12811000000	USD
CY2021	us-gaap	Proceeds From Sale And Maturity Of Available For Sale Securities ProceedsFromSaleAndMaturityOfAvailableForSaleSecurities	10079000000	USD
CY2020	us-gaap	Proceeds From Sale And Maturity Of Available For Sale Securities ProceedsFromSaleAndMaturityOfAvailableForSaleSecurities	8748200000	USD
CY2019	us-gaap	Proceeds From Sale And Maturity Of Available For Sale Securities ProceedsFromSaleAndMaturityOfAvailableForSaleSecurities	11057200000	USD
CY2021	us-gaap	Payments For Proceeds From Loans And Leases PaymentsForProceedsFromLoansAndLeases	6744700000	USD
CY2020	us-gaap	Payments For Proceeds From Loans And Leases PaymentsForProceedsFromLoansAndLeases	2316700000	USD
CY2019	us-gaap	Payments For Proceeds From Loans And Leases PaymentsForProceedsFromLoansAndLeases	-1087900000	USD
CY2021	us-gaap	Payments To Acquire Property Plant And Equipment PaymentsToAcquirePropertyPlantAndEquipment	95500000	USD
CY2020	us-gaap	Payments To Acquire Property Plant And Equipment PaymentsToAcquirePropertyPlantAndEquipment	135800000	USD
CY2019	us-gaap	Payments To Acquire Property Plant And Equipment PaymentsToAcquirePropertyPlantAndEquipment	158000000.0	USD
CY2021	us-gaap	Payments For Software PaymentsForSoftware	419600000	USD
CY2020	us-gaap	Payments For Software PaymentsForSoftware	424600000	USD
CY2019	us-gaap	Payments For Software PaymentsForSoftware	441800000	USD
CY2021	ntrs	Net Change In Client Security Settlement Receivables NetChangeInClientSecuritySettlementReceivables	801400000	USD
CY2020	ntrs	Net Change In Client Security Settlement Receivables NetChangeInClientSecuritySettlementReceivables	226800000	USD
CY2021	us-gaap	Payments To Acquire Interest In Subsidiaries And Affiliates PaymentsToAcquireInterestInSubsidiariesAndAffiliates	0	USD
CY2020	us-gaap	Payments To Acquire Interest In Subsidiaries And Affiliates PaymentsToAcquireInterestInSubsidiariesAndAffiliates	0	USD
CY2019	us-gaap	Payments To Acquire Interest In Subsidiaries And Affiliates PaymentsToAcquireInterestInSubsidiariesAndAffiliates	10500000	USD
CY2021	us-gaap	Payments To Acquire Life Insurance Policies PaymentsToAcquireLifeInsurancePolicies	0	USD
CY2020	us-gaap	Payments To Acquire Life Insurance Policies PaymentsToAcquireLifeInsurancePolicies	0	USD
CY2019	us-gaap	Payments To Acquire Life Insurance Policies PaymentsToAcquireLifeInsurancePolicies	1500000000	USD
CY2021	us-gaap	Payments For Proceeds From Other Investing Activities PaymentsForProceedsFromOtherInvestingActivities	163700000	USD
CY2020	us-gaap	Payments For Proceeds From Other Investing Activities PaymentsForProceedsFromOtherInvestingActivities	322700000	USD
CY2019	us-gaap	Payments For Proceeds From Other Investing Activities PaymentsForProceedsFromOtherInvestingActivities	-225100000	USD
CY2021	us-gaap	Net Cash Provided By Used In Investing Activities NetCashProvidedByUsedInInvestingActivities	-18602600000	USD
CY2020	us-gaap	Net Cash Provided By Used In Investing Activities NetCashProvidedByUsedInInvestingActivities	-29923000000	USD
CY2019	us-gaap	Net Cash Provided By Used In Investing Activities NetCashProvidedByUsedInInvestingActivities	-3405000000	USD
CY2021	us-gaap	Increase Decrease In Deposits IncreaseDecreaseInDeposits	17885500000	USD
CY2020	us-gaap	Increase Decrease In Deposits IncreaseDecreaseInDeposits	32137900000	USD
CY2019	us-gaap	Increase Decrease In Deposits IncreaseDecreaseInDeposits	4263600000	USD
CY2021	ntrs	Change In Federal Funds Purchased ChangeInFederalFundsPurchased	260000000.0	USD
CY2020	ntrs	Change In Federal Funds Purchased ChangeInFederalFundsPurchased	292700000	USD
CY2019	ntrs	Change In Federal Funds Purchased ChangeInFederalFundsPurchased	2041300000	USD
CY2021	us-gaap	Proceeds From Payments For In Securities Sold Under Agreements To Repurchase ProceedsFromPaymentsForInSecuritiesSoldUnderAgreementsToRepurchase	492100000	USD
CY2020	us-gaap	Proceeds From Payments For In Securities Sold Under Agreements To Repurchase ProceedsFromPaymentsForInSecuritiesSoldUnderAgreementsToRepurchase	-450000000.0	USD
CY2019	us-gaap	Proceeds From Payments For In Securities Sold Under Agreements To Repurchase ProceedsFromPaymentsForInSecuritiesSoldUnderAgreementsToRepurchase	320900000	USD
CY2021	us-gaap	Proceeds From Repayments Of Short Term Debt Maturing In Three Months Or Less ProceedsFromRepaymentsOfShortTermDebtMaturingInThreeMonthsOrLess	-426500000	USD
CY2020	us-gaap	Proceeds From Repayments Of Short Term Debt Maturing In Three Months Or Less ProceedsFromRepaymentsOfShortTermDebtMaturingInThreeMonthsOrLess	-2698300000	USD
CY2019	us-gaap	Proceeds From Repayments Of Short Term Debt Maturing In Three Months Or Less ProceedsFromRepaymentsOfShortTermDebtMaturingInThreeMonthsOrLess	-1184500000	USD
CY2021	us-gaap	Payments For Repurchase Of Preferred Stock And Preference Stock PaymentsForRepurchaseOfPreferredStockAndPreferenceStock	0	USD
CY2020	us-gaap	Payments For Repurchase Of Preferred Stock And Preference Stock PaymentsForRepurchaseOfPreferredStockAndPreferenceStock	400000000.0	USD
CY2019	us-gaap	Payments For Repurchase Of Preferred Stock And Preference Stock PaymentsForRepurchaseOfPreferredStockAndPreferenceStock	0	USD
CY2021	us-gaap	Proceeds From Issuance Of Senior Long Term Debt ProceedsFromIssuanceOfSeniorLongTermDebt	0	USD
CY2020	us-gaap	Proceeds From Issuance Of Senior Long Term Debt ProceedsFromIssuanceOfSeniorLongTermDebt	993200000	USD
CY2019	us-gaap	Proceeds From Issuance Of Senior Long Term Debt ProceedsFromIssuanceOfSeniorLongTermDebt	498000000.0	USD
CY2021	us-gaap	Repayments Of Senior Debt RepaymentsOfSeniorDebt	500000000.0	USD
CY2020	us-gaap	Repayments Of Senior Debt RepaymentsOfSeniorDebt	508600000	USD
CY2019	us-gaap	Repayments Of Senior Debt RepaymentsOfSeniorDebt	0	USD
CY2021	us-gaap	Repayments Of Subordinated Debt RepaymentsOfSubordinatedDebt	278800000	USD
CY2020	us-gaap	Repayments Of Subordinated Debt RepaymentsOfSubordinatedDebt	0	USD
CY2019	us-gaap	Repayments Of Subordinated Debt RepaymentsOfSubordinatedDebt	0	USD
CY2021	us-gaap	Proceeds From Issuance Of Preferred Stock And Preference Stock ProceedsFromIssuanceOfPreferredStockAndPreferenceStock	0	USD
CY2020	us-gaap	Proceeds From Issuance Of Preferred Stock And Preference Stock ProceedsFromIssuanceOfPreferredStockAndPreferenceStock	0	USD
CY2019	us-gaap	Proceeds From Issuance Of Preferred Stock And Preference Stock ProceedsFromIssuanceOfPreferredStockAndPreferenceStock	392500000	USD
CY2021	us-gaap	Payments For Repurchase Of Common Stock PaymentsForRepurchaseOfCommonStock	267600000	USD
CY2020	us-gaap	Payments For Repurchase Of Common Stock PaymentsForRepurchaseOfCommonStock	299800000	USD
CY2019	us-gaap	Payments For Repurchase Of Common Stock PaymentsForRepurchaseOfCommonStock	1100200000	USD
CY2021	us-gaap	Proceeds From Stock Options Exercised ProceedsFromStockOptionsExercised	53800000	USD
CY2020	us-gaap	Proceeds From Stock Options Exercised ProceedsFromStockOptionsExercised	19500000	USD
CY2019	us-gaap	Proceeds From Stock Options Exercised ProceedsFromStockOptionsExercised	44000000.0	USD
CY2021	us-gaap	Payments Of Dividends Common Stock PaymentsOfDividendsCommonStock	583300000	USD
CY2020	us-gaap	Payments Of Dividends Common Stock PaymentsOfDividendsCommonStock	584600000	USD
CY2019	us-gaap	Payments Of Dividends Common Stock PaymentsOfDividendsCommonStock	529700000	USD
CY2021	us-gaap	Payments Of Dividends Preferred Stock And Preference Stock PaymentsOfDividendsPreferredStockAndPreferenceStock	41800000	USD
CY2020	us-gaap	Payments Of Dividends Preferred Stock And Preference Stock PaymentsOfDividendsPreferredStockAndPreferenceStock	45900000	USD
CY2019	us-gaap	Payments Of Dividends Preferred Stock And Preference Stock PaymentsOfDividendsPreferredStockAndPreferenceStock	46400000	USD
CY2021	us-gaap	Proceeds From Payments For Other Financing Activities ProceedsFromPaymentsForOtherFinancingActivities	100000	USD
CY2020	us-gaap	Proceeds From Payments For Other Financing Activities ProceedsFromPaymentsForOtherFinancingActivities	1200000	USD
CY2019	us-gaap	Proceeds From Payments For Other Financing Activities ProceedsFromPaymentsForOtherFinancingActivities	-1000000.0	USD
CY2021	us-gaap	Net Cash Provided By Used In Financing Activities NetCashProvidedByUsedInFinancingActivities	16073500000	USD
CY2020	us-gaap	Net Cash Provided By Used In Financing Activities NetCashProvidedByUsedInFinancingActivities	27871900000	USD
CY2019	us-gaap	Net Cash Provided By Used In Financing Activities NetCashProvidedByUsedInFinancingActivities	615900000	USD
CY2021	us-gaap	Effect Of Exchange Rate On Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents EffectOfExchangeRateOnCashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	-159600000	USD
CY2020	us-gaap	Effect Of Exchange Rate On Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents EffectOfExchangeRateOnCashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	84600000	USD
CY2019	us-gaap	Effect Of Exchange Rate On Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents EffectOfExchangeRateOnCashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	74700000	USD
CY2021	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents Period Increase Decrease Including Exchange Rate Effect CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect	-1332700000	USD
CY2020	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents Period Increase Decrease Including Exchange Rate Effect CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect	-69700000	USD
CY2019	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents Period Increase Decrease Including Exchange Rate Effect CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect	-122400000	USD
CY2020Q4	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	4389500000	USD
CY2019Q4	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	4459200000	USD
CY2018Q4	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	4581600000	USD
CY2021Q4	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	3056800000	USD
CY2020Q4	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	4389500000	USD
CY2019Q4	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	4459200000	USD
CY2021	us-gaap	Interest Paid Net InterestPaidNet	30800000	USD
CY2020	us-gaap	Interest Paid Net InterestPaidNet	226800000	USD
CY2019	us-gaap	Interest Paid Net InterestPaidNet	845500000	USD
CY2021	us-gaap	Income Taxes Paid IncomeTaxesPaid	371000000.0	USD
CY2020	us-gaap	Income Taxes Paid IncomeTaxesPaid	327700000	USD
CY2019	us-gaap	Income Taxes Paid IncomeTaxesPaid	437000000.0	USD
CY2021	us-gaap	Transfer To Other Real Estate TransferToOtherRealEstate	12900000	USD
CY2020	us-gaap	Transfer To Other Real Estate TransferToOtherRealEstate	200000	USD
CY2019	us-gaap	Transfer To Other Real Estate TransferToOtherRealEstate	3500000	USD
CY2021	us-gaap	Debt Securities Held To Maturity Transfer Amount DebtSecuritiesHeldToMaturityTransferAmount	6864100000	USD
CY2020	us-gaap	Debt Securities Held To Maturity Transfer Amount DebtSecuritiesHeldToMaturityTransferAmount	301500000	USD
CY2019	us-gaap	Debt Securities Held To Maturity Transfer Amount DebtSecuritiesHeldToMaturityTransferAmount	160800000	USD
CY2021	us-gaap	Financing Receivable Reclassification To Held For Sale FinancingReceivableReclassificationToHeldForSale	0	USD
CY2020	us-gaap	Financing Receivable Reclassification To Held For Sale FinancingReceivableReclassificationToHeldForSale	0	USD
CY2019	us-gaap	Financing Receivable Reclassification To Held For Sale FinancingReceivableReclassificationToHeldForSale	53600000	USD
CY2021	ntrs	Numberof Client Focused Reportable Segment NumberofClientFocusedReportableSegment	2	segment
CY2021	us-gaap	Use Of Estimates UseOfEstimates	Use of Estimates in the Preparation of Financial Statements. The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions in the application of certain of our significant accounting policies that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the consolidated financial statements and the reported amounts of revenue and expense during the reporting period. Actual results could differ from those estimates.
CY2021Q4	us-gaap	Debt Securities Available For Sale Amortized Cost Excluding Accrued Interest After Allowance For Credit Loss DebtSecuritiesAvailableForSaleAmortizedCostExcludingAccruedInterestAfterAllowanceForCreditLoss	37948500000	USD
CY2021Q4	us-gaap	Available For Sale Debt Securities Accumulated Gross Unrealized Gain Before Tax AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedGainBeforeTax	310600000	USD
CY2021Q4	us-gaap	Available For Sale Debt Securities Accumulated Gross Unrealized Loss Before Tax AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedLossBeforeTax	248600000	USD
CY2021Q4	us-gaap	Debt Securities Available For Sale Excluding Accrued Interest DebtSecuritiesAvailableForSaleExcludingAccruedInterest	38010500000	USD
CY2020Q4	us-gaap	Debt Securities Available For Sale Amortized Cost Excluding Accrued Interest After Allowance For Credit Loss DebtSecuritiesAvailableForSaleAmortizedCostExcludingAccruedInterestAfterAllowanceForCreditLoss	41155700000	USD
CY2020Q4	us-gaap	Available For Sale Debt Securities Accumulated Gross Unrealized Gain Before Tax AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedGainBeforeTax	897600000	USD
CY2020Q4	us-gaap	Available For Sale Debt Securities Accumulated Gross Unrealized Loss Before Tax AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedLossBeforeTax	31300000	USD
CY2020Q4	us-gaap	Debt Securities Available For Sale Excluding Accrued Interest DebtSecuritiesAvailableForSaleExcludingAccruedInterest	42022000000	USD
CY2021Q4	us-gaap	Available For Sale Securities Debt Maturities Within One Year Amortized Cost AvailableForSaleSecuritiesDebtMaturitiesWithinOneYearAmortizedCost	5009600000	USD
CY2021Q4	us-gaap	Available For Sale Securities Debt Maturities Within One Year Fair Value AvailableForSaleSecuritiesDebtMaturitiesWithinOneYearFairValue	5028900000	USD
CY2021Q4	us-gaap	Available For Sale Securities Debt Maturities After One Through Five Years Amortized Cost AvailableForSaleSecuritiesDebtMaturitiesAfterOneThroughFiveYearsAmortizedCost	19648500000	USD
CY2021Q4	us-gaap	Available For Sale Securities Debt Maturities After One Through Five Years Fair Value AvailableForSaleSecuritiesDebtMaturitiesAfterOneThroughFiveYearsFairValue	19718100000	USD
CY2021Q4	us-gaap	Available For Sale Securities Debt Maturities After Five Through Ten Years Amortized Cost AvailableForSaleSecuritiesDebtMaturitiesAfterFiveThroughTenYearsAmortizedCost	11748300000	USD
CY2021Q4	us-gaap	Available For Sale Securities Debt Maturities After Five Through Ten Years Fair Value AvailableForSaleSecuritiesDebtMaturitiesAfterFiveThroughTenYearsFairValue	11725500000	USD
CY2021Q4	us-gaap	Available For Sale Securities Debt Maturities After Ten Years Amortized Cost AvailableForSaleSecuritiesDebtMaturitiesAfterTenYearsAmortizedCost	1542100000	USD
CY2021Q4	us-gaap	Available For Sale Securities Debt Maturities After Ten Years Fair Value AvailableForSaleSecuritiesDebtMaturitiesAfterTenYearsFairValue	1538000000	USD
CY2021Q4	us-gaap	Debt Securities Available For Sale Amortized Cost Excluding Accrued Interest After Allowance For Credit Loss DebtSecuritiesAvailableForSaleAmortizedCostExcludingAccruedInterestAfterAllowanceForCreditLoss	37948500000	USD
CY2021Q4	us-gaap	Debt Securities Available For Sale Excluding Accrued Interest DebtSecuritiesAvailableForSaleExcludingAccruedInterest	38010500000	USD
CY2021Q4	us-gaap	Debt Securities Available For Sale Continuous Unrealized Loss Position Less Than12 Months DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12Months	16660700000	USD
CY2021Q4	us-gaap	Debt Securities Available For Sale Continuous Unrealized Loss Position Less Than12 Months Accumulated Loss DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12MonthsAccumulatedLoss	223600000	USD
CY2021Q4	us-gaap	Debt Securities Available For Sale Continuous Unrealized Loss Position12 Months Or Longer DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLonger	2037000000	USD
CY2021Q4	us-gaap	Debt Securities Available For Sale Continuous Unrealized Loss Position12 Months Or Longer Accumulated Loss DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLongerAccumulatedLoss	25000000.0	USD
CY2021Q4	us-gaap	Debt Securities Available For Sale Unrealized Loss Position DebtSecuritiesAvailableForSaleUnrealizedLossPosition	18697700000	USD
CY2021Q4	us-gaap	Debt Securities Available For Sale Unrealized Loss Position Accumulated Loss DebtSecuritiesAvailableForSaleUnrealizedLossPositionAccumulatedLoss	248600000	USD
CY2020Q4	us-gaap	Debt Securities Available For Sale Continuous Unrealized Loss Position Less Than12 Months DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12Months	2995700000	USD
CY2020Q4	us-gaap	Debt Securities Available For Sale Continuous Unrealized Loss Position Less Than12 Months Accumulated Loss DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12MonthsAccumulatedLoss	15300000	USD
CY2020Q4	us-gaap	Debt Securities Available For Sale Continuous Unrealized Loss Position12 Months Or Longer DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLonger	3370900000	USD
CY2020Q4	us-gaap	Debt Securities Available For Sale Continuous Unrealized Loss Position12 Months Or Longer Accumulated Loss DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLongerAccumulatedLoss	16000000.0	USD
CY2020Q4	us-gaap	Debt Securities Available For Sale Unrealized Loss Position DebtSecuritiesAvailableForSaleUnrealizedLossPosition	6366600000	USD
CY2020Q4	us-gaap	Debt Securities Available For Sale Unrealized Loss Position Accumulated Loss DebtSecuritiesAvailableForSaleUnrealizedLossPositionAccumulatedLoss	31300000	USD
CY2021Q4	ntrs	Number Of Securities Unrealized Losses Position NumberOfSecuritiesUnrealizedLossesPosition	1233	investment
CY2021Q4	us-gaap	Debt Securities Available For Sale Unrealized Loss Position DebtSecuritiesAvailableForSaleUnrealizedLossPosition	18700000000	USD
CY2021Q4	us-gaap	Debt Securities Available For Sale Unrealized Loss Position Accumulated Loss DebtSecuritiesAvailableForSaleUnrealizedLossPositionAccumulatedLoss	248600000	USD
CY2020Q4	ntrs	Number Of Securities Unrealized Losses Position NumberOfSecuritiesUnrealizedLossesPosition	412	investment
CY2020Q4	us-gaap	Debt Securities Available For Sale Unrealized Loss Position DebtSecuritiesAvailableForSaleUnrealizedLossPosition	6400000000	USD
CY2020Q4	us-gaap	Debt Securities Available For Sale Unrealized Loss Position Accumulated Loss DebtSecuritiesAvailableForSaleUnrealizedLossPositionAccumulatedLoss	31300000	USD
CY2021Q4	us-gaap	Debt Securities Held To Maturity Excluding Accrued Interest Before Allowance For Credit Loss DebtSecuritiesHeldToMaturityExcludingAccruedInterestBeforeAllowanceForCreditLoss	23564500000	USD
CY2021Q4	us-gaap	Held To Maturity Securities Accumulated Unrecognized Holding Gain HeldToMaturitySecuritiesAccumulatedUnrecognizedHoldingGain	34500000	USD
CY2021Q4	us-gaap	Debt Securities Held To Maturity Excluding Accrued Interest Before Allowance For Credit Loss DebtSecuritiesHeldToMaturityExcludingAccruedInterestBeforeAllowanceForCreditLoss	23564500000	USD
CY2021Q4	us-gaap	Held To Maturity Securities Accumulated Unrecognized Holding Loss HeldToMaturitySecuritiesAccumulatedUnrecognizedHoldingLoss	283600000	USD
CY2021Q4	us-gaap	Held To Maturity Securities Fair Value HeldToMaturitySecuritiesFairValue	23315400000	USD
CY2020Q4	us-gaap	Debt Securities Held To Maturity Excluding Accrued Interest Before Allowance For Credit Loss DebtSecuritiesHeldToMaturityExcludingAccruedInterestBeforeAllowanceForCreditLoss	17791100000	USD
CY2020Q4	us-gaap	Held To Maturity Securities Accumulated Unrecognized Holding Gain HeldToMaturitySecuritiesAccumulatedUnrecognizedHoldingGain	84300000	USD
CY2020Q4	us-gaap	Held To Maturity Securities Accumulated Unrecognized Holding Loss HeldToMaturitySecuritiesAccumulatedUnrecognizedHoldingLoss	78000000.0	USD
CY2020Q4	us-gaap	Held To Maturity Securities Fair Value HeldToMaturitySecuritiesFairValue	17797400000	USD
CY2021Q4	us-gaap	Debt Securities Held To Maturity Excluding Accrued Interest Before Allowance For Credit Loss DebtSecuritiesHeldToMaturityExcludingAccruedInterestBeforeAllowanceForCreditLoss	23600000000	USD
CY2020Q4	us-gaap	Debt Securities Held To Maturity Excluding Accrued Interest Before Allowance For Credit Loss DebtSecuritiesHeldToMaturityExcludingAccruedInterestBeforeAllowanceForCreditLoss	17800000000	USD
CY2021Q4	us-gaap	Held To Maturity Securities Debt Maturities Within One Year Net Carrying Amount HeldToMaturitySecuritiesDebtMaturitiesWithinOneYearNetCarryingAmount	8597500000	USD
CY2021Q4	us-gaap	Held To Maturity Securities Debt Maturities Within One Year Fair Value HeldToMaturitySecuritiesDebtMaturitiesWithinOneYearFairValue	8585000000	USD
CY2021Q4	us-gaap	Held To Maturity Securities Debt Maturities After One Through Five Years Net Carrying Amount HeldToMaturitySecuritiesDebtMaturitiesAfterOneThroughFiveYearsNetCarryingAmount	10740600000	USD
CY2021Q4	us-gaap	Held To Maturity Securities Debt Maturities After One Through Five Years Fair Value HeldToMaturitySecuritiesDebtMaturitiesAfterOneThroughFiveYearsFairValue	10631800000	USD
CY2021Q4	us-gaap	Held To Maturity Securities Debt Maturities After Five Through Ten Years Net Carrying Amount HeldToMaturitySecuritiesDebtMaturitiesAfterFiveThroughTenYearsNetCarryingAmount	3292300000	USD
CY2021Q4	us-gaap	Held To Maturity Securities Debt Maturities After Five Through Ten Years Fair Value HeldToMaturitySecuritiesDebtMaturitiesAfterFiveThroughTenYearsFairValue	3235400000	USD
CY2021Q4	us-gaap	Held To Maturity Securities Debt Maturities After Ten Years Net Carrying Amount HeldToMaturitySecuritiesDebtMaturitiesAfterTenYearsNetCarryingAmount	934100000	USD
CY2021Q4	us-gaap	Held To Maturity Securities Debt Maturities After Ten Years Fair Value HeldToMaturitySecuritiesDebtMaturitiesAfterTenYearsFairValue	863200000	USD
CY2021Q4	us-gaap	Held To Maturity Securities Fair Value HeldToMaturitySecuritiesFairValue	23315400000	USD
CY2021	ntrs	Held To Maturity Securities Transferred From Available For Sale HeldToMaturitySecuritiesTransferredFromAvailableForSale	6900000000	USD
CY2020	ntrs	Held To Maturity Securities Transferred From Available For Sale HeldToMaturitySecuritiesTransferredFromAvailableForSale	301500000	USD
CY2021Q4	us-gaap	Debt Securities Held To Maturity Excluding Accrued Interest Before Allowance For Credit Loss DebtSecuritiesHeldToMaturityExcludingAccruedInterestBeforeAllowanceForCreditLoss	23564500000	USD
CY2021Q4	ntrs	Debt Securities Held To Maturity Percent Of Portfolio DebtSecuritiesHeldToMaturityPercentOfPortfolio	1
CY2020Q4	us-gaap	Debt Securities Held To Maturity Excluding Accrued Interest Before Allowance For Credit Loss DebtSecuritiesHeldToMaturityExcludingAccruedInterestBeforeAllowanceForCreditLoss	17791100000	USD
CY2020Q4	ntrs	Debt Securities Held To Maturity Percent Of Portfolio DebtSecuritiesHeldToMaturityPercentOfPortfolio	1
CY2021	ntrs	Proceeds From Sale Of Investment Securities ProceedsFromSaleOfInvestmentSecurities	116700000	USD
CY2020	ntrs	Proceeds From Sale Of Investment Securities ProceedsFromSaleOfInvestmentSecurities	879900000	USD
CY2019	ntrs	Proceeds From Sale Of Investment Securities ProceedsFromSaleOfInvestmentSecurities	1200000000	USD
CY2021	us-gaap	Debt Securities Available For Sale Realized Gain DebtSecuritiesAvailableForSaleRealizedGain	1400000	USD
CY2020	us-gaap	Debt Securities Available For Sale Realized Gain DebtSecuritiesAvailableForSaleRealizedGain	3400000	USD
CY2019	us-gaap	Debt Securities Available For Sale Realized Gain DebtSecuritiesAvailableForSaleRealizedGain	2400000	USD
CY2021	us-gaap	Debt Securities Available For Sale Realized Loss DebtSecuritiesAvailableForSaleRealizedLoss	1700000	USD
CY2020	us-gaap	Debt Securities Available For Sale Realized Loss DebtSecuritiesAvailableForSaleRealizedLoss	3800000	USD
CY2019	us-gaap	Debt Securities Available For Sale Realized Loss DebtSecuritiesAvailableForSaleRealizedLoss	3500000	USD
CY2021	us-gaap	Other Than Temporary Impairment Loss Debt Securities Portion Recognized In Earnings OtherThanTemporaryImpairmentLossDebtSecuritiesPortionRecognizedInEarnings	0	USD
CY2020	us-gaap	Other Than Temporary Impairment Loss Debt Securities Portion Recognized In Earnings OtherThanTemporaryImpairmentLossDebtSecuritiesPortionRecognizedInEarnings	0	USD
CY2019	us-gaap	Other Than Temporary Impairment Loss Debt Securities Portion Recognized In Earnings OtherThanTemporaryImpairmentLossDebtSecuritiesPortionRecognizedInEarnings	300000	USD
CY2021	us-gaap	Realized Investment Gains Losses RealizedInvestmentGainsLosses	-300000	USD
CY2020	us-gaap	Realized Investment Gains Losses RealizedInvestmentGainsLosses	-400000	USD
CY2019	us-gaap	Realized Investment Gains Losses RealizedInvestmentGainsLosses	-1400000	USD
CY2021	us-gaap	Schedule Of Resale Agreements ScheduleOfResaleAgreements	<table style="border-collapse:collapse;display:inline-table;margin-bottom:5pt;vertical-align:text-bottom;width:100.000%"><tr><td style="width:1.0%"/><td style="width:78.627%"/><td style="width:0.1%"/><td style="width:1.0%"/><td style="width:9.036%"/><td style="width:0.1%"/><td style="width:1.0%"/><td style="width:9.037%"/><td style="width:0.1%"/></tr><tr><td colspan="3" style="padding:2px 1pt;text-align:left;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:7pt;font-weight:400;line-height:100%">($ In Millions)</span></td><td colspan="3" style="padding:2px 1pt;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:7pt;font-weight:700;line-height:100%">2021</span></td><td colspan="3" style="padding:2px 1pt;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:7pt;font-weight:400;line-height:100%">2020</span></td></tr><tr><td colspan="3" style="background-color:#cceeff;border-top:1pt solid #000000;padding:2px 1pt;text-align:left;vertical-align:top"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:100%">Balance at December 31</span></td><td style="background-color:#cceeff;border-top:1pt solid #000000;padding:2px 0 2px 1pt;text-align:left;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:700;line-height:100%">$</span></td><td style="background-color:#cceeff;border-top:1pt solid #000000;padding:2px 0;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:700;line-height:100%">686.4</span><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:100%"> </span></td><td style="background-color:#cceeff;border-top:1pt solid #000000;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"/><td style="background-color:#cceeff;border-top:1pt solid #000000;padding:2px 0 2px 1pt;text-align:left;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:100%">$</span></td><td style="background-color:#cceeff;border-top:1pt solid #000000;padding:2px 0;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:100%">1,596.5 </span></td><td style="background-color:#cceeff;border-top:1pt solid #000000;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"/></tr><tr><td colspan="3" style="background-color:#ffffff;padding:2px 1pt;text-align:left;vertical-align:top"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:100%">Average Balance During the Year</span></td><td colspan="2" style="background-color:#ffffff;padding:2px 0 2px 1pt;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:700;line-height:100%">1,067.4</span><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:100%"> </span></td><td style="background-color:#ffffff;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"/><td colspan="2" style="background-color:#ffffff;padding:2px 0 2px 1pt;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:100%">1,253.1 </span></td><td style="background-color:#ffffff;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"/></tr><tr><td colspan="3" style="background-color:#cceeff;padding:2px 1pt;text-align:left;vertical-align:top"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:100%">Average Interest Rate Earned During the Year</span></td><td colspan="2" style="background-color:#cceeff;padding:2px 0 2px 1pt;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:700;line-height:100%">0.33</span><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:100%"> </span></td><td style="background-color:#cceeff;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:700;line-height:100%">%</span></td><td colspan="2" style="background-color:#cceeff;padding:2px 0 2px 1pt;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:100%">0.31 </span></td><td style="background-color:#cceeff;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:100%">%</span></td></tr><tr><td colspan="3" style="background-color:#ffffff;padding:2px 1pt;text-align:left;vertical-align:top"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:100%">Maximum Month-End Balance During the Year</span></td><td style="background-color:#ffffff;padding:2px 0 2px 1pt;text-align:left;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:700;line-height:100%">$</span></td><td style="background-color:#ffffff;padding:2px 0;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:700;line-height:100%">1,819.1</span><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:100%"> </span></td><td style="background-color:#ffffff;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"/><td style="background-color:#ffffff;padding:2px 0 2px 1pt;text-align:left;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:100%">$</span></td><td style="background-color:#ffffff;padding:2px 0;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:100%">2,055.6 </span></td><td style="background-color:#ffffff;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"/></tr></table>
CY2021Q4	us-gaap	Securities Purchased Under Agreements To Resell SecuritiesPurchasedUnderAgreementsToResell	686400000	USD
CY2020Q4	us-gaap	Securities Purchased Under Agreements To Resell SecuritiesPurchasedUnderAgreementsToResell	1596500000	USD
CY2021	ntrs	Securities Purchased Under Agreement To Resell Average Balance During Period SecuritiesPurchasedUnderAgreementToResellAverageBalanceDuringPeriod	1067400000	USD
CY2020	ntrs	Securities Purchased Under Agreement To Resell Average Balance During Period SecuritiesPurchasedUnderAgreementToResellAverageBalanceDuringPeriod	1253100000	USD
CY2021	ntrs	Securities Purchased Under Agreement To Resell Average Interest Rate Earned During Period SecuritiesPurchasedUnderAgreementToResellAverageInterestRateEarnedDuringPeriod	0.0033
CY2020	ntrs	Securities Purchased Under Agreement To Resell Average Interest Rate Earned During Period SecuritiesPurchasedUnderAgreementToResellAverageInterestRateEarnedDuringPeriod	0.0031
CY2021	ntrs	Securities Purchased Under Agreement To Resell Maximum Month End Balance During Period SecuritiesPurchasedUnderAgreementToResellMaximumMonthEndBalanceDuringPeriod	1819100000	USD
CY2020	ntrs	Securities Purchased Under Agreement To Resell Maximum Month End Balance During Period SecuritiesPurchasedUnderAgreementToResellMaximumMonthEndBalanceDuringPeriod	2055600000	USD
CY2021	us-gaap	Schedule Of Repurchase Agreements ScheduleOfRepurchaseAgreements	<table style="border-collapse:collapse;display:inline-table;margin-bottom:5pt;vertical-align:text-bottom;width:100.000%"><tr><td style="width:1.0%"/><td style="width:78.627%"/><td style="width:0.1%"/><td style="width:1.0%"/><td style="width:9.036%"/><td style="width:0.1%"/><td style="width:1.0%"/><td style="width:9.037%"/><td style="width:0.1%"/></tr><tr><td colspan="3" style="padding:2px 1pt;text-align:left;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:7pt;font-weight:400;line-height:100%">($ In Millions)</span></td><td colspan="3" style="padding:2px 1pt;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:7pt;font-weight:700;line-height:100%">2021</span></td><td colspan="3" style="padding:2px 1pt;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:7pt;font-weight:400;line-height:100%">2020</span></td></tr><tr><td colspan="3" style="background-color:#cceeff;border-top:1pt solid #000000;padding:2px 1pt;text-align:left;vertical-align:top"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:100%">Balance at December 31</span></td><td style="background-color:#cceeff;border-top:1pt solid #000000;padding:2px 0 2px 1pt;text-align:left;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:700;line-height:100%">$</span></td><td style="background-color:#cceeff;border-top:1pt solid #000000;padding:2px 0;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:700;line-height:100%">531.9</span><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:100%"> </span></td><td style="background-color:#cceeff;border-top:1pt solid #000000;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"/><td style="background-color:#cceeff;border-top:1pt solid #000000;padding:2px 0 2px 1pt;text-align:left;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:100%">$</span></td><td style="background-color:#cceeff;border-top:1pt solid #000000;padding:2px 0;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:100%">39.8 </span></td><td style="background-color:#cceeff;border-top:1pt solid #000000;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"/></tr><tr><td colspan="3" style="background-color:#ffffff;padding:2px 1pt;text-align:left;vertical-align:top"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:100%">Average Balance During the Year</span></td><td colspan="2" style="background-color:#ffffff;padding:2px 0 2px 1pt;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:700;line-height:100%">232.0</span><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:100%"> </span></td><td style="background-color:#ffffff;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"/><td colspan="2" style="background-color:#ffffff;padding:2px 0 2px 1pt;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:100%">218.3 </span></td><td style="background-color:#ffffff;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"/></tr><tr><td colspan="3" style="background-color:#cceeff;padding:2px 1pt;text-align:left;vertical-align:top"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:100%">Average Interest Rate Paid During the Year</span></td><td colspan="2" style="background-color:#cceeff;padding:2px 0 2px 1pt;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:700;line-height:100%">0.07</span><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:100%"> </span></td><td style="background-color:#cceeff;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:700;line-height:100%">%</span></td><td colspan="2" style="background-color:#cceeff;padding:2px 0 2px 1pt;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:100%">0.47 </span></td><td style="background-color:#cceeff;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:100%">%</span></td></tr><tr><td colspan="3" style="background-color:#ffffff;padding:2px 1pt;text-align:left;vertical-align:top"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:100%">Maximum Month-End Balance During the Year</span></td><td style="background-color:#ffffff;padding:2px 0 2px 1pt;text-align:left;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:700;line-height:100%">$</span></td><td style="background-color:#ffffff;padding:2px 0;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:700;line-height:100%">892.6</span><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:100%"> </span></td><td style="background-color:#ffffff;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"/><td style="background-color:#ffffff;padding:2px 0 2px 1pt;text-align:left;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:100%">$</span></td><td style="background-color:#ffffff;padding:2px 0;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:100%">269.8 </span></td><td style="background-color:#ffffff;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"/></tr></table>
CY2021Q4	us-gaap	Securities Sold Under Agreements To Repurchase SecuritiesSoldUnderAgreementsToRepurchase	531900000	USD
CY2020Q4	us-gaap	Securities Sold Under Agreements To Repurchase SecuritiesSoldUnderAgreementsToRepurchase	39800000	USD
CY2021	ntrs	Securities Sold Under Agreements To Repurchase Average Balance During Period SecuritiesSoldUnderAgreementsToRepurchaseAverageBalanceDuringPeriod	232000000.0	USD
CY2020	ntrs	Securities Sold Under Agreements To Repurchase Average Balance During Period SecuritiesSoldUnderAgreementsToRepurchaseAverageBalanceDuringPeriod	218300000	USD
CY2021	ntrs	Securities Sold Under Agreements To Repurchase Average Interest Rate Paid During Period SecuritiesSoldUnderAgreementsToRepurchaseAverageInterestRatePaidDuringPeriod	0.0007
CY2020	ntrs	Securities Sold Under Agreements To Repurchase Average Interest Rate Paid During Period SecuritiesSoldUnderAgreementsToRepurchaseAverageInterestRatePaidDuringPeriod	0.0047
CY2021	ntrs	Securities Sold Under Agreements To Repurchase Maximum Month End Balance During Period SecuritiesSoldUnderAgreementsToRepurchaseMaximumMonthEndBalanceDuringPeriod	892600000	USD
CY2020	ntrs	Securities Sold Under Agreements To Repurchase Maximum Month End Balance During Period SecuritiesSoldUnderAgreementsToRepurchaseMaximumMonthEndBalanceDuringPeriod	269800000	USD
CY2021Q4	us-gaap	Secured Debt Repurchase Agreements SecuredDebtRepurchaseAgreements	531900000	USD
CY2020Q4	us-gaap	Secured Debt Repurchase Agreements SecuredDebtRepurchaseAgreements	39800000	USD
CY2021Q4	us-gaap	Debt Securities Available For Sale Amortized Cost Allowance For Credit Loss Excluding Accrued Interest DebtSecuritiesAvailableForSaleAmortizedCostAllowanceForCreditLossExcludingAccruedInterest	531900000	USD
CY2020Q4	us-gaap	Debt Securities Available For Sale Amortized Cost Allowance For Credit Loss Excluding Accrued Interest DebtSecuritiesAvailableForSaleAmortizedCostAllowanceForCreditLossExcludingAccruedInterest	39800000	USD
CY2021Q4	ntrs	Cash Collateral Deposited With Not Offset Against Derivative Liabilities CashCollateralDepositedWithNotOffsetAgainstDerivativeLiabilities	0	USD
CY2020Q4	ntrs	Cash Collateral Deposited With Not Offset Against Derivative Liabilities CashCollateralDepositedWithNotOffsetAgainstDerivativeLiabilities	0	USD
CY2021Q4	us-gaap	Financing Receivable Excluding Accrued Interest Before Allowance For Credit Loss FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLoss	40480600000	USD
CY2020Q4	us-gaap	Financing Receivable Excluding Accrued Interest Before Allowance For Credit Loss FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLoss	33759700000	USD
CY2021	ntrs	Line Of Credit Draw Down Period LineOfCreditDrawDownPeriod	P10Y
CY2021Q4	ntrs	Loans Receivable Overdraft Advances LoansReceivableOverdraftAdvances	1600000000	USD
CY2020Q4	ntrs	Loans Receivable Overdraft Advances LoansReceivableOverdraftAdvances	1100000000	USD
CY2021Q4	ntrs	Overdrawn Demand Deposit Accounts OverdrawnDemandDepositAccounts	8000000	USD
CY2020Q4	ntrs	Overdrawn Demand Deposit Accounts OverdrawnDemandDepositAccounts	26400000	USD
CY2021Q4	us-gaap	Loans Receivable Held For Sale Net Not Part Of Disposal Group LoansReceivableHeldForSaleNetNotPartOfDisposalGroup	12300000	USD
CY2020Q4	us-gaap	Loans Receivable Held For Sale Net Not Part Of Disposal Group LoansReceivableHeldForSaleNetNotPartOfDisposalGroup	0	USD
CY2021Q4	us-gaap	Leveraged Leases Net Investment In Leveraged Leases Disclosure Rental Receivables Net LeveragedLeasesNetInvestmentInLeveragedLeasesDisclosureRentalReceivablesNet	11400000	USD
CY2020Q4	us-gaap	Leveraged Leases Net Investment In Leveraged Leases Disclosure Rental Receivables Net LeveragedLeasesNetInvestmentInLeveragedLeasesDisclosureRentalReceivablesNet	11800000	USD
CY2021Q4	us-gaap	Leveraged Leases Net Investment In Leveraged Leases Disclosure Residual Value Of Leased Assets LeveragedLeasesNetInvestmentInLeveragedLeasesDisclosureResidualValueOfLeasedAssets	0	USD
CY2020Q4	us-gaap	Leveraged Leases Net Investment In Leveraged Leases Disclosure Residual Value Of Leased Assets LeveragedLeasesNetInvestmentInLeveragedLeasesDisclosureResidualValueOfLeasedAssets	0	USD
CY2021Q4	us-gaap	Leveraged Leases Net Investment In Leveraged Leases Disclosure Deferred Income LeveragedLeasesNetInvestmentInLeveragedLeasesDisclosureDeferredIncome	400000	USD
CY2020Q4	us-gaap	Leveraged Leases Net Investment In Leveraged Leases Disclosure Deferred Income LeveragedLeasesNetInvestmentInLeveragedLeasesDisclosureDeferredIncome	400000	USD
CY2021Q4	us-gaap	Leveraged Leases Net Investment In Leveraged Leases Disclosure Investment In Leveraged Leases Net LeveragedLeasesNetInvestmentInLeveragedLeasesDisclosureInvestmentInLeveragedLeasesNet	11000000.0	USD
CY2020Q4	us-gaap	Leveraged Leases Net Investment In Leveraged Leases Disclosure Investment In Leveraged Leases Net LeveragedLeasesNetInvestmentInLeveragedLeasesDisclosureInvestmentInLeveragedLeasesNet	11400000	USD
CY2021Q4	us-gaap	Leveraged Leases Net Investment In Leveraged Leases Disclosure Investment In Leveraged Leases Net LeveragedLeasesNetInvestmentInLeveragedLeasesDisclosureInvestmentInLeveragedLeasesNet	11000000.0	USD
CY2020Q4	us-gaap	Leveraged Leases Net Investment In Leveraged Leases Disclosure Investment In Leveraged Leases Net LeveragedLeasesNetInvestmentInLeveragedLeasesDisclosureInvestmentInLeveragedLeasesNet	11400000	USD
CY2021Q4	us-gaap	Financing Receivable Originated In Current Fiscal Year FinancingReceivableOriginatedInCurrentFiscalYear	8703300000	USD
CY2021Q4	us-gaap	Financing Receivable Originated In Fiscal Year Before Latest Fiscal Year FinancingReceivableOriginatedInFiscalYearBeforeLatestFiscalYear	4382700000	USD
CY2021Q4	us-gaap	Financing Receivable Originated Two Years Before Latest Fiscal Year FinancingReceivableOriginatedTwoYearsBeforeLatestFiscalYear	2626700000	USD
CY2021Q4	us-gaap	Financing Receivable Originated Three Years Before Latest Fiscal Year FinancingReceivableOriginatedThreeYearsBeforeLatestFiscalYear	931600000	USD
CY2021Q4	us-gaap	Financing Receivable Originated Four Years Before Latest Fiscal Year FinancingReceivableOriginatedFourYearsBeforeLatestFiscalYear	675700000	USD
CY2021Q4	us-gaap	Financing Receivable Originated Five Or More Years Before Latest Fiscal Year FinancingReceivableOriginatedFiveOrMoreYearsBeforeLatestFiscalYear	2490300000	USD
CY2021Q4	us-gaap	Financing Receivable Revolving FinancingReceivableRevolving	20378900000	USD
CY2021Q4	us-gaap	Financing Receivable Revolving Converted To Term Loan FinancingReceivableRevolvingConvertedToTermLoan	291400000	USD
CY2021Q4	us-gaap	Financing Receivable Excluding Accrued Interest Before Allowance For Credit Loss FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLoss	40480600000	USD
CY2020Q4	us-gaap	Financing Receivable Originated In Current Fiscal Year FinancingReceivableOriginatedInCurrentFiscalYear	7448600000	USD
CY2020Q4	us-gaap	Financing Receivable Originated In Fiscal Year Before Latest Fiscal Year FinancingReceivableOriginatedInFiscalYearBeforeLatestFiscalYear	3667900000	USD
CY2020Q4	us-gaap	Financing Receivable Originated Two Years Before Latest Fiscal Year FinancingReceivableOriginatedTwoYearsBeforeLatestFiscalYear	1352600000	USD
CY2020Q4	us-gaap	Financing Receivable Originated Three Years Before Latest Fiscal Year FinancingReceivableOriginatedThreeYearsBeforeLatestFiscalYear	1123100000	USD
CY2020Q4	us-gaap	Financing Receivable Originated Four Years Before Latest Fiscal Year FinancingReceivableOriginatedFourYearsBeforeLatestFiscalYear	1254800000	USD
CY2020Q4	us-gaap	Financing Receivable Originated Five Or More Years Before Latest Fiscal Year FinancingReceivableOriginatedFiveOrMoreYearsBeforeLatestFiscalYear	3128500000	USD
CY2020Q4	us-gaap	Financing Receivable Revolving FinancingReceivableRevolving	15453600000	USD
CY2020Q4	us-gaap	Financing Receivable Revolving Converted To Term Loan FinancingReceivableRevolvingConvertedToTermLoan	330600000	USD
CY2020Q4	us-gaap	Financing Receivable Excluding Accrued Interest Before Allowance For Credit Loss FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLoss	33759700000	USD
CY2021Q4	ntrs	Financing Receivable Accrual FinancingReceivableAccrual	40358300000	USD
CY2021Q4	us-gaap	Financing Receivable Recorded Investment Nonaccrual Status FinancingReceivableRecordedInvestmentNonaccrualStatus	122300000	USD
CY2021Q4	us-gaap	Financing Receivable Excluding Accrued Interest Before Allowance For Credit Loss FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLoss	40480600000	USD
CY2021Q4	us-gaap	Financing Receivable Nonaccrual No Allowance FinancingReceivableNonaccrualNoAllowance	97300000	USD
CY2021Q4	us-gaap	Other Real Estate And Foreclosed Assets OtherRealEstateAndForeclosedAssets	3000000.0	USD
CY2021Q4	ntrs	Financing Receivable Nonaccrual Including Other Real Estate Owned FinancingReceivableNonaccrualIncludingOtherRealEstateOwned	125300000	USD
CY2020Q4	ntrs	Financing Receivable Accrual FinancingReceivableAccrual	33628000000	USD
CY2020Q4	us-gaap	Financing Receivable Recorded Investment Nonaccrual Status FinancingReceivableRecordedInvestmentNonaccrualStatus	131700000	USD
CY2020Q4	us-gaap	Financing Receivable Excluding Accrued Interest Before Allowance For Credit Loss FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLoss	33759700000	USD
CY2020Q4	us-gaap	Financing Receivable Nonaccrual No Allowance FinancingReceivableNonaccrualNoAllowance	98100000	USD
CY2020Q4	us-gaap	Other Real Estate And Foreclosed Assets OtherRealEstateAndForeclosedAssets	700000	USD
CY2020Q4	ntrs	Financing Receivable Nonaccrual Including Other Real Estate Owned FinancingReceivableNonaccrualIncludingOtherRealEstateOwned	132400000	USD
CY2021	us-gaap	Financing Receivable Nonaccrual Interest Income FinancingReceivableNonaccrualInterestIncome	4600000	USD
CY2020	us-gaap	Financing Receivable Nonaccrual Interest Income FinancingReceivableNonaccrualInterestIncome	4600000	USD
CY2019	us-gaap	Financing Receivable Nonaccrual Interest Income FinancingReceivableNonaccrualInterestIncome	7300000	USD
CY2021Q4	ntrs	Financing Receivable Nonaccrual Troubled Debt Restructuring FinancingReceivableNonaccrualTroubledDebtRestructuring	76700000	USD
CY2020Q4	ntrs	Financing Receivable Nonaccrual Troubled Debt Restructuring FinancingReceivableNonaccrualTroubledDebtRestructuring	38900000	USD
CY2021Q4	us-gaap	Financing Receivable Modifications Recorded Investment FinancingReceivableModificationsRecordedInvestment	16500000	USD
CY2020Q4	us-gaap	Financing Receivable Modifications Recorded Investment FinancingReceivableModificationsRecordedInvestment	29300000	USD
CY2021Q4	us-gaap	Loans And Leases Receivable Impaired Commitment To Lend LoansAndLeasesReceivableImpairedCommitmentToLend	200000	USD
CY2020Q4	us-gaap	Loans And Leases Receivable Impaired Commitment To Lend LoansAndLeasesReceivableImpairedCommitmentToLend	10400000	USD
CY2021	us-gaap	Financing Receivable Modifications Number Of Contracts2 FinancingReceivableModificationsNumberOfContracts2	19	contract
CY2021	us-gaap	Financing Receivable Modifications Post Modification Recorded Investment2 FinancingReceivableModificationsPostModificationRecordedInvestment2	56900000	USD
CY2021	ntrs	Financing Receivable Troubled Debt Restructuring Postmodification Unpaid Principal Balance FinancingReceivableTroubledDebtRestructuringPostmodificationUnpaidPrincipalBalance	63500000	USD
CY2020	us-gaap	Financing Receivable Modifications Number Of Contracts2 FinancingReceivableModificationsNumberOfContracts2	25	contract
CY2020	us-gaap	Financing Receivable Modifications Post Modification Recorded Investment2 FinancingReceivableModificationsPostModificationRecordedInvestment2	40500000	USD
CY2020	ntrs	Financing Receivable Troubled Debt Restructuring Postmodification Unpaid Principal Balance FinancingReceivableTroubledDebtRestructuringPostmodificationUnpaidPrincipalBalance	41200000	USD
CY2021	us-gaap	Financing Receivable Modifications Subsequent Default Number Of Contracts1 FinancingReceivableModificationsSubsequentDefaultNumberOfContracts1	2	loan
CY2020	us-gaap	Financing Receivable Modifications Subsequent Default Number Of Contracts1 FinancingReceivableModificationsSubsequentDefaultNumberOfContracts1	0	loan
CY2021Q4	us-gaap	Other Real Estate And Foreclosed Assets OtherRealEstateAndForeclosedAssets	3000000	USD
CY2020Q4	us-gaap	Other Real Estate And Foreclosed Assets OtherRealEstateAndForeclosedAssets	700000	USD
CY2021Q4	us-gaap	Mortgage Loans In Process Of Foreclosure Amount MortgageLoansInProcessOfForeclosureAmount	2600000	USD
CY2020Q4	us-gaap	Mortgage Loans In Process Of Foreclosure Amount MortgageLoansInProcessOfForeclosureAmount	7900000	USD
CY2021Q4	ntrs	Financing Receivable Percentage Of Loans Granted Payment Deferral In Past Due Or Nonaccrual Status FinancingReceivablePercentageOfLoansGrantedPaymentDeferralInPastDueOrNonaccrualStatus	0.10
CY2021	ntrs	Financing Receivable Credit Loss Estimate Time Period FinancingReceivableCreditLossEstimateTimePeriod	P2Y
CY2020Q4	us-gaap	Financing Receivable Allowance For Credit Loss Excluding Accrued Interest FinancingReceivableAllowanceForCreditLossExcludingAccruedInterest	190700000	USD
CY2020Q4	us-gaap	Off Balance Sheet Credit Loss Liability OffBalanceSheetCreditLossLiability	61100000	USD
CY2020Q4	us-gaap	Debt Securities Held To Maturity Allowance For Credit Loss Excluding Accrued Interest DebtSecuritiesHeldToMaturityAllowanceForCreditLossExcludingAccruedInterest	7300000	USD
CY2020Q4	ntrs	Other Financial Assets Allowance For Credit Loss Excluding Accrued Interest OtherFinancialAssetsAllowanceForCreditLossExcludingAccruedInterest	800000	USD
CY2020Q4	ntrs	Allowance For Credit Loss AllowanceForCreditLoss	259900000	USD
CY2021	us-gaap	Financing Receivable Allowance For Credit Losses Write Offs FinancingReceivableAllowanceForCreditLossesWriteOffs	700000	USD
CY2021	ntrs	Off Balance Sheet Allowance For Credit Loss Writeoff OffBalanceSheetAllowanceForCreditLossWriteoff	0	USD
CY2021	us-gaap	Debt Securities Held To Maturity Allowance For Credit Loss Writeoff DebtSecuritiesHeldToMaturityAllowanceForCreditLossWriteoff	0	USD
CY2021	ntrs	Other Financial Assets Allowance For Credit Loss Writeoff OtherFinancialAssetsAllowanceForCreditLossWriteoff	0	USD
CY2021	ntrs	Allowance For Credit Loss Writeoff AllowanceForCreditLossWriteoff	700000	USD
CY2021	us-gaap	Financing Receivable Allowance For Credit Losses Recovery FinancingReceivableAllowanceForCreditLossesRecovery	7000000.0	USD
CY2021	ntrs	Off Balance Sheet Credit Loss Liability Recovery OffBalanceSheetCreditLossLiabilityRecovery	0	USD
CY2021	us-gaap	Debt Securities Held To Maturity Allowance For Credit Loss Recovery DebtSecuritiesHeldToMaturityAllowanceForCreditLossRecovery	0	USD
CY2021	ntrs	Other Financial Assets Allowance For Credit Loss Recovery OtherFinancialAssetsAllowanceForCreditLossRecovery	0	USD
CY2021	ntrs	Allowance For Credit Loss Recovery AllowanceForCreditLossRecovery	7000000.0	USD
CY2021	us-gaap	Financing Receivable Allowance For Credit Loss Writeoff After Recovery FinancingReceivableAllowanceForCreditLossWriteoffAfterRecovery	-6300000	USD
CY2021	ntrs	Off Balance Sheet Credit Loss Liability Changein Present Value Expense Reversal OffBalanceSheetCreditLossLiabilityChangeinPresentValueExpenseReversal	0	USD
CY2021	us-gaap	Debt Securities Held To Maturity Change In Present Value Expense Reversal DebtSecuritiesHeldToMaturityChangeInPresentValueExpenseReversal	0	USD
CY2021	ntrs	Other Financial Assets Change In Present Value Expense Reversal OtherFinancialAssetsChangeInPresentValueExpenseReversal	0	USD
CY2021	us-gaap	Financing Receivable Allowance For Credit Loss Writeoff After Recovery FinancingReceivableAllowanceForCreditLossWriteoffAfterRecovery	-6300000	USD
CY2021	us-gaap	Provision For Loan Losses Expensed ProvisionForLoanLossesExpensed	-58600000	USD
CY2021	us-gaap	Off Balance Sheet Credit Loss Liability Credit Loss Expense Reversal OffBalanceSheetCreditLossLiabilityCreditLossExpenseReversal	-27000000.0	USD
CY2021	us-gaap	Debt Securities Held To Maturity Credit Loss Expense Reversal DebtSecuritiesHeldToMaturityCreditLossExpenseReversal	3900000	USD
CY2021	ntrs	Other Financial Assets Credit Loss Expense Reversal OtherFinancialAssetsCreditLossExpenseReversal	200000	USD
CY2021	ntrs	Credit Loss Expense Reversal CreditLossExpenseReversal	-81500000	USD
CY2021Q4	us-gaap	Financing Receivable Allowance For Credit Loss Excluding Accrued Interest FinancingReceivableAllowanceForCreditLossExcludingAccruedInterest	138400000	USD
CY2021Q4	us-gaap	Off Balance Sheet Credit Loss Liability OffBalanceSheetCreditLossLiability	34100000	USD
CY2021Q4	us-gaap	Debt Securities Held To Maturity Allowance For Credit Loss Excluding Accrued Interest DebtSecuritiesHeldToMaturityAllowanceForCreditLossExcludingAccruedInterest	11200000	USD
CY2021Q4	ntrs	Other Financial Assets Allowance For Credit Loss Excluding Accrued Interest OtherFinancialAssetsAllowanceForCreditLossExcludingAccruedInterest	1000000.0	USD
CY2021Q4	ntrs	Allowance For Credit Loss AllowanceForCreditLoss	184700000	USD
CY2019Q4	us-gaap	Financing Receivable Allowance For Credit Loss Excluding Accrued Interest FinancingReceivableAllowanceForCreditLossExcludingAccruedInterest	104500000	USD
CY2019Q4	us-gaap	Off Balance Sheet Credit Loss Liability OffBalanceSheetCreditLossLiability	19900000	USD
CY2019Q4	us-gaap	Debt Securities Held To Maturity Allowance For Credit Loss Excluding Accrued Interest DebtSecuritiesHeldToMaturityAllowanceForCreditLossExcludingAccruedInterest	0	USD
CY2019Q4	ntrs	Other Financial Assets Allowance For Credit Loss Excluding Accrued Interest OtherFinancialAssetsAllowanceForCreditLossExcludingAccruedInterest	0	USD
CY2019Q4	ntrs	Allowance For Credit Loss AllowanceForCreditLoss	124400000	USD
CY2020	us-gaap	Financing Receivable Allowance For Credit Losses Write Offs FinancingReceivableAllowanceForCreditLossesWriteOffs	9700000	USD
CY2020	ntrs	Off Balance Sheet Allowance For Credit Loss Writeoff OffBalanceSheetAllowanceForCreditLossWriteoff	0	USD
CY2020	us-gaap	Debt Securities Held To Maturity Allowance For Credit Loss Writeoff DebtSecuritiesHeldToMaturityAllowanceForCreditLossWriteoff	0	USD
CY2020	ntrs	Other Financial Assets Allowance For Credit Loss Writeoff OtherFinancialAssetsAllowanceForCreditLossWriteoff	0	USD
CY2020	ntrs	Allowance For Credit Loss Writeoff AllowanceForCreditLossWriteoff	9700000	USD
CY2020	us-gaap	Financing Receivable Allowance For Credit Losses Recovery FinancingReceivableAllowanceForCreditLossesRecovery	6500000	USD
CY2020	ntrs	Off Balance Sheet Credit Loss Liability Recovery OffBalanceSheetCreditLossLiabilityRecovery	0	USD
CY2020	us-gaap	Debt Securities Held To Maturity Allowance For Credit Loss Recovery DebtSecuritiesHeldToMaturityAllowanceForCreditLossRecovery	0	USD
CY2020	ntrs	Other Financial Assets Allowance For Credit Loss Recovery OtherFinancialAssetsAllowanceForCreditLossRecovery	0	USD
CY2020	ntrs	Allowance For Credit Loss Recovery AllowanceForCreditLossRecovery	6500000	USD
CY2020	us-gaap	Financing Receivable Allowance For Credit Loss Writeoff After Recovery FinancingReceivableAllowanceForCreditLossWriteoffAfterRecovery	3200000	USD
CY2020	ntrs	Off Balance Sheet Credit Loss Liability Changein Present Value Expense Reversal OffBalanceSheetCreditLossLiabilityChangeinPresentValueExpenseReversal	0	USD
CY2020	us-gaap	Debt Securities Held To Maturity Change In Present Value Expense Reversal DebtSecuritiesHeldToMaturityChangeInPresentValueExpenseReversal	0	USD
CY2020	ntrs	Other Financial Assets Change In Present Value Expense Reversal OtherFinancialAssetsChangeInPresentValueExpenseReversal	0	USD
CY2020	us-gaap	Financing Receivable Allowance For Credit Loss Writeoff After Recovery FinancingReceivableAllowanceForCreditLossWriteoffAfterRecovery	3200000	USD
CY2020	us-gaap	Provision For Loan Losses Expensed ProvisionForLoanLossesExpensed	91600000	USD
CY2020	us-gaap	Off Balance Sheet Credit Loss Liability Credit Loss Expense Reversal OffBalanceSheetCreditLossLiabilityCreditLossExpenseReversal	32300000	USD
CY2020	us-gaap	Debt Securities Held To Maturity Credit Loss Expense Reversal DebtSecuritiesHeldToMaturityCreditLossExpenseReversal	700000	USD
CY2020	ntrs	Other Financial Assets Credit Loss Expense Reversal OtherFinancialAssetsCreditLossExpenseReversal	400000	USD
CY2020	ntrs	Credit Loss Expense Reversal CreditLossExpenseReversal	125000000.0	USD
CY2020Q4	us-gaap	Financing Receivable Allowance For Credit Loss Excluding Accrued Interest FinancingReceivableAllowanceForCreditLossExcludingAccruedInterest	190700000	USD
CY2020Q4	us-gaap	Off Balance Sheet Credit Loss Liability OffBalanceSheetCreditLossLiability	61100000	USD
CY2020Q4	us-gaap	Debt Securities Held To Maturity Allowance For Credit Loss Excluding Accrued Interest DebtSecuritiesHeldToMaturityAllowanceForCreditLossExcludingAccruedInterest	7300000	USD
CY2020Q4	ntrs	Other Financial Assets Allowance For Credit Loss Excluding Accrued Interest OtherFinancialAssetsAllowanceForCreditLossExcludingAccruedInterest	800000	USD
CY2020Q4	ntrs	Allowance For Credit Loss AllowanceForCreditLoss	259900000	USD
CY2018Q4	us-gaap	Financing Receivable Allowance For Credit Loss Excluding Accrued Interest FinancingReceivableAllowanceForCreditLossExcludingAccruedInterest	112600000	USD
CY2018Q4	us-gaap	Off Balance Sheet Credit Loss Liability OffBalanceSheetCreditLossLiability	25600000	USD
CY2018Q4	ntrs	Allowance For Credit Loss AllowanceForCreditLoss	138200000	USD
CY2019	us-gaap	Financing Receivable Allowance For Credit Losses Write Offs FinancingReceivableAllowanceForCreditLossesWriteOffs	6500000	USD
CY2019	ntrs	Off Balance Sheet Allowance For Credit Loss Writeoff OffBalanceSheetAllowanceForCreditLossWriteoff	0	USD
CY2019	ntrs	Allowance For Credit Loss Writeoff AllowanceForCreditLossWriteoff	6500000	USD
CY2019	us-gaap	Financing Receivable Allowance For Credit Losses Recovery FinancingReceivableAllowanceForCreditLossesRecovery	7200000	USD
CY2019	ntrs	Off Balance Sheet Credit Loss Liability Recovery OffBalanceSheetCreditLossLiabilityRecovery	0	USD
CY2019	ntrs	Allowance For Credit Loss Recovery AllowanceForCreditLossRecovery	7200000	USD
CY2019	us-gaap	Financing Receivable Allowance For Credit Loss Writeoff After Recovery FinancingReceivableAllowanceForCreditLossWriteoffAfterRecovery	-700000	USD
CY2019	ntrs	Off Balance Sheet Credit Loss Liability Changein Present Value Expense Reversal OffBalanceSheetCreditLossLiabilityChangeinPresentValueExpenseReversal	0	USD
CY2019	us-gaap	Financing Receivable Allowance For Credit Loss Writeoff After Recovery FinancingReceivableAllowanceForCreditLossWriteoffAfterRecovery	-700000	USD
CY2019	us-gaap	Provision For Loan Losses Expensed ProvisionForLoanLossesExpensed	-8800000	USD
CY2019	us-gaap	Off Balance Sheet Credit Loss Liability Credit Loss Expense Reversal OffBalanceSheetCreditLossLiabilityCreditLossExpenseReversal	-5700000	USD
CY2019	ntrs	Credit Loss Expense Reversal CreditLossExpenseReversal	-14500000	USD
CY2019Q4	us-gaap	Financing Receivable Allowance For Credit Loss Excluding Accrued Interest FinancingReceivableAllowanceForCreditLossExcludingAccruedInterest	104500000	USD
CY2019Q4	us-gaap	Off Balance Sheet Credit Loss Liability OffBalanceSheetCreditLossLiability	19900000	USD
CY2019Q4	ntrs	Allowance For Credit Loss AllowanceForCreditLoss	124400000	USD
CY2021	ntrs	Credit Loss Expense Reversal CreditLossExpenseReversal	-81500000	USD
CY2020	ntrs	Credit Loss Expense Reversal CreditLossExpenseReversal	125000000	USD
CY2021	us-gaap	Financing Receivable Allowance For Credit Loss Writeoff After Recovery FinancingReceivableAllowanceForCreditLossWriteoffAfterRecovery	-6300000	USD
CY2020	us-gaap	Financing Receivable Allowance For Credit Loss Writeoff After Recovery FinancingReceivableAllowanceForCreditLossWriteoffAfterRecovery	3200000	USD
CY2020Q4	us-gaap	Financing Receivable Allowance For Credit Loss Excluding Accrued Interest FinancingReceivableAllowanceForCreditLossExcludingAccruedInterest	190700000	USD
CY2020Q4	us-gaap	Off Balance Sheet Credit Loss Liability OffBalanceSheetCreditLossLiability	61100000	USD
CY2021	us-gaap	Financing Receivable Allowance For Credit Losses Write Offs FinancingReceivableAllowanceForCreditLossesWriteOffs	700000	USD
CY2021	ntrs	Off Balance Sheet Allowance For Credit Loss Writeoff OffBalanceSheetAllowanceForCreditLossWriteoff	0	USD
CY2021	us-gaap	Financing Receivable Allowance For Credit Losses Recovery FinancingReceivableAllowanceForCreditLossesRecovery	7000000.0	USD
CY2021	ntrs	Off Balance Sheet Credit Loss Liability Recovery OffBalanceSheetCreditLossLiabilityRecovery	0	USD
CY2021	us-gaap	Financing Receivable Allowance For Credit Loss Writeoff After Recovery FinancingReceivableAllowanceForCreditLossWriteoffAfterRecovery	-6300000	USD
CY2021	ntrs	Off Balance Sheet Credit Loss Liability Changein Present Value Expense Reversal OffBalanceSheetCreditLossLiabilityChangeinPresentValueExpenseReversal	0	USD
CY2021	us-gaap	Provision For Loan Losses Expensed ProvisionForLoanLossesExpensed	-58600000	USD
CY2021	us-gaap	Off Balance Sheet Credit Loss Liability Credit Loss Expense Reversal OffBalanceSheetCreditLossLiabilityCreditLossExpenseReversal	-27000000.0	USD
CY2021Q4	us-gaap	Financing Receivable Allowance For Credit Loss Excluding Accrued Interest FinancingReceivableAllowanceForCreditLossExcludingAccruedInterest	138400000	USD
CY2021Q4	us-gaap	Off Balance Sheet Credit Loss Liability OffBalanceSheetCreditLossLiability	34100000	USD
CY2019Q4	us-gaap	Financing Receivable Allowance For Credit Loss Excluding Accrued Interest FinancingReceivableAllowanceForCreditLossExcludingAccruedInterest	104500000	USD
CY2019Q4	us-gaap	Off Balance Sheet Credit Loss Liability OffBalanceSheetCreditLossLiability	19900000	USD
CY2020	us-gaap	Financing Receivable Allowance For Credit Losses Write Offs FinancingReceivableAllowanceForCreditLossesWriteOffs	9700000	USD
CY2020	ntrs	Off Balance Sheet Allowance For Credit Loss Writeoff OffBalanceSheetAllowanceForCreditLossWriteoff	0	USD
CY2020	us-gaap	Financing Receivable Allowance For Credit Losses Recovery FinancingReceivableAllowanceForCreditLossesRecovery	6500000	USD
CY2020	ntrs	Off Balance Sheet Credit Loss Liability Recovery OffBalanceSheetCreditLossLiabilityRecovery	0	USD
CY2020	us-gaap	Financing Receivable Allowance For Credit Loss Writeoff After Recovery FinancingReceivableAllowanceForCreditLossWriteoffAfterRecovery	3200000	USD
CY2020	ntrs	Off Balance Sheet Credit Loss Liability Changein Present Value Expense Reversal OffBalanceSheetCreditLossLiabilityChangeinPresentValueExpenseReversal	0	USD
CY2020	us-gaap	Provision For Loan Losses Expensed ProvisionForLoanLossesExpensed	91600000	USD
CY2020	us-gaap	Off Balance Sheet Credit Loss Liability Credit Loss Expense Reversal OffBalanceSheetCreditLossLiabilityCreditLossExpenseReversal	32300000	USD
CY2020Q4	us-gaap	Financing Receivable Allowance For Credit Loss Excluding Accrued Interest FinancingReceivableAllowanceForCreditLossExcludingAccruedInterest	190700000	USD
CY2020Q4	us-gaap	Off Balance Sheet Credit Loss Liability OffBalanceSheetCreditLossLiability	61100000	USD
CY2018Q4	us-gaap	Financing Receivable Allowance For Credit Loss Excluding Accrued Interest FinancingReceivableAllowanceForCreditLossExcludingAccruedInterest	112600000	USD
CY2018Q4	us-gaap	Off Balance Sheet Credit Loss Liability OffBalanceSheetCreditLossLiability	25600000	USD
CY2019	us-gaap	Financing Receivable Allowance For Credit Losses Write Offs FinancingReceivableAllowanceForCreditLossesWriteOffs	6500000	USD
CY2019	ntrs	Off Balance Sheet Allowance For Credit Loss Writeoff OffBalanceSheetAllowanceForCreditLossWriteoff	0	USD
CY2019	us-gaap	Financing Receivable Allowance For Credit Losses Recovery FinancingReceivableAllowanceForCreditLossesRecovery	7200000	USD
CY2019	ntrs	Off Balance Sheet Credit Loss Liability Recovery OffBalanceSheetCreditLossLiabilityRecovery	0	USD
CY2019	us-gaap	Financing Receivable Allowance For Credit Loss Writeoff After Recovery FinancingReceivableAllowanceForCreditLossWriteoffAfterRecovery	-700000	USD
CY2019	ntrs	Off Balance Sheet Credit Loss Liability Changein Present Value Expense Reversal OffBalanceSheetCreditLossLiabilityChangeinPresentValueExpenseReversal	0	USD
CY2019	us-gaap	Provision For Loan Losses Expensed ProvisionForLoanLossesExpensed	-8800000	USD
CY2019	us-gaap	Off Balance Sheet Credit Loss Liability Credit Loss Expense Reversal OffBalanceSheetCreditLossLiabilityCreditLossExpenseReversal	-5700000	USD
CY2019Q4	us-gaap	Financing Receivable Allowance For Credit Loss Excluding Accrued Interest FinancingReceivableAllowanceForCreditLossExcludingAccruedInterest	104500000	USD
CY2019Q4	us-gaap	Off Balance Sheet Credit Loss Liability OffBalanceSheetCreditLossLiability	19900000	USD
CY2021Q4	us-gaap	Financing Receivable Individually Evaluated For Impairment FinancingReceivableIndividuallyEvaluatedForImpairment	166600000	USD
CY2020Q4	us-gaap	Financing Receivable Individually Evaluated For Impairment FinancingReceivableIndividuallyEvaluatedForImpairment	131700000	USD
CY2021Q4	us-gaap	Financing Receivable Collectively Evaluated For Impairment FinancingReceivableCollectivelyEvaluatedForImpairment	40314000000	USD
CY2020Q4	us-gaap	Financing Receivable Collectively Evaluated For Impairment FinancingReceivableCollectivelyEvaluatedForImpairment	33628000000	USD
CY2021Q4	us-gaap	Financing Receivable Excluding Accrued Interest Before Allowance For Credit Loss FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLoss	40480600000	USD
CY2020Q4	us-gaap	Financing Receivable Excluding Accrued Interest Before Allowance For Credit Loss FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLoss	33759700000	USD
CY2021Q4	us-gaap	Financing Receivable Allowance For Credit Losses Individually Evaluated For Impairment1 FinancingReceivableAllowanceForCreditLossesIndividuallyEvaluatedForImpairment1	10100000	USD
CY2020Q4	us-gaap	Financing Receivable Allowance For Credit Losses Individually Evaluated For Impairment1 FinancingReceivableAllowanceForCreditLossesIndividuallyEvaluatedForImpairment1	9100000	USD
CY2021Q4	us-gaap	Financing Receivable Allowance For Credit Losses Collectively Evaluated For Impairment FinancingReceivableAllowanceForCreditLossesCollectivelyEvaluatedForImpairment	128300000	USD
CY2020Q4	us-gaap	Financing Receivable Allowance For Credit Losses Collectively Evaluated For Impairment FinancingReceivableAllowanceForCreditLossesCollectivelyEvaluatedForImpairment	181600000	USD
CY2021Q4	us-gaap	Financing Receivable Allowance For Credit Loss Excluding Accrued Interest FinancingReceivableAllowanceForCreditLossExcludingAccruedInterest	138400000	USD
CY2020Q4	us-gaap	Financing Receivable Allowance For Credit Loss Excluding Accrued Interest FinancingReceivableAllowanceForCreditLossExcludingAccruedInterest	190700000	USD
CY2021Q4	ntrs	Off Balance Sheet Credit Loss Liability Individually Evaluated For Impairment OffBalanceSheetCreditLossLiabilityIndividuallyEvaluatedForImpairment	0	USD
CY2020Q4	ntrs	Off Balance Sheet Credit Loss Liability Individually Evaluated For Impairment OffBalanceSheetCreditLossLiabilityIndividuallyEvaluatedForImpairment	1600000	USD
CY2021Q4	ntrs	Off Balance Sheet Credit Loss Liability Collectively Evaluated For Impairment OffBalanceSheetCreditLossLiabilityCollectivelyEvaluatedForImpairment	34100000	USD
CY2020Q4	ntrs	Off Balance Sheet Credit Loss Liability Collectively Evaluated For Impairment OffBalanceSheetCreditLossLiabilityCollectivelyEvaluatedForImpairment	59500000	USD
CY2021Q4	us-gaap	Off Balance Sheet Credit Loss Liability OffBalanceSheetCreditLossLiability	34100000	USD
CY2020Q4	us-gaap	Off Balance Sheet Credit Loss Liability OffBalanceSheetCreditLossLiability	61100000	USD
CY2021Q4	ntrs	Financing Receivable Allowance For Credit Losses And Off Balance Sheet Credit Loss Liability FinancingReceivableAllowanceForCreditLossesAndOffBalanceSheetCreditLossLiability	172500000	USD
CY2020Q4	ntrs	Financing Receivable Allowance For Credit Losses And Off Balance Sheet Credit Loss Liability FinancingReceivableAllowanceForCreditLossesAndOffBalanceSheetCreditLossLiability	251800000	USD
CY2020Q4	us-gaap	Debt Securities Held To Maturity Allowance For Credit Loss Excluding Accrued Interest DebtSecuritiesHeldToMaturityAllowanceForCreditLossExcludingAccruedInterest	7300000	USD
CY2021	us-gaap	Debt Securities Held To Maturity Credit Loss Expense Reversal DebtSecuritiesHeldToMaturityCreditLossExpenseReversal	3900000	USD
CY2021Q4	us-gaap	Debt Securities Held To Maturity Allowance For Credit Loss Excluding Accrued Interest DebtSecuritiesHeldToMaturityAllowanceForCreditLossExcludingAccruedInterest	11200000	USD
CY2019Q4	us-gaap	Debt Securities Held To Maturity Allowance For Credit Loss Excluding Accrued Interest DebtSecuritiesHeldToMaturityAllowanceForCreditLossExcludingAccruedInterest	0	USD
CY2020	us-gaap	Debt Securities Held To Maturity Credit Loss Expense Reversal DebtSecuritiesHeldToMaturityCreditLossExpenseReversal	700000	USD
CY2020Q4	us-gaap	Debt Securities Held To Maturity Allowance For Credit Loss Excluding Accrued Interest DebtSecuritiesHeldToMaturityAllowanceForCreditLossExcludingAccruedInterest	7300000	USD
CY2020Q1	us-gaap	Other Than Temporary Impairment Loss Debt Securities Portion Recognized In Earnings OtherThanTemporaryImpairmentLossDebtSecuritiesPortionRecognizedInEarnings	4400000	USD
CY2021Q4	ntrs	Other Financial Assets Allowance For Credit Loss Excluding Accrued Interest OtherFinancialAssetsAllowanceForCreditLossExcludingAccruedInterest	1000000	USD
CY2020Q4	ntrs	Other Financial Assets Allowance For Credit Loss Excluding Accrued Interest OtherFinancialAssetsAllowanceForCreditLossExcludingAccruedInterest	800000	USD
CY2021Q4	us-gaap	Financing Receivable Accrued Interest After Allowance For Credit Loss FinancingReceivableAccruedInterestAfterAllowanceForCreditLoss	62600000	USD
CY2020Q4	us-gaap	Financing Receivable Accrued Interest After Allowance For Credit Loss FinancingReceivableAccruedInterestAfterAllowanceForCreditLoss	55300000	USD
CY2021Q4	us-gaap	Debt Securities Held To Maturity Accrued Interest After Allowance For Credit Loss DebtSecuritiesHeldToMaturityAccruedInterestAfterAllowanceForCreditLoss	30400000	USD
CY2020Q4	us-gaap	Debt Securities Held To Maturity Accrued Interest After Allowance For Credit Loss DebtSecuritiesHeldToMaturityAccruedInterestAfterAllowanceForCreditLoss	26500000	USD
CY2021Q4	us-gaap	Debt Securities Available For Sale Accrued Interest After Allowance For Credit Loss DebtSecuritiesAvailableForSaleAccruedInterestAfterAllowanceForCreditLoss	129700000	USD
CY2020Q4	us-gaap	Debt Securities Available For Sale Accrued Interest After Allowance For Credit Loss DebtSecuritiesAvailableForSaleAccruedInterestAfterAllowanceForCreditLoss	153600000	USD
CY2021Q4	ntrs	Other Financial Assets Accrued Interest After Allowance For Credit Loss OtherFinancialAssetsAccruedInterestAfterAllowanceForCreditLoss	2300000	USD
CY2020Q4	ntrs	Other Financial Assets Accrued Interest After Allowance For Credit Loss OtherFinancialAssetsAccruedInterestAfterAllowanceForCreditLoss	1400000	USD
CY2021Q4	us-gaap	Interest Receivable InterestReceivable	225000000.0	USD
CY2020Q4	us-gaap	Interest Receivable InterestReceivable	236800000	USD
CY2021Q4	ntrs	Credit Risk To Banks Non Interest Bearing Balances Held At Banks CreditRiskToBanksNonInterestBearingBalancesHeldAtBanks	1900000000	USD
CY2021Q4	ntrs	Credit Risk To Banks CreditRiskToBanks	3000000000	USD
CY2021Q4	us-gaap	Federal Funds Sold And Securities Purchased Under Agreements To Resell FederalFundsSoldAndSecuritiesPurchasedUnderAgreementsToResell	686400000	USD
CY2020Q4	ntrs	Credit Risk To Banks Non Interest Bearing Balances Held At Banks CreditRiskToBanksNonInterestBearingBalancesHeldAtBanks	4400000000	USD
CY2020Q4	ntrs	Credit Risk To Banks CreditRiskToBanks	4300000000	USD
CY2020Q4	us-gaap	Securities Purchased Under Agreements To Resell SecuritiesPurchasedUnderAgreementsToResell	1600000000	USD
CY2021Q4	ntrs	Loans And Leases Receivable Residential Real Estate LoansAndLeasesReceivableResidentialRealEstate	6300000000	USD
CY2020Q4	ntrs	Loans And Leases Receivable Residential Real Estate LoansAndLeasesReceivableResidentialRealEstate	6000000000	USD
CY2021Q4	ntrs	Residential Real Estate Loans Percentage Of Total Us Loansand Leases ResidentialRealEstateLoansPercentageOfTotalUSLoansandLeases	0.17
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CY2021Q4	ntrs	Loans And Leases Receivable Residential Real Estate LoansAndLeasesReceivableResidentialRealEstate	6300000000	USD
CY2021Q4	us-gaap	Property Plant And Equipment Gross PropertyPlantAndEquipmentGross	1221100000	USD
CY2021Q4	us-gaap	Accumulated Depreciation Depletion And Amortization Property Plant And Equipment AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment	732400000	USD
CY2021Q4	us-gaap	Property Plant And Equipment Net PropertyPlantAndEquipmentNet	488700000	USD
CY2020Q4	us-gaap	Property Plant And Equipment Gross PropertyPlantAndEquipmentGross	1612600000	USD
CY2020Q4	us-gaap	Accumulated Depreciation Depletion And Amortization Property Plant And Equipment AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment	1097700000	USD
CY2020Q4	us-gaap	Property Plant And Equipment Net PropertyPlantAndEquipmentNet	514900000	USD
CY2021	us-gaap	Depreciation Nonproduction DepreciationNonproduction	110800000	USD
CY2020	us-gaap	Depreciation Nonproduction DepreciationNonproduction	116500000	USD
CY2019	us-gaap	Depreciation Nonproduction DepreciationNonproduction	103200000	USD
CY2021	us-gaap	Operating Lease Cost OperatingLeaseCost	96200000	USD
CY2020	us-gaap	Operating Lease Cost OperatingLeaseCost	119400000	USD
CY2021	us-gaap	Variable Lease Cost VariableLeaseCost	37300000	USD
CY2020	us-gaap	Variable Lease Cost VariableLeaseCost	32700000	USD
CY2021	us-gaap	Sublease Income SubleaseIncome	4500000	USD
CY2020	us-gaap	Sublease Income SubleaseIncome	4800000	USD
CY2021	us-gaap	Lease Cost LeaseCost	129000000.0	USD
CY2020	us-gaap	Lease Cost LeaseCost	147300000	USD
CY2021Q4	us-gaap	Lessee Operating Lease Liability Payments Due Next Twelve Months LesseeOperatingLeaseLiabilityPaymentsDueNextTwelveMonths	93200000	USD
CY2021Q4	us-gaap	Lessee Operating Lease Liability Payments Due Year Two LesseeOperatingLeaseLiabilityPaymentsDueYearTwo	88900000	USD
CY2021Q4	us-gaap	Lessee Operating Lease Liability Payments Due Year Three LesseeOperatingLeaseLiabilityPaymentsDueYearThree	80300000	USD
CY2021Q4	us-gaap	Lessee Operating Lease Liability Payments Due Year Four LesseeOperatingLeaseLiabilityPaymentsDueYearFour	82600000	USD
CY2021Q4	us-gaap	Lessee Operating Lease Liability Payments Due Year Five LesseeOperatingLeaseLiabilityPaymentsDueYearFive	61700000	USD
CY2021Q4	us-gaap	Lessee Operating Lease Liability Payments Due After Year Five LesseeOperatingLeaseLiabilityPaymentsDueAfterYearFive	346500000	USD
CY2021Q4	us-gaap	Lessee Operating Lease Liability Payments Due LesseeOperatingLeaseLiabilityPaymentsDue	753200000	USD
CY2021Q4	us-gaap	Lessee Operating Lease Liability Undiscounted Excess Amount LesseeOperatingLeaseLiabilityUndiscountedExcessAmount	90100000	USD
CY2021Q4	us-gaap	Operating Lease Liability OperatingLeaseLiability	663100000	USD
CY2021Q4	ntrs	Lessee Operating Lease Lease Notyet Commenced Liability LesseeOperatingLeaseLeaseNotyetCommencedLiability	22000000	USD
CY2021Q4	us-gaap	Operating Lease Right Of Use Asset OperatingLeaseRightOfUseAsset	531200000	USD
CY2020Q4	us-gaap	Operating Lease Right Of Use Asset OperatingLeaseRightOfUseAsset	560500000	USD
CY2021Q4	us-gaap	Operating Lease Liability OperatingLeaseLiability	663100000	USD
CY2020Q4	us-gaap	Operating Lease Liability OperatingLeaseLiability	700600000	USD
CY2021Q4	us-gaap	Operating Lease Weighted Average Remaining Lease Term1 OperatingLeaseWeightedAverageRemainingLeaseTerm1	P9Y7M6D
CY2020Q4	us-gaap	Operating Lease Weighted Average Remaining Lease Term1 OperatingLeaseWeightedAverageRemainingLeaseTerm1	P10Y
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CY2020Q4	us-gaap	Operating Lease Weighted Average Discount Rate Percent OperatingLeaseWeightedAverageDiscountRatePercent	0.025
CY2021	us-gaap	Operating Lease Payments OperatingLeasePayments	69500000	USD
CY2020	us-gaap	Operating Lease Payments OperatingLeasePayments	107900000	USD
CY2021	us-gaap	Right Of Use Asset Obtained In Exchange For Operating Lease Liability RightOfUseAssetObtainedInExchangeForOperatingLeaseLiability	58500000	USD
CY2020	us-gaap	Right Of Use Asset Obtained In Exchange For Operating Lease Liability RightOfUseAssetObtainedInExchangeForOperatingLeaseLiability	164800000	USD
CY2019Q4	us-gaap	Goodwill Goodwill	696800000	USD
CY2020	us-gaap	Goodwill Foreign Currency Translation Gain Loss GoodwillForeignCurrencyTranslationGainLoss	10400000	USD
CY2020Q4	us-gaap	Goodwill Goodwill	707200000	USD
CY2021	us-gaap	Goodwill Acquired During Period GoodwillAcquiredDuringPeriod	4200000	USD
CY2021	us-gaap	Goodwill Foreign Currency Translation Gain Loss GoodwillForeignCurrencyTranslationGainLoss	-5200000	USD
CY2021Q4	us-gaap	Goodwill Goodwill	706200000	USD
CY2020	us-gaap	Goodwill Transfers GoodwillTransfers	9300000	USD
CY2021Q4	ntrs	Contractual Maturities Time Deposits250000 Or More Next Twelve Months ContractualMaturitiesTimeDeposits250000OrMoreNextTwelveMonths	1008800000	USD
CY2021Q4	ntrs	Contractual Maturities Time Deposits250000 Or More Year Two ContractualMaturitiesTimeDeposits250000OrMoreYearTwo	13800000	USD
CY2021Q4	ntrs	Contractual Maturities Time Deposits250000 Or More Year Three ContractualMaturitiesTimeDeposits250000OrMoreYearThree	1500000	USD
CY2021Q4	ntrs	Contractual Maturities Time Deposits250000 Or More Year Four ContractualMaturitiesTimeDeposits250000OrMoreYearFour	300000	USD
CY2021Q4	ntrs	Contractual Maturities Time Deposits250000 Or More Year Five ContractualMaturitiesTimeDeposits250000OrMoreYearFive	800000	USD
CY2021Q4	ntrs	Contractual Maturities Time Deposits250000 Or More After Year Five ContractualMaturitiesTimeDeposits250000OrMoreAfterYearFive	0	USD
CY2021Q4	ntrs	Time Deposits250000 Or More TimeDeposits250000OrMore	1025200000	USD
CY2020Q4	us-gaap	Time Deposits At Or Above Fdic Insurance Limit TimeDepositsAtOrAboveFDICInsuranceLimit	906800000	USD
CY2020Q4	us-gaap	Interest Bearing Domestic Deposit Certificates Of Deposits InterestBearingDomesticDepositCertificatesOfDeposits	701400000	USD
CY2020Q4	us-gaap	Deposits Foreign DepositsForeign	205400000	USD
CY2021Q4	us-gaap	Senior Notes SeniorNotes	2505500000	USD
CY2020Q4	us-gaap	Senior Notes SeniorNotes	3122400000	USD
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CY2020Q4	ntrs	Long Term Debt Qualifying As Risk Based Capital LongTermDebtQualifyingAsRiskBasedCapital	949700000	USD
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CY2021Q4	us-gaap	Repayments Of Subordinated Debt RepaymentsOfSubordinatedDebt	278800000	USD
CY2021Q4	ntrs	Trust Preferred Securities TrustPreferredSecurities	0	USD
CY2020Q4	ntrs	Trust Preferred Securities TrustPreferredSecurities	277800000	USD
CY2021Q4	us-gaap	Preferred Stock Shares Authorized PreferredStockSharesAuthorized	10000000	shares
CY2021	us-gaap	Treasury Stock Shares Acquired TreasuryStockSharesAcquired	2527544	shares
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CY2021	us-gaap	Treasury Stock Value Acquired Cost Method TreasuryStockValueAcquiredCostMethod	267600000	USD
CY2018Q3	us-gaap	Stock Repurchase Program Number Of Shares Authorized To Be Repurchased StockRepurchaseProgramNumberOfSharesAuthorizedToBeRepurchased	25000000	shares
CY2021	us-gaap	Treasury Stock Acquired Average Cost Per Share TreasuryStockAcquiredAverageCostPerShare	105.90
CY2020	us-gaap	Treasury Stock Acquired Average Cost Per Share TreasuryStockAcquiredAverageCostPerShare	91.49
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CY2021	us-gaap	Stock Issued During Period Shares Share Based Compensation StockIssuedDuringPeriodSharesShareBasedCompensation	1162484	shares
CY2020	us-gaap	Stock Issued During Period Shares Share Based Compensation StockIssuedDuringPeriodSharesShareBasedCompensation	1512035	shares
CY2019	us-gaap	Stock Issued During Period Shares Share Based Compensation StockIssuedDuringPeriodSharesShareBasedCompensation	1688931	shares
CY2021	us-gaap	Stock Issued During Period Shares Stock Options Exercised StockIssuedDuringPeriodSharesStockOptionsExercised	837757	shares
CY2020	us-gaap	Stock Issued During Period Shares Stock Options Exercised StockIssuedDuringPeriodSharesStockOptionsExercised	344686	shares
CY2019	us-gaap	Stock Issued During Period Shares Stock Options Exercised StockIssuedDuringPeriodSharesStockOptionsExercised	786931	shares
CY2021	us-gaap	Stock Redeemed Or Called During Period Shares StockRedeemedOrCalledDuringPeriodShares	2527544	shares
CY2020	us-gaap	Stock Redeemed Or Called During Period Shares StockRedeemedOrCalledDuringPeriodShares	3276589	shares
CY2019	us-gaap	Stock Redeemed Or Called During Period Shares StockRedeemedOrCalledDuringPeriodShares	11778866	shares
CY2021Q4	us-gaap	Common Stock Shares Outstanding CommonStockSharesOutstanding	207761875	shares
CY2020Q4	us-gaap	Common Stock Shares Outstanding CommonStockSharesOutstanding	208289178	shares
CY2019Q4	us-gaap	Common Stock Shares Outstanding CommonStockSharesOutstanding	209709046	shares
CY2019	us-gaap	Other Comprehensive Income Loss Net Of Tax Portion Attributable To Parent OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent	259000000.0	USD
CY2020	us-gaap	Other Comprehensive Income Loss Net Of Tax Portion Attributable To Parent OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent	622700000	USD
CY2021	us-gaap	Other Comprehensive Income Loss Net Of Tax Portion Attributable To Parent OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent	-463600000	USD
CY2021	us-gaap	Other Comprehensive Income Loss Before Tax Portion Attributable To Parent OtherComprehensiveIncomeLossBeforeTaxPortionAttributableToParent	-590200000	USD
CY2021	us-gaap	Other Comprehensive Income Loss Tax Portion Attributable To Parent1 OtherComprehensiveIncomeLossTaxPortionAttributableToParent1	-126600000	USD
CY2021	us-gaap	Other Comprehensive Income Loss Net Of Tax Portion Attributable To Parent OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent	-463600000	USD
CY2020	us-gaap	Other Comprehensive Income Loss Before Tax Portion Attributable To Parent OtherComprehensiveIncomeLossBeforeTaxPortionAttributableToParent	790800000	USD
CY2020	us-gaap	Other Comprehensive Income Loss Tax Portion Attributable To Parent1 OtherComprehensiveIncomeLossTaxPortionAttributableToParent1	168100000	USD
CY2020	us-gaap	Other Comprehensive Income Loss Net Of Tax Portion Attributable To Parent OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent	622700000	USD
CY2019	us-gaap	Other Comprehensive Income Loss Before Tax Portion Attributable To Parent OtherComprehensiveIncomeLossBeforeTaxPortionAttributableToParent	347900000	USD
CY2019	us-gaap	Other Comprehensive Income Loss Tax Portion Attributable To Parent1 OtherComprehensiveIncomeLossTaxPortionAttributableToParent1	88900000	USD
CY2019	us-gaap	Other Comprehensive Income Loss Net Of Tax Portion Attributable To Parent OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent	259000000.0	USD
CY2021	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	208075522	shares
CY2020	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	208319412	shares
CY2019	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	214525547	shares
CY2021	us-gaap	Net Income Loss NetIncomeLoss	1545300000	USD
CY2020	us-gaap	Net Income Loss NetIncomeLoss	1209300000	USD
CY2019	us-gaap	Net Income Loss NetIncomeLoss	1492200000	USD
CY2021	us-gaap	Preferred Stock Dividends Income Statement Impact PreferredStockDividendsIncomeStatementImpact	41800000	USD
CY2020	us-gaap	Preferred Stock Dividends Income Statement Impact PreferredStockDividendsIncomeStatementImpact	56200000	USD
CY2019	us-gaap	Preferred Stock Dividends Income Statement Impact PreferredStockDividendsIncomeStatementImpact	46400000	USD
CY2021	us-gaap	Net Income Loss Available To Common Stockholders Basic NetIncomeLossAvailableToCommonStockholdersBasic	1503500000	USD
CY2020	us-gaap	Net Income Loss Available To Common Stockholders Basic NetIncomeLossAvailableToCommonStockholdersBasic	1153100000	USD
CY2019	us-gaap	Net Income Loss Available To Common Stockholders Basic NetIncomeLossAvailableToCommonStockholdersBasic	1445800000	USD
CY2021	us-gaap	Undistributed Earnings Loss Allocated To Participating Securities Basic UndistributedEarningsLossAllocatedToParticipatingSecuritiesBasic	12900000	USD
CY2020	us-gaap	Undistributed Earnings Loss Allocated To Participating Securities Basic UndistributedEarningsLossAllocatedToParticipatingSecuritiesBasic	12100000	USD
CY2019	us-gaap	Undistributed Earnings Loss Allocated To Participating Securities Basic UndistributedEarningsLossAllocatedToParticipatingSecuritiesBasic	16900000	USD
CY2021	ntrs	Net Income Loss Allocated To Common Stockholders Basic NetIncomeLossAllocatedToCommonStockholdersBasic	1490600000	USD
CY2020	ntrs	Net Income Loss Allocated To Common Stockholders Basic NetIncomeLossAllocatedToCommonStockholdersBasic	1141000000	USD
CY2019	ntrs	Net Income Loss Allocated To Common Stockholders Basic NetIncomeLossAllocatedToCommonStockholdersBasic	1428900000	USD
CY2021	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	7.16
CY2020	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	5.48
CY2019	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	6.66
CY2021	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	208075522	shares
CY2020	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	208319412	shares
CY2019	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	214525547	shares
CY2021	us-gaap	Incremental Common Shares Attributable To Share Based Payment Arrangements IncrementalCommonSharesAttributableToShareBasedPaymentArrangements	823708	shares
CY2020	us-gaap	Incremental Common Shares Attributable To Share Based Payment Arrangements IncrementalCommonSharesAttributableToShareBasedPaymentArrangements	688574	shares
CY2019	us-gaap	Incremental Common Shares Attributable To Share Based Payment Arrangements IncrementalCommonSharesAttributableToShareBasedPaymentArrangements	1075602	shares
CY2021	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	208899230	shares
CY2020	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	209007986	shares
CY2019	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	215601149	shares
CY2021	us-gaap	Net Income Loss Available To Common Stockholders Diluted NetIncomeLossAvailableToCommonStockholdersDiluted	1490600000	USD
CY2020	us-gaap	Net Income Loss Available To Common Stockholders Diluted NetIncomeLossAvailableToCommonStockholdersDiluted	1141100000	USD
CY2019	us-gaap	Net Income Loss Available To Common Stockholders Diluted NetIncomeLossAvailableToCommonStockholdersDiluted	1428900000	USD
CY2021	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	7.14
CY2020	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	5.46
CY2019	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	6.63
CY2020	us-gaap	Antidilutive Securities Excluded From Computation Of Earnings Per Share Amount AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount	0	shares
CY2021	us-gaap	Antidilutive Securities Excluded From Computation Of Earnings Per Share Amount AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount	0	shares
CY2019	us-gaap	Antidilutive Securities Excluded From Computation Of Earnings Per Share Amount AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount	0	shares
CY2021	us-gaap	Revenue From Contract With Customer Excluding Assessed Tax RevenueFromContractWithCustomerExcludingAssessedTax	4361100000	USD
CY2020	us-gaap	Revenue From Contract With Customer Excluding Assessed Tax RevenueFromContractWithCustomerExcludingAssessedTax	3995000000	USD
CY2019	us-gaap	Revenue From Contract With Customer Excluding Assessed Tax RevenueFromContractWithCustomerExcludingAssessedTax	3852100000	USD
CY2021	us-gaap	Foreign Currency Transaction Gain Loss Before Tax ForeignCurrencyTransactionGainLossBeforeTax	292600000	USD
CY2020	us-gaap	Foreign Currency Transaction Gain Loss Before Tax ForeignCurrencyTransactionGainLossBeforeTax	290400000	USD
CY2019	us-gaap	Foreign Currency Transaction Gain Loss Before Tax ForeignCurrencyTransactionGainLossBeforeTax	250900000	USD
CY2021	ntrs	Treasury Management Fees TreasuryManagementFees	44300000	USD
CY2020	ntrs	Treasury Management Fees TreasuryManagementFees	45400000	USD
CY2019	ntrs	Treasury Management Fees TreasuryManagementFees	44500000	USD
CY2021	ntrs	Security Commissionsand Trading Income SecurityCommissionsandTradingIncome	140200000	USD
CY2020	ntrs	Security Commissionsand Trading Income SecurityCommissionsandTradingIncome	133200000	USD
CY2019	ntrs	Security Commissionsand Trading Income SecurityCommissionsandTradingIncome	103600000	USD
CY2021	us-gaap	Other Operating Income OtherOperatingIncome	243900000	USD
CY2020	us-gaap	Other Operating Income OtherOperatingIncome	194000000.0	USD
CY2019	us-gaap	Other Operating Income OtherOperatingIncome	145500000	USD
CY2021	us-gaap	Marketable Securities Gain Loss MarketableSecuritiesGainLoss	-300000	USD
CY2020	us-gaap	Marketable Securities Gain Loss MarketableSecuritiesGainLoss	-400000	USD
CY2019	us-gaap	Marketable Securities Gain Loss MarketableSecuritiesGainLoss	-1400000	USD
CY2021	ntrs	Other Noninterest Income OtherNoninterestIncome	720700000	USD
CY2020	ntrs	Other Noninterest Income OtherNoninterestIncome	662600000	USD
CY2019	ntrs	Other Noninterest Income OtherNoninterestIncome	543100000	USD
CY2021	us-gaap	Noninterest Income NoninterestIncome	5081800000	USD
CY2020	us-gaap	Noninterest Income NoninterestIncome	4657600000	USD
CY2019	us-gaap	Noninterest Income NoninterestIncome	4395200000	USD
CY2021	ntrs	Security Commissionsand Trading Income SecurityCommissionsandTradingIncome	140200000	USD
CY2021	us-gaap	Other Operating Income OtherOperatingIncome	243900000	USD
CY2020	ntrs	Security Commissionsand Trading Income SecurityCommissionsandTradingIncome	133200000	USD
CY2020	us-gaap	Other Operating Income OtherOperatingIncome	194000000	USD
CY2019	ntrs	Security Commissionsand Trading Income SecurityCommissionsandTradingIncome	103600000	USD
CY2019	us-gaap	Other Operating Income OtherOperatingIncome	145500000	USD
CY2021Q4	us-gaap	Contract With Customer Asset Net ContractWithCustomerAssetNet	1052100000	USD
CY2020Q4	us-gaap	Contract With Customer Asset Net ContractWithCustomerAssetNet	935800000	USD
CY2021	us-gaap	Interest And Fee Income Loans And Leases InterestAndFeeIncomeLoansAndLeases	713500000	USD
CY2020	us-gaap	Interest And Fee Income Loans And Leases InterestAndFeeIncomeLoansAndLeases	774600000	USD
CY2019	us-gaap	Interest And Fee Income Loans And Leases InterestAndFeeIncomeLoansAndLeases	1153400000	USD
CY2021	us-gaap	Interest Income Securities Taxable InterestIncomeSecuritiesTaxable	667600000	USD
CY2020	us-gaap	Interest Income Securities Taxable InterestIncomeSecuritiesTaxable	812400000	USD
CY2019	us-gaap	Interest Income Securities Taxable InterestIncomeSecuritiesTaxable	1070700000	USD
CY2021	us-gaap	Interest Income Securities Tax Exempt InterestIncomeSecuritiesTaxExempt	1500000	USD
CY2020	us-gaap	Interest Income Securities Tax Exempt InterestIncomeSecuritiesTaxExempt	1400000	USD
CY2019	us-gaap	Interest Income Securities Tax Exempt InterestIncomeSecuritiesTaxExempt	3800000	USD
CY2021	us-gaap	Interest Income Deposits With Financial Institutions InterestIncomeDepositsWithFinancialInstitutions	9100000	USD
CY2020	us-gaap	Interest Income Deposits With Financial Institutions InterestIncomeDepositsWithFinancialInstitutions	22400000	USD
CY2019	us-gaap	Interest Income Deposits With Financial Institutions InterestIncomeDepositsWithFinancialInstitutions	72400000	USD
CY2021	ntrs	Interest Income Federal Reserve Deposits And Other InterestIncomeFederalReserveDepositsAndOther	14800000	USD
CY2020	ntrs	Interest Income Federal Reserve Deposits And Other InterestIncomeFederalReserveDepositsAndOther	32700000	USD
CY2019	ntrs	Interest Income Federal Reserve Deposits And Other InterestIncomeFederalReserveDepositsAndOther	199600000	USD
CY2021	us-gaap	Interest And Dividend Income Operating InterestAndDividendIncomeOperating	1406500000	USD
CY2020	us-gaap	Interest And Dividend Income Operating InterestAndDividendIncomeOperating	1643500000	USD
CY2019	us-gaap	Interest And Dividend Income Operating InterestAndDividendIncomeOperating	2499900000	USD
CY2021	us-gaap	Interest Expense Deposits InterestExpenseDeposits	-61300000	USD
CY2020	us-gaap	Interest Expense Deposits InterestExpenseDeposits	48400000	USD
CY2019	us-gaap	Interest Expense Deposits InterestExpenseDeposits	488900000	USD
CY2021	us-gaap	Interest Expense Federal Funds Purchased InterestExpenseFederalFundsPurchased	-400000	USD
CY2020	us-gaap	Interest Expense Federal Funds Purchased InterestExpenseFederalFundsPurchased	2200000	USD
CY2019	us-gaap	Interest Expense Federal Funds Purchased InterestExpenseFederalFundsPurchased	25900000	USD
CY2021	us-gaap	Interest Expense Securities Sold Under Agreements To Repurchase InterestExpenseSecuritiesSoldUnderAgreementsToRepurchase	200000	USD
CY2020	us-gaap	Interest Expense Securities Sold Under Agreements To Repurchase InterestExpenseSecuritiesSoldUnderAgreementsToRepurchase	1000000.0	USD
CY2019	us-gaap	Interest Expense Securities Sold Under Agreements To Repurchase InterestExpenseSecuritiesSoldUnderAgreementsToRepurchase	6400000	USD
CY2021	us-gaap	Interest Expense Other Short Term Borrowings InterestExpenseOtherShortTermBorrowings	14200000	USD
CY2020	us-gaap	Interest Expense Other Short Term Borrowings InterestExpenseOtherShortTermBorrowings	45300000	USD
CY2019	us-gaap	Interest Expense Other Short Term Borrowings InterestExpenseOtherShortTermBorrowings	181700000	USD
CY2021	ntrs	Interest Expense Senior Notes InterestExpenseSeniorNotes	48300000	USD
CY2020	ntrs	Interest Expense Senior Notes InterestExpenseSeniorNotes	72700000	USD
CY2019	ntrs	Interest Expense Senior Notes InterestExpenseSeniorNotes	72600000	USD
CY2021	us-gaap	Interest Expense Other Long Term Debt InterestExpenseOtherLongTermDebt	21100000	USD
CY2020	us-gaap	Interest Expense Other Long Term Debt InterestExpenseOtherLongTermDebt	26500000	USD
CY2019	us-gaap	Interest Expense Other Long Term Debt InterestExpenseOtherLongTermDebt	38300000	USD
CY2021	us-gaap	Interest Expense Junior Subordinated Debentures InterestExpenseJuniorSubordinatedDebentures	1700000	USD
CY2020	us-gaap	Interest Expense Junior Subordinated Debentures InterestExpenseJuniorSubordinatedDebentures	4200000	USD
CY2019	us-gaap	Interest Expense Junior Subordinated Debentures InterestExpenseJuniorSubordinatedDebentures	8200000	USD
CY2021	us-gaap	Interest Expense InterestExpense	23800000	USD
CY2020	us-gaap	Interest Expense InterestExpense	200300000	USD
CY2019	us-gaap	Interest Expense InterestExpense	822000000.0	USD
CY2021	us-gaap	Interest Income Expense Net InterestIncomeExpenseNet	1382700000	USD
CY2020	us-gaap	Interest Income Expense Net InterestIncomeExpenseNet	1443200000	USD
CY2019	us-gaap	Interest Income Expense Net InterestIncomeExpenseNet	1677900000	USD
CY2021Q4	ntrs	Low And Negative Interest Rates Percentage Of Interest Bearing Deposits LowAndNegativeInterestRatesPercentageOfInterestBearingDeposits	0.68
CY2021	us-gaap	Other Operating Income OtherOperatingIncome	243900000	USD
CY2020	us-gaap	Other Operating Income OtherOperatingIncome	194000000.0	USD
CY2019	us-gaap	Other Operating Income OtherOperatingIncome	145500000	USD
CY2021	us-gaap	Marketing And Advertising Expense MarketingAndAdvertisingExpense	65500000	USD
CY2020	us-gaap	Marketing And Advertising Expense MarketingAndAdvertisingExpense	59200000	USD
CY2019	us-gaap	Marketing And Advertising Expense MarketingAndAdvertisingExpense	104200000	USD
CY2021	us-gaap	Other Labor Related Expenses OtherLaborRelatedExpenses	33900000	USD
CY2020	us-gaap	Other Labor Related Expenses OtherLaborRelatedExpenses	29400000	USD
CY2019	us-gaap	Other Labor Related Expenses OtherLaborRelatedExpenses	42800000	USD
CY2021	us-gaap	Federal Deposit Insurance Corporation Premium Expense FederalDepositInsuranceCorporationPremiumExpense	14600000	USD
CY2020	us-gaap	Federal Deposit Insurance Corporation Premium Expense FederalDepositInsuranceCorporationPremiumExpense	11800000	USD
CY2019	us-gaap	Federal Deposit Insurance Corporation Premium Expense FederalDepositInsuranceCorporationPremiumExpense	9900000	USD
CY2021	us-gaap	Amortization Of Intangible Assets AmortizationOfIntangibleAssets	14800000	USD
CY2020	us-gaap	Amortization Of Intangible Assets AmortizationOfIntangibleAssets	16900000	USD
CY2019	us-gaap	Amortization Of Intangible Assets AmortizationOfIntangibleAssets	16600000	USD
CY2021	ntrs	Noninterest Expense Other NoninterestExpenseOther	170300000	USD
CY2020	ntrs	Noninterest Expense Other NoninterestExpenseOther	229400000	USD
CY2019	ntrs	Noninterest Expense Other NoninterestExpenseOther	156300000	USD
CY2021	us-gaap	Other Noninterest Expense OtherNoninterestExpense	299100000	USD
CY2020	us-gaap	Other Noninterest Expense OtherNoninterestExpense	346700000	USD
CY2019	us-gaap	Other Noninterest Expense OtherNoninterestExpense	329800000	USD
CY2021	us-gaap	Effective Income Tax Rate Reconciliation At Federal Statutory Income Tax Rate EffectiveIncomeTaxRateReconciliationAtFederalStatutoryIncomeTaxRate	0.210
CY2020	us-gaap	Effective Income Tax Rate Reconciliation At Federal Statutory Income Tax Rate EffectiveIncomeTaxRateReconciliationAtFederalStatutoryIncomeTaxRate	0.210
CY2019	us-gaap	Effective Income Tax Rate Reconciliation At Federal Statutory Income Tax Rate EffectiveIncomeTaxRateReconciliationAtFederalStatutoryIncomeTaxRate	0.210
CY2021	us-gaap	Effective Income Tax Rate Reconciliation Tax Exempt Income EffectiveIncomeTaxRateReconciliationTaxExemptIncome	0.006
CY2020	us-gaap	Effective Income Tax Rate Reconciliation Tax Exempt Income EffectiveIncomeTaxRateReconciliationTaxExemptIncome	0.009
CY2019	us-gaap	Effective Income Tax Rate Reconciliation Tax Exempt Income EffectiveIncomeTaxRateReconciliationTaxExemptIncome	0.006
CY2021	us-gaap	Effective Income Tax Rate Reconciliation Foreign Income Tax Rate Differential EffectiveIncomeTaxRateReconciliationForeignIncomeTaxRateDifferential	0.001
CY2020	us-gaap	Effective Income Tax Rate Reconciliation Foreign Income Tax Rate Differential EffectiveIncomeTaxRateReconciliationForeignIncomeTaxRateDifferential	0.007
CY2019	us-gaap	Effective Income Tax Rate Reconciliation Foreign Income Tax Rate Differential EffectiveIncomeTaxRateReconciliationForeignIncomeTaxRateDifferential	0.002
CY2021	ntrs	Income Tax Reconciliation Leveraged Lease Adjustments IncomeTaxReconciliationLeveragedLeaseAdjustments	-0.004
CY2020	ntrs	Income Tax Reconciliation Leveraged Lease Adjustments IncomeTaxReconciliationLeveragedLeaseAdjustments	-0.006
CY2019	ntrs	Income Tax Reconciliation Leveraged Lease Adjustments IncomeTaxReconciliationLeveragedLeaseAdjustments	-0.009
CY2021	us-gaap	Effective Income Tax Rate Reconciliation Tax Credits EffectiveIncomeTaxRateReconciliationTaxCredits	0.016
CY2020	us-gaap	Effective Income Tax Rate Reconciliation Tax Credits EffectiveIncomeTaxRateReconciliationTaxCredits	0.017
CY2019	us-gaap	Effective Income Tax Rate Reconciliation Tax Credits EffectiveIncomeTaxRateReconciliationTaxCredits	0.010
CY2021	us-gaap	Effective Income Tax Rate Reconciliation Prior Year Income Taxes EffectiveIncomeTaxRateReconciliationPriorYearIncomeTaxes	0
CY2020	us-gaap	Effective Income Tax Rate Reconciliation Prior Year Income Taxes EffectiveIncomeTaxRateReconciliationPriorYearIncomeTaxes	0.016
CY2019	us-gaap	Effective Income Tax Rate Reconciliation Prior Year Income Taxes EffectiveIncomeTaxRateReconciliationPriorYearIncomeTaxes	0
CY2021	us-gaap	Effective Income Tax Rate Reconciliation State And Local Income Taxes EffectiveIncomeTaxRateReconciliationStateAndLocalIncomeTaxes	0.034
CY2020	us-gaap	Effective Income Tax Rate Reconciliation State And Local Income Taxes EffectiveIncomeTaxRateReconciliationStateAndLocalIncomeTaxes	0.032
CY2019	us-gaap	Effective Income Tax Rate Reconciliation State And Local Income Taxes EffectiveIncomeTaxRateReconciliationStateAndLocalIncomeTaxes	0.028
CY2021	us-gaap	Effective Income Tax Rate Reconciliation Change In Deferred Tax Assets Valuation Allowance EffectiveIncomeTaxRateReconciliationChangeInDeferredTaxAssetsValuationAllowance	0.006
CY2020	us-gaap	Effective Income Tax Rate Reconciliation Change In Deferred Tax Assets Valuation Allowance EffectiveIncomeTaxRateReconciliationChangeInDeferredTaxAssetsValuationAllowance	0.016
CY2019	us-gaap	Effective Income Tax Rate Reconciliation Change In Deferred Tax Assets Valuation Allowance EffectiveIncomeTaxRateReconciliationChangeInDeferredTaxAssetsValuationAllowance	0.015
CY2021	us-gaap	Effective Income Tax Rate Reconciliation Other Adjustments EffectiveIncomeTaxRateReconciliationOtherAdjustments	0.006
CY2020	us-gaap	Effective Income Tax Rate Reconciliation Other Adjustments EffectiveIncomeTaxRateReconciliationOtherAdjustments	0.008
CY2019	us-gaap	Effective Income Tax Rate Reconciliation Other Adjustments EffectiveIncomeTaxRateReconciliationOtherAdjustments	0.002
CY2021	us-gaap	Effective Income Tax Rate Continuing Operations EffectiveIncomeTaxRateContinuingOperations	0.231
CY2020	us-gaap	Effective Income Tax Rate Continuing Operations EffectiveIncomeTaxRateContinuingOperations	0.257
CY2019	us-gaap	Effective Income Tax Rate Continuing Operations EffectiveIncomeTaxRateContinuingOperations	0.232
CY2021	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	464800000	USD
CY2020	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	418300000	USD
CY2021	us-gaap	Effective Income Tax Rate Continuing Operations EffectiveIncomeTaxRateContinuingOperations	0.231
CY2020	us-gaap	Effective Income Tax Rate Continuing Operations EffectiveIncomeTaxRateContinuingOperations	0.257
CY2021	us-gaap	Income Tax Reconciliation Prior Year Income Taxes IncomeTaxReconciliationPriorYearIncomeTaxes	26800000	USD
CY2021	us-gaap	Income Tax Reconciliation Prior Year Income Taxes IncomeTaxReconciliationPriorYearIncomeTaxes	26800000	USD
CY2021Q4	us-gaap	Unrecognized Tax Benefits UnrecognizedTaxBenefits	25300000	USD
CY2020Q4	us-gaap	Unrecognized Tax Benefits UnrecognizedTaxBenefits	22400000	USD
CY2021Q4	us-gaap	Unrecognized Tax Benefits That Would Impact Effective Tax Rate UnrecognizedTaxBenefitsThatWouldImpactEffectiveTaxRate	23900000	USD
CY2020Q4	us-gaap	Unrecognized Tax Benefits That Would Impact Effective Tax Rate UnrecognizedTaxBenefitsThatWouldImpactEffectiveTaxRate	20700000	USD
CY2020Q4	us-gaap	Unrecognized Tax Benefits UnrecognizedTaxBenefits	22400000	USD
CY2019Q4	us-gaap	Unrecognized Tax Benefits UnrecognizedTaxBenefits	25300000	USD
CY2018Q4	us-gaap	Unrecognized Tax Benefits UnrecognizedTaxBenefits	21900000	USD
CY2021	us-gaap	Unrecognized Tax Benefits Increases Resulting From Current Period Tax Positions UnrecognizedTaxBenefitsIncreasesResultingFromCurrentPeriodTaxPositions	1200000	USD
CY2020	us-gaap	Unrecognized Tax Benefits Increases Resulting From Current Period Tax Positions UnrecognizedTaxBenefitsIncreasesResultingFromCurrentPeriodTaxPositions	900000	USD
CY2019	us-gaap	Unrecognized Tax Benefits Increases Resulting From Current Period Tax Positions UnrecognizedTaxBenefitsIncreasesResultingFromCurrentPeriodTaxPositions	900000	USD
CY2021	us-gaap	Unrecognized Tax Benefits Increases Resulting From Prior Period Tax Positions UnrecognizedTaxBenefitsIncreasesResultingFromPriorPeriodTaxPositions	4200000	USD
CY2020	us-gaap	Unrecognized Tax Benefits Increases Resulting From Prior Period Tax Positions UnrecognizedTaxBenefitsIncreasesResultingFromPriorPeriodTaxPositions	400000	USD
CY2019	us-gaap	Unrecognized Tax Benefits Increases Resulting From Prior Period Tax Positions UnrecognizedTaxBenefitsIncreasesResultingFromPriorPeriodTaxPositions	4000000.0	USD
CY2021	us-gaap	Unrecognized Tax Benefits Decreases Resulting From Prior Period Tax Positions UnrecognizedTaxBenefitsDecreasesResultingFromPriorPeriodTaxPositions	2500000	USD
CY2020	us-gaap	Unrecognized Tax Benefits Decreases Resulting From Prior Period Tax Positions UnrecognizedTaxBenefitsDecreasesResultingFromPriorPeriodTaxPositions	4200000	USD
CY2019	us-gaap	Unrecognized Tax Benefits Decreases Resulting From Prior Period Tax Positions UnrecognizedTaxBenefitsDecreasesResultingFromPriorPeriodTaxPositions	1500000	USD
CY2021	us-gaap	Unrecognized Tax Benefits Reductions Resulting From Lapse Of Applicable Statute Of Limitations UnrecognizedTaxBenefitsReductionsResultingFromLapseOfApplicableStatuteOfLimitations	0	USD
CY2020	us-gaap	Unrecognized Tax Benefits Reductions Resulting From Lapse Of Applicable Statute Of Limitations UnrecognizedTaxBenefitsReductionsResultingFromLapseOfApplicableStatuteOfLimitations	0	USD
CY2019	us-gaap	Unrecognized Tax Benefits Reductions Resulting From Lapse Of Applicable Statute Of Limitations UnrecognizedTaxBenefitsReductionsResultingFromLapseOfApplicableStatuteOfLimitations	0	USD
CY2021Q4	us-gaap	Unrecognized Tax Benefits UnrecognizedTaxBenefits	25300000	USD
CY2020Q4	us-gaap	Unrecognized Tax Benefits UnrecognizedTaxBenefits	22400000	USD
CY2019Q4	us-gaap	Unrecognized Tax Benefits UnrecognizedTaxBenefits	25300000	USD
CY2021	us-gaap	Income Tax Examination Penalties And Interest Expense IncomeTaxExaminationPenaltiesAndInterestExpense	400000	USD
CY2020	us-gaap	Income Tax Examination Penalties And Interest Expense IncomeTaxExaminationPenaltiesAndInterestExpense	1200000	USD
CY2019	us-gaap	Income Tax Examination Penalties And Interest Expense IncomeTaxExaminationPenaltiesAndInterestExpense	1300000	USD
CY2021Q4	us-gaap	Income Tax Examination Penalties And Interest Accrued IncomeTaxExaminationPenaltiesAndInterestAccrued	9200000	USD
CY2020Q4	us-gaap	Income Tax Examination Penalties And Interest Accrued IncomeTaxExaminationPenaltiesAndInterestAccrued	9600000	USD
CY2021	us-gaap	Current Federal Tax Expense Benefit CurrentFederalTaxExpenseBenefit	241500000	USD
CY2020	us-gaap	Current Federal Tax Expense Benefit CurrentFederalTaxExpenseBenefit	203000000.0	USD
CY2019	us-gaap	Current Federal Tax Expense Benefit CurrentFederalTaxExpenseBenefit	216400000	USD
CY2021	us-gaap	Current State And Local Tax Expense Benefit CurrentStateAndLocalTaxExpenseBenefit	74000000.0	USD
CY2020	us-gaap	Current State And Local Tax Expense Benefit CurrentStateAndLocalTaxExpenseBenefit	57200000	USD
CY2019	us-gaap	Current State And Local Tax Expense Benefit CurrentStateAndLocalTaxExpenseBenefit	50700000	USD
CY2021	us-gaap	Current Foreign Tax Expense Benefit CurrentForeignTaxExpenseBenefit	147300000	USD
CY2020	us-gaap	Current Foreign Tax Expense Benefit CurrentForeignTaxExpenseBenefit	141700000	USD
CY2019	us-gaap	Current Foreign Tax Expense Benefit CurrentForeignTaxExpenseBenefit	150500000	USD
CY2021	us-gaap	Current Income Tax Expense Benefit CurrentIncomeTaxExpenseBenefit	462800000	USD
CY2020	us-gaap	Current Income Tax Expense Benefit CurrentIncomeTaxExpenseBenefit	401900000	USD
CY2019	us-gaap	Current Income Tax Expense Benefit CurrentIncomeTaxExpenseBenefit	417600000	USD
CY2021	us-gaap	Deferred Federal Income Tax Expense Benefit DeferredFederalIncomeTaxExpenseBenefit	-11700000	USD
CY2020	us-gaap	Deferred Federal Income Tax Expense Benefit DeferredFederalIncomeTaxExpenseBenefit	8800000	USD
CY2019	us-gaap	Deferred Federal Income Tax Expense Benefit DeferredFederalIncomeTaxExpenseBenefit	16500000	USD
CY2021	us-gaap	Deferred State And Local Income Tax Expense Benefit DeferredStateAndLocalIncomeTaxExpenseBenefit	12000000.0	USD
CY2020	us-gaap	Deferred State And Local Income Tax Expense Benefit DeferredStateAndLocalIncomeTaxExpenseBenefit	5400000	USD
CY2019	us-gaap	Deferred State And Local Income Tax Expense Benefit DeferredStateAndLocalIncomeTaxExpenseBenefit	16500000	USD
CY2021	us-gaap	Deferred Foreign Income Tax Expense Benefit DeferredForeignIncomeTaxExpenseBenefit	1700000	USD
CY2020	us-gaap	Deferred Foreign Income Tax Expense Benefit DeferredForeignIncomeTaxExpenseBenefit	2200000	USD
CY2019	us-gaap	Deferred Foreign Income Tax Expense Benefit DeferredForeignIncomeTaxExpenseBenefit	1300000	USD
CY2021	us-gaap	Deferred Income Tax Expense Benefit DeferredIncomeTaxExpenseBenefit	2000000.0	USD
CY2020	us-gaap	Deferred Income Tax Expense Benefit DeferredIncomeTaxExpenseBenefit	16400000	USD
CY2019	us-gaap	Deferred Income Tax Expense Benefit DeferredIncomeTaxExpenseBenefit	34300000	USD
CY2021	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	464800000	USD
CY2020	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	418300000	USD
CY2019	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	451900000	USD
CY2021	us-gaap	Other Comprehensive Income Loss Tax OtherComprehensiveIncomeLossTax	-126600000	USD
CY2020	us-gaap	Other Comprehensive Income Loss Tax OtherComprehensiveIncomeLossTax	168100000	USD
CY2019	us-gaap	Other Comprehensive Income Loss Tax OtherComprehensiveIncomeLossTax	88900000	USD
CY2021Q4	us-gaap	Deferred Tax Liabilities Leasing Arrangements DeferredTaxLiabilitiesLeasingArrangements	7000000.0	USD
CY2020Q4	us-gaap	Deferred Tax Liabilities Leasing Arrangements DeferredTaxLiabilitiesLeasingArrangements	9000000.0	USD
CY2021Q4	us-gaap	Deferred Tax Liabilities Deferred Expense Capitalized Software DeferredTaxLiabilitiesDeferredExpenseCapitalizedSoftware	271800000	USD
CY2020Q4	us-gaap	Deferred Tax Liabilities Deferred Expense Capitalized Software DeferredTaxLiabilitiesDeferredExpenseCapitalizedSoftware	268100000	USD
CY2021Q4	us-gaap	Deferred Tax Liabilities Property Plant And Equipment DeferredTaxLiabilitiesPropertyPlantAndEquipment	181300000	USD
CY2020Q4	us-gaap	Deferred Tax Liabilities Property Plant And Equipment DeferredTaxLiabilitiesPropertyPlantAndEquipment	147000000.0	USD
CY2021Q4	us-gaap	Deferred Tax Liabilities Unrealized Gains On Trading Securities DeferredTaxLiabilitiesUnrealizedGainsOnTradingSecurities	82800000	USD
CY2020Q4	us-gaap	Deferred Tax Liabilities Unrealized Gains On Trading Securities DeferredTaxLiabilitiesUnrealizedGainsOnTradingSecurities	247600000	USD
CY2021Q4	ntrs	Deferred Tax Liabilities Compensation And Benefits DeferredTaxLiabilitiesCompensationAndBenefits	65600000	USD
CY2020Q4	ntrs	Deferred Tax Liabilities Compensation And Benefits DeferredTaxLiabilitiesCompensationAndBenefits	43800000	USD
CY2021Q4	ntrs	Deferred Tax Liabilities State Taxes DeferredTaxLiabilitiesStateTaxes	76300000	USD
CY2020Q4	ntrs	Deferred Tax Liabilities State Taxes DeferredTaxLiabilitiesStateTaxes	67400000	USD
CY2021Q4	us-gaap	Deferred Tax Liabilities Other DeferredTaxLiabilitiesOther	23300000	USD
CY2020Q4	us-gaap	Deferred Tax Liabilities Other DeferredTaxLiabilitiesOther	18700000	USD
CY2021Q4	us-gaap	Deferred Income Tax Liabilities DeferredIncomeTaxLiabilities	708100000	USD
CY2020Q4	us-gaap	Deferred Income Tax Liabilities DeferredIncomeTaxLiabilities	801600000	USD
CY2021Q4	us-gaap	Deferred Tax Assets Tax Deferred Expense Reserves And Accruals Provision For Loan Losses DeferredTaxAssetsTaxDeferredExpenseReservesAndAccrualsProvisionForLoanLosses	38600000	USD
CY2020Q4	us-gaap	Deferred Tax Assets Tax Deferred Expense Reserves And Accruals Provision For Loan Losses DeferredTaxAssetsTaxDeferredExpenseReservesAndAccrualsProvisionForLoanLosses	54500000	USD
CY2021Q4	ntrs	Deferred Tax Assets Tax Credit Carryforwards And Operating Loss Carryforwards DeferredTaxAssetsTaxCreditCarryforwardsAndOperatingLossCarryforwards	68200000	USD
CY2020Q4	ntrs	Deferred Tax Assets Tax Credit Carryforwards And Operating Loss Carryforwards DeferredTaxAssetsTaxCreditCarryforwardsAndOperatingLossCarryforwards	55200000	USD
CY2021Q4	us-gaap	Deferred Tax Assets Other DeferredTaxAssetsOther	85400000	USD
CY2020Q4	us-gaap	Deferred Tax Assets Other DeferredTaxAssetsOther	38400000	USD
CY2021Q4	us-gaap	Deferred Tax Assets Gross DeferredTaxAssetsGross	192200000	USD
CY2020Q4	us-gaap	Deferred Tax Assets Gross DeferredTaxAssetsGross	148100000	USD
CY2021Q4	us-gaap	Deferred Tax Assets Valuation Allowance DeferredTaxAssetsValuationAllowance	68200000	USD
CY2020Q4	us-gaap	Deferred Tax Assets Valuation Allowance DeferredTaxAssetsValuationAllowance	55200000	USD
CY2021Q4	us-gaap	Deferred Tax Assets Net DeferredTaxAssetsNet	124000000.0	USD
CY2020Q4	us-gaap	Deferred Tax Assets Net DeferredTaxAssetsNet	92900000	USD
CY2021Q4	us-gaap	Deferred Tax Liabilities DeferredTaxLiabilities	584100000	USD
CY2020Q4	us-gaap	Deferred Tax Liabilities DeferredTaxLiabilities	708700000	USD
CY2021	us-gaap	Defined Benefit Plan Actuarial Gain Loss DefinedBenefitPlanActuarialGainLoss	31500000	USD
CY2020	us-gaap	Defined Benefit Plan Actuarial Gain Loss DefinedBenefitPlanActuarialGainLoss	-176000000	USD
CY2021	ntrs	Number Of Investments Held In Diversified Portfolios NumberOfInvestmentsHeldInDiversifiedPortfolios	1	investment
CY2021Q4	us-gaap	Derivative Number Of Instruments Held DerivativeNumberOfInstrumentsHeld	3	numberOfDerivativeInstruments
CY2020Q4	us-gaap	Derivative Number Of Instruments Held DerivativeNumberOfInstrumentsHeld	5	numberOfDerivativeInstruments
CY2021	us-gaap	Defined Benefit Plan Assumptions Used Calculating Net Periodic Benefit Cost Expected Long Term Return On Assets DefinedBenefitPlanAssumptionsUsedCalculatingNetPeriodicBenefitCostExpectedLongTermReturnOnAssets	0.0525
CY2021	ntrs	Defined Benefit Plan Minimum Retirement Age DefinedBenefitPlanMinimumRetirementAge	55	age
CY2021	ntrs	Defined Benefit Plan Minimum Service Term DefinedBenefitPlanMinimumServiceTerm	P15Y
CY2021	us-gaap	Defined Contribution Plan Cost Recognized DefinedContributionPlanCostRecognized	65300000	USD
CY2020	us-gaap	Defined Contribution Plan Cost Recognized DefinedContributionPlanCostRecognized	62900000	USD
CY2019	us-gaap	Defined Contribution Plan Cost Recognized DefinedContributionPlanCostRecognized	57600000	USD
CY2019	us-gaap	Sharebased Compensation Arrangement By Sharebased Payment Award Options Vested In Period Fair Value1 SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedInPeriodFairValue1	6600000	USD
CY2021	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Exercises In Period Total Intrinsic Value ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue	41300000	USD
CY2021	us-gaap	Allocated Share Based Compensation Expense AllocatedShareBasedCompensationExpense	95500000	USD
CY2020	us-gaap	Allocated Share Based Compensation Expense AllocatedShareBasedCompensationExpense	91400000	USD
CY2019	us-gaap	Allocated Share Based Compensation Expense AllocatedShareBasedCompensationExpense	107900000	USD
CY2021	us-gaap	Employee Service Share Based Compensation Tax Benefit From Compensation Expense EmployeeServiceShareBasedCompensationTaxBenefitFromCompensationExpense	24000000.0	USD
CY2020	us-gaap	Employee Service Share Based Compensation Tax Benefit From Compensation Expense EmployeeServiceShareBasedCompensationTaxBenefitFromCompensationExpense	22900000	USD
CY2019	us-gaap	Employee Service Share Based Compensation Tax Benefit From Compensation Expense EmployeeServiceShareBasedCompensationTaxBenefitFromCompensationExpense	26700000	USD
CY2021Q4	us-gaap	Employee Service Share Based Compensation Nonvested Awards Total Compensation Cost Not Yet Recognized EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized	71800000	USD
CY2021	us-gaap	Sharebased Compensation Arrangement By Sharebased Payment Award Options Vested In Period Fair Value1 SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedInPeriodFairValue1	2200000	USD
CY2020	us-gaap	Sharebased Compensation Arrangement By Sharebased Payment Award Options Vested In Period Fair Value1 SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedInPeriodFairValue1	4500000	USD
CY2021	us-gaap	Sharebased Compensation Arrangement By Sharebased Payment Award Options Nonvested Options Forfeited Weighted Average Grant Date Fair Value SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsNonvestedOptionsForfeitedWeightedAverageGrantDateFairValue	0
CY2020	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Exercises In Period Total Intrinsic Value ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue	13600000	USD
CY2019	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Exercises In Period Total Intrinsic Value ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue	35400000	USD
CY2021	us-gaap	Proceeds From Stock Options Exercised ProceedsFromStockOptionsExercised	53800000	USD
CY2020	us-gaap	Proceeds From Stock Options Exercised ProceedsFromStockOptionsExercised	19500000	USD
CY2019	us-gaap	Proceeds From Stock Options Exercised ProceedsFromStockOptionsExercised	44000000.0	USD
CY2021	ntrs	Employee Service Share Based Compensation Tax Benefit Realized From Exercise Of Stock Option EmployeeServiceShareBasedCompensationTaxBenefitRealizedFromExerciseOfStockOption	41300000	USD
CY2020	ntrs	Employee Service Share Based Compensation Tax Benefit Realized From Exercise Of Stock Option EmployeeServiceShareBasedCompensationTaxBenefitRealizedFromExerciseOfStockOption	13400000	USD
CY2019	ntrs	Employee Service Share Based Compensation Tax Benefit Realized From Exercise Of Stock Option EmployeeServiceShareBasedCompensationTaxBenefitRealizedFromExerciseOfStockOption	35200000	USD
CY2020Q4	us-gaap	Sharebased Compensation Arrangement By Sharebased Payment Award Options Nonvested Number Of Shares SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsNonvestedNumberOfShares	114829	shares
CY2020Q4	us-gaap	Sharebased Compensation Arrangement By Sharebased Payment Award Options Nonvested Weighted Average Grant Date Fair Value SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsNonvestedWeightedAverageGrantDateFairValue	19.18
CY2021	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Grants In Period ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriod	0	shares
CY2021	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Grants In Period Weighted Average Grant Date Fair Value ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue	0
CY2021	us-gaap	Sharebased Compensation Arrangement By Sharebased Payment Award Options Vested Number Of Shares SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedNumberOfShares	114829	shares
CY2021	us-gaap	Sharebased Compensation Arrangement By Sharebased Payment Award Options Vested Weighted Average Grant Date Fair Value SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedWeightedAverageGrantDateFairValue	19.18
CY2021	us-gaap	Sharebased Compensation Arrangement By Sharebased Payment Award Options Nonvested Options Forfeited Number Of Shares SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsNonvestedOptionsForfeitedNumberOfShares	0	shares
CY2021Q4	us-gaap	Sharebased Compensation Arrangement By Sharebased Payment Award Options Nonvested Number Of Shares SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsNonvestedNumberOfShares	0	shares
CY2021Q4	us-gaap	Sharebased Compensation Arrangement By Sharebased Payment Award Options Nonvested Weighted Average Grant Date Fair Value SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsNonvestedWeightedAverageGrantDateFairValue	0
CY2021Q4	us-gaap	Deferred Compensation Arrangement With Individual Cash Award Granted Amount DeferredCompensationArrangementWithIndividualCashAwardGrantedAmount	377100000	USD
CY2020Q4	us-gaap	Deferred Compensation Arrangement With Individual Cash Award Granted Amount DeferredCompensationArrangementWithIndividualCashAwardGrantedAmount	296200000	USD
CY2019Q4	us-gaap	Deferred Compensation Arrangement With Individual Cash Award Granted Amount DeferredCompensationArrangementWithIndividualCashAwardGrantedAmount	326100000	USD
CY2021	us-gaap	Loss Contingency Disclosures LossContingencyDisclosures	Commitments and Contingent Liabilities<div style="text-align:justify"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:700;line-height:120%">Off-Balance Sheet Financial Instruments, Guarantees and Other Commitments. </span><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%">Northern Trust, in the normal course of business, enters into various types of commitments and issues letters of credit to meet the liquidity and credit enhancement needs of its clients. The contractual amounts of these instruments represent the maximum potential credit exposure should the instrument be fully drawn upon and the client default. To control the credit risk associated with entering into commitments and issuing letters of credit, Northern Trust subjects such activities to the same credit quality and monitoring controls as its lending activities. Northern Trust does not believe the total contractual amount of these instruments to be representative of its future credit exposure or funding requirements. </span></div><div style="text-align:justify;text-indent:18pt"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%">The following table provides details of Northern Trust's off-balance sheet financial instruments as of December 31, 2021 and 2020.</span></div><div style="text-align:justify"><span><br/></span></div><div style="text-align:justify"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:700;line-height:120%">TABLE 124: SUMMARY OF OFF-BALANCE SHEET FINANCIAL INSTRUMENTS</span></div><div style="margin-top:5pt"><table style="border-collapse:collapse;display:inline-table;margin-bottom:5pt;vertical-align:text-bottom;width:100.000%"><tr><td style="width:1.0%"/><td style="width:40.718%"/><td style="width:0.1%"/><td style="width:1.0%"/><td style="width:8.596%"/><td style="width:0.1%"/><td style="width:1.0%"/><td style="width:8.596%"/><td style="width:0.1%"/><td style="width:1.0%"/><td style="width:8.596%"/><td style="width:0.1%"/><td style="width:1.0%"/><td style="width:8.596%"/><td style="width:0.1%"/><td style="width:1.0%"/><td style="width:8.596%"/><td style="width:0.1%"/><td style="width:1.0%"/><td style="width:8.602%"/><td style="width:0.1%"/></tr><tr><td colspan="3" style="padding:0 1pt"/><td colspan="18" style="padding:2px 1pt;text-align:center;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:7pt;font-weight:400;line-height:100%">DECEMBER 31,</span></td></tr><tr><td colspan="3" style="padding:0 1pt"/><td colspan="9" style="padding:2px 1pt;text-align:center;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:7pt;font-weight:700;line-height:100%">2021</span></td><td colspan="9" style="padding:2px 1pt;text-align:center;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:7pt;font-weight:400;line-height:100%">2020</span></td></tr><tr><td colspan="3" style="padding:2px 1pt;text-align:left;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:7pt;font-weight:400;line-height:100%">($ In Millions)</span></td><td colspan="3" style="border-top:1pt solid #000;padding:2px 1pt;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:7pt;font-weight:700;line-height:100%">ONE YEAR AND LESS</span></td><td colspan="3" style="border-top:1pt solid #000;padding:2px 1pt;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:7pt;font-weight:700;line-height:100%">OVER ONE YEAR</span></td><td colspan="3" style="border-top:1pt solid #000;padding:2px 1pt;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:7pt;font-weight:700;line-height:100%">TOTAL</span></td><td colspan="3" style="border-top:1pt solid #000;padding:2px 1pt;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:7pt;font-weight:400;line-height:100%">ONE YEAR AND LESS</span></td><td colspan="3" style="border-top:1pt solid #000;padding:2px 1pt;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:7pt;font-weight:400;line-height:100%">OVER ONE YEAR</span></td><td colspan="3" style="border-top:1pt solid #000;padding:2px 1pt;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:7pt;font-weight:400;line-height:100%">TOTAL</span></td></tr><tr><td colspan="3" style="background-color:#cceeff;border-top:1pt solid #000;padding:2px 1pt;text-align:left;vertical-align:bottom"><div><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:100%">Undrawn Commitments</span><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:5.2pt;font-weight:400;line-height:100%;position:relative;top:-2.8pt;vertical-align:baseline">(1)</span></div></td><td style="background-color:#cceeff;border-top:1pt solid #000;padding:2px 0 2px 1pt;text-align:left;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:700;line-height:100%">$</span></td><td style="background-color:#cceeff;border-top:1pt solid #000;padding:2px 0;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:700;line-height:100%">9,567.0</span><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:100%"> </span></td><td style="background-color:#cceeff;border-top:1pt solid #000;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"/><td style="background-color:#cceeff;border-top:1pt solid #000;padding:2px 0 2px 1pt;text-align:left;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:700;line-height:100%">$</span></td><td style="background-color:#cceeff;border-top:1pt solid #000;padding:2px 0;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:700;line-height:100%">17,855.2</span><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:100%"> </span></td><td style="background-color:#cceeff;border-top:1pt solid #000;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"/><td style="background-color:#cceeff;border-top:1pt solid #000;padding:2px 0 2px 1pt;text-align:left;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:700;line-height:100%">$</span></td><td style="background-color:#cceeff;border-top:1pt solid #000;padding:2px 0;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:700;line-height:100%">27,422.2</span><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:100%"> </span></td><td style="background-color:#cceeff;border-top:1pt solid #000;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"/><td style="background-color:#cceeff;border-top:1pt solid #000;padding:2px 0 2px 1pt;text-align:left;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:100%">$</span></td><td style="background-color:#cceeff;border-top:1pt solid #000;padding:2px 0;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:100%">11,260.5 </span></td><td style="background-color:#cceeff;border-top:1pt solid #000;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"/><td style="background-color:#cceeff;border-top:1pt solid #000;padding:2px 0 2px 1pt;text-align:left;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:100%">$</span></td><td style="background-color:#cceeff;border-top:1pt solid #000;padding:2px 0;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:100%">17,678.0 </span></td><td style="background-color:#cceeff;border-top:1pt solid #000;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"/><td style="background-color:#cceeff;border-top:1pt solid #000;padding:2px 0 2px 1pt;text-align:left;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:100%">$</span></td><td style="background-color:#cceeff;border-top:1pt solid #000;padding:2px 0;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:100%">28,938.5 </span></td><td style="background-color:#cceeff;border-top:1pt solid #000;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"/></tr><tr><td colspan="3" style="background-color:#ffffff;padding:2px 1pt;text-align:left;vertical-align:bottom"><div><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:100%">Standby Letters of Credit and Financial Guarantees</span><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:5.2pt;font-weight:400;line-height:100%;position:relative;top:-2.8pt;vertical-align:baseline">(2)(3)</span></div></td><td colspan="2" style="background-color:#ffffff;padding:2px 0 2px 1pt;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:700;line-height:100%">3,485.6</span><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:100%"> </span></td><td style="background-color:#ffffff;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"/><td colspan="2" style="background-color:#ffffff;padding:2px 0 2px 1pt;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:700;line-height:100%">553.9</span><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:100%"> </span></td><td style="background-color:#ffffff;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"/><td colspan="2" style="background-color:#ffffff;padding:2px 0 2px 1pt;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:700;line-height:100%">4,039.5</span><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:100%"> </span></td><td style="background-color:#ffffff;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"/><td colspan="2" style="background-color:#ffffff;padding:2px 0 2px 1pt;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:100%">1,228.1 </span></td><td style="background-color:#ffffff;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"/><td colspan="2" style="background-color:#ffffff;padding:2px 0 2px 1pt;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:100%">763.5 </span></td><td style="background-color:#ffffff;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"/><td colspan="2" style="background-color:#ffffff;padding:2px 0 2px 1pt;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:100%">1,991.6 </span></td><td style="background-color:#ffffff;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"/></tr><tr><td colspan="3" style="background-color:#cceeff;padding:2px 1pt;text-align:left;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:100%">Commercial Letters of Credit</span></td><td colspan="2" style="background-color:#cceeff;padding:2px 0 2px 1pt;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:700;line-height:100%">68.5</span><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:100%"> </span></td><td style="background-color:#cceeff;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"/><td colspan="2" style="background-color:#cceeff;padding:2px 0 2px 1pt;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:700;line-height:100%">1.1</span><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:100%"> </span></td><td style="background-color:#cceeff;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"/><td colspan="2" style="background-color:#cceeff;padding:2px 0 2px 1pt;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:700;line-height:100%">69.6</span><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:100%"> </span></td><td style="background-color:#cceeff;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"/><td colspan="2" style="background-color:#cceeff;padding:2px 0 2px 1pt;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:100%">54.6 </span></td><td style="background-color:#cceeff;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"/><td colspan="2" style="background-color:#cceeff;padding:2px 0 2px 1pt;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:100%">— </span></td><td style="background-color:#cceeff;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"/><td colspan="2" style="background-color:#cceeff;padding:2px 0 2px 1pt;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:100%">54.6 </span></td><td style="background-color:#cceeff;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"/></tr><tr><td colspan="3" style="background-color:#ffffff;padding:2px 1pt;text-align:left;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:100%">Custody Securities Lent with Indemnification</span></td><td colspan="2" style="background-color:#ffffff;padding:2px 0 2px 1pt;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:700;line-height:100%">170,445.3</span><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:100%"> </span></td><td style="background-color:#ffffff;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"/><td colspan="2" style="background-color:#ffffff;padding:2px 0 2px 1pt;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:700;line-height:100%">—</span><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:100%"> </span></td><td style="background-color:#ffffff;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"/><td colspan="2" style="background-color:#ffffff;padding:2px 0 2px 1pt;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:700;line-height:100%">170,445.3</span><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:100%"> </span></td><td style="background-color:#ffffff;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"/><td colspan="2" style="background-color:#ffffff;padding:2px 0 2px 1pt;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:100%">157,478.0 </span></td><td style="background-color:#ffffff;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"/><td colspan="2" style="background-color:#ffffff;padding:2px 0 2px 1pt;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:100%">— </span></td><td style="background-color:#ffffff;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"/><td colspan="2" style="background-color:#ffffff;padding:2px 0 2px 1pt;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:100%">157,478.0 </span></td><td style="background-color:#ffffff;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"/></tr><tr><td colspan="3" style="display:none"/><td colspan="3" style="display:none"/><td colspan="3" style="display:none"/><td colspan="3" style="display:none"/><td colspan="3" style="display:none"/><td colspan="3" style="display:none"/><td colspan="3" style="display:none"/></tr><tr><td colspan="3" style="background-color:#cceeff;border-top:1pt solid #000;padding:2px 1pt;text-align:left;vertical-align:top"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:100%">Total Off-Balance Sheet Financial Instruments</span></td><td style="background-color:#cceeff;border-top:1pt solid #000;padding:2px 0 2px 1pt;text-align:left;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:700;line-height:100%">$</span></td><td style="background-color:#cceeff;border-top:1pt solid #000;padding:2px 0;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:700;line-height:100%">183,566.4</span><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:100%"> </span></td><td style="background-color:#cceeff;border-top:1pt solid #000;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"/><td style="background-color:#cceeff;border-top:1pt solid #000;padding:2px 0 2px 1pt;text-align:left;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:700;line-height:100%">$</span></td><td style="background-color:#cceeff;border-top:1pt solid #000;padding:2px 0;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:700;line-height:100%">18,410.2</span><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:100%"> </span></td><td style="background-color:#cceeff;border-top:1pt solid #000;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"/><td style="background-color:#cceeff;border-top:1pt solid #000;padding:2px 0 2px 1pt;text-align:left;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:700;line-height:100%">$</span></td><td style="background-color:#cceeff;border-top:1pt solid #000;padding:2px 0;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:700;line-height:100%">201,976.6</span><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:100%"> </span></td><td style="background-color:#cceeff;border-top:1pt solid #000;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"/><td style="background-color:#cceeff;border-top:1pt solid #000;padding:2px 0 2px 1pt;text-align:left;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:100%">$</span></td><td style="background-color:#cceeff;border-top:1pt solid #000;padding:2px 0;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:100%">170,021.2 </span></td><td style="background-color:#cceeff;border-top:1pt solid #000;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"/><td style="background-color:#cceeff;border-top:1pt solid #000;padding:2px 0 2px 1pt;text-align:left;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:100%">$</span></td><td style="background-color:#cceeff;border-top:1pt solid #000;padding:2px 0;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:100%">18,441.5 </span></td><td style="background-color:#cceeff;border-top:1pt solid #000;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"/><td style="background-color:#cceeff;border-top:1pt solid #000;padding:2px 0 2px 1pt;text-align:left;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:100%">$</span></td><td style="background-color:#cceeff;border-top:1pt solid #000;padding:2px 0;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:100%">188,462.7 </span></td><td style="background-color:#cceeff;border-top:1pt solid #000;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"/></tr></table></div><div style="text-align:justify"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:4.55pt;font-style:italic;font-weight:400;line-height:120%;position:relative;top:-2.44pt;vertical-align:baseline">(1)</span><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:7pt;font-style:italic;font-weight:400;line-height:120%"> These amounts exclude $366.6 million and $384.7 million of commitments participated to others at December 31, 2021 and 2020, respectively.</span></div><div style="text-align:justify"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:4.55pt;font-style:italic;font-weight:400;line-height:120%;position:relative;top:-2.44pt;vertical-align:baseline">(2) </span><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:7pt;font-style:italic;font-weight:400;line-height:120%">These amounts include $30.5 million and $24.2 million of standby letters of credit secured by cash deposits or participated to others as of December 31, 2021 and 2020, respectively.</span></div><div style="text-align:justify"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:4.55pt;font-style:italic;font-weight:400;line-height:120%;position:relative;top:-2.44pt;vertical-align:baseline">(3) </span><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:7pt;font-style:italic;font-weight:400;line-height:120%">This amount includes a $2,309.6 million guarantee to the Fixed Income Clearing Corporation (FICC) under the sponsored member program, without taking into consideration the related collateral, as of December 31, 2021. As of December 31, 2020, there was no guarantee to the FICC as Northern Trust became a sponsored member during the third quarter of 2021. </span></div><div style="text-align:justify"><span><br/></span></div><div style="text-align:justify;text-indent:18pt"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-style:italic;font-weight:700;line-height:120%">Undrawn Commitments</span><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%"> generally have fixed expiration dates or other termination clauses. Since a significant portion of the commitments are expected to expire without being drawn upon, the total commitment amount does not necessarily represent future loans or liquidity requirements.</span></div><div style="text-align:justify;text-indent:18pt"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-style:italic;font-weight:700;line-height:120%">Standby Letters of Credit</span><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%"> obligate Northern Trust to meet certain financial obligations of its clients, if, under the contractual terms of the agreement, the clients are unable to do so. These instruments are primarily issued to support public and private financial commitments, including commercial paper, bond financing, initial margin requirements on futures exchanges, and similar transactions. Northern Trust is obligated to meet the entire financial obligation of these agreements and in certain cases is able to recover the amounts paid through recourse against collateral received or other participants.</span></div><div style="text-align:justify;text-indent:18pt"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-style:italic;font-weight:700;line-height:120%">Financial Guarantees</span><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%"> are issued by Northern Trust to guarantee the performance of a client to a third party under certain arrangements.</span></div><div style="text-align:justify;text-indent:18pt"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-style:italic;font-weight:700;line-height:120%">Commercial Letters of Credit</span><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%"> are instruments issued by Northern Trust on behalf of its clients that authorize a third party (the beneficiary) to draw drafts up to a stipulated amount under the specified terms and conditions of the agreement and other similar instruments. Commercial letters of credit are issued primarily to facilitate international trade.</span></div><div style="text-align:justify;text-indent:18pt"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-style:italic;font-weight:700;line-height:120%">Custody Securities Lent with Indemnification</span><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%"> involves Northern Trust lending securities owned by clients to borrowers who are reviewed and approved by the Northern Trust Capital Markets Credit Committee, as part of its securities custody activities and at the direction of its clients. In connection with these activities, Northern Trust has issued indemnifications to certain clients against certain losses that are a direct result of a borrower’s failure to return securities when due, should the value of such securities exceed the value of the collateral required to be posted. Borrowers are required to collateralize fully securities received with cash or marketable securities. As securities are loaned, collateral is maintained at a minimum 100% of the fair value of the securities plus accrued interest. The collateral is revalued on a daily basis. The amount of securities loaned as of December 31, 2021 and 2020 subject to indemnification was $170.4 billion and $157.5 billion, respectively. Because of the credit quality of the borrowers and the requirement to fully collateralize securities borrowed, management believes that the exposure to credit loss from this activity is not significant and no liability was recorded at December 31, 2021, or 2020 related to these indemnifications.</span></div><div style="text-align:justify;text-indent:18pt"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-style:italic;font-weight:700;line-height:120%">Unsettled Repurchase and Reverse Repurchase Agreements</span><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:700;line-height:120%">.</span><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%"> Northern Trust enters into repurchase agreements and reverse repurchase agreements which may settle at a future date. In repurchase agreements, Northern Trust receives cash from and provides securities as collateral to a counterparty. In reverse repurchase agreements, Northern Trust advances cash to and receives securities as collateral from a counterparty. These transactions are recorded on the consolidated balance sheets on the settlement date. As of December 31, 2021 and 2020, there were no unsettled repurchase or reverse repurchase agreements.</span></div><div style="text-align:justify;text-indent:18pt"><span><br/></span></div><div style="text-align:justify;text-indent:18pt"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:700;line-height:120%">Sponsored Member Program. </span><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%">Effective during the third quarter of 2021, Northern Trust became an approved Government Securities Division (GSD) netting and sponsoring member in the FICC sponsored member program, through which Northern Trust submits eligible repurchase and reverse repurchase transactions in U.S. Government securities between Northern Trust and its sponsored member clients for novation and clearing. Northern Trust may sponsor clients to clear their eligible repurchase transactions with the FICC. As a sponsoring member, Northern Trust guarantees to the FICC the prompt and full payment and performance of its sponsored member clients’ respective obligations under the FICC GSD’s rules. To mitigate Northern Trust’s credit exposure under this guarantee, Northern Trust obtains a security interest in its sponsored member clients’ collateral. Please refer to Note 28, “Offsetting of Assets and Liabilities” for additional information on Northern Trust’s repurchase and reverse repurchase agreements.</span></div><div style="text-align:justify;text-indent:18pt"><span><br/></span></div><div style="text-align:justify;text-indent:18pt"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:700;line-height:120%">Clearing and Settlement Organizations.</span><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%"> The Bank is a participating member of various cash, securities and foreign exchange clearing and settlement organizations. It participates in these organizations on behalf of its clients and on its own behalf as a result of its own activities. A wide variety of cash and securities transactions are settled through these organizations, including those involving obligations of states and political subdivisions, asset-backed securities, commercial paper, dollar placements, and securities issued by the Government National Mortgage Association. </span></div><div style="text-align:justify;text-indent:18pt"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%">Certain of these industry clearing and settlement exchanges require their members to guarantee their obligations and liabilities and/or to provide liquidity support in the event other members do not honor their obligations as stipulated in each clearing organization’s membership agreement. Exposure related to these agreements varies, primarily as a result of fluctuations in the volume of transactions cleared through the organizations. At December 31, 2021 and 2020, Northern Trust has not recorded any material liabilities under these arrangements as Northern Trust believes the likelihood that a clearing or settlement exchange (of which Northern Trust is a member) would become insolvent is remote. Controls related to these clearing transactions are closely monitored by management to protect the assets of Northern Trust and its clients.</span></div><div style="text-indent:18pt"><span><br/></span></div><div style="text-align:justify;text-indent:18pt"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:700;line-height:120%">Legal Proceedings.</span><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%"> In the normal course of business, the Corporation and its subsidiaries are routinely defendants in or parties to pending and threatened legal actions, and are subject to regulatory examinations, information-gathering requests, investigations, and proceedings, both formal and informal. In certain legal actions, claims for substantial monetary damages are asserted. In regulatory matters, claims for disgorgement, restitution, penalties and/or other remedial actions or sanctions may be sought. </span></div><div style="text-align:justify;text-indent:18pt"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%">Based on current knowledge, after consultation with legal counsel and after taking into account current accruals, management does not believe that losses, fines or penalties, if any, arising from pending litigation or threatened legal actions or regulatory matters either individually or in the aggregate, after giving effect to applicable reserves and insurance coverage will have a material adverse effect on the consolidated financial position or liquidity of the Corporation, although such matters could have a material adverse effect on the Corporation’s operating results for a particular period.</span></div><div style="text-align:justify;text-indent:18pt"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%">Under GAAP, (i) an event is “probable” if the “future event or events are likely to occur”; (ii) an event is “reasonably possible” if “the chance of the future event or events occurring is more than remote but less than likely”; and (iii) an event is “remote” if “the chance of the future event or events occurring is slight.”</span></div><div style="text-align:justify;text-indent:18pt"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%">The outcome of litigation and regulatory matters is inherently difficult to predict and/or the range of loss often cannot be reasonably estimated, particularly for matters that (i) will be decided by a jury, (ii) are in early stages, (iii) involve uncertainty as to the likelihood of a class being certified or the ultimate size of the class, (iv) are subject to appeals or motions, (v) involve significant factual issues to be resolved, including with respect to the amount of damages, (vi) do not specify the amount of damages sought or (vii) seek very large damages based on novel and complex damage and liability legal theories. Accordingly, the Corporation cannot reasonably estimate the eventual outcome of these pending matters, the timing of their ultimate resolution or what the eventual loss, fines or penalties, if any, related to each pending matter will be.</span></div><div style="text-align:justify;text-indent:18pt"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%">In accordance with applicable accounting guidance, the Corporation records accruals for litigation and regulatory matters when those matters present loss contingencies that are both probable and reasonably estimable. When loss contingencies are not both probable and reasonably estimable, the Corporation does not record accruals. No material accruals have been recorded for pending litigation or threatened legal actions or regulatory matters. </span></div><div style="text-align:justify;text-indent:18pt"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%">For a limited number of matters for which a loss is reasonably possible in future periods, whether in excess of an accrued liability or where there is no accrued liability, the Corporation is able to estimate a range of possible loss. As </span></div><div style="text-align:justify"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%">of December 31, 2021, the Corporation has estimated the range of reasonably possible loss for these matters to be from zero to approximately $20 million in the aggregate. The Corporation’s estimate with respect to the aggregate range of reasonably possible loss is based upon currently available information and is subject to significant judgment and a variety of assumptions and known and unknown uncertainties. The matters underlying the estimated range will change from time to time, and actual results may vary significantly from the current estimate. </span></div><div style="text-align:justify;text-indent:18pt"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%">In certain other pending matters, there may be a range of reasonably possible loss (including reasonably possible loss in excess of amounts accrued) that cannot be reasonably estimated for the reasons described above. Such matters are not included in the estimated range of reasonably possible loss discussed above. </span></div><div style="text-align:justify;text-indent:18pt"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%">In 2015, Northern Trust Fiduciary Services (Guernsey) Limited (NTFS), an indirect subsidiary of the Corporation, was charged by a French investigating magistrate judge with complicity in estate tax fraud in connection with the administration of two trusts for which it serves as trustee. Charges also were brought against a number of other persons and entities related to this matter. In 2017, a French court found no estate tax fraud had occurred and NTFS and all other persons and entities charged were acquitted. The Public Prosecutor’s Office of France appealed the court decision and in June 2018 a French appellate court issued its opinion on the matter, acquitting all persons and entities charged, including NTFS. In January 2021, the Cour de Cassation, the highest court in France, reversed the June 2018 appellate court ruling, requiring a re-trial at the appellate court level. The re-trial proceedings in the appellate court have not yet been scheduled. As trustee, NTFS provided no tax advice and had no involvement in the preparation or filing of the challenged estate tax filings.</span></div><div style="text-align:justify;text-indent:18pt"><span><br/></span></div><div style="text-align:justify;text-indent:18pt"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:700;line-height:120%">Visa Class B Common Shares.</span><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%"> Northern Trust, as a member of Visa U.S.A. Inc. (Visa U.S.A.) and in connection with the 2007 restructuring of Visa U.S.A. and its affiliates and the 2008 initial public offering of Visa Inc. (Visa), received certain Visa Class B common shares. The Visa Class B common shares are subject to certain selling restrictions until the final resolution of certain litigation related to interchange fees involving Visa (the covered litigation), at which time the shares are convertible into Visa Class A common shares based on a conversion rate dependent upon the ultimate cost of resolving the covered litigation. On June 28, 2018, September 27, 2019 and December 29, 2021, Visa deposited an additional $600 million, $300 million, and $250 million, respectively, into an escrow account previously established with respect to the covered litigation. As a result of the additional contributions to the escrow account, the rate at which Visa Class B common shares will convert into Visa Class A common shares was reduced. </span></div><div style="text-align:justify;text-indent:18pt"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%">In September 2018, Visa reached a proposed class settlement agreement covering damage claims but not injunctive relief claims regarding the covered litigation. In December 2019, the district court granted final approval for the proposed class settlement agreement. Certain merchants have opted out of the class settlement and are pursuing claims separately, while other merchants have appealed the approval order granted by the district court. The ultimate resolution of the covered litigation, the timing for removal of the selling restrictions on the Visa Class B common shares and the rate at which such shares will ultimately convert into Visa Class A common shares are uncertain.</span></div><div style="text-align:justify;text-indent:18pt"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%">In June 2016 and 2015, Northern Trust recorded a $123.1 million and $99.9 million net gain on the sale of 1.1 million and 1.0 million of its Visa Class B common shares, respectively. These sales do not affect Northern Trust’s risk related to the impact of the covered litigation on the rate at which such shares will ultimately convert into Visa Class A common shares. Northern Trust continued to hold approximately 4.1 million Visa Class B common shares, which are recorded at their original cost basis of zero, as of both December 31, 2021 and 2020.</span></div>
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CY2020Q4	ntrs	Securities Received As Collateral At Fair Value SecuritiesReceivedAsCollateralAtFairValue	1680700000	USD
CY2021Q4	us-gaap	Fair Value Of Securities Received As Collateral That Have Been Resold Or Repledged FairValueOfSecuritiesReceivedAsCollateralThatHaveBeenResoldOrRepledged	1419000000	USD
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CY2019	us-gaap	Foreign Currency Transaction Gain Loss Before Tax ForeignCurrencyTransactionGainLossBeforeTax	250900000	USD
CY2021	us-gaap	Noninterest Income Other NoninterestIncomeOther	428100000	USD
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CY2019	us-gaap	Noninterest Income Other NoninterestIncomeOther	292200000	USD
CY2021	us-gaap	Noninterest Income NoninterestIncome	5081800000	USD
CY2020	us-gaap	Noninterest Income NoninterestIncome	4657600000	USD
CY2019	us-gaap	Noninterest Income NoninterestIncome	4395200000	USD
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CY2020	ntrs	Interest Revenue Expense Net Including Fully Taxable Equivalent Adjustment InterestRevenueExpenseNetIncludingFullyTaxableEquivalentAdjustment	1477600000	USD
CY2019	ntrs	Interest Revenue Expense Net Including Fully Taxable Equivalent Adjustment InterestRevenueExpenseNetIncludingFullyTaxableEquivalentAdjustment	1710700000	USD
CY2021	ntrs	Revenue Including Fully Taxable Equivalent Adjustment RevenueIncludingFullyTaxableEquivalentAdjustment	6500100000	USD
CY2020	ntrs	Revenue Including Fully Taxable Equivalent Adjustment RevenueIncludingFullyTaxableEquivalentAdjustment	6135200000	USD
CY2019	ntrs	Revenue Including Fully Taxable Equivalent Adjustment RevenueIncludingFullyTaxableEquivalentAdjustment	6105900000	USD
CY2021	ntrs	Credit Loss Expense Reversal And Available For Sale Allowance For Credit Loss CreditLossExpenseReversalAndAvailableForSaleAllowanceForCreditLoss	-81500000	USD
CY2020	ntrs	Credit Loss Expense Reversal And Available For Sale Allowance For Credit Loss CreditLossExpenseReversalAndAvailableForSaleAllowanceForCreditLoss	125000000.0	USD
CY2019	ntrs	Credit Loss Expense Reversal And Available For Sale Allowance For Credit Loss CreditLossExpenseReversalAndAvailableForSaleAllowanceForCreditLoss	-14500000	USD
CY2021	us-gaap	Noninterest Expense NoninterestExpense	4535900000	USD
CY2020	us-gaap	Noninterest Expense NoninterestExpense	4348200000	USD
CY2019	us-gaap	Noninterest Expense NoninterestExpense	4143500000	USD
CY2021	ntrs	Income Loss Before Income Taxes Including Fully Taxable Equivalent Adjustment IncomeLossBeforeIncomeTaxesIncludingFullyTaxableEquivalentAdjustment	2045700000	USD
CY2020	ntrs	Income Loss Before Income Taxes Including Fully Taxable Equivalent Adjustment IncomeLossBeforeIncomeTaxesIncludingFullyTaxableEquivalentAdjustment	1662000000	USD
CY2019	ntrs	Income Loss Before Income Taxes Including Fully Taxable Equivalent Adjustment IncomeLossBeforeIncomeTaxesIncludingFullyTaxableEquivalentAdjustment	1976900000	USD
CY2021	ntrs	Income Tax Expense Benefit Including Fully Taxable Equivalent Adjustment IncomeTaxExpenseBenefitIncludingFullyTaxableEquivalentAdjustment	500400000	USD
CY2020	ntrs	Income Tax Expense Benefit Including Fully Taxable Equivalent Adjustment IncomeTaxExpenseBenefitIncludingFullyTaxableEquivalentAdjustment	452700000	USD
CY2019	ntrs	Income Tax Expense Benefit Including Fully Taxable Equivalent Adjustment IncomeTaxExpenseBenefitIncludingFullyTaxableEquivalentAdjustment	484700000	USD
CY2021	us-gaap	Net Income Loss NetIncomeLoss	1545300000	USD
CY2020	us-gaap	Net Income Loss NetIncomeLoss	1209300000	USD
CY2019	us-gaap	Net Income Loss NetIncomeLoss	1492200000	USD
CY2021	ntrs	Segment Reporting Information Consolidated Average Assets SegmentReportingInformationConsolidatedAverageAssets	156363200000	USD
CY2020	ntrs	Segment Reporting Information Consolidated Average Assets SegmentReportingInformationConsolidatedAverageAssets	136811100000	USD
CY2019	ntrs	Segment Reporting Information Consolidated Average Assets SegmentReportingInformationConsolidatedAverageAssets	117551400000	USD
CY2021	ntrs	Segment Reporting Information Fully Taxable Equivalent Adjustment SegmentReportingInformationFullyTaxableEquivalentAdjustment	35600000	USD
CY2020	ntrs	Segment Reporting Information Fully Taxable Equivalent Adjustment SegmentReportingInformationFullyTaxableEquivalentAdjustment	34400000	USD
CY2019	ntrs	Segment Reporting Information Fully Taxable Equivalent Adjustment SegmentReportingInformationFullyTaxableEquivalentAdjustment	32800000	USD
CY2021Q4	us-gaap	Assets Assets	183889800000	USD
CY2021	us-gaap	Revenues Revenues	6464500000	USD
CY2021	us-gaap	Income Loss From Continuing Operations Before Income Taxes Extraordinary Items Noncontrolling Interest IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest	2010100000	USD
CY2021	us-gaap	Net Income Loss NetIncomeLoss	1545300000	USD
CY2020Q4	us-gaap	Assets Assets	170003900000	USD
CY2020	us-gaap	Revenues Revenues	6100800000	USD
CY2020	us-gaap	Income Loss From Continuing Operations Before Income Taxes Extraordinary Items Noncontrolling Interest IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest	1627600000	USD
CY2020	us-gaap	Net Income Loss NetIncomeLoss	1209300000	USD
CY2019Q4	us-gaap	Assets Assets	136828400000	USD
CY2019	us-gaap	Revenues Revenues	6073100000	USD
CY2019	us-gaap	Income Loss From Continuing Operations Before Income Taxes Extraordinary Items Noncontrolling Interest IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest	1944100000	USD
CY2019	us-gaap	Net Income Loss NetIncomeLoss	1492200000	USD
CY2021	dei	Auditor Name AuditorName	KPMG LLP
CY2021	dei	Auditor Location AuditorLocation	Chicago, IL
CY2021	dei	Auditor Firm AuditorFirmId

Files In Submission

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$NTRS
NORTHERN TRUST CORP Stock $ntrs

2021 Q4 Form 10-K Financial Statement

#000007312422000071 Filed on February 28, 2022

Income Statement

Balance Sheet

Cashflow Statement

Facts In Submission

Files In Submission

$NTRS NORTHERN TRUST CORP Stock $ntrs

2021 Q4 Form 10-K Financial Statement

#000007312422000071 Filed on February 28, 2022

Income Statement

Balance Sheet

Cashflow Statement

Facts In Submission

Files In Submission

$NTRS
NORTHERN TRUST CORP Stock $ntrs