$CMA
Comerica Inc Stock $cma

$cma Overview Financials Valuation SEC Filings Company Website

2020 Q4 Form 10-K Financial Statement

#000002841221000054 Filed on February 09, 2021

Income Statement

Concept	2020 Q4	2019 Q4	2019 Q3
Revenue	$489.0M	$659.0M	$711.0M
YoY Change	-25.8%	-6.39%	5.33%
Cost Of Revenue
YoY Change
Gross Profit
YoY Change
Gross Profit Margin
Selling, General & Admin
YoY Change
% of Gross Profit
Research & Development
YoY Change
% of Gross Profit
Depreciation & Amortization	$26.00M	$30.00M	$27.00M
YoY Change	-13.33%	0.0%	-10.0%
% of Gross Profit
Operating Expenses
YoY Change
Operating Profit
YoY Change
Interest Expense	$20.00M	$115.0M	$125.0M
YoY Change	-82.61%	27.78%	64.47%
% of Operating Profit
Other Income/Expense, Net
YoY Change
Pretax Income	$286.0M	$351.0M	$372.0M
YoY Change	-18.52%	-12.25%	-2.36%
Income Tax	$65.00M	$82.00M	$80.00M
% Of Pretax Income	22.73%	23.36%	21.51%
Net Earnings	$221.0M	$269.0M	$292.0M
YoY Change	-17.84%	-13.23%	-8.18%
Net Earnings / Revenue	45.19%	40.82%	41.07%
Basic Earnings Per Share	$1.54	$1.87	$1.98
Diluted Earnings Per Share	$1.53	$1.85	$1.96
COMMON SHARES
Basic Shares Outstanding	139.1M shares	144.2M shares	147.0M shares
Diluted Shares Outstanding			148.0M shares

Balance Sheet

Concept	2020 Q4	2019 Q4	2019 Q3
SHORT-TERM ASSETS
Cash & Short-Term Investments
YoY Change
Cash & Equivalents	$15.77B	$5.818B	$4.117B
Short-Term Investments
Other Short-Term Assets
YoY Change
Inventory
Prepaid Expenses
Receivables
Other Receivables
Total Short-Term Assets
YoY Change
LONG-TERM ASSETS
Property, Plant & Equipment	$459.0M	$457.0M	$467.0M
YoY Change	0.44%	-3.79%	-1.06%
Goodwill	$635.0M	$635.0M
YoY Change	0.0%	0.0%
Intangibles
YoY Change
Long-Term Investments
YoY Change
Other Assets
YoY Change
Total Long-Term Assets
YoY Change
TOTAL ASSETS
Total Short-Term Assets
Total Long-Term Assets
Total Assets	$88.13B	$73.40B	$72.85B
YoY Change	20.06%	3.65%	1.96%
SHORT-TERM LIABILITIES
YoY Change
Accounts Payable
YoY Change
Accrued Expenses	$1.482B	$1.440B	$1.477B
YoY Change	2.92%	15.85%	27.99%
Deferred Revenue
YoY Change
Short-Term Debt	$0.00	$71.00M	$51.00M
YoY Change	-100.0%	61.36%	-39.29%
Long-Term Debt Due
YoY Change
Total Short-Term Liabilities	$1.482B	$1.440B	$1.477B
YoY Change	2.92%	15.85%	27.99%
LONG-TERM LIABILITIES
Long-Term Debt	$2.928B	$3.469B	$3.511B
YoY Change	-15.6%	30.27%	34.11%
Other Long-Term Liabilities
YoY Change
Total Long-Term Liabilities	$2.928B	$3.469B	$3.511B
YoY Change	-15.6%	30.27%	34.11%
TOTAL LIABILITIES
Total Short-Term Liabilities	$1.482B	$1.440B	$1.477B
Total Long-Term Liabilities	$2.928B	$3.469B	$3.511B
Total Liabilities	$80.08B	$66.08B	$65.65B
YoY Change	21.19%	4.37%	3.12%
SHAREHOLDERS EQUITY
Retained Earnings	$9.727B	$9.538B	$9.369B
YoY Change	1.98%	8.62%	9.11%
Common Stock	$3.326B	$3.315B	$3.313B
YoY Change	0.33%	0.79%	0.85%
Preferred Stock
YoY Change
Treasury Stock (at cost)	$5.461B	$5.291B	$5.146B
YoY Change	3.21%	33.81%	48.09%
Treasury Stock Shares	89.00M shares	86.07M shares	84.03M shares
Shareholders Equity	$8.050B	$7.327B	$7.200B
YoY Change
Total Liabilities & Shareholders Equity	$88.13B	$73.40B	$72.85B
YoY Change	20.06%	3.65%	1.96%

Cashflow Statement

Concept	2020 Q4	2019 Q4	2019 Q3
OPERATING ACTIVITIES
Net Income	$221.0M	$269.0M	$292.0M
YoY Change	-17.84%	-13.23%	-8.18%
Depreciation, Depletion And Amortization	$26.00M	$30.00M	$27.00M
YoY Change	-13.33%	0.0%	-10.0%
Cash From Operating Activities	$208.0M	$221.0M	$444.0M
YoY Change	-5.88%	-65.95%	25.78%
INVESTING ACTIVITIES
Capital Expenditures	-$28.00M	-$24.00M	-$33.00M
YoY Change	16.67%	-4.0%	37.5%
Acquisitions
YoY Change
Other Investing Activities	$56.00M	$1.120B	$264.0M
YoY Change	-95.0%	-196.72%	-65.58%
Cash From Investing Activities	$28.00M	$1.096B	$231.0M
YoY Change	-97.45%	-192.65%	-68.91%
FINANCING ACTIVITIES
Cash Dividend Paid
YoY Change
Common Stock Issuance & Retirement, Net
YoY Change
Debt Paid & Issued, Net
YoY Change
Cash From Financing Activities	4.390B	384.0M	-139.0M
YoY Change	1043.23%	-151.61%	-84.84%
NET CHANGE
Cash From Operating Activities	208.0M	221.0M	444.0M
Cash From Investing Activities	28.00M	1.096B	231.0M
Cash From Financing Activities	4.390B	384.0M	-139.0M
Net Change In Cash	4.626B	1.701B	536.0M
YoY Change	171.96%	-233.1%	199.44%
FREE CASH FLOW
Cash From Operating Activities	$208.0M	$221.0M	$444.0M
Capital Expenditures	-$28.00M	-$24.00M	-$33.00M
Free Cash Flow	$236.0M	$245.0M	$477.0M
YoY Change	-3.67%	-63.65%	26.53%

Facts In Submission

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CY2020	dei	Entity File Number EntityFileNumber	1-10706
CY2020	dei	Entity Registrant Name EntityRegistrantName	Comerica Incorporated
CY2020	dei	Entity Incorporation State Country Code EntityIncorporationStateCountryCode	DE
CY2020	dei	Entity Tax Identification Number EntityTaxIdentificationNumber	38-1998421
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CY2020	dei	Security12b Title Security12bTitle	Common Stock, $5 par value
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CY2020	us-gaap	Bank Owned Life Insurance Income BankOwnedLifeInsuranceIncome	44000000	USD
CY2019	us-gaap	Bank Owned Life Insurance Income BankOwnedLifeInsuranceIncome	41000000	USD
CY2018	us-gaap	Bank Owned Life Insurance Income BankOwnedLifeInsuranceIncome	39000000	USD
CY2020	us-gaap	Foreign Currency Transaction Gain Before Tax ForeignCurrencyTransactionGainBeforeTax	40000000	USD
CY2019	us-gaap	Foreign Currency Transaction Gain Before Tax ForeignCurrencyTransactionGainBeforeTax	44000000	USD
CY2018	us-gaap	Foreign Currency Transaction Gain Before Tax ForeignCurrencyTransactionGainBeforeTax	47000000	USD
CY2020	cma	Letter Of Credit Fees LetterOfCreditFees	37000000	USD
CY2019	cma	Letter Of Credit Fees LetterOfCreditFees	38000000	USD
CY2018	cma	Letter Of Credit Fees LetterOfCreditFees	40000000	USD
CY2020	us-gaap	Brokerage Commissions Revenue BrokerageCommissionsRevenue	21000000	USD
CY2019	us-gaap	Brokerage Commissions Revenue BrokerageCommissionsRevenue	28000000	USD
CY2018	us-gaap	Brokerage Commissions Revenue BrokerageCommissionsRevenue	27000000	USD
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CY2019	us-gaap	Debt And Equity Securities Gain Loss DebtAndEquitySecuritiesGainLoss	-7000000	USD
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CY2019	us-gaap	Noninterest Income Other Operating Income NoninterestIncomeOtherOperatingIncome	109000000	USD
CY2018	us-gaap	Noninterest Income Other Operating Income NoninterestIncomeOtherOperatingIncome	96000000	USD
CY2020	us-gaap	Noninterest Income NoninterestIncome	1001000000	USD
CY2019	us-gaap	Noninterest Income NoninterestIncome	1010000000	USD
CY2018	us-gaap	Noninterest Income NoninterestIncome	976000000	USD
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CY2018	us-gaap	Labor And Related Expense LaborAndRelatedExpense	1009000000	USD
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CY2019	cma	Outside Processing Fee Expense OutsideProcessingFeeExpense	264000000	USD
CY2018	cma	Outside Processing Fee Expense OutsideProcessingFeeExpense	255000000	USD
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CY2019	us-gaap	Occupancy Net OccupancyNet	154000000	USD
CY2018	us-gaap	Occupancy Net OccupancyNet	152000000	USD
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CY2019	cma	Software Expenses SoftwareExpenses	117000000	USD
CY2018	cma	Software Expenses SoftwareExpenses	125000000	USD
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CY2019	us-gaap	Equipment Expense EquipmentExpense	50000000	USD
CY2018	us-gaap	Equipment Expense EquipmentExpense	48000000	USD
CY2020	us-gaap	Advertising Expense AdvertisingExpense	35000000	USD
CY2019	us-gaap	Advertising Expense AdvertisingExpense	34000000	USD
CY2018	us-gaap	Advertising Expense AdvertisingExpense	30000000	USD
CY2020	us-gaap	Federal Deposit Insurance Corporation Premium Expense FederalDepositInsuranceCorporationPremiumExpense	33000000	USD
CY2019	us-gaap	Federal Deposit Insurance Corporation Premium Expense FederalDepositInsuranceCorporationPremiumExpense	23000000	USD
CY2018	us-gaap	Federal Deposit Insurance Corporation Premium Expense FederalDepositInsuranceCorporationPremiumExpense	42000000	USD
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CY2019	us-gaap	Restructuring Charges RestructuringCharges	0	USD
CY2018	us-gaap	Restructuring Charges RestructuringCharges	53000000	USD
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CY2019	us-gaap	Other Noninterest Expense OtherNoninterestExpense	81000000	USD
CY2018	us-gaap	Other Noninterest Expense OtherNoninterestExpense	80000000	USD
CY2020	us-gaap	Noninterest Expense NoninterestExpense	1784000000	USD
CY2019	us-gaap	Noninterest Expense NoninterestExpense	1743000000	USD
CY2018	us-gaap	Noninterest Expense NoninterestExpense	1794000000	USD
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CY2019	cma	Income Loss From Continuing Operations Before Income Taxes IncomeLossFromContinuingOperationsBeforeIncomeTaxes	1532000000	USD
CY2018	cma	Income Loss From Continuing Operations Before Income Taxes IncomeLossFromContinuingOperationsBeforeIncomeTaxes	1535000000	USD
CY2020	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	117000000	USD
CY2019	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	334000000	USD
CY2018	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	300000000	USD
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CY2018	us-gaap	Profit Loss ProfitLoss	1235000000	USD
CY2020	us-gaap	Undistributed Earnings Loss Allocated To Participating Securities Diluted UndistributedEarningsLossAllocatedToParticipatingSecuritiesDiluted	2000000	USD
CY2019	us-gaap	Undistributed Earnings Loss Allocated To Participating Securities Diluted UndistributedEarningsLossAllocatedToParticipatingSecuritiesDiluted	7000000	USD
CY2018	us-gaap	Undistributed Earnings Loss Allocated To Participating Securities Diluted UndistributedEarningsLossAllocatedToParticipatingSecuritiesDiluted	8000000	USD
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CY2018	us-gaap	Dividends Preferred Stock Stock DividendsPreferredStockStock	0	USD
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CY2019	us-gaap	Net Income Loss Available To Common Stockholders Basic NetIncomeLossAvailableToCommonStockholdersBasic	1191000000	USD
CY2018	us-gaap	Net Income Loss Available To Common Stockholders Basic NetIncomeLossAvailableToCommonStockholdersBasic	1227000000	USD
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CY2018	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	7.20
CY2020	us-gaap	Dividends Common Stock Cash DividendsCommonStockCash	378000000	USD
CY2019	us-gaap	Dividends Common Stock Cash DividendsCommonStockCash	398000000	USD
CY2018	us-gaap	Dividends Common Stock Cash DividendsCommonStockCash	309000000	USD
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CY2018	us-gaap	Common Stock Dividends Per Share Declared CommonStockDividendsPerShareDeclared	1.84
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CY2018	us-gaap	Profit Loss ProfitLoss	1235000000	USD
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CY2019	us-gaap	Other Comprehensive Income Unrealized Gain Loss On Derivatives Arising During Period Before Tax OtherComprehensiveIncomeUnrealizedGainLossOnDerivativesArisingDuringPeriodBeforeTax	257000000	USD
CY2018	us-gaap	Other Comprehensive Income Unrealized Gain Loss On Derivatives Arising During Period Before Tax OtherComprehensiveIncomeUnrealizedGainLossOnDerivativesArisingDuringPeriodBeforeTax	-69000000	USD
CY2020	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci For Sale Of Securities Before Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIForSaleOfSecuritiesBeforeTax	0	USD
CY2019	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci For Sale Of Securities Before Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIForSaleOfSecuritiesBeforeTax	-8000000	USD
CY2018	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci For Sale Of Securities Before Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIForSaleOfSecuritiesBeforeTax	-20000000	USD
CY2020	us-gaap	Other Comprehensive Income Loss Available For Sale Securities Adjustment Before Tax OtherComprehensiveIncomeLossAvailableForSaleSecuritiesAdjustmentBeforeTax	191000000	USD
CY2019	us-gaap	Other Comprehensive Income Loss Available For Sale Securities Adjustment Before Tax OtherComprehensiveIncomeLossAvailableForSaleSecuritiesAdjustmentBeforeTax	265000000	USD
CY2018	us-gaap	Other Comprehensive Income Loss Available For Sale Securities Adjustment Before Tax OtherComprehensiveIncomeLossAvailableForSaleSecuritiesAdjustmentBeforeTax	-49000000	USD
CY2020	us-gaap	Gain Loss On Cash Flow Hedge Ineffectiveness Net GainLossOnCashFlowHedgeIneffectivenessNet	229000000	USD
CY2019	us-gaap	Gain Loss On Cash Flow Hedge Ineffectiveness Net GainLossOnCashFlowHedgeIneffectivenessNet	44000000	USD
CY2018	us-gaap	Other Comprehensive Income Unrealized Gain Loss On Derivatives Arising During Period Tax OtherComprehensiveIncomeUnrealizedGainLossOnDerivativesArisingDuringPeriodTax	0	USD
CY2020	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci On Derivatives Before Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIOnDerivativesBeforeTax	70000000	USD
CY2019	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci On Derivatives Before Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIOnDerivativesBeforeTax	0	USD
CY2018	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci On Derivatives Before Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIOnDerivativesBeforeTax	0	USD
CY2020	us-gaap	Other Comprehensive Income Loss Derivatives Qualifying As Hedges Before Tax OtherComprehensiveIncomeLossDerivativesQualifyingAsHedgesBeforeTax	159000000	USD
CY2019	us-gaap	Other Comprehensive Income Loss Derivatives Qualifying As Hedges Before Tax OtherComprehensiveIncomeLossDerivativesQualifyingAsHedgesBeforeTax	44000000	USD
CY2018	us-gaap	Other Comprehensive Income Loss Derivatives Qualifying As Hedges Before Tax OtherComprehensiveIncomeLossDerivativesQualifyingAsHedgesBeforeTax	0	USD
CY2020	us-gaap	Other Comprehensive Income Loss Pension And Other Postretirement Benefit Plans Net Unamortized Gain Loss Arising During Period Before Tax OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansNetUnamortizedGainLossArisingDuringPeriodBeforeTax	142000000	USD
CY2019	us-gaap	Other Comprehensive Income Loss Pension And Other Postretirement Benefit Plans Net Unamortized Gain Loss Arising During Period Before Tax OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansNetUnamortizedGainLossArisingDuringPeriodBeforeTax	163000000	USD
CY2018	us-gaap	Other Comprehensive Income Loss Pension And Other Postretirement Benefit Plans Net Unamortized Gain Loss Arising During Period Before Tax OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansNetUnamortizedGainLossArisingDuringPeriodBeforeTax	-191000000	USD
CY2020	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci Pension And Other Postretirement Benefit Plans For Net Gain Loss Before Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetGainLossBeforeTax	63000000	USD
CY2019	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci Pension And Other Postretirement Benefit Plans For Net Gain Loss Before Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetGainLossBeforeTax	42000000	USD
CY2018	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci Pension And Other Postretirement Benefit Plans For Net Gain Loss Before Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetGainLossBeforeTax	61000000	USD
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CY2019	us-gaap	Other Comprehensive Income Loss Amortization Adjustment From Aoci Pension And Other Postretirement Benefit Plans For Net Prior Service Cost Credit Before Tax OtherComprehensiveIncomeLossAmortizationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetPriorServiceCostCreditBeforeTax	-27000000	USD
CY2018	us-gaap	Other Comprehensive Income Loss Amortization Adjustment From Aoci Pension And Other Postretirement Benefit Plans For Net Prior Service Cost Credit Before Tax OtherComprehensiveIncomeLossAmortizationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetPriorServiceCostCreditBeforeTax	-27000000	USD
CY2020	us-gaap	Other Comprehensive Income Loss Pension And Other Postretirement Benefit Plans Adjustment Before Tax OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansAdjustmentBeforeTax	-178000000	USD
CY2019	us-gaap	Other Comprehensive Income Loss Pension And Other Postretirement Benefit Plans Adjustment Before Tax OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansAdjustmentBeforeTax	-178000000	USD
CY2018	us-gaap	Other Comprehensive Income Loss Pension And Other Postretirement Benefit Plans Adjustment Before Tax OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansAdjustmentBeforeTax	157000000	USD
CY2020	us-gaap	Other Comprehensive Income Loss Before Tax OtherComprehensiveIncomeLossBeforeTax	528000000	USD
CY2019	us-gaap	Other Comprehensive Income Loss Before Tax OtherComprehensiveIncomeLossBeforeTax	487000000	USD
CY2018	us-gaap	Other Comprehensive Income Loss Before Tax OtherComprehensiveIncomeLossBeforeTax	-206000000	USD
CY2020	us-gaap	Other Comprehensive Income Loss Tax OtherComprehensiveIncomeLossTax	125000000	USD
CY2019	us-gaap	Other Comprehensive Income Loss Tax OtherComprehensiveIncomeLossTax	113000000	USD
CY2018	us-gaap	Other Comprehensive Income Loss Tax OtherComprehensiveIncomeLossTax	-47000000	USD
CY2020	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	403000000	USD
CY2019	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	374000000	USD
CY2018	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	-159000000	USD
CY2020	us-gaap	Comprehensive Income Net Of Tax Including Portion Attributable To Noncontrolling Interest ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest	877000000	USD
CY2019	us-gaap	Comprehensive Income Net Of Tax Including Portion Attributable To Noncontrolling Interest ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest	1572000000	USD
CY2018	us-gaap	Comprehensive Income Net Of Tax Including Portion Attributable To Noncontrolling Interest ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest	1076000000	USD
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CY2018	us-gaap	Profit Loss ProfitLoss	1235000000	USD
CY2018	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	-159000000	USD
CY2018	us-gaap	Dividends Common Stock Cash DividendsCommonStockCash	309000000	USD
CY2018	us-gaap	Treasury Stock Value Acquired Cost Method TreasuryStockValueAcquiredCostMethod	1329000000	USD
CY2018	us-gaap	Stock Issued During Period Value Share Based Compensation StockIssuedDuringPeriodValueShareBasedCompensation	-43000000	USD
CY2018	cma	Stock Issued During Period Value Warrants Exercised StockIssuedDuringPeriodValueWarrantsExercised	0	USD
CY2018	us-gaap	Adjustments To Additional Paid In Capital Sharebased Compensation Requisite Service Period Recognition Value AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue	48000000	USD
CY2018Q4	us-gaap	Stockholders Equity Including Portion Attributable To Noncontrolling Interest StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest	7507000000	USD
CY2019	cma	Cumulative Effect Of Change In Accounting Principle CumulativeEffectOfChangeInAccountingPrinciple	-14000000	USD
CY2019	us-gaap	Profit Loss ProfitLoss	1198000000	USD
CY2019	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	374000000	USD
CY2019	us-gaap	Dividends Common Stock Cash DividendsCommonStockCash	398000000	USD
CY2019	us-gaap	Treasury Stock Value Acquired Cost Method TreasuryStockValueAcquiredCostMethod	1380000000	USD
CY2019	us-gaap	Stock Issued During Period Value Share Based Compensation StockIssuedDuringPeriodValueShareBasedCompensation	-1000000	USD
CY2019	us-gaap	Adjustments To Additional Paid In Capital Sharebased Compensation Requisite Service Period Recognition Value AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue	39000000	USD
CY2019Q4	us-gaap	Stockholders Equity Including Portion Attributable To Noncontrolling Interest StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest	7327000000	USD
CY2020	cma	Cumulative Effect Of Change In Accounting Principle CumulativeEffectOfChangeInAccountingPrinciple	13000000	USD
CY2020	us-gaap	Profit Loss ProfitLoss	474000000	USD
CY2020	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	403000000	USD
CY2020	us-gaap	Dividends Common Stock Cash DividendsCommonStockCash	378000000	USD
CY2020	us-gaap	Dividends Preferred Stock Cash DividendsPreferredStockCash	13000000	USD
CY2020	us-gaap	Treasury Stock Value Acquired Cost Method TreasuryStockValueAcquiredCostMethod	194000000	USD
CY2020	us-gaap	Stock And Warrants Issued During Period Value Preferred Stock And Warrants StockAndWarrantsIssuedDuringPeriodValuePreferredStockAndWarrants	394000000	USD
CY2020	us-gaap	Stock Issued During Period Value Share Based Compensation StockIssuedDuringPeriodValueShareBasedCompensation	0	USD
CY2020	us-gaap	Adjustments To Additional Paid In Capital Sharebased Compensation Requisite Service Period Recognition Value AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue	24000000	USD
CY2020Q4	us-gaap	Stockholders Equity Including Portion Attributable To Noncontrolling Interest StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest	8050000000	USD
CY2020	us-gaap	Profit Loss ProfitLoss	474000000	USD
CY2019	us-gaap	Profit Loss ProfitLoss	1198000000	USD
CY2018	us-gaap	Profit Loss ProfitLoss	1235000000	USD
CY2020	us-gaap	Provision For Loan Lease And Other Losses ProvisionForLoanLeaseAndOtherLosses	537000000	USD
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CY2020	us-gaap	Deferred Income Tax Expense Benefit DeferredIncomeTaxExpenseBenefit	-89000000	USD
CY2019	us-gaap	Deferred Income Tax Expense Benefit DeferredIncomeTaxExpenseBenefit	12000000	USD
CY2018	us-gaap	Deferred Income Tax Expense Benefit DeferredIncomeTaxExpenseBenefit	24000000	USD
CY2020	us-gaap	Depreciation And Amortization DepreciationAndAmortization	108000000	USD
CY2019	us-gaap	Depreciation And Amortization DepreciationAndAmortization	114000000	USD
CY2018	us-gaap	Depreciation And Amortization DepreciationAndAmortization	120000000	USD
CY2020	us-gaap	Defined Benefit Plan Net Periodic Benefit Cost DefinedBenefitPlanNetPeriodicBenefitCost	-25000000	USD
CY2019	us-gaap	Defined Benefit Plan Net Periodic Benefit Cost DefinedBenefitPlanNetPeriodicBenefitCost	-29000000	USD
CY2018	us-gaap	Defined Benefit Plan Net Periodic Benefit Cost DefinedBenefitPlanNetPeriodicBenefitCost	-18000000	USD
CY2020	us-gaap	Share Based Compensation ShareBasedCompensation	24000000	USD
CY2019	us-gaap	Share Based Compensation ShareBasedCompensation	39000000	USD
CY2018	us-gaap	Share Based Compensation ShareBasedCompensation	48000000	USD
CY2020	us-gaap	Accretion Amortization Of Discounts And Premiums Investments AccretionAmortizationOfDiscountsAndPremiumsInvestments	-15000000	USD
CY2019	us-gaap	Accretion Amortization Of Discounts And Premiums Investments AccretionAmortizationOfDiscountsAndPremiumsInvestments	-2000000	USD
CY2018	us-gaap	Accretion Amortization Of Discounts And Premiums Investments AccretionAmortizationOfDiscountsAndPremiumsInvestments	-3000000	USD
CY2020	cma	Accretion Of Discount On Receivables Acquired In Transfer AccretionOfDiscountOnReceivablesAcquiredInTransfer	0	USD
CY2019	cma	Accretion Of Discount On Receivables Acquired In Transfer AccretionOfDiscountOnReceivablesAcquiredInTransfer	0	USD
CY2018	cma	Accretion Of Discount On Receivables Acquired In Transfer AccretionOfDiscountOnReceivablesAcquiredInTransfer	1000000	USD
CY2020	us-gaap	Debt And Equity Securities Gain Loss DebtAndEquitySecuritiesGainLoss	0	USD
CY2019	us-gaap	Debt And Equity Securities Gain Loss DebtAndEquitySecuritiesGainLoss	-7000000	USD
CY2018	us-gaap	Debt And Equity Securities Gain Loss DebtAndEquitySecuritiesGainLoss	-19000000	USD
CY2020	us-gaap	Gains Losses On Sales Of Other Real Estate GainsLossesOnSalesOfOtherRealEstate	1000000	USD
CY2019	us-gaap	Gains Losses On Sales Of Other Real Estate GainsLossesOnSalesOfOtherRealEstate	-1000000	USD
CY2018	us-gaap	Gains Losses On Sales Of Other Real Estate GainsLossesOnSalesOfOtherRealEstate	1000000	USD
CY2020	us-gaap	Increase Decrease In Interest And Dividends Receivable IncreaseDecreaseInInterestAndDividendsReceivable	-25000000	USD
CY2019	us-gaap	Increase Decrease In Interest And Dividends Receivable IncreaseDecreaseInInterestAndDividendsReceivable	-17000000	USD
CY2018	us-gaap	Increase Decrease In Interest And Dividends Receivable IncreaseDecreaseInInterestAndDividendsReceivable	45000000	USD
CY2020	us-gaap	Increase Decrease In Accrued Liabilities IncreaseDecreaseInAccruedLiabilities	-29000000	USD
CY2019	us-gaap	Increase Decrease In Accrued Liabilities IncreaseDecreaseInAccruedLiabilities	-27000000	USD
CY2018	us-gaap	Increase Decrease In Accrued Liabilities IncreaseDecreaseInAccruedLiabilities	49000000	USD
CY2020	us-gaap	Increase Decrease In Other Operating Capital Net IncreaseDecreaseInOtherOperatingCapitalNet	111000000	USD
CY2019	us-gaap	Increase Decrease In Other Operating Capital Net IncreaseDecreaseInOtherOperatingCapitalNet	318000000	USD
CY2018	us-gaap	Increase Decrease In Other Operating Capital Net IncreaseDecreaseInOtherOperatingCapitalNet	-184000000	USD
CY2020	us-gaap	Net Cash Provided By Used In Operating Activities NetCashProvidedByUsedInOperatingActivities	928000000	USD
CY2019	us-gaap	Net Cash Provided By Used In Operating Activities NetCashProvidedByUsedInOperatingActivities	1090000000	USD
CY2018	us-gaap	Net Cash Provided By Used In Operating Activities NetCashProvidedByUsedInOperatingActivities	1616000000	USD
CY2020	us-gaap	Proceeds From Maturities Prepayments And Calls Of Available For Sale Securities ProceedsFromMaturitiesPrepaymentsAndCallsOfAvailableForSaleSecurities	3350000000	USD
CY2019	us-gaap	Proceeds From Maturities Prepayments And Calls Of Available For Sale Securities ProceedsFromMaturitiesPrepaymentsAndCallsOfAvailableForSaleSecurities	2262000000	USD
CY2018	us-gaap	Proceeds From Maturities Prepayments And Calls Of Available For Sale Securities ProceedsFromMaturitiesPrepaymentsAndCallsOfAvailableForSaleSecurities	1781000000	USD
CY2020	us-gaap	Proceeds From Sale Of Available For Sale Securities ProceedsFromSaleOfAvailableForSaleSecurities	0	USD
CY2019	us-gaap	Proceeds From Sale Of Available For Sale Securities ProceedsFromSaleOfAvailableForSaleSecurities	987000000	USD
CY2018	us-gaap	Proceeds From Sale Of Available For Sale Securities ProceedsFromSaleOfAvailableForSaleSecurities	1256000000	USD
CY2020	us-gaap	Payments To Acquire Available For Sale Securities PaymentsToAcquireAvailableForSaleSecurities	5804000000	USD
CY2019	us-gaap	Payments To Acquire Available For Sale Securities PaymentsToAcquireAvailableForSaleSecurities	3346000000	USD
CY2018	us-gaap	Payments To Acquire Available For Sale Securities PaymentsToAcquireAvailableForSaleSecurities	3032000000	USD
CY2020	us-gaap	Payments For Proceeds From Loans And Leases PaymentsForProceedsFromLoansAndLeases	2136000000	USD
CY2019	us-gaap	Payments For Proceeds From Loans And Leases PaymentsForProceedsFromLoansAndLeases	324000000	USD
CY2018	us-gaap	Payments For Proceeds From Loans And Leases PaymentsForProceedsFromLoansAndLeases	1045000000	USD
CY2020	us-gaap	Proceeds From Sale Of Foreclosed Assets ProceedsFromSaleOfForeclosedAssets	5000000	USD
CY2019	us-gaap	Proceeds From Sale Of Foreclosed Assets ProceedsFromSaleOfForeclosedAssets	1000000	USD
CY2018	us-gaap	Proceeds From Sale Of Foreclosed Assets ProceedsFromSaleOfForeclosedAssets	8000000	USD
CY2020	cma	Net Increase In Fixed Assets NetIncreaseInFixedAssets	79000000	USD
CY2019	cma	Net Increase In Fixed Assets NetIncreaseInFixedAssets	86000000	USD
CY2018	cma	Net Increase In Fixed Assets NetIncreaseInFixedAssets	90000000	USD
CY2020	us-gaap	Payments To Acquire Federal Home Loan Bank Stock PaymentsToAcquireFederalHomeLoanBankStock	51000000	USD
CY2019	us-gaap	Payments To Acquire Federal Home Loan Bank Stock PaymentsToAcquireFederalHomeLoanBankStock	201000000	USD
CY2018	us-gaap	Payments To Acquire Federal Home Loan Bank Stock PaymentsToAcquireFederalHomeLoanBankStock	41000000	USD
CY2020	us-gaap	Proceeds From Sale Of Federal Home Loan Bank Stock ProceedsFromSaleOfFederalHomeLoanBankStock	92000000	USD
CY2019	us-gaap	Proceeds From Sale Of Federal Home Loan Bank Stock ProceedsFromSaleOfFederalHomeLoanBankStock	201000000	USD
CY2018	us-gaap	Proceeds From Sale Of Federal Home Loan Bank Stock ProceedsFromSaleOfFederalHomeLoanBankStock	0	USD
CY2020	us-gaap	Proceeds From Life Insurance Policies ProceedsFromLifeInsurancePolicies	20000000	USD
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CY2018	us-gaap	Proceeds From Life Insurance Policies ProceedsFromLifeInsurancePolicies	9000000	USD
CY2020	cma	Increase Decrease In Other Investing Assets And Liabilities Net IncreaseDecreaseInOtherInvestingAssetsAndLiabilitiesNet	-1000000	USD
CY2019	cma	Increase Decrease In Other Investing Assets And Liabilities Net IncreaseDecreaseInOtherInvestingAssetsAndLiabilitiesNet	-2000000	USD
CY2018	cma	Increase Decrease In Other Investing Assets And Liabilities Net IncreaseDecreaseInOtherInvestingAssetsAndLiabilitiesNet	2000000	USD
CY2020	us-gaap	Net Cash Provided By Used In Investing Activities NetCashProvidedByUsedInInvestingActivities	4602000000	USD
CY2019	us-gaap	Net Cash Provided By Used In Investing Activities NetCashProvidedByUsedInInvestingActivities	494000000	USD
CY2018	us-gaap	Net Cash Provided By Used In Investing Activities NetCashProvidedByUsedInInvestingActivities	1156000000	USD
CY2020	us-gaap	Increase Decrease In Deposits IncreaseDecreaseInDeposits	15554000000	USD
CY2019	us-gaap	Increase Decrease In Deposits IncreaseDecreaseInDeposits	1711000000	USD
CY2018	us-gaap	Increase Decrease In Deposits IncreaseDecreaseInDeposits	-2082000000	USD
CY2020	us-gaap	Proceeds From Repayments Of Short Term Debt ProceedsFromRepaymentsOfShortTermDebt	-71000000	USD
CY2019	us-gaap	Proceeds From Repayments Of Short Term Debt ProceedsFromRepaymentsOfShortTermDebt	27000000	USD
CY2018	us-gaap	Proceeds From Repayments Of Short Term Debt ProceedsFromRepaymentsOfShortTermDebt	34000000	USD
CY2020	us-gaap	Repayments Of Debt RepaymentsOfDebt	1675000000	USD
CY2019	us-gaap	Repayments Of Debt RepaymentsOfDebt	350000000	USD
CY2018	us-gaap	Repayments Of Debt RepaymentsOfDebt	0	USD
CY2020	us-gaap	Proceeds From Issuance Of Long Term Debt ProceedsFromIssuanceOfLongTermDebt	0	USD
CY2019	us-gaap	Proceeds From Issuance Of Long Term Debt ProceedsFromIssuanceOfLongTermDebt	1050000000	USD
CY2018	us-gaap	Proceeds From Issuance Of Long Term Debt ProceedsFromIssuanceOfLongTermDebt	1850000000	USD
CY2020	us-gaap	Stock And Warrants Issued During Period Value Preferred Stock And Warrants StockAndWarrantsIssuedDuringPeriodValuePreferredStockAndWarrants	394000000	USD
CY2019	us-gaap	Stock And Warrants Issued During Period Value Preferred Stock And Warrants StockAndWarrantsIssuedDuringPeriodValuePreferredStockAndWarrants	0	USD
CY2018	us-gaap	Stock And Warrants Issued During Period Value Preferred Stock And Warrants StockAndWarrantsIssuedDuringPeriodValuePreferredStockAndWarrants	0	USD
CY2020	us-gaap	Payments Of Dividends Preferred Stock And Preference Stock PaymentsOfDividendsPreferredStockAndPreferenceStock	8000000	USD
CY2019	us-gaap	Payments Of Dividends Preferred Stock And Preference Stock PaymentsOfDividendsPreferredStockAndPreferenceStock	0	USD
CY2018	us-gaap	Payments Of Dividends Preferred Stock And Preference Stock PaymentsOfDividendsPreferredStockAndPreferenceStock	0	USD
CY2020	us-gaap	Payments For Repurchase Of Common Stock PaymentsForRepurchaseOfCommonStock	199000000	USD
CY2019	us-gaap	Payments For Repurchase Of Common Stock PaymentsForRepurchaseOfCommonStock	1394000000	USD
CY2018	us-gaap	Payments For Repurchase Of Common Stock PaymentsForRepurchaseOfCommonStock	1338000000	USD
CY2020	us-gaap	Payments Of Dividends Common Stock PaymentsOfDividendsCommonStock	375000000	USD
CY2019	us-gaap	Payments Of Dividends Common Stock PaymentsOfDividendsCommonStock	402000000	USD
CY2018	us-gaap	Payments Of Dividends Common Stock PaymentsOfDividendsCommonStock	263000000	USD
CY2020	us-gaap	Proceeds From Issuance Of Common Stock ProceedsFromIssuanceOfCommonStock	4000000	USD
CY2019	us-gaap	Proceeds From Issuance Of Common Stock ProceedsFromIssuanceOfCommonStock	18000000	USD
CY2018	us-gaap	Proceeds From Issuance Of Common Stock ProceedsFromIssuanceOfCommonStock	52000000	USD
CY2020	cma	Increase Decrease In Other Financing Assets And Liabilities Net IncreaseDecreaseInOtherFinancingAssetsAndLiabilitiesNet	1000000	USD
CY2019	cma	Increase Decrease In Other Financing Assets And Liabilities Net IncreaseDecreaseInOtherFinancingAssetsAndLiabilitiesNet	-1000000	USD
CY2018	cma	Increase Decrease In Other Financing Assets And Liabilities Net IncreaseDecreaseInOtherFinancingAssetsAndLiabilitiesNet	-3000000	USD
CY2020	us-gaap	Net Cash Provided By Used In Financing Activities NetCashProvidedByUsedInFinancingActivities	13623000000	USD
CY2019	us-gaap	Net Cash Provided By Used In Financing Activities NetCashProvidedByUsedInFinancingActivities	661000000	USD
CY2018	us-gaap	Net Cash Provided By Used In Financing Activities NetCashProvidedByUsedInFinancingActivities	-1744000000	USD
CY2020	us-gaap	Cash And Cash Equivalents Period Increase Decrease CashAndCashEquivalentsPeriodIncreaseDecrease	9949000000	USD
CY2019	us-gaap	Cash And Cash Equivalents Period Increase Decrease CashAndCashEquivalentsPeriodIncreaseDecrease	1257000000	USD
CY2018	us-gaap	Cash And Cash Equivalents Period Increase Decrease CashAndCashEquivalentsPeriodIncreaseDecrease	-1284000000	USD
CY2019Q4	us-gaap	Cash And Cash Equivalents At Carrying Value CashAndCashEquivalentsAtCarryingValue	5818000000	USD
CY2018Q4	us-gaap	Cash And Cash Equivalents At Carrying Value CashAndCashEquivalentsAtCarryingValue	4561000000	USD
CY2017Q4	us-gaap	Cash And Cash Equivalents At Carrying Value CashAndCashEquivalentsAtCarryingValue	5845000000	USD
CY2020Q4	us-gaap	Cash And Cash Equivalents At Carrying Value CashAndCashEquivalentsAtCarryingValue	15767000000	USD
CY2019Q4	us-gaap	Cash And Cash Equivalents At Carrying Value CashAndCashEquivalentsAtCarryingValue	5818000000	USD
CY2018Q4	us-gaap	Cash And Cash Equivalents At Carrying Value CashAndCashEquivalentsAtCarryingValue	4561000000	USD
CY2020	us-gaap	Interest Paid InterestPaid	203000000	USD
CY2019	us-gaap	Interest Paid InterestPaid	462000000	USD
CY2018	us-gaap	Interest Paid InterestPaid	261000000	USD
CY2020	us-gaap	Income Taxes Paid Net IncomeTaxesPaidNet	141000000	USD
CY2019	us-gaap	Income Taxes Paid Net IncomeTaxesPaidNet	266000000	USD
CY2018	us-gaap	Income Taxes Paid Net IncomeTaxesPaidNet	200000000	USD
CY2020	us-gaap	Transfer To Other Real Estate TransferToOtherRealEstate	1000000	USD
CY2019	us-gaap	Transfer To Other Real Estate TransferToOtherRealEstate	12000000	USD
CY2018	us-gaap	Transfer To Other Real Estate TransferToOtherRealEstate	3000000	USD
CY2020	us-gaap	Debt Securities Held To Maturity Transfer Amount DebtSecuritiesHeldToMaturityTransferAmount	0	USD
CY2019	us-gaap	Debt Securities Held To Maturity Transfer Amount DebtSecuritiesHeldToMaturityTransferAmount	0	USD
CY2018	us-gaap	Debt Securities Held To Maturity Transfer Amount DebtSecuritiesHeldToMaturityTransferAmount	1266000000	USD
CY2020	cma	Transfer Of Available For Sale Securities To Held To Maturity Securities TransferOfAvailableForSaleSecuritiesToHeldToMaturitySecurities	0	USD
CY2019	cma	Transfer Of Available For Sale Securities To Held To Maturity Securities TransferOfAvailableForSaleSecuritiesToHeldToMaturitySecurities	0	USD
CY2018	cma	Transfer Of Available For Sale Securities To Held To Maturity Securities TransferOfAvailableForSaleSecuritiesToHeldToMaturitySecurities	81000000	USD
CY2020	cma	Number Of Geographic Markets NumberOfGeographicMarkets	3	markets
CY2020Q4	us-gaap	Fair Value Investments Entities That Calculate Net Asset Value Per Share Unfunded Committments FairValueInvestmentsEntitiesThatCalculateNetAssetValuePerShareUnfundedCommittments	1000000	USD
CY2020Q4	us-gaap	Federal Home Loan Bank Stock FederalHomeLoanBankStock	122000000	USD
CY2019Q4	us-gaap	Federal Home Loan Bank Stock FederalHomeLoanBankStock	163000000	USD
CY2020Q4	us-gaap	Federal Reserve Bank Stock FederalReserveBankStock	85000000	USD
CY2019Q4	us-gaap	Federal Reserve Bank Stock FederalReserveBankStock	85000000	USD
CY2020Q4	us-gaap	Loans And Leases Receivable Deferred Income LoansAndLeasesReceivableDeferredIncome	145000000	USD
CY2019Q4	us-gaap	Loans And Leases Receivable Deferred Income LoansAndLeasesReceivableDeferredIncome	103000000	USD
CY2020Q4	cma	Net Fees From Ppp Loans NetFeesFromPPPLoans	55000000	USD
CY2019Q4	cma	Overallallowanceforcreditlosses Overallallowanceforcreditlosses	668000000	USD
CY2020Q1	cma	Businessloanspercentofportfolio Businessloanspercentofportfolio	0.91
CY2020Q1	cma	Reductioninbusinessloansallowanceforcreditlosses Reductioninbusinessloansallowanceforcreditlosses	42000000	USD
CY2020Q1	cma	Increaseinretailloansallowanceforcreditlosses Increaseinretailloansallowanceforcreditlosses	25000000	USD
CY2020Q4	us-gaap	Hosting Arrangement Service Contract Implementation Cost Capitalized After Accumulated Amortization HostingArrangementServiceContractImplementationCostCapitalizedAfterAccumulatedAmortization	2000000	USD
CY2020	us-gaap	Hosting Arrangement Service Contract Implementation Cost Expense Amortization HostingArrangementServiceContractImplementationCostExpenseAmortization	33000000	USD
CY2020	cma	Number Of Major Business Segments NumberOfMajorBusinessSegments	3	segments
CY2020	us-gaap	Guarantees Indemnifications And Warranties Policies GuaranteesIndemnificationsAndWarrantiesPolicies	<div style="margin-top:6pt;text-align:justify"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:700;line-height:120%">Financial Guarantees</span></div><div style="margin-top:6pt;text-align:justify;text-indent:36pt"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%">Certain guarantee contracts or indemnification agreements that contingently require the Corporation, as guarantor, to make payments to the guaranteed party are initially measured at fair value and included in accrued expenses and other liabilities on the Consolidated Balance Sheets. The subsequent accounting for the liability depends on the nature of the underlying guarantee. The release from risk is accounted for under a particular guarantee when the guarantee expires or is settled, or by a systematic and rational amortization method.</span></div><div style="margin-top:6pt;text-align:justify;text-indent:36pt"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%">Further information on the Corporation’s obligations under guarantees is included in Note 8.</span></div>
CY2020	cma	Defined Benefit Plan Investment Gain Loss Amortization Adjustment Allowable Percentage DefinedBenefitPlanInvestmentGainLossAmortizationAdjustmentAllowablePercentage	0.10
CY2020	cma	Defined Benefit Plan Actuarial Gain Loss Amortization Adjustment Allowable Percentage DefinedBenefitPlanActuarialGainLossAmortizationAdjustmentAllowablePercentage	0.10
CY2020Q4	us-gaap	Available For Sale Securities Amortized Cost AvailableForSaleSecuritiesAmortizedCost	14752000000	USD
CY2020Q4	us-gaap	Available For Sale Securities Accumulated Gross Unrealized Gain Before Tax AvailableForSaleSecuritiesAccumulatedGrossUnrealizedGainBeforeTax	279000000	USD
CY2020Q4	us-gaap	Available For Sale Securities Accumulated Gross Unrealized Loss Before Tax AvailableForSaleSecuritiesAccumulatedGrossUnrealizedLossBeforeTax	3000000	USD
CY2020Q4	us-gaap	Available For Sale Securities AvailableForSaleSecurities	15028000000	USD
CY2019Q4	us-gaap	Available For Sale Securities Amortized Cost AvailableForSaleSecuritiesAmortizedCost	12313000000	USD
CY2019Q4	us-gaap	Available For Sale Securities Accumulated Gross Unrealized Gain Before Tax AvailableForSaleSecuritiesAccumulatedGrossUnrealizedGainBeforeTax	113000000	USD
CY2019Q4	us-gaap	Available For Sale Securities Accumulated Gross Unrealized Loss Before Tax AvailableForSaleSecuritiesAccumulatedGrossUnrealizedLossBeforeTax	28000000	USD
CY2019Q4	us-gaap	Available For Sale Securities AvailableForSaleSecurities	12398000000	USD
CY2020Q4	us-gaap	Available For Sale Securities Continuous Unrealized Loss Position Less Than Twelve Months Fair Value AvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThanTwelveMonthsFairValue	2071000000	USD
CY2020Q4	us-gaap	Available For Sale Securities Continuous Unrealized Loss Position Less Than12 Months Accumulated Loss AvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThan12MonthsAccumulatedLoss	3000000	USD
CY2020Q4	us-gaap	Available For Sale Securities Continuous Unrealized Loss Position Twelve Months Or Longer Fair Value AvailableForSaleSecuritiesContinuousUnrealizedLossPositionTwelveMonthsOrLongerFairValue	0	USD
CY2020Q4	us-gaap	Available For Sale Securities Continuous Unrealized Loss Position12 Months Or Longer Accumulated Loss AvailableForSaleSecuritiesContinuousUnrealizedLossPosition12MonthsOrLongerAccumulatedLoss	0	USD
CY2020Q4	us-gaap	Available For Sale Securities Continuous Unrealized Loss Position Fair Value AvailableForSaleSecuritiesContinuousUnrealizedLossPositionFairValue	2071000000	USD
CY2020Q4	us-gaap	Available For Sale Securities Continuous Unrealized Loss Position Accumulated Loss AvailableForSaleSecuritiesContinuousUnrealizedLossPositionAccumulatedLoss	3000000	USD
CY2019Q4	us-gaap	Available For Sale Securities Continuous Unrealized Loss Position Less Than Twelve Months Fair Value AvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThanTwelveMonthsFairValue	1494000000	USD
CY2019Q4	us-gaap	Available For Sale Securities Continuous Unrealized Loss Position Less Than12 Months Accumulated Loss AvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThan12MonthsAccumulatedLoss	7000000	USD
CY2019Q4	us-gaap	Available For Sale Securities Continuous Unrealized Loss Position Twelve Months Or Longer Fair Value AvailableForSaleSecuritiesContinuousUnrealizedLossPositionTwelveMonthsOrLongerFairValue	1906000000	USD
CY2019Q4	us-gaap	Available For Sale Securities Continuous Unrealized Loss Position12 Months Or Longer Accumulated Loss AvailableForSaleSecuritiesContinuousUnrealizedLossPosition12MonthsOrLongerAccumulatedLoss	21000000	USD
CY2019Q4	us-gaap	Available For Sale Securities Continuous Unrealized Loss Position Fair Value AvailableForSaleSecuritiesContinuousUnrealizedLossPositionFairValue	3400000000	USD
CY2019Q4	us-gaap	Available For Sale Securities Continuous Unrealized Loss Position Accumulated Loss AvailableForSaleSecuritiesContinuousUnrealizedLossPositionAccumulatedLoss	28000000	USD
CY2020Q4	us-gaap	Availableforsale Securities In Unrealized Loss Positions Qualitative Disclosure Number Of Positions1 AvailableforsaleSecuritiesInUnrealizedLossPositionsQualitativeDisclosureNumberOfPositions1	32
CY2019	cma	Repositioningloweryieldingtreasurysecurities Repositioningloweryieldingtreasurysecurities	1000000000.0	USD
CY2018	cma	Repositioningloweryieldingtreasurysecurities Repositioningloweryieldingtreasurysecurities	1300000000	USD
CY2020Q4	us-gaap	Debt Securities Available For Sale Restricted DebtSecuritiesAvailableForSaleRestricted	5100000000	USD
CY2020Q4	us-gaap	Financial Instruments Owned And Pledged As Collateral At Fair Value FinancialInstrumentsOwnedAndPledgedAsCollateralAtFairValue	4400000000	USD
CY2020Q4	us-gaap	Debt Instrument Unused Borrowing Capacity Amount DebtInstrumentUnusedBorrowingCapacityAmount	4200000000	USD
CY2020Q4	us-gaap	Securities Borrowed Liability SecuritiesBorrowedLiability	646000000	USD
CY2020Q4	cma	Liabilities Secured By Pledged Securities LiabilitiesSecuredByPledgedSecurities	488000000	USD
CY2020Q4	cma	Loans Past Due And Still Accruing LoansPastDueAndStillAccruing	449000000	USD
CY2020Q4	us-gaap	Loans And Leases Receivable Impaired Nonperforming Nonaccrual Of Interest LoansAndLeasesReceivableImpairedNonperformingNonaccrualOfInterest	347000000	USD
CY2020Q4	cma	Current Loans CurrentLoans	51495000000	USD
CY2020Q4	us-gaap	Loans And Leases Receivable Net Of Deferred Income LoansAndLeasesReceivableNetOfDeferredIncome	52291000000	USD
CY2019Q4	cma	Loans Past Due And Still Accruing LoansPastDueAndStillAccruing	153000000	USD
CY2019Q4	us-gaap	Loans And Leases Receivable Impaired Nonperforming Nonaccrual Of Interest LoansAndLeasesReceivableImpairedNonperformingNonaccrualOfInterest	199000000	USD
CY2019Q4	cma	Current Loans CurrentLoans	50017000000	USD
CY2019Q4	us-gaap	Loans And Leases Receivable Net Of Deferred Income LoansAndLeasesReceivableNetOfDeferredIncome	50369000000	USD
CY2020Q4	us-gaap	Financing Receivable Originated In Current Fiscal Year FinancingReceivableOriginatedInCurrentFiscalYear	9714000000	USD
CY2020Q4	us-gaap	Financing Receivable Originated In Fiscal Year Before Latest Fiscal Year FinancingReceivableOriginatedInFiscalYearBeforeLatestFiscalYear	5957000000	USD
CY2020Q4	us-gaap	Financing Receivable Originated Two Years Before Latest Fiscal Year FinancingReceivableOriginatedTwoYearsBeforeLatestFiscalYear	4523000000	USD
CY2020Q4	us-gaap	Financing Receivable Originated Three Years Before Latest Fiscal Year FinancingReceivableOriginatedThreeYearsBeforeLatestFiscalYear	3243000000	USD
CY2020Q4	us-gaap	Financing Receivable Originated Four Years Before Latest Fiscal Year FinancingReceivableOriginatedFourYearsBeforeLatestFiscalYear	1913000000	USD
CY2020Q4	us-gaap	Financing Receivable Originated Five Or More Years Before Latest Fiscal Year FinancingReceivableOriginatedFiveOrMoreYearsBeforeLatestFiscalYear	4282000000	USD
CY2020Q4	us-gaap	Financing Receivable Revolving FinancingReceivableRevolving	22570000000	USD
CY2020Q4	us-gaap	Financing Receivable Revolving Converted To Term Loan FinancingReceivableRevolvingConvertedToTermLoan	89000000	USD
CY2020Q4	us-gaap	Loans And Leases Receivable Net Of Deferred Income LoansAndLeasesReceivableNetOfDeferredIncome	52291000000	USD
CY2019Q4	us-gaap	Loans And Leases Receivable Net Of Deferred Income LoansAndLeasesReceivableNetOfDeferredIncome	50369000000	USD
CY2020Q4	us-gaap	Interest Receivable InterestReceivable	141000000	USD
CY2019Q4	us-gaap	Interest Receivable InterestReceivable	172000000	USD
CY2019Q4	us-gaap	Financing Receivable Allowance For Credit Losses FinancingReceivableAllowanceForCreditLosses	668000000	USD
CY2018Q4	us-gaap	Financing Receivable Allowance For Credit Losses FinancingReceivableAllowanceForCreditLosses	701000000	USD
CY2017Q4	us-gaap	Financing Receivable Allowance For Credit Losses FinancingReceivableAllowanceForCreditLosses	754000000	USD
CY2020	us-gaap	Provision For Loan Lease And Other Losses ProvisionForLoanLeaseAndOtherLosses	537000000	USD
CY2019	us-gaap	Provision For Loan Lease And Other Losses ProvisionForLoanLeaseAndOtherLosses	74000000	USD
CY2018	us-gaap	Provision For Loan Lease And Other Losses ProvisionForLoanLeaseAndOtherLosses	-1000000	USD
CY2020Q4	us-gaap	Financing Receivable Allowance For Credit Losses FinancingReceivableAllowanceForCreditLosses	992000000	USD
CY2019Q4	us-gaap	Financing Receivable Allowance For Credit Losses FinancingReceivableAllowanceForCreditLosses	668000000	USD
CY2018Q4	us-gaap	Financing Receivable Allowance For Credit Losses FinancingReceivableAllowanceForCreditLosses	701000000	USD
CY2020Q4	cma	Financing Receivable Ratio Of Allowance For Credit Losses To All Loans FinancingReceivableRatioOfAllowanceForCreditLossesToAllLoans	0.0190
CY2019Q4	cma	Financing Receivable Ratio Of Allowance For Credit Losses To All Loans FinancingReceivableRatioOfAllowanceForCreditLossesToAllLoans	0.0133
CY2018Q4	cma	Financing Receivable Ratio Of Allowance For Credit Losses To All Loans FinancingReceivableRatioOfAllowanceForCreditLossesToAllLoans	0.0140
CY2020Q4	cma	Financing Receivable Ratio Of Allowance For Loan Losses To All Loans Excluding Ppp Loans FinancingReceivableRatioOfAllowanceForLoanLossesToAllLoansExcludingPPPLoans	0.0203
CY2020	us-gaap	Financing Receivable Nonaccrual Interest Income FinancingReceivableNonaccrualInterestIncome	0	USD
CY2019	us-gaap	Financing Receivable Nonaccrual Interest Income FinancingReceivableNonaccrualInterestIncome	0	USD
CY2020Q4	us-gaap	Financing Receivable Nonaccrual No Allowance FinancingReceivableNonaccrualNoAllowance	127000000	USD
CY2020Q4	us-gaap	Financing Receivable Recorded Investment Nonaccrual Status FinancingReceivableRecordedInvestmentNonaccrualStatus	220000000	USD
CY2020Q4	us-gaap	Loans And Leases Receivable Impaired Nonperforming Nonaccrual Of Interest LoansAndLeasesReceivableImpairedNonperformingNonaccrualOfInterest	347000000	USD
CY2019Q4	us-gaap	Financing Receivable Nonaccrual No Allowance FinancingReceivableNonaccrualNoAllowance	69000000	USD
CY2019Q4	us-gaap	Financing Receivable Recorded Investment Nonaccrual Status FinancingReceivableRecordedInvestmentNonaccrualStatus	130000000	USD
CY2019Q4	us-gaap	Loans And Leases Receivable Impaired Nonperforming Nonaccrual Of Interest LoansAndLeasesReceivableImpairedNonperformingNonaccrualOfInterest	199000000	USD
CY2020Q4	us-gaap	Foreclosed Assets ForeclosedAssets	8000000	USD
CY2019Q4	us-gaap	Foreclosed Assets ForeclosedAssets	11000000	USD
CY2019Q4	us-gaap	Mortgage Loans In Process Of Foreclosure Amount MortgageLoansInProcessOfForeclosureAmount	0	USD
CY2020Q4	us-gaap	Mortgage Loans In Process Of Foreclosure Amount MortgageLoansInProcessOfForeclosureAmount	0	USD
CY2020	us-gaap	Financing Receivable Modifications Post Modification Recorded Investment2 FinancingReceivableModificationsPostModificationRecordedInvestment2	22000000	USD
CY2019	us-gaap	Financing Receivable Modifications Post Modification Recorded Investment2 FinancingReceivableModificationsPostModificationRecordedInvestment2	29000000	USD
CY2020Q4	us-gaap	Loans And Leases Receivable Impaired Commitment To Lend LoansAndLeasesReceivableImpairedCommitmentToLend	0	USD
CY2019Q4	us-gaap	Loans And Leases Receivable Impaired Commitment To Lend LoansAndLeasesReceivableImpairedCommitmentToLend	3000000	USD
CY2020Q4	cma	Total Automotive Loans TotalAutomotiveLoans	6785000000	USD
CY2019Q4	cma	Total Automotive Loans TotalAutomotiveLoans	8663000000	USD
CY2020Q4	cma	Total Automotive Exposure TotalAutomotiveExposure	11920000000	USD
CY2019Q4	cma	Total Automotive Exposure TotalAutomotiveExposure	12035000000	USD
CY2020Q4	us-gaap	Land Land	86000000	USD
CY2019Q4	us-gaap	Land Land	86000000	USD
CY2020Q4	us-gaap	Buildings And Improvements Gross BuildingsAndImprovementsGross	847000000	USD
CY2019Q4	us-gaap	Buildings And Improvements Gross BuildingsAndImprovementsGross	818000000	USD
CY2020Q4	us-gaap	Furniture And Fixtures Gross FurnitureAndFixturesGross	485000000	USD
CY2019Q4	us-gaap	Furniture And Fixtures Gross FurnitureAndFixturesGross	513000000	USD
CY2020Q4	us-gaap	Property Plant And Equipment Gross PropertyPlantAndEquipmentGross	1418000000	USD
CY2019Q4	us-gaap	Property Plant And Equipment Gross PropertyPlantAndEquipmentGross	1417000000	USD
CY2020Q4	us-gaap	Accumulated Depreciation Depletion And Amortization Property Plant And Equipment AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment	959000000	USD
CY2019Q4	us-gaap	Accumulated Depreciation Depletion And Amortization Property Plant And Equipment AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment	960000000	USD
CY2020Q4	us-gaap	Property Plant And Equipment Net PropertyPlantAndEquipmentNet	459000000	USD
CY2019Q4	us-gaap	Property Plant And Equipment Net PropertyPlantAndEquipmentNet	457000000	USD
CY2020	us-gaap	Lease Cost LeaseCost	79000000	USD
CY2019	us-gaap	Lease Cost LeaseCost	81000000	USD
CY2018	us-gaap	Lease Cost LeaseCost	75000000	USD
CY2020Q4	us-gaap	Goodwill Goodwill	635000000	USD
CY2019Q4	us-gaap	Goodwill Goodwill	635000000	USD
CY2020Q4	cma	Derivative Assets Cash Collateral DerivativeAssetsCashCollateral	19000000	USD
CY2020Q4	us-gaap	Derivative Asset Fair Value Of Collateral DerivativeAssetFairValueOfCollateral	44000000	USD
CY2020Q4	cma	Cash Collateral Posted For Derivatives In Liability Position CashCollateralPostedForDerivativesInLiabilityPosition	49000000	USD
CY2020Q4	us-gaap	Derivative Net Liability Position Aggregate Fair Value DerivativeNetLiabilityPositionAggregateFairValue	0	USD
CY2020Q4	us-gaap	Derivative Notional Amount DerivativeNotionalAmount	35185000000	USD
CY2020Q4	us-gaap	Derivative Fair Value Of Derivative Asset DerivativeFairValueOfDerivativeAsset	700000000	USD
CY2020Q4	us-gaap	Derivative Fair Value Of Derivative Liability DerivativeFairValueOfDerivativeLiability	229000000	USD
CY2019Q4	us-gaap	Derivative Notional Amount DerivativeNotionalAmount	30134000000	USD
CY2019Q4	us-gaap	Derivative Fair Value Of Derivative Asset DerivativeFairValueOfDerivativeAsset	317000000	USD
CY2019Q4	us-gaap	Derivative Fair Value Of Derivative Liability DerivativeFairValueOfDerivativeLiability	141000000	USD
CY2020Q4	us-gaap	Derivative Asset Fair Value Gross Liability DerivativeAssetFairValueGrossLiability	83000000	USD
CY2020Q4	us-gaap	Derivative Liability Fair Value Gross Asset DerivativeLiabilityFairValueGrossAsset	83000000	USD
CY2019Q4	us-gaap	Derivative Asset Fair Value Gross Liability DerivativeAssetFairValueGrossLiability	63000000	USD
CY2019Q4	us-gaap	Derivative Liability Fair Value Gross Asset DerivativeLiabilityFairValueGrossAsset	63000000	USD
CY2020Q4	us-gaap	Derivative Asset Collateral Obligation To Return Cash Offset DerivativeAssetCollateralObligationToReturnCashOffset	17000000	USD
CY2020Q4	us-gaap	Derivative Liability Collateral Right To Reclaim Cash Offset DerivativeLiabilityCollateralRightToReclaimCashOffset	48000000	USD
CY2019Q4	us-gaap	Derivative Asset Collateral Obligation To Return Cash Offset DerivativeAssetCollateralObligationToReturnCashOffset	11000000	USD
CY2019Q4	us-gaap	Derivative Liability Collateral Right To Reclaim Cash Offset DerivativeLiabilityCollateralRightToReclaimCashOffset	12000000	USD
CY2020Q4	us-gaap	Derivative Assets DerivativeAssets	600000000	USD
CY2020Q4	us-gaap	Derivative Liabilities DerivativeLiabilities	98000000	USD
CY2019Q4	us-gaap	Derivative Assets DerivativeAssets	243000000	USD
CY2019Q4	us-gaap	Derivative Liabilities DerivativeLiabilities	66000000	USD
CY2020Q4	us-gaap	Derivative Collateral Obligation To Return Securities DerivativeCollateralObligationToReturnSecurities	0	USD
CY2020Q4	us-gaap	Derivative Collateral Right To Reclaim Securities DerivativeCollateralRightToReclaimSecurities	42000000	USD
CY2019Q4	us-gaap	Derivative Collateral Obligation To Return Securities DerivativeCollateralObligationToReturnSecurities	0	USD
CY2019Q4	us-gaap	Derivative Collateral Right To Reclaim Securities DerivativeCollateralRightToReclaimSecurities	21000000	USD
CY2020Q4	us-gaap	Derivative Fair Value Of Derivative Asset Amount Offset Against Collateral DerivativeFairValueOfDerivativeAssetAmountOffsetAgainstCollateral	600000000	USD
CY2020Q4	us-gaap	Derivative Fair Value Of Derivative Liability Amount Offset Against Collateral DerivativeFairValueOfDerivativeLiabilityAmountOffsetAgainstCollateral	56000000	USD
CY2019Q4	us-gaap	Derivative Fair Value Of Derivative Asset Amount Offset Against Collateral DerivativeFairValueOfDerivativeAssetAmountOffsetAgainstCollateral	243000000	USD
CY2019Q4	us-gaap	Derivative Fair Value Of Derivative Liability Amount Offset Against Collateral DerivativeFairValueOfDerivativeLiabilityAmountOffsetAgainstCollateral	45000000	USD
CY2020Q4	us-gaap	Derivative Credit Risk Valuation Adjustment Derivative Assets DerivativeCreditRiskValuationAdjustmentDerivativeAssets	27000000	USD
CY2019Q4	us-gaap	Derivative Credit Risk Valuation Adjustment Derivative Assets DerivativeCreditRiskValuationAdjustmentDerivativeAssets	9000000	USD
CY2020	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci On Derivatives Before Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIOnDerivativesBeforeTax	70000000	USD
CY2018	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci On Derivatives Before Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIOnDerivativesBeforeTax	0	USD
CY2019	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci On Derivatives Before Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIOnDerivativesBeforeTax	0	USD
CY2020	us-gaap	Interest Expense Long Term Debt InterestExpenseLongTermDebt	80000000	USD
CY2019	us-gaap	Interest Expense Long Term Debt InterestExpenseLongTermDebt	197000000	USD
CY2018	us-gaap	Interest Expense Long Term Debt InterestExpenseLongTermDebt	144000000	USD
CY2019	us-gaap	Gain Loss On Foreign Currency Derivative Instruments Not Designated As Hedging Instruments GainLossOnForeignCurrencyDerivativeInstrumentsNotDesignatedAsHedgingInstruments	0	USD
CY2018	us-gaap	Gain Loss On Foreign Currency Derivative Instruments Not Designated As Hedging Instruments GainLossOnForeignCurrencyDerivativeInstrumentsNotDesignatedAsHedgingInstruments	0	USD
CY2020	us-gaap	Gain Loss On Foreign Currency Derivative Instruments Not Designated As Hedging Instruments GainLossOnForeignCurrencyDerivativeInstrumentsNotDesignatedAsHedgingInstruments	0	USD
CY2020Q4	cma	Allowance For Off Balance Sheet Credit Losses AllowanceForOffBalanceSheetCreditLosses	44000000	USD
CY2019Q4	cma	Allowance For Off Balance Sheet Credit Losses AllowanceForOffBalanceSheetCreditLosses	31000000	USD
CY2020Q4	cma	Carrying Value Of Unused Commitments To Extend Credit CarryingValueOfUnusedCommitmentsToExtendCredit	37000000	USD
CY2019Q4	cma	Carrying Value Of Unused Commitments To Extend Credit CarryingValueOfUnusedCommitmentsToExtendCredit	25000000	USD
CY2020	cma	Longest Expiration Year Letters Of Credit LongestExpirationYearLettersOfCredit	2028
CY2020Q4	cma	Risk Participations Covering Standby And Commercial Letters Of Credit RiskParticipationsCoveringStandbyAndCommercialLettersOfCredit	150000000	USD
CY2019Q4	cma	Risk Participations Covering Standby And Commercial Letters Of Credit RiskParticipationsCoveringStandbyAndCommercialLettersOfCredit	161000000	USD
CY2020Q4	us-gaap	Letters Of Credit Outstanding Amount LettersOfCreditOutstandingAmount	3300000000	USD
CY2019Q4	us-gaap	Letters Of Credit Outstanding Amount LettersOfCreditOutstandingAmount	3300000000	USD
CY2020Q4	cma	Carrying Value Of Standby And Commercial Letters Of Credit CarryingValueOfStandbyAndCommercialLettersOfCredit	31000000	USD
CY2020Q4	cma	Carrying Value Of Standby And Commercial Letters Of Credit Included In Deferred Fees CarryingValueOfStandbyAndCommercialLettersOfCreditIncludedInDeferredFees	24000000	USD
CY2020Q4	cma	Carrying Value Of Standby And Commercial Letters Of Credit Included In Allowance For Credit Losses On Lending Related Commitments CarryingValueOfStandbyAndCommercialLettersOfCreditIncludedInAllowanceForCreditLossesOnLendingRelatedCommitments	7000000	USD
CY2019Q4	cma	Carrying Value Of Standby And Commercial Letters Of Credit CarryingValueOfStandbyAndCommercialLettersOfCredit	32000000	USD
CY2019Q4	cma	Carrying Value Of Standby And Commercial Letters Of Credit Included In Deferred Fees CarryingValueOfStandbyAndCommercialLettersOfCreditIncludedInDeferredFees	26000000	USD
CY2019Q4	cma	Carrying Value Of Standby And Commercial Letters Of Credit Included In Allowance For Credit Losses On Lending Related Commitments CarryingValueOfStandbyAndCommercialLettersOfCreditIncludedInAllowanceForCreditLossesOnLendingRelatedCommitments	6000000	USD
CY2020Q4	cma	Total Internally Classified Watch List Letters Of Credit TotalInternallyClassifiedWatchListLettersOfCredit	73000000	USD
CY2019Q4	cma	Total Internally Classified Watch List Letters Of Credit TotalInternallyClassifiedWatchListLettersOfCredit	44000000	USD
CY2020Q4	cma	Watch List Letters Of Credit As Percentage Of Total Letters Of Credit WatchListLettersOfCreditAsPercentageOfTotalLettersOfCredit	0.022
CY2019Q4	cma	Watch List Letters Of Credit As Percentage Of Total Letters Of Credit WatchListLettersOfCreditAsPercentageOfTotalLettersOfCredit	0.013
CY2020Q4	cma	Notional Amount Of Derivative Credit Risk Participation Agreements NotionalAmountOfDerivativeCreditRiskParticipationAgreements	1100000000	USD
CY2019Q4	cma	Notional Amount Of Derivative Credit Risk Participation Agreements NotionalAmountOfDerivativeCreditRiskParticipationAgreements	786000000	USD
CY2020Q4	cma	Fair Value Amount Of Derivative Credit Risk Participation Agreements FairValueAmountOfDerivativeCreditRiskParticipationAgreements	3000000	USD
CY2020Q4	us-gaap	Credit Derivative Maximum Exposure Undiscounted CreditDerivativeMaximumExposureUndiscounted	62000000	USD
CY2019Q4	us-gaap	Credit Derivative Maximum Exposure Undiscounted CreditDerivativeMaximumExposureUndiscounted	20000000	USD
CY2020	us-gaap	Variable Interest Entity Activity Between Vie And Entity Expense VariableInterestEntityActivityBetweenVIEAndEntityExpense	165000000	USD
CY2019	us-gaap	Variable Interest Entity Financial Or Other Support Amount VariableInterestEntityFinancialOrOtherSupportAmount	0	USD
CY2018	us-gaap	Variable Interest Entity Financial Or Other Support Amount VariableInterestEntityFinancialOrOtherSupportAmount	0	USD
CY2020	us-gaap	Variable Interest Entity Financial Or Other Support Amount VariableInterestEntityFinancialOrOtherSupportAmount	0	USD
CY2020Q4	us-gaap	Time Deposit Maturities Next Rolling Twelve Months TimeDepositMaturitiesNextRollingTwelveMonths	1823000000	USD
CY2020Q4	us-gaap	Time Deposit Maturities Year Two TimeDepositMaturitiesYearTwo	298000000	USD
CY2020Q4	us-gaap	Time Deposit Maturities Year Three TimeDepositMaturitiesYearThree	24000000	USD
CY2020Q4	us-gaap	Time Deposit Maturities Year Four TimeDepositMaturitiesYearFour	12000000	USD
CY2020Q4	us-gaap	Time Deposit Maturities Year Five TimeDepositMaturitiesYearFive	20000000	USD
CY2020Q4	us-gaap	Time Deposit Maturities After Year Five TimeDepositMaturitiesAfterYearFive	22000000	USD
CY2020Q4	us-gaap	Time Deposits TimeDeposits	2199000000	USD
CY2020Q4	cma	Domestic Time Deposits250000or More DomesticTimeDeposits250000orMore	632000000	USD
CY2019Q4	cma	Domestic Time Deposits250000or More DomesticTimeDeposits250000orMore	956000000	USD
CY2020Q4	cma	Foreign Time Deposits250000 Or More ForeignTimeDeposits250000OrMore	66000000	USD
CY2019Q4	cma	Foreign Time Deposits250000 Or More ForeignTimeDeposits250000OrMore	91000000	USD
CY2020Q4	us-gaap	Pledged Financial Instruments Not Separately Reported Loans Receivable Pledged For Other Arrangements PledgedFinancialInstrumentsNotSeparatelyReportedLoansReceivablePledgedForOtherArrangements	18000000000.0	USD
CY2020Q4	us-gaap	Line Of Credit Facility Current Borrowing Capacity LineOfCreditFacilityCurrentBorrowingCapacity	14200000000	USD
CY2020Q4	us-gaap	Long Term Debt LongTermDebt	5728000000	USD
CY2019Q4	us-gaap	Long Term Debt LongTermDebt	7269000000	USD
CY2020Q4	us-gaap	Pledged Financial Instruments Not Separately Reported Loans Receivable Pledged For Federal Home Loan Bank Debt PledgedFinancialInstrumentsNotSeparatelyReportedLoansReceivablePledgedForFederalHomeLoanBankDebt	19500000000	USD
CY2020Q4	us-gaap	Financial Instruments Owned And Pledged As Collateral At Fair Value FinancialInstrumentsOwnedAndPledgedAsCollateralAtFairValue	4400000000	USD
CY2020Q4	us-gaap	Federal Home Loan Bank Advances Long Term FederalHomeLoanBankAdvancesLongTerm	2800000000	USD
CY2020Q4	us-gaap	Line Of Credit Facility Remaining Borrowing Capacity LineOfCreditFacilityRemainingBorrowingCapacity	12000000000.0	USD
CY2020Q4	us-gaap	Unamortized Debt Issuance Expense UnamortizedDebtIssuanceExpense	10000000	USD
CY2019Q4	us-gaap	Unamortized Debt Issuance Expense UnamortizedDebtIssuanceExpense	12000000	USD
CY2020Q4	us-gaap	Long Term Debt Maturities Repayments Of Principal In Next Rolling Twelve Months LongTermDebtMaturitiesRepaymentsOfPrincipalInNextRollingTwelveMonths	0	USD
CY2020Q4	us-gaap	Long Term Debt Maturities Repayments Of Principal In Rolling Year Two LongTermDebtMaturitiesRepaymentsOfPrincipalInRollingYearTwo	0	USD
CY2020Q4	us-gaap	Long Term Debt Maturities Repayments Of Principal In Rolling Year Three LongTermDebtMaturitiesRepaymentsOfPrincipalInRollingYearThree	850000000	USD
CY2020Q4	us-gaap	Long Term Debt Maturities Repayments Of Principal In Rolling Year Four LongTermDebtMaturitiesRepaymentsOfPrincipalInRollingYearFour	500000000	USD
CY2020Q4	us-gaap	Long Term Debt Maturities Repayments Of Principal In Rolling Year Five LongTermDebtMaturitiesRepaymentsOfPrincipalInRollingYearFive	350000000	USD
CY2020Q4	us-gaap	Long Term Debt Maturities Repayments Of Principal In Rolling After Year Five LongTermDebtMaturitiesRepaymentsOfPrincipalInRollingAfterYearFive	3750000000	USD
CY2020Q4	us-gaap	Debt Instrument Carrying Amount DebtInstrumentCarryingAmount	5450000000	USD
CY2020Q4	cma	Depositary Shares Issued DepositarySharesIssued	400000	shares
CY2020	us-gaap	Preferred Stock Dividend Rate Percentage PreferredStockDividendRatePercentage	0.05625
CY2020Q4	us-gaap	Preferred Stock Liquidation Preference Value PreferredStockLiquidationPreferenceValue	100000	USD
CY2020Q4	us-gaap	Preferred Stock Liquidation Preference PreferredStockLiquidationPreference	1000
CY2020	us-gaap	Proceeds From Issuance Of Preferred Stock Preference Stock And Warrants ProceedsFromIssuanceOfPreferredStockPreferenceStockAndWarrants	400000000	USD
CY2019Q4	us-gaap	Accumulated Other Comprehensive Income Loss Available For Sale Securities Adjustment Net Of Tax AccumulatedOtherComprehensiveIncomeLossAvailableForSaleSecuritiesAdjustmentNetOfTax	65000000	USD
CY2018Q4	us-gaap	Accumulated Other Comprehensive Income Loss Available For Sale Securities Adjustment Net Of Tax AccumulatedOtherComprehensiveIncomeLossAvailableForSaleSecuritiesAdjustmentNetOfTax	-138000000	USD
CY2017Q4	us-gaap	Accumulated Other Comprehensive Income Loss Available For Sale Securities Adjustment Net Of Tax AccumulatedOtherComprehensiveIncomeLossAvailableForSaleSecuritiesAdjustmentNetOfTax	-101000000	USD
CY2020	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci For Investment Transferred From Available For Sale To Equity Method Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAociForInvestmentTransferredFromAvailableForSaleToEquityMethodTax	0	USD
CY2019	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci For Investment Transferred From Available For Sale To Equity Method Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAociForInvestmentTransferredFromAvailableForSaleToEquityMethodTax	0	USD
CY2018	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci For Investment Transferred From Available For Sale To Equity Method Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAociForInvestmentTransferredFromAvailableForSaleToEquityMethodTax	1000000	USD
CY2020	us-gaap	Other Comprehensive Income Unrealized Gain Loss On Derivatives Arising During Period Before Tax OtherComprehensiveIncomeUnrealizedGainLossOnDerivativesArisingDuringPeriodBeforeTax	191000000	USD
CY2019	us-gaap	Other Comprehensive Income Unrealized Gain Loss On Derivatives Arising During Period Before Tax OtherComprehensiveIncomeUnrealizedGainLossOnDerivativesArisingDuringPeriodBeforeTax	257000000	USD
CY2018	us-gaap	Other Comprehensive Income Unrealized Gain Loss On Derivatives Arising During Period Before Tax OtherComprehensiveIncomeUnrealizedGainLossOnDerivativesArisingDuringPeriodBeforeTax	-69000000	USD
CY2020	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodTax	45000000	USD
CY2019	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodTax	60000000	USD
CY2018	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodTax	-16000000	USD
CY2020	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Net Of Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodNetOfTax	146000000	USD
CY2019	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Net Of Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodNetOfTax	197000000	USD
CY2018	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Net Of Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodNetOfTax	-53000000	USD
CY2020	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci For Sale Of Securities Before Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIForSaleOfSecuritiesBeforeTax	0	USD
CY2019	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci For Sale Of Securities Before Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIForSaleOfSecuritiesBeforeTax	-8000000	USD
CY2018	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci For Sale Of Securities Before Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIForSaleOfSecuritiesBeforeTax	-20000000	USD
CY2020	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci For Sale Of Securities Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIForSaleOfSecuritiesTax	0	USD
CY2019	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci For Sale Of Securities Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIForSaleOfSecuritiesTax	-2000000	USD
CY2018	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci For Sale Of Securities Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIForSaleOfSecuritiesTax	-5000000	USD
CY2020	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci For Sale Of Securities Net Of Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIForSaleOfSecuritiesNetOfTax	0	USD
CY2019	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci For Sale Of Securities Net Of Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIForSaleOfSecuritiesNetOfTax	-6000000	USD
CY2018	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci For Sale Of Securities Net Of Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIForSaleOfSecuritiesNetOfTax	-15000000	USD
CY2020	us-gaap	Other Comprehensive Income Loss Available For Sale Securities Adjustment Net Of Tax OtherComprehensiveIncomeLossAvailableForSaleSecuritiesAdjustmentNetOfTax	146000000	USD
CY2019	us-gaap	Other Comprehensive Income Loss Available For Sale Securities Adjustment Net Of Tax OtherComprehensiveIncomeLossAvailableForSaleSecuritiesAdjustmentNetOfTax	203000000	USD
CY2018	us-gaap	Other Comprehensive Income Loss Available For Sale Securities Adjustment Net Of Tax OtherComprehensiveIncomeLossAvailableForSaleSecuritiesAdjustmentNetOfTax	-38000000	USD
CY2020Q4	us-gaap	Accumulated Other Comprehensive Income Loss Available For Sale Securities Adjustment Net Of Tax AccumulatedOtherComprehensiveIncomeLossAvailableForSaleSecuritiesAdjustmentNetOfTax	211000000	USD
CY2019Q4	us-gaap	Accumulated Other Comprehensive Income Loss Available For Sale Securities Adjustment Net Of Tax AccumulatedOtherComprehensiveIncomeLossAvailableForSaleSecuritiesAdjustmentNetOfTax	65000000	USD
CY2018Q4	us-gaap	Accumulated Other Comprehensive Income Loss Available For Sale Securities Adjustment Net Of Tax AccumulatedOtherComprehensiveIncomeLossAvailableForSaleSecuritiesAdjustmentNetOfTax	-138000000	USD
CY2019Q4	us-gaap	Accumulated Other Comprehensive Income Loss Cumulative Changes In Net Gain Loss From Cash Flow Hedges Effect Net Of Tax AccumulatedOtherComprehensiveIncomeLossCumulativeChangesInNetGainLossFromCashFlowHedgesEffectNetOfTax	34000000	USD
CY2018Q4	us-gaap	Accumulated Other Comprehensive Income Loss Cumulative Changes In Net Gain Loss From Cash Flow Hedges Effect Net Of Tax AccumulatedOtherComprehensiveIncomeLossCumulativeChangesInNetGainLossFromCashFlowHedgesEffectNetOfTax	0	USD
CY2017Q4	us-gaap	Accumulated Other Comprehensive Income Loss Cumulative Changes In Net Gain Loss From Cash Flow Hedges Effect Net Of Tax AccumulatedOtherComprehensiveIncomeLossCumulativeChangesInNetGainLossFromCashFlowHedgesEffectNetOfTax	0	USD
CY2020	us-gaap	Gain Loss On Cash Flow Hedge Ineffectiveness Net GainLossOnCashFlowHedgeIneffectivenessNet	229000000	USD
CY2019	us-gaap	Gain Loss On Cash Flow Hedge Ineffectiveness Net GainLossOnCashFlowHedgeIneffectivenessNet	44000000	USD
CY2018	us-gaap	Gain Loss On Cash Flow Hedge Ineffectiveness Net GainLossOnCashFlowHedgeIneffectivenessNet	0	USD
CY2020	us-gaap	Other Comprehensive Income Unrealized Gain Loss On Derivatives Arising During Period Tax OtherComprehensiveIncomeUnrealizedGainLossOnDerivativesArisingDuringPeriodTax	56000000	USD
CY2019	us-gaap	Other Comprehensive Income Unrealized Gain Loss On Derivatives Arising During Period Tax OtherComprehensiveIncomeUnrealizedGainLossOnDerivativesArisingDuringPeriodTax	10000000	USD
CY2018	us-gaap	Other Comprehensive Income Unrealized Gain Loss On Derivatives Arising During Period Tax OtherComprehensiveIncomeUnrealizedGainLossOnDerivativesArisingDuringPeriodTax	0	USD
CY2020	us-gaap	Other Comprehensive Income Unrealized Gain Loss On Derivatives Arising During Period Net Of Tax OtherComprehensiveIncomeUnrealizedGainLossOnDerivativesArisingDuringPeriodNetOfTax	173000000	USD
CY2019	us-gaap	Other Comprehensive Income Unrealized Gain Loss On Derivatives Arising During Period Net Of Tax OtherComprehensiveIncomeUnrealizedGainLossOnDerivativesArisingDuringPeriodNetOfTax	34000000	USD
CY2018	us-gaap	Other Comprehensive Income Unrealized Gain Loss On Derivatives Arising During Period Net Of Tax OtherComprehensiveIncomeUnrealizedGainLossOnDerivativesArisingDuringPeriodNetOfTax	0	USD
CY2020	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci On Derivatives Before Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIOnDerivativesBeforeTax	70000000	USD
CY2019	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci On Derivatives Before Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIOnDerivativesBeforeTax	0	USD
CY2018	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci On Derivatives Before Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIOnDerivativesBeforeTax	0	USD
CY2020	us-gaap	Other Comprehensive Income Defined Benefit Plans Net Unamortized Gain Loss Arising During Period Tax OtherComprehensiveIncomeDefinedBenefitPlansNetUnamortizedGainLossArisingDuringPeriodTax	18000000	USD
CY2019	us-gaap	Other Comprehensive Income Defined Benefit Plans Net Unamortized Gain Loss Arising During Period Tax OtherComprehensiveIncomeDefinedBenefitPlansNetUnamortizedGainLossArisingDuringPeriodTax	0	USD
CY2018	us-gaap	Other Comprehensive Income Defined Benefit Plans Net Unamortized Gain Loss Arising During Period Tax OtherComprehensiveIncomeDefinedBenefitPlansNetUnamortizedGainLossArisingDuringPeriodTax	0	USD
CY2020	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci On Derivatives Net Of Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIOnDerivativesNetOfTax	52000000	USD
CY2019	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci On Derivatives Net Of Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIOnDerivativesNetOfTax	0	USD
CY2018	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci On Derivatives Net Of Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIOnDerivativesNetOfTax	0	USD
CY2020	us-gaap	Other Comprehensive Income Loss Derivatives Qualifying As Hedges Net Of Tax OtherComprehensiveIncomeLossDerivativesQualifyingAsHedgesNetOfTax	121000000	USD
CY2019	us-gaap	Other Comprehensive Income Loss Derivatives Qualifying As Hedges Net Of Tax OtherComprehensiveIncomeLossDerivativesQualifyingAsHedgesNetOfTax	34000000	USD
CY2018	us-gaap	Other Comprehensive Income Loss Derivatives Qualifying As Hedges Net Of Tax OtherComprehensiveIncomeLossDerivativesQualifyingAsHedgesNetOfTax	0	USD
CY2020Q4	us-gaap	Accumulated Other Comprehensive Income Loss Cumulative Changes In Net Gain Loss From Cash Flow Hedges Effect Net Of Tax AccumulatedOtherComprehensiveIncomeLossCumulativeChangesInNetGainLossFromCashFlowHedgesEffectNetOfTax	155000000	USD
CY2019Q4	us-gaap	Accumulated Other Comprehensive Income Loss Cumulative Changes In Net Gain Loss From Cash Flow Hedges Effect Net Of Tax AccumulatedOtherComprehensiveIncomeLossCumulativeChangesInNetGainLossFromCashFlowHedgesEffectNetOfTax	34000000	USD
CY2018Q4	us-gaap	Accumulated Other Comprehensive Income Loss Cumulative Changes In Net Gain Loss From Cash Flow Hedges Effect Net Of Tax AccumulatedOtherComprehensiveIncomeLossCumulativeChangesInNetGainLossFromCashFlowHedgesEffectNetOfTax	0	USD
CY2019Q4	us-gaap	Accumulated Other Comprehensive Income Loss Defined Benefit Pension And Other Postretirement Plans Net Of Tax AccumulatedOtherComprehensiveIncomeLossDefinedBenefitPensionAndOtherPostretirementPlansNetOfTax	-334000000	USD
CY2018Q4	us-gaap	Accumulated Other Comprehensive Income Loss Defined Benefit Pension And Other Postretirement Plans Net Of Tax AccumulatedOtherComprehensiveIncomeLossDefinedBenefitPensionAndOtherPostretirementPlansNetOfTax	-471000000	USD
CY2017Q4	us-gaap	Accumulated Other Comprehensive Income Loss Defined Benefit Pension And Other Postretirement Plans Net Of Tax AccumulatedOtherComprehensiveIncomeLossDefinedBenefitPensionAndOtherPostretirementPlansNetOfTax	-350000000	USD
CY2020	us-gaap	Other Comprehensive Income Loss Pension And Other Postretirement Benefit Plans Net Unamortized Gain Loss Arising During Period Before Tax OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansNetUnamortizedGainLossArisingDuringPeriodBeforeTax	142000000	USD
CY2019	us-gaap	Other Comprehensive Income Loss Pension And Other Postretirement Benefit Plans Net Unamortized Gain Loss Arising During Period Before Tax OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansNetUnamortizedGainLossArisingDuringPeriodBeforeTax	163000000	USD
CY2018	us-gaap	Other Comprehensive Income Loss Pension And Other Postretirement Benefit Plans Net Unamortized Gain Loss Arising During Period Before Tax OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansNetUnamortizedGainLossArisingDuringPeriodBeforeTax	-191000000	USD
CY2020	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci On Derivatives Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIOnDerivativesTax	34000000	USD
CY2019	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci On Derivatives Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIOnDerivativesTax	38000000	USD
CY2018	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci On Derivatives Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIOnDerivativesTax	-44000000	USD
CY2020	us-gaap	Other Comprehensive Income Defined Benefit Plans Net Unamortized Gain Loss Arising During Period Net Of Tax OtherComprehensiveIncomeDefinedBenefitPlansNetUnamortizedGainLossArisingDuringPeriodNetOfTax	108000000	USD
CY2019	us-gaap	Other Comprehensive Income Defined Benefit Plans Net Unamortized Gain Loss Arising During Period Net Of Tax OtherComprehensiveIncomeDefinedBenefitPlansNetUnamortizedGainLossArisingDuringPeriodNetOfTax	125000000	USD
CY2018	us-gaap	Other Comprehensive Income Defined Benefit Plans Net Unamortized Gain Loss Arising During Period Net Of Tax OtherComprehensiveIncomeDefinedBenefitPlansNetUnamortizedGainLossArisingDuringPeriodNetOfTax	-147000000	USD
CY2020	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci Pension And Other Postretirement Benefit Plans For Net Gain Loss Before Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetGainLossBeforeTax	63000000	USD
CY2019	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci Pension And Other Postretirement Benefit Plans For Net Gain Loss Before Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetGainLossBeforeTax	42000000	USD
CY2018	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci Pension And Other Postretirement Benefit Plans For Net Gain Loss Before Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetGainLossBeforeTax	61000000	USD
CY2020	us-gaap	Other Comprehensive Income Loss Amortization Adjustment From Aoci Pension And Other Postretirement Benefit Plans For Net Prior Service Cost Credit Before Tax OtherComprehensiveIncomeLossAmortizationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetPriorServiceCostCreditBeforeTax	-27000000	USD
CY2019	us-gaap	Other Comprehensive Income Loss Amortization Adjustment From Aoci Pension And Other Postretirement Benefit Plans For Net Prior Service Cost Credit Before Tax OtherComprehensiveIncomeLossAmortizationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetPriorServiceCostCreditBeforeTax	-27000000	USD
CY2018	us-gaap	Other Comprehensive Income Loss Amortization Adjustment From Aoci Pension And Other Postretirement Benefit Plans For Net Prior Service Cost Credit Before Tax OtherComprehensiveIncomeLossAmortizationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetPriorServiceCostCreditBeforeTax	-27000000	USD
CY2020	cma	Other Comprehensive Income Loss Reclassification Adjustment Pension And Other Postretirement Benefit Plans Recognized In Net Periodic Defined Benefit Cost Before Tax OtherComprehensiveIncomeLossReclassificationAdjustmentPensionAndOtherPostretirementBenefitPlansRecognizedInNetPeriodicDefinedBenefitCostBeforeTax	36000000	USD
CY2019	cma	Other Comprehensive Income Loss Reclassification Adjustment Pension And Other Postretirement Benefit Plans Recognized In Net Periodic Defined Benefit Cost Before Tax OtherComprehensiveIncomeLossReclassificationAdjustmentPensionAndOtherPostretirementBenefitPlansRecognizedInNetPeriodicDefinedBenefitCostBeforeTax	15000000	USD
CY2018	cma	Other Comprehensive Income Loss Reclassification Adjustment Pension And Other Postretirement Benefit Plans Recognized In Net Periodic Defined Benefit Cost Before Tax OtherComprehensiveIncomeLossReclassificationAdjustmentPensionAndOtherPostretirementBenefitPlansRecognizedInNetPeriodicDefinedBenefitCostBeforeTax	34000000	USD
CY2020	cma	Other Comprehensive Income Loss Reclassification Adjustment Pension And Other Postretirement Benefit Plans Recognized In Net Periodic Defined Benefit Cost Tax OtherComprehensiveIncomeLossReclassificationAdjustmentPensionAndOtherPostretirementBenefitPlansRecognizedInNetPeriodicDefinedBenefitCostTax	8000000	USD
CY2019	cma	Other Comprehensive Income Loss Reclassification Adjustment Pension And Other Postretirement Benefit Plans Recognized In Net Periodic Defined Benefit Cost Tax OtherComprehensiveIncomeLossReclassificationAdjustmentPensionAndOtherPostretirementBenefitPlansRecognizedInNetPeriodicDefinedBenefitCostTax	3000000	USD
CY2018	cma	Other Comprehensive Income Loss Reclassification Adjustment Pension And Other Postretirement Benefit Plans Recognized In Net Periodic Defined Benefit Cost Tax OtherComprehensiveIncomeLossReclassificationAdjustmentPensionAndOtherPostretirementBenefitPlansRecognizedInNetPeriodicDefinedBenefitCostTax	8000000	USD
CY2020	cma	Other Comprehensive Income Loss Reclassification Adjustment Pension And Other Postretirement Benefit Plans Recognized In Net Periodic Defined Benefit Cost Net Of Tax OtherComprehensiveIncomeLossReclassificationAdjustmentPensionAndOtherPostretirementBenefitPlansRecognizedInNetPeriodicDefinedBenefitCostNetOfTax	28000000	USD
CY2019	cma	Other Comprehensive Income Loss Reclassification Adjustment Pension And Other Postretirement Benefit Plans Recognized In Net Periodic Defined Benefit Cost Net Of Tax OtherComprehensiveIncomeLossReclassificationAdjustmentPensionAndOtherPostretirementBenefitPlansRecognizedInNetPeriodicDefinedBenefitCostNetOfTax	12000000	USD
CY2018	cma	Other Comprehensive Income Loss Reclassification Adjustment Pension And Other Postretirement Benefit Plans Recognized In Net Periodic Defined Benefit Cost Net Of Tax OtherComprehensiveIncomeLossReclassificationAdjustmentPensionAndOtherPostretirementBenefitPlansRecognizedInNetPeriodicDefinedBenefitCostNetOfTax	26000000	USD
CY2020	us-gaap	Other Comprehensive Income Loss Pension And Other Postretirement Benefit Plans Adjustment Net Of Tax OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansAdjustmentNetOfTax	-136000000	USD
CY2019	us-gaap	Other Comprehensive Income Loss Pension And Other Postretirement Benefit Plans Adjustment Net Of Tax OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansAdjustmentNetOfTax	-137000000	USD
CY2018	us-gaap	Other Comprehensive Income Loss Pension And Other Postretirement Benefit Plans Adjustment Net Of Tax OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansAdjustmentNetOfTax	121000000	USD
CY2020Q4	us-gaap	Accumulated Other Comprehensive Income Loss Defined Benefit Pension And Other Postretirement Plans Net Of Tax AccumulatedOtherComprehensiveIncomeLossDefinedBenefitPensionAndOtherPostretirementPlansNetOfTax	-198000000	USD
CY2019Q4	us-gaap	Accumulated Other Comprehensive Income Loss Defined Benefit Pension And Other Postretirement Plans Net Of Tax AccumulatedOtherComprehensiveIncomeLossDefinedBenefitPensionAndOtherPostretirementPlansNetOfTax	-334000000	USD
CY2018Q4	us-gaap	Accumulated Other Comprehensive Income Loss Defined Benefit Pension And Other Postretirement Plans Net Of Tax AccumulatedOtherComprehensiveIncomeLossDefinedBenefitPensionAndOtherPostretirementPlansNetOfTax	-471000000	USD
CY2020Q4	us-gaap	Accumulated Other Comprehensive Income Loss Net Of Tax AccumulatedOtherComprehensiveIncomeLossNetOfTax	168000000	USD
CY2019Q4	us-gaap	Accumulated Other Comprehensive Income Loss Net Of Tax AccumulatedOtherComprehensiveIncomeLossNetOfTax	-235000000	USD
CY2018Q4	us-gaap	Accumulated Other Comprehensive Income Loss Net Of Tax AccumulatedOtherComprehensiveIncomeLossNetOfTax	-609000000	USD
CY2020	us-gaap	Profit Loss ProfitLoss	474000000	USD
CY2019	us-gaap	Profit Loss ProfitLoss	1198000000	USD
CY2018	us-gaap	Profit Loss ProfitLoss	1235000000	USD
CY2020	us-gaap	Undistributed Earnings Loss Allocated To Participating Securities Diluted UndistributedEarningsLossAllocatedToParticipatingSecuritiesDiluted	2000000	USD
CY2019	us-gaap	Undistributed Earnings Loss Allocated To Participating Securities Diluted UndistributedEarningsLossAllocatedToParticipatingSecuritiesDiluted	7000000	USD
CY2018	us-gaap	Undistributed Earnings Loss Allocated To Participating Securities Diluted UndistributedEarningsLossAllocatedToParticipatingSecuritiesDiluted	8000000	USD
CY2020	us-gaap	Dividends Preferred Stock Stock DividendsPreferredStockStock	13000000	USD
CY2019	us-gaap	Dividends Preferred Stock Stock DividendsPreferredStockStock	0	USD
CY2018	us-gaap	Dividends Preferred Stock Stock DividendsPreferredStockStock	0	USD
CY2020	us-gaap	Net Income Loss Available To Common Stockholders Basic NetIncomeLossAvailableToCommonStockholdersBasic	459000000	USD
CY2019	us-gaap	Net Income Loss Available To Common Stockholders Basic NetIncomeLossAvailableToCommonStockholdersBasic	1191000000	USD
CY2018	us-gaap	Net Income Loss Available To Common Stockholders Basic NetIncomeLossAvailableToCommonStockholdersBasic	1227000000	USD
CY2020	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	139000000	shares
CY2019	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	150000000	shares
CY2018	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	168000000	shares
CY2020	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	3.29
CY2019	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	7.95
CY2018	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	7.31
CY2020	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	139000000	shares
CY2019	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	150000000	shares
CY2018	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	168000000	shares
CY2020	us-gaap	Incremental Common Shares Attributable To Share Based Payment Arrangements IncrementalCommonSharesAttributableToShareBasedPaymentArrangements	1000000	shares
CY2019	us-gaap	Incremental Common Shares Attributable To Share Based Payment Arrangements IncrementalCommonSharesAttributableToShareBasedPaymentArrangements	1000000	shares
CY2018	us-gaap	Incremental Common Shares Attributable To Share Based Payment Arrangements IncrementalCommonSharesAttributableToShareBasedPaymentArrangements	2000000	shares
CY2020	us-gaap	Incremental Common Shares Attributable To Call Options And Warrants IncrementalCommonSharesAttributableToCallOptionsAndWarrants	0	shares
CY2019	us-gaap	Incremental Common Shares Attributable To Call Options And Warrants IncrementalCommonSharesAttributableToCallOptionsAndWarrants	0	shares
CY2018	us-gaap	Incremental Common Shares Attributable To Call Options And Warrants IncrementalCommonSharesAttributableToCallOptionsAndWarrants	1000000	shares
CY2020	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	140000000	shares
CY2019	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	151000000	shares
CY2018	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	171000000	shares
CY2020	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	3.27
CY2019	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	7.87
CY2018	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	7.20
CY2020	cma	Stockoptionsexcludedbecauseexercisepricesweregreaterthanaveragemarketpriceofshares Stockoptionsexcludedbecauseexercisepricesweregreaterthanaveragemarketpriceofshares	1498000	shares
CY2019	cma	Stockoptionsexcludedbecauseexercisepricesweregreaterthanaveragemarketpriceofshares Stockoptionsexcludedbecauseexercisepricesweregreaterthanaveragemarketpriceofshares	543000	shares
CY2018	cma	Stockoptionsexcludedbecauseexercisepricesweregreaterthanaveragemarketpriceofshares Stockoptionsexcludedbecauseexercisepricesweregreaterthanaveragemarketpriceofshares	193000	shares
CY2020	us-gaap	Allocated Share Based Compensation Expense AllocatedShareBasedCompensationExpense	24000000	USD
CY2019	us-gaap	Allocated Share Based Compensation Expense AllocatedShareBasedCompensationExpense	39000000	USD
CY2018	us-gaap	Allocated Share Based Compensation Expense AllocatedShareBasedCompensationExpense	48000000	USD
CY2020	us-gaap	Employee Service Share Based Compensation Tax Benefit From Compensation Expense EmployeeServiceShareBasedCompensationTaxBenefitFromCompensationExpense	6000000	USD
CY2019	us-gaap	Employee Service Share Based Compensation Tax Benefit From Compensation Expense EmployeeServiceShareBasedCompensationTaxBenefitFromCompensationExpense	9000000	USD
CY2018	us-gaap	Employee Service Share Based Compensation Tax Benefit From Compensation Expense EmployeeServiceShareBasedCompensationTaxBenefitFromCompensationExpense	11000000	USD
CY2020Q4	us-gaap	Employee Service Share Based Compensation Nonvested Awards Total Compensation Cost Not Yet Recognized EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized	32000000	USD
CY2020Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Number Of Shares Authorized ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized	6100000	shares
CY2020Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Number Of Shares Available For Grant ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant	4000000.0	shares
CY2020	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Grants In Period Weighted Average Grant Date Fair Value ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue	13.03
CY2019	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Grants In Period Weighted Average Grant Date Fair Value ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue	22.27
CY2018	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Grants In Period Weighted Average Grant Date Fair Value ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue	30.32
CY2020	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Fair Value Assumptions Risk Free Interest Rate ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate	0.0165
CY2019	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Fair Value Assumptions Risk Free Interest Rate ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate	0.0274
CY2018	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Fair Value Assumptions Risk Free Interest Rate ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate	0.0263
CY2020	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Fair Value Assumptions Expected Dividend Rate ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate	0.0414
CY2019	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Fair Value Assumptions Expected Dividend Rate ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate	0.0300
CY2018	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Fair Value Assumptions Expected Dividend Rate ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate	0.0300
CY2020	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Fair Value Assumptions Expected Volatility Rate ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate	0.27
CY2019	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Fair Value Assumptions Expected Volatility Rate ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate	0.30
CY2018	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Fair Value Assumptions Expected Volatility Rate ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate	0.36
CY2020Q4	us-gaap	Share Price SharePrice	55.86
CY2020	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Exercises In Period Total Intrinsic Value ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue	6000000	USD
CY2019	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Exercises In Period Total Intrinsic Value ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue	20000000	USD
CY2018	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Exercises In Period Total Intrinsic Value ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue	81000000	USD
CY2020	us-gaap	Other Comprehensive Income Loss Pension And Other Postretirement Benefit Plans Net Unamortized Gain Loss Arising During Period Before Tax OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansNetUnamortizedGainLossArisingDuringPeriodBeforeTax	142000000	USD
CY2020	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci Pension And Other Postretirement Benefit Plans For Net Gain Loss Before Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetGainLossBeforeTax	63000000	USD
CY2020	us-gaap	Other Comprehensive Income Loss Amortization Adjustment From Aoci Pension And Other Postretirement Benefit Plans For Net Prior Service Cost Credit Before Tax OtherComprehensiveIncomeLossAmortizationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetPriorServiceCostCreditBeforeTax	-27000000	USD
CY2020	us-gaap	Other Comprehensive Income Loss Pension And Other Postretirement Benefit Plans Adjustment Before Tax OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansAdjustmentBeforeTax	-178000000	USD
CY2020Q4	cma	Assets Fair Value Disclosure Excluding Assets Valuedat Nav AssetsFairValueDisclosureExcludingAssetsValuedatNAV	2712000000	USD
CY2020Q4	us-gaap	Defined Benefit Plan Fair Value Of Plan Assets DefinedBenefitPlanFairValueOfPlanAssets	3349000000	USD
CY2019Q4	cma	Assets Fair Value Disclosure Excluding Assets Valuedat Nav AssetsFairValueDisclosureExcludingAssetsValuedatNAV	2480000000	USD
CY2019Q4	us-gaap	Defined Benefit Plan Fair Value Of Plan Assets DefinedBenefitPlanFairValueOfPlanAssets	2949000000	USD
CY2020Q4	us-gaap	Defined Benefit Plan Expected Future Employer Contributions Next Fiscal Year DefinedBenefitPlanExpectedFutureEmployerContributionsNextFiscalYear	0	USD
CY2020	us-gaap	Defined Contribution Plan Employer Matching Contribution Percent Of Match DefinedContributionPlanEmployerMatchingContributionPercentOfMatch	1
CY2020	us-gaap	Defined Contribution Plan Employer Matching Contribution Percent DefinedContributionPlanEmployerMatchingContributionPercent	0.04
CY2020	us-gaap	Defined Contribution Plan Cost Recognized DefinedContributionPlanCostRecognized	24000000	USD
CY2019	us-gaap	Defined Contribution Plan Cost Recognized DefinedContributionPlanCostRecognized	22000000	USD
CY2018	us-gaap	Defined Contribution Plan Cost Recognized DefinedContributionPlanCostRecognized	21000000	USD
CY2020	us-gaap	Current Federal Tax Expense Benefit CurrentFederalTaxExpenseBenefit	171000000	USD
CY2019	us-gaap	Current Federal Tax Expense Benefit CurrentFederalTaxExpenseBenefit	267000000	USD
CY2018	us-gaap	Current Federal Tax Expense Benefit CurrentFederalTaxExpenseBenefit	227000000	USD
CY2020	us-gaap	Current Foreign Tax Expense Benefit CurrentForeignTaxExpenseBenefit	5000000	USD
CY2019	us-gaap	Current Foreign Tax Expense Benefit CurrentForeignTaxExpenseBenefit	7000000	USD
CY2018	us-gaap	Current Foreign Tax Expense Benefit CurrentForeignTaxExpenseBenefit	10000000	USD
CY2020	us-gaap	Current State And Local Tax Expense Benefit CurrentStateAndLocalTaxExpenseBenefit	30000000	USD
CY2019	us-gaap	Current State And Local Tax Expense Benefit CurrentStateAndLocalTaxExpenseBenefit	48000000	USD
CY2018	us-gaap	Current State And Local Tax Expense Benefit CurrentStateAndLocalTaxExpenseBenefit	39000000	USD
CY2020	us-gaap	Current Income Tax Expense Benefit CurrentIncomeTaxExpenseBenefit	206000000	USD
CY2019	us-gaap	Current Income Tax Expense Benefit CurrentIncomeTaxExpenseBenefit	322000000	USD
CY2018	us-gaap	Current Income Tax Expense Benefit CurrentIncomeTaxExpenseBenefit	276000000	USD
CY2020	us-gaap	Deferred Federal Income Tax Expense Benefit DeferredFederalIncomeTaxExpenseBenefit	-79000000	USD
CY2019	us-gaap	Deferred Federal Income Tax Expense Benefit DeferredFederalIncomeTaxExpenseBenefit	16000000	USD
CY2018	us-gaap	Deferred Federal Income Tax Expense Benefit DeferredFederalIncomeTaxExpenseBenefit	29000000	USD
CY2020	us-gaap	Deferred State And Local Income Tax Expense Benefit DeferredStateAndLocalIncomeTaxExpenseBenefit	-10000000	USD
CY2019	us-gaap	Deferred State And Local Income Tax Expense Benefit DeferredStateAndLocalIncomeTaxExpenseBenefit	-4000000	USD
CY2018	us-gaap	Deferred State And Local Income Tax Expense Benefit DeferredStateAndLocalIncomeTaxExpenseBenefit	3000000	USD
CY2020	cma	Remeasurementofdeferredtaxes Remeasurementofdeferredtaxes	0	USD
CY2019	cma	Remeasurementofdeferredtaxes Remeasurementofdeferredtaxes	0	USD
CY2018	cma	Remeasurementofdeferredtaxes Remeasurementofdeferredtaxes	-8000000	USD
CY2020	us-gaap	Deferred Income Tax Expense Benefit DeferredIncomeTaxExpenseBenefit	-89000000	USD
CY2019	us-gaap	Deferred Income Tax Expense Benefit DeferredIncomeTaxExpenseBenefit	12000000	USD
CY2018	us-gaap	Deferred Income Tax Expense Benefit DeferredIncomeTaxExpenseBenefit	24000000	USD
CY2020	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	117000000	USD
CY2019	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	334000000	USD
CY2018	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	300000000	USD
CY2020	cma	Income Loss From Continuing Operations Before Income Taxes IncomeLossFromContinuingOperationsBeforeIncomeTaxes	591000000	USD
CY2020	us-gaap	Income Loss From Continuing Operations Before Income Taxes Foreign IncomeLossFromContinuingOperationsBeforeIncomeTaxesForeign	19000000	USD
CY2018	cma	Reductionindeferredtaxadjustment Reductionindeferredtaxadjustment	99000000	USD
CY2017	cma	Provisional Adjustment In Deferred Tax Adjustment ProvisionalAdjustmentInDeferredTaxAdjustment	107000000	USD
CY2018	cma	Deferredtaxadjustmentfor Tax Cutand Jobact DeferredtaxadjustmentforTaxCutandJobact	-8000000	USD
CY2020	us-gaap	Income Tax Reconciliation Income Tax Expense Benefit At Federal Statutory Income Tax Rate IncomeTaxReconciliationIncomeTaxExpenseBenefitAtFederalStatutoryIncomeTaxRate	124000000	USD
CY2020	us-gaap	Effective Income Tax Rate Reconciliation At Federal Statutory Income Tax Rate EffectiveIncomeTaxRateReconciliationAtFederalStatutoryIncomeTaxRate	0.210
CY2019	us-gaap	Income Tax Reconciliation Income Tax Expense Benefit At Federal Statutory Income Tax Rate IncomeTaxReconciliationIncomeTaxExpenseBenefitAtFederalStatutoryIncomeTaxRate	322000000	USD
CY2019	us-gaap	Effective Income Tax Rate Reconciliation At Federal Statutory Income Tax Rate EffectiveIncomeTaxRateReconciliationAtFederalStatutoryIncomeTaxRate	0.210
CY2018	us-gaap	Income Tax Reconciliation Income Tax Expense Benefit At Federal Statutory Income Tax Rate IncomeTaxReconciliationIncomeTaxExpenseBenefitAtFederalStatutoryIncomeTaxRate	323000000	USD
CY2018	us-gaap	Effective Income Tax Rate Reconciliation At Federal Statutory Income Tax Rate EffectiveIncomeTaxRateReconciliationAtFederalStatutoryIncomeTaxRate	0.210
CY2020	us-gaap	Income Tax Reconciliation State And Local Income Taxes IncomeTaxReconciliationStateAndLocalIncomeTaxes	17000000	USD
CY2020	us-gaap	Effective Income Tax Rate Reconciliation State And Local Income Taxes EffectiveIncomeTaxRateReconciliationStateAndLocalIncomeTaxes	0.028
CY2019	us-gaap	Income Tax Reconciliation State And Local Income Taxes IncomeTaxReconciliationStateAndLocalIncomeTaxes	33000000	USD
CY2019	us-gaap	Effective Income Tax Rate Reconciliation State And Local Income Taxes EffectiveIncomeTaxRateReconciliationStateAndLocalIncomeTaxes	0.022
CY2018	us-gaap	Income Tax Reconciliation State And Local Income Taxes IncomeTaxReconciliationStateAndLocalIncomeTaxes	35000000	USD
CY2018	us-gaap	Effective Income Tax Rate Reconciliation State And Local Income Taxes EffectiveIncomeTaxRateReconciliationStateAndLocalIncomeTaxes	0.023
CY2020	cma	Taxbenefitsfromemployeestocktransactions Taxbenefitsfromemployeestocktransactions	1000000	USD
CY2020	cma	Income Tax Effects Allocated Directlyto Equity Employee Stock Options Percentage IncomeTaxEffectsAllocatedDirectlytoEquityEmployeeStockOptionsPercentage	-0.002
CY2019	cma	Taxbenefitsfromemployeestocktransactions Taxbenefitsfromemployeestocktransactions	12000000	USD
CY2019	cma	Income Tax Effects Allocated Directlyto Equity Employee Stock Options Percentage IncomeTaxEffectsAllocatedDirectlytoEquityEmployeeStockOptionsPercentage	-0.008
CY2018	cma	Taxbenefitsfromemployeestocktransactions Taxbenefitsfromemployeestocktransactions	23000000	USD
CY2018	cma	Income Tax Effects Allocated Directlyto Equity Employee Stock Options Percentage IncomeTaxEffectsAllocatedDirectlytoEquityEmployeeStockOptionsPercentage	-0.015
CY2020	cma	Tax Capitalizationandrecovery TaxCapitalizationandrecovery	0	USD
CY2020	cma	Tax Capitalizationandrecoverypercent TaxCapitalizationandrecoverypercent	0
CY2019	cma	Tax Capitalizationandrecovery TaxCapitalizationandrecovery	0	USD
CY2019	cma	Tax Capitalizationandrecoverypercent TaxCapitalizationandrecoverypercent	0
CY2018	cma	Tax Capitalizationandrecovery TaxCapitalizationandrecovery	-17000000	USD
CY2018	cma	Tax Capitalizationandrecoverypercent TaxCapitalizationandrecoverypercent	-0.011
CY2020	us-gaap	Income Tax Reconciliation Tax Credits Other IncomeTaxReconciliationTaxCreditsOther	12000000	USD
CY2020	us-gaap	Effective Income Tax Rate Reconciliation Tax Credits Other EffectiveIncomeTaxRateReconciliationTaxCreditsOther	0.020
CY2019	us-gaap	Income Tax Reconciliation Tax Credits Other IncomeTaxReconciliationTaxCreditsOther	11000000	USD
CY2019	us-gaap	Effective Income Tax Rate Reconciliation Tax Credits Other EffectiveIncomeTaxRateReconciliationTaxCreditsOther	0.007
CY2018	us-gaap	Income Tax Reconciliation Tax Credits Other IncomeTaxReconciliationTaxCreditsOther	12000000	USD
CY2018	us-gaap	Effective Income Tax Rate Reconciliation Tax Credits Other EffectiveIncomeTaxRateReconciliationTaxCreditsOther	0.008
CY2020	us-gaap	Income Tax Reconciliation Tax Exempt Income IncomeTaxReconciliationTaxExemptIncome	10000000	USD
CY2020	us-gaap	Effective Income Tax Rate Reconciliation Tax Exempt Income EffectiveIncomeTaxRateReconciliationTaxExemptIncome	0.017
CY2019	us-gaap	Income Tax Reconciliation Tax Exempt Income IncomeTaxReconciliationTaxExemptIncome	9000000	USD
CY2019	us-gaap	Effective Income Tax Rate Reconciliation Tax Exempt Income EffectiveIncomeTaxRateReconciliationTaxExemptIncome	0.006
CY2018	us-gaap	Income Tax Reconciliation Tax Exempt Income IncomeTaxReconciliationTaxExemptIncome	9000000	USD
CY2018	us-gaap	Effective Income Tax Rate Reconciliation Tax Exempt Income EffectiveIncomeTaxRateReconciliationTaxExemptIncome	0.006
CY2020	cma	Deferredtaxadjustmentfor Tax Cutand Jobact DeferredtaxadjustmentforTaxCutandJobact	0	USD
CY2020	cma	Deferred Tax Adjustmentfor Tax Cutad Job Act Percentage DeferredTaxAdjustmentforTaxCutadJobActPercentage	0
CY2019	cma	Deferredtaxadjustmentfor Tax Cutand Jobact DeferredtaxadjustmentforTaxCutandJobact	0	USD
CY2019	cma	Deferred Tax Adjustmentfor Tax Cutad Job Act Percentage DeferredTaxAdjustmentforTaxCutadJobActPercentage	0
CY2018	cma	Deferredtaxadjustmentfor Tax Cutand Jobact DeferredtaxadjustmentforTaxCutandJobact	-8000000	USD
CY2018	cma	Deferred Tax Adjustmentfor Tax Cutad Job Act Percentage DeferredTaxAdjustmentforTaxCutadJobActPercentage	-0.005
CY2020	us-gaap	Income Tax Reconciliation Nondeductible Expense Other IncomeTaxReconciliationNondeductibleExpenseOther	7000000	USD
CY2020	us-gaap	Effective Income Tax Rate Reconciliation Nondeductible Expense Other EffectiveIncomeTaxRateReconciliationNondeductibleExpenseOther	0.012
CY2019	us-gaap	Income Tax Reconciliation Nondeductible Expense Other IncomeTaxReconciliationNondeductibleExpenseOther	5000000	USD
CY2019	us-gaap	Effective Income Tax Rate Reconciliation Nondeductible Expense Other EffectiveIncomeTaxRateReconciliationNondeductibleExpenseOther	0.003
CY2018	us-gaap	Income Tax Reconciliation Nondeductible Expense Other IncomeTaxReconciliationNondeductibleExpenseOther	8000000	USD
CY2018	us-gaap	Effective Income Tax Rate Reconciliation Nondeductible Expense Other EffectiveIncomeTaxRateReconciliationNondeductibleExpenseOther	0.005
CY2020	us-gaap	Income Tax Reconciliation Tax Contingencies IncomeTaxReconciliationTaxContingencies	0	USD
CY2020	us-gaap	Effective Income Tax Rate Reconciliation Tax Contingencies EffectiveIncomeTaxRateReconciliationTaxContingencies	0
CY2019	us-gaap	Income Tax Reconciliation Tax Contingencies IncomeTaxReconciliationTaxContingencies	0	USD
CY2019	us-gaap	Effective Income Tax Rate Reconciliation Tax Contingencies EffectiveIncomeTaxRateReconciliationTaxContingencies	0
CY2018	us-gaap	Income Tax Reconciliation Tax Contingencies IncomeTaxReconciliationTaxContingencies	4000000	USD
CY2018	us-gaap	Effective Income Tax Rate Reconciliation Tax Contingencies EffectiveIncomeTaxRateReconciliationTaxContingencies	0.003
CY2020	cma	Income Tax Reconciliation Interest On Income Tax Liabilities IncomeTaxReconciliationInterestOnIncomeTaxLiabilities	-2000000	USD
CY2020	cma	Effective Income Tax Rate Reconciliation Interest On Income Tax Liabilities EffectiveIncomeTaxRateReconciliationInterestOnIncomeTaxLiabilities	-0.003
CY2019	cma	Income Tax Reconciliation Interest On Income Tax Liabilities IncomeTaxReconciliationInterestOnIncomeTaxLiabilities	2000000	USD
CY2019	cma	Effective Income Tax Rate Reconciliation Interest On Income Tax Liabilities EffectiveIncomeTaxRateReconciliationInterestOnIncomeTaxLiabilities	0.001
CY2018	cma	Income Tax Reconciliation Interest On Income Tax Liabilities IncomeTaxReconciliationInterestOnIncomeTaxLiabilities	-3000000	USD
CY2018	cma	Effective Income Tax Rate Reconciliation Interest On Income Tax Liabilities EffectiveIncomeTaxRateReconciliationInterestOnIncomeTaxLiabilities	-0.002
CY2020	us-gaap	Income Tax Reconciliation Other Adjustments IncomeTaxReconciliationOtherAdjustments	-6000000	USD
CY2020	us-gaap	Effective Income Tax Rate Reconciliation Other Adjustments EffectiveIncomeTaxRateReconciliationOtherAdjustments	-0.010
CY2019	us-gaap	Income Tax Reconciliation Other Adjustments IncomeTaxReconciliationOtherAdjustments	4000000	USD
CY2019	us-gaap	Effective Income Tax Rate Reconciliation Other Adjustments EffectiveIncomeTaxRateReconciliationOtherAdjustments	0.002
CY2018	us-gaap	Income Tax Reconciliation Other Adjustments IncomeTaxReconciliationOtherAdjustments	2000000	USD
CY2018	us-gaap	Effective Income Tax Rate Reconciliation Other Adjustments EffectiveIncomeTaxRateReconciliationOtherAdjustments	0.001
CY2020	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	117000000	USD
CY2020	us-gaap	Effective Income Tax Rate Continuing Operations EffectiveIncomeTaxRateContinuingOperations	0.198
CY2019	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	334000000	USD
CY2019	us-gaap	Effective Income Tax Rate Continuing Operations EffectiveIncomeTaxRateContinuingOperations	0.217
CY2018	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	300000000	USD
CY2018	us-gaap	Effective Income Tax Rate Continuing Operations EffectiveIncomeTaxRateContinuingOperations	0.195
CY2020Q4	us-gaap	Unrecognized Tax Benefits Income Tax Penalties And Interest Accrued UnrecognizedTaxBenefitsIncomeTaxPenaltiesAndInterestAccrued	6000000	USD
CY2019Q4	us-gaap	Unrecognized Tax Benefits Income Tax Penalties And Interest Accrued UnrecognizedTaxBenefitsIncomeTaxPenaltiesAndInterestAccrued	8000000	USD
CY2019Q4	us-gaap	Unrecognized Tax Benefits UnrecognizedTaxBenefits	17000000	USD
CY2018Q4	us-gaap	Unrecognized Tax Benefits UnrecognizedTaxBenefits	14000000	USD
CY2017Q4	us-gaap	Unrecognized Tax Benefits UnrecognizedTaxBenefits	10000000	USD
CY2020	us-gaap	Unrecognized Tax Benefits Increases Resulting From Prior Period Tax Positions UnrecognizedTaxBenefitsIncreasesResultingFromPriorPeriodTaxPositions	1000000	USD
CY2019	us-gaap	Unrecognized Tax Benefits Increases Resulting From Prior Period Tax Positions UnrecognizedTaxBenefitsIncreasesResultingFromPriorPeriodTaxPositions	4000000	USD
CY2018	us-gaap	Unrecognized Tax Benefits Increases Resulting From Prior Period Tax Positions UnrecognizedTaxBenefitsIncreasesResultingFromPriorPeriodTaxPositions	9000000	USD
CY2020	us-gaap	Unrecognized Tax Benefits Increases Resulting From Current Period Tax Positions UnrecognizedTaxBenefitsIncreasesResultingFromCurrentPeriodTaxPositions	2000000	USD
CY2019	us-gaap	Unrecognized Tax Benefits Increases Resulting From Current Period Tax Positions UnrecognizedTaxBenefitsIncreasesResultingFromCurrentPeriodTaxPositions	0	USD
CY2018	us-gaap	Unrecognized Tax Benefits Increases Resulting From Current Period Tax Positions UnrecognizedTaxBenefitsIncreasesResultingFromCurrentPeriodTaxPositions	0	USD
CY2020	us-gaap	Unrecognized Tax Benefits Decreases Resulting From Settlements With Taxing Authorities UnrecognizedTaxBenefitsDecreasesResultingFromSettlementsWithTaxingAuthorities	1000000	USD
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CY2019	cma	Unrecognized Tax Benefits Decrease Resultingfrom Other Tax Position Changes UnrecognizedTaxBenefitsDecreaseResultingfromOtherTaxPositionChanges	0	USD
CY2018	cma	Unrecognized Tax Benefits Decrease Resultingfrom Other Tax Position Changes UnrecognizedTaxBenefitsDecreaseResultingfromOtherTaxPositionChanges	-1000000	USD
CY2020Q4	us-gaap	Unrecognized Tax Benefits UnrecognizedTaxBenefits	19000000	USD
CY2019Q4	us-gaap	Unrecognized Tax Benefits UnrecognizedTaxBenefits	17000000	USD
CY2018Q4	us-gaap	Unrecognized Tax Benefits UnrecognizedTaxBenefits	14000000	USD
CY2020Q4	us-gaap	Decrease In Unrecognized Tax Benefits Is Reasonably Possible DecreaseInUnrecognizedTaxBenefitsIsReasonablyPossible	5000000	USD
CY2020Q4	us-gaap	Unrecognized Tax Benefits That Would Impact Effective Tax Rate UnrecognizedTaxBenefitsThatWouldImpactEffectiveTaxRate	15000000	USD
CY2019Q4	us-gaap	Unrecognized Tax Benefits That Would Impact Effective Tax Rate UnrecognizedTaxBenefitsThatWouldImpactEffectiveTaxRate	14000000	USD
CY2020Q4	us-gaap	Deferred Tax Assets Tax Deferred Expense Reserves And Accruals Provision For Loan Losses DeferredTaxAssetsTaxDeferredExpenseReservesAndAccrualsProvisionForLoanLosses	199000000	USD
CY2019Q4	us-gaap	Deferred Tax Assets Tax Deferred Expense Reserves And Accruals Provision For Loan Losses DeferredTaxAssetsTaxDeferredExpenseReservesAndAccrualsProvisionForLoanLosses	134000000	USD
CY2020Q4	us-gaap	Deferred Tax Assets Tax Deferred Expense Compensation And Benefits Employee Compensation DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefitsEmployeeCompensation	59000000	USD
CY2019Q4	us-gaap	Deferred Tax Assets Tax Deferred Expense Compensation And Benefits Employee Compensation DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefitsEmployeeCompensation	61000000	USD
CY2020Q4	cma	Deferred Tax Assets Deferred Loan Orgination Fees And Costs DeferredTaxAssetsDeferredLoanOrginationFeesAndCosts	19000000	USD
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CY2020Q4	cma	Deferred Tax Assets Operating Lease Liability DeferredTaxAssetsOperatingLeaseLiability	72000000	USD
CY2019Q4	cma	Deferred Tax Assets Operating Lease Liability DeferredTaxAssetsOperatingLeaseLiability	77000000	USD
CY2020Q4	us-gaap	Deferred Tax Assets Other DeferredTaxAssetsOther	55000000	USD
CY2019Q4	us-gaap	Deferred Tax Assets Other DeferredTaxAssetsOther	49000000	USD
CY2020Q4	us-gaap	Deferred Tax Assets Gross DeferredTaxAssetsGross	404000000	USD
CY2019Q4	us-gaap	Deferred Tax Assets Gross DeferredTaxAssetsGross	329000000	USD
CY2020Q4	us-gaap	Deferred Tax Assets Valuation Allowance DeferredTaxAssetsValuationAllowance	3000000	USD
CY2019Q4	us-gaap	Deferred Tax Assets Valuation Allowance DeferredTaxAssetsValuationAllowance	3000000	USD
CY2020Q4	us-gaap	Deferred Tax Assets Net DeferredTaxAssetsNet	401000000	USD
CY2019Q4	us-gaap	Deferred Tax Assets Net DeferredTaxAssetsNet	326000000	USD
CY2020Q4	us-gaap	Deferred Tax Liabilities Leasing Arrangements DeferredTaxLiabilitiesLeasingArrangements	70000000	USD
CY2019Q4	us-gaap	Deferred Tax Liabilities Leasing Arrangements DeferredTaxLiabilitiesLeasingArrangements	73000000	USD
CY2020Q4	cma	Deferred Tax Liabilities Tax Deferred Income Compensationand Benefits Pensions DeferredTaxLiabilitiesTaxDeferredIncomeCompensationandBenefitsPensions	140000000	USD
CY2019Q4	cma	Deferred Tax Liabilities Tax Deferred Income Compensationand Benefits Pensions DeferredTaxLiabilitiesTaxDeferredIncomeCompensationandBenefitsPensions	91000000	USD
CY2020Q4	us-gaap	Deferred Tax Liabilities Property Plant And Equipment DeferredTaxLiabilitiesPropertyPlantAndEquipment	11000000	USD
CY2019Q4	us-gaap	Deferred Tax Liabilities Property Plant And Equipment DeferredTaxLiabilitiesPropertyPlantAndEquipment	21000000	USD
CY2020Q4	cma	Deferred Tax Liability Hedginggainsandlosses DeferredTaxLiabilityHedginggainsandlosses	-47000000	USD
CY2019Q4	cma	Deferred Tax Liability Hedginggainsandlosses DeferredTaxLiabilityHedginggainsandlosses	-10000000	USD
CY2020Q4	cma	Deferred Tax Liability Lease Rightof Use Asset DeferredTaxLiabilityLeaseRightofUseAsset	-64000000	USD
CY2019Q4	cma	Deferred Tax Liability Lease Rightof Use Asset DeferredTaxLiabilityLeaseRightofUseAsset	-69000000	USD
CY2020Q4	cma	Deferred Tax Liabilitynetunrealizedgainsoninvestmentsecuritiesavailableforsale DeferredTaxLiabilitynetunrealizedgainsoninvestmentsecuritiesavailableforsale	-65000000	USD
CY2019Q4	cma	Deferred Tax Liabilitynetunrealizedgainsoninvestmentsecuritiesavailableforsale DeferredTaxLiabilitynetunrealizedgainsoninvestmentsecuritiesavailableforsale	-20000000	USD
CY2020Q4	us-gaap	Deferred Income Tax Liabilities DeferredIncomeTaxLiabilities	397000000	USD
CY2019Q4	us-gaap	Deferred Income Tax Liabilities DeferredIncomeTaxLiabilities	284000000	USD
CY2020Q4	us-gaap	Deferred Tax Assets Liabilities Net DeferredTaxAssetsLiabilitiesNet	4000000	USD
CY2019Q4	us-gaap	Deferred Tax Assets Liabilities Net DeferredTaxAssetsLiabilitiesNet	42000000	USD
CY2019Q4	us-gaap	Deferred Tax Assets Operating Loss Carryforwards State And Local DeferredTaxAssetsOperatingLossCarryforwardsStateAndLocal	3000000	USD
CY2020Q4	us-gaap	Deferred Tax Assets Operating Loss Carryforwards State And Local DeferredTaxAssetsOperatingLossCarryforwardsStateAndLocal	3000000	USD
CY2020Q4	us-gaap	Deferred Tax Assets Valuation Allowance DeferredTaxAssetsValuationAllowance	3000000	USD
CY2020Q4	cma	Loans And Leases Receivable Related Parties Beginning Of Period LoansAndLeasesReceivableRelatedPartiesBeginningOfPeriod	74000000	USD
CY2020Q4	cma	Loans And Leases Receivable Related Parties End Of Period LoansAndLeasesReceivableRelatedPartiesEndOfPeriod	80000000	USD
CY2020	us-gaap	Loans And Leases Receivable Related Parties Additions LoansAndLeasesReceivableRelatedPartiesAdditions	231000000	USD
CY2020	us-gaap	Loans And Leases Receivable Related Parties Proceeds LoansAndLeasesReceivableRelatedPartiesProceeds	225000000	USD
CY2020	cma	Average Reserve Requirement AverageReserveRequirement	135000000	USD
CY2019	cma	Average Reserve Requirement AverageReserveRequirement	586000000	USD
CY2020Q4	us-gaap	Statutory Accounting Practices Statutory Amount Available For Dividend Payments With Regulatory Approval StatutoryAccountingPracticesStatutoryAmountAvailableForDividendPaymentsWithRegulatoryApproval	12000000	USD
CY2020	cma	Cash Dividends Paid To Parent Company By Bank Subsidiaries CashDividendsPaidToParentCompanyByBankSubsidiaries	498000000	USD
CY2019	cma	Cash Dividends Paid To Parent Company By Bank Subsidiaries CashDividendsPaidToParentCompanyByBankSubsidiaries	1200000000	USD
CY2018	cma	Cash Dividends Paid To Parent Company By Bank Subsidiaries CashDividendsPaidToParentCompanyByBankSubsidiaries	1100000000	USD
CY2019Q4	cma	Total Risk Based Capital TotalRiskBasedCapital	0.10
CY2020Q4	cma	Total Risk Based Capital TotalRiskBasedCapital	0.10
CY2020Q4	cma	Tier1 Risk Based Capital Tier1RiskBasedCapital	0.06
CY2019Q4	cma	Tier1 Risk Based Capital Tier1RiskBasedCapital	0.06
CY2020Q4	us-gaap	Tier One Risk Based Capital TierOneRiskBasedCapital	4000000000.0	USD
CY2020Q4	us-gaap	Capital Capital	5400000000	USD
CY2019Q4	us-gaap	Tier One Risk Based Capital TierOneRiskBasedCapital	4100000000	USD
CY2019Q4	us-gaap	Capital Capital	5500000000	USD
CY2020	us-gaap	Legal Fees LegalFees	17000000	USD
CY2019	us-gaap	Legal Fees LegalFees	15000000	USD
CY2018	us-gaap	Legal Fees LegalFees	17000000	USD
CY2018	us-gaap	Profit Loss ProfitLoss	1235000000	USD
CY2018	cma	Net Credit Related Charge Offs NetCreditRelatedChargeOffs	51000000	USD
CY2020	cma	Number Of Major Business Segments NumberOfMajorBusinessSegments	3	segments
CY2020	cma	Number Of Major Business Segments NumberOfMajorBusinessSegments	3	segments
CY2020	us-gaap	Interest Income Expense Net InterestIncomeExpenseNet	1911000000	USD
CY2020	us-gaap	Provision For Loan Lease And Other Losses ProvisionForLoanLeaseAndOtherLosses	537000000	USD
CY2020	us-gaap	Noninterest Income NoninterestIncome	1001000000	USD
CY2020	us-gaap	Noninterest Expense NoninterestExpense	1784000000	USD
CY2020	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	117000000	USD
CY2020	us-gaap	Profit Loss ProfitLoss	474000000	USD
CY2020	cma	Net Credit Related Charge Offs NetCreditRelatedChargeOffs	196000000	USD
CY2020	cma	Segment Reporting Average Assets SegmentReportingAverageAssets	81146000000	USD
CY2020	cma	Average Balance During Period Loans And Leases Receivable Net Of Deferred Income AverageBalanceDuringPeriodLoansAndLeasesReceivableNetOfDeferredIncome	51631000000	USD
CY2020	cma	Average Balance During Period Deposits AverageBalanceDuringPeriodDeposits	65038000000	USD
CY2020	cma	Return On Average Assets ReturnOnAverageAssets	0.0058
CY2020	cma	Efficiency Ratio EfficiencyRatio	0.6115
CY2019	us-gaap	Interest Income Expense Net InterestIncomeExpenseNet	2339000000	USD
CY2019	us-gaap	Provision For Loan Lease And Other Losses ProvisionForLoanLeaseAndOtherLosses	74000000	USD
CY2019	us-gaap	Noninterest Income NoninterestIncome	1010000000	USD
CY2019	us-gaap	Noninterest Expense NoninterestExpense	1743000000	USD
CY2019	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	334000000	USD
CY2019	us-gaap	Profit Loss ProfitLoss	1198000000	USD
CY2019	cma	Net Credit Related Charge Offs NetCreditRelatedChargeOffs	107000000	USD
CY2019	cma	Segment Reporting Average Assets SegmentReportingAverageAssets	71488000000	USD
CY2019	cma	Average Balance During Period Loans And Leases Receivable Net Of Deferred Income AverageBalanceDuringPeriodLoansAndLeasesReceivableNetOfDeferredIncome	50511000000	USD
CY2019	cma	Average Balance During Period Deposits AverageBalanceDuringPeriodDeposits	55481000000	USD
CY2019	cma	Return On Average Assets ReturnOnAverageAssets	0.0168
CY2019	cma	Efficiency Ratio EfficiencyRatio	0.5182
CY2018	us-gaap	Interest Income Expense Net InterestIncomeExpenseNet	2352000000	USD
CY2018	us-gaap	Provision For Loan Lease And Other Losses ProvisionForLoanLeaseAndOtherLosses	-1000000	USD
CY2018	us-gaap	Noninterest Income NoninterestIncome	976000000	USD
CY2018	us-gaap	Noninterest Expense NoninterestExpense	1794000000	USD
CY2018	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	300000000	USD
CY2018	cma	Segment Reporting Average Assets SegmentReportingAverageAssets	70724000000	USD
CY2018	cma	Average Balance During Period Loans And Leases Receivable Net Of Deferred Income AverageBalanceDuringPeriodLoansAndLeasesReceivableNetOfDeferredIncome	48766000000	USD
CY2018	cma	Average Balance During Period Deposits AverageBalanceDuringPeriodDeposits	55935000000	USD
CY2018	cma	Return On Average Assets ReturnOnAverageAssets	0.0175
CY2018	cma	Efficiency Ratio EfficiencyRatio	0.5356
CY2020	cma	Number Of Geographic Markets NumberOfGeographicMarkets	3	markets
CY2020	cma	Number Of Geographic Markets NumberOfGeographicMarkets	3	markets
CY2020	us-gaap	Interest Income Expense Net InterestIncomeExpenseNet	1911000000	USD
CY2020	us-gaap	Provision For Loan Lease And Other Losses ProvisionForLoanLeaseAndOtherLosses	537000000	USD
CY2020	us-gaap	Noninterest Income NoninterestIncome	1001000000	USD
CY2020	us-gaap	Noninterest Expense NoninterestExpense	1784000000	USD
CY2020	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	117000000	USD
CY2020	us-gaap	Profit Loss ProfitLoss	474000000	USD
CY2020	cma	Net Credit Related Charge Offs NetCreditRelatedChargeOffs	196000000	USD
CY2020	cma	Segment Reporting Average Assets SegmentReportingAverageAssets	81146000000	USD
CY2020	cma	Average Balance During Period Loans And Leases Receivable Net Of Deferred Income AverageBalanceDuringPeriodLoansAndLeasesReceivableNetOfDeferredIncome	51631000000	USD
CY2018	us-gaap	Provision For Loan Lease And Other Losses ProvisionForLoanLeaseAndOtherLosses	-1000000	USD
CY2020	cma	Average Balance During Period Deposits AverageBalanceDuringPeriodDeposits	65038000000	USD
CY2020	cma	Return On Average Assets ReturnOnAverageAssets	0.0058
CY2020	cma	Efficiency Ratio EfficiencyRatio	0.6115
CY2019	us-gaap	Interest Income Expense Net InterestIncomeExpenseNet	2339000000	USD
CY2019	us-gaap	Provision For Loan Lease And Other Losses ProvisionForLoanLeaseAndOtherLosses	74000000	USD
CY2019	us-gaap	Noninterest Income NoninterestIncome	1010000000	USD
CY2019	us-gaap	Noninterest Expense NoninterestExpense	1743000000	USD
CY2019	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	334000000	USD
CY2019	us-gaap	Profit Loss ProfitLoss	1198000000	USD
CY2019	cma	Net Credit Related Charge Offs NetCreditRelatedChargeOffs	107000000	USD
CY2019	cma	Segment Reporting Average Assets SegmentReportingAverageAssets	71488000000	USD
CY2019	cma	Average Balance During Period Loans And Leases Receivable Net Of Deferred Income AverageBalanceDuringPeriodLoansAndLeasesReceivableNetOfDeferredIncome	50511000000	USD
CY2019	cma	Average Balance During Period Deposits AverageBalanceDuringPeriodDeposits	55481000000	USD
CY2019	cma	Return On Average Assets ReturnOnAverageAssets	0.0168
CY2019	cma	Efficiency Ratio EfficiencyRatio	0.5182
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CY2020Q4	us-gaap	Common Stock Par Or Stated Value Per Share CommonStockParOrStatedValuePerShare	5
CY2018	us-gaap	Noninterest Income NoninterestIncome	976000000	USD
CY2018	us-gaap	Noninterest Expense NoninterestExpense	1794000000	USD
CY2018	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	300000000	USD
CY2018	us-gaap	Profit Loss ProfitLoss	1235000000	USD
CY2018	cma	Net Credit Related Charge Offs NetCreditRelatedChargeOffs	51000000	USD
CY2018	cma	Segment Reporting Average Assets SegmentReportingAverageAssets	70724000000	USD
CY2018	cma	Average Balance During Period Loans And Leases Receivable Net Of Deferred Income AverageBalanceDuringPeriodLoansAndLeasesReceivableNetOfDeferredIncome	48766000000	USD
CY2018	cma	Average Balance During Period Deposits AverageBalanceDuringPeriodDeposits	55935000000	USD
CY2018	cma	Return On Average Assets ReturnOnAverageAssets	0.0175
CY2018	cma	Efficiency Ratio EfficiencyRatio	0.5356
CY2020Q4	us-gaap	Preferred Stock No Par Value PreferredStockNoParValue	0
CY2020Q4	us-gaap	Preferred Stock Shares Authorized PreferredStockSharesAuthorized	4000	shares
CY2020Q4	us-gaap	Preferred Stock Shares Issued PreferredStockSharesIssued	4000	shares
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CY2020Q4	us-gaap	Common Stock Shares Issued CommonStockSharesIssued	228164824	shares
CY2020Q4	us-gaap	Treasury Stock Shares TreasuryStockShares	88997430	shares
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CY2019Q4	us-gaap	Treasury Stock Shares TreasuryStockShares	86069234	shares
CY2020Q4	us-gaap	Interest And Dividend Income Operating InterestAndDividendIncomeOperating	489000000	USD
CY2020Q3	us-gaap	Interest And Dividend Income Operating InterestAndDividendIncomeOperating	484000000	USD
CY2020Q2	us-gaap	Interest And Dividend Income Operating InterestAndDividendIncomeOperating	511000000	USD
CY2020Q1	us-gaap	Interest And Dividend Income Operating InterestAndDividendIncomeOperating	609000000	USD
CY2020Q4	us-gaap	Interest Expense InterestExpense	20000000	USD
CY2020Q3	us-gaap	Interest Expense InterestExpense	26000000	USD
CY2020Q2	us-gaap	Interest Expense InterestExpense	40000000	USD
CY2020Q1	us-gaap	Interest Expense InterestExpense	96000000	USD
CY2020Q4	us-gaap	Interest Income Expense Net InterestIncomeExpenseNet	469000000	USD
CY2020Q3	us-gaap	Interest Income Expense Net InterestIncomeExpenseNet	458000000	USD
CY2020Q2	us-gaap	Interest Income Expense Net InterestIncomeExpenseNet	471000000	USD
CY2020Q1	us-gaap	Interest Income Expense Net InterestIncomeExpenseNet	513000000	USD
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CY2020Q1	us-gaap	Debt And Equity Securities Gain Loss DebtAndEquitySecuritiesGainLoss	-1000000	USD
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CY2020Q3	cma	Non Interest Income Excluding Net Securities Gains NonInterestIncomeExcludingNetSecuritiesGains	252000000	USD
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CY2020Q1	cma	Non Interest Income Excluding Net Securities Gains NonInterestIncomeExcludingNetSecuritiesGains	238000000	USD
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CY2020Q3	us-gaap	Noninterest Expense NoninterestExpense	446000000	USD
CY2020Q2	us-gaap	Noninterest Expense NoninterestExpense	440000000	USD
CY2020Q1	us-gaap	Noninterest Expense NoninterestExpense	425000000	USD
CY2020Q4	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	63000000	USD
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CY2020Q2	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	27000000	USD
CY2020Q1	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	-21000000	USD
CY2020Q4	us-gaap	Profit Loss ProfitLoss	215000000	USD
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CY2020Q2	us-gaap	Profit Loss ProfitLoss	113000000	USD
CY2020Q1	us-gaap	Profit Loss ProfitLoss	-65000000	USD
CY2020Q4	us-gaap	Undistributed Earnings Loss Allocated To Participating Securities Diluted UndistributedEarningsLossAllocatedToParticipatingSecuritiesDiluted	1000000	USD
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CY2020Q2	us-gaap	Undistributed Earnings Loss Allocated To Participating Securities Diluted UndistributedEarningsLossAllocatedToParticipatingSecuritiesDiluted	1000000	USD
CY2020Q1	us-gaap	Undistributed Earnings Loss Allocated To Participating Securities Diluted UndistributedEarningsLossAllocatedToParticipatingSecuritiesDiluted	0	USD
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CY2020Q4	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	1.50
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CY2020Q1	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	-0.46
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CY2020Q3	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	1.44
CY2020Q2	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	0.80
CY2020Q1	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	-0.46
CY2020Q4	us-gaap	Comprehensive Income Net Of Tax Including Portion Attributable To Noncontrolling Interest ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest	267000000	USD
CY2020Q3	us-gaap	Comprehensive Income Net Of Tax Including Portion Attributable To Noncontrolling Interest ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest	169000000	USD
CY2020Q2	us-gaap	Comprehensive Income Net Of Tax Including Portion Attributable To Noncontrolling Interest ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest	97000000	USD
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CY2019Q4	us-gaap	Interest And Dividend Income Operating InterestAndDividendIncomeOperating	659000000	USD
CY2019Q3	us-gaap	Interest And Dividend Income Operating InterestAndDividendIncomeOperating	711000000	USD
CY2019Q2	us-gaap	Interest And Dividend Income Operating InterestAndDividendIncomeOperating	727000000	USD
CY2019Q1	us-gaap	Interest And Dividend Income Operating InterestAndDividendIncomeOperating	710000000	USD
CY2019Q4	us-gaap	Interest Expense InterestExpense	115000000	USD
CY2019Q3	us-gaap	Interest Expense InterestExpense	125000000	USD
CY2019Q2	us-gaap	Interest Expense InterestExpense	124000000	USD
CY2019Q1	us-gaap	Interest Expense InterestExpense	104000000	USD
CY2019Q4	us-gaap	Interest Income Expense Net InterestIncomeExpenseNet	544000000	USD
CY2019Q3	us-gaap	Interest Income Expense Net InterestIncomeExpenseNet	586000000	USD
CY2019Q2	us-gaap	Interest Income Expense Net InterestIncomeExpenseNet	603000000	USD
CY2019Q1	us-gaap	Interest Income Expense Net InterestIncomeExpenseNet	606000000	USD
CY2019Q4	us-gaap	Provision For Loan Lease And Other Losses ProvisionForLoanLeaseAndOtherLosses	8000000	USD
CY2019Q3	us-gaap	Provision For Loan Lease And Other Losses ProvisionForLoanLeaseAndOtherLosses	35000000	USD
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CY2019Q1	us-gaap	Provision For Loan Lease And Other Losses ProvisionForLoanLeaseAndOtherLosses	-13000000	USD
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CY2019Q1	us-gaap	Debt And Equity Securities Gain Loss DebtAndEquitySecuritiesGainLoss	-8000000	USD
CY2019Q4	cma	Non Interest Income Excluding Net Securities Gains NonInterestIncomeExcludingNetSecuritiesGains	265000000	USD
CY2019Q3	cma	Non Interest Income Excluding Net Securities Gains NonInterestIncomeExcludingNetSecuritiesGains	256000000	USD
CY2019Q2	cma	Non Interest Income Excluding Net Securities Gains NonInterestIncomeExcludingNetSecuritiesGains	250000000	USD
CY2019Q1	cma	Non Interest Income Excluding Net Securities Gains NonInterestIncomeExcludingNetSecuritiesGains	246000000	USD
CY2019Q4	us-gaap	Noninterest Expense NoninterestExpense	451000000	USD
CY2019Q3	us-gaap	Noninterest Expense NoninterestExpense	435000000	USD
CY2019Q2	us-gaap	Noninterest Expense NoninterestExpense	424000000	USD
CY2019Q1	us-gaap	Noninterest Expense NoninterestExpense	433000000	USD
CY2019Q4	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	82000000	USD
CY2019Q3	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	80000000	USD
CY2019Q2	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	87000000	USD
CY2019Q1	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	85000000	USD
CY2019Q4	us-gaap	Profit Loss ProfitLoss	269000000	USD
CY2019Q3	us-gaap	Profit Loss ProfitLoss	292000000	USD
CY2019Q2	us-gaap	Profit Loss ProfitLoss	298000000	USD
CY2019Q1	us-gaap	Profit Loss ProfitLoss	339000000	USD
CY2019Q4	us-gaap	Undistributed Earnings Loss Allocated To Participating Securities Diluted UndistributedEarningsLossAllocatedToParticipatingSecuritiesDiluted	2000000	USD
CY2019Q3	us-gaap	Undistributed Earnings Loss Allocated To Participating Securities Diluted UndistributedEarningsLossAllocatedToParticipatingSecuritiesDiluted	2000000	USD
CY2019Q2	us-gaap	Undistributed Earnings Loss Allocated To Participating Securities Diluted UndistributedEarningsLossAllocatedToParticipatingSecuritiesDiluted	1000000	USD
CY2019Q1	us-gaap	Undistributed Earnings Loss Allocated To Participating Securities Diluted UndistributedEarningsLossAllocatedToParticipatingSecuritiesDiluted	2000000	USD
CY2019Q4	us-gaap	Net Income Loss Available To Common Stockholders Basic NetIncomeLossAvailableToCommonStockholdersBasic	267000000	USD
CY2019Q3	us-gaap	Net Income Loss Available To Common Stockholders Basic NetIncomeLossAvailableToCommonStockholdersBasic	290000000	USD
CY2019Q2	us-gaap	Net Income Loss Available To Common Stockholders Basic NetIncomeLossAvailableToCommonStockholdersBasic	297000000	USD
CY2019Q1	us-gaap	Net Income Loss Available To Common Stockholders Basic NetIncomeLossAvailableToCommonStockholdersBasic	337000000	USD
CY2019Q4	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	1.87
CY2019Q3	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	1.98
CY2019Q2	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	1.95
CY2019Q1	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	2.14
CY2019Q4	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	1.85
CY2019Q3	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	1.96
CY2019Q2	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	1.94
CY2019Q1	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	2.11
CY2019Q4	us-gaap	Comprehensive Income Net Of Tax Including Portion Attributable To Noncontrolling Interest ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest	370000000	USD
CY2019Q3	us-gaap	Comprehensive Income Net Of Tax Including Portion Attributable To Noncontrolling Interest ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest	338000000	USD
CY2019Q2	us-gaap	Comprehensive Income Net Of Tax Including Portion Attributable To Noncontrolling Interest ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest	429000000	USD
CY2019Q1	us-gaap	Comprehensive Income Net Of Tax Including Portion Attributable To Noncontrolling Interest ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest	435000000	USD
CY2020	us-gaap	Revenue From Contract With Customer Excluding Assessed Tax RevenueFromContractWithCustomerExcludingAssessedTax	758000000	USD
CY2020	cma	Othersourcesofnoninterestincome Othersourcesofnoninterestincome	243000000	USD
CY2020	us-gaap	Noninterest Income NoninterestIncome	1001000000	USD
CY2019	us-gaap	Revenue From Contract With Customer Excluding Assessed Tax RevenueFromContractWithCustomerExcludingAssessedTax	749000000	USD
CY2019	cma	Othersourcesofnoninterestincome Othersourcesofnoninterestincome	261000000	USD
CY2019	us-gaap	Noninterest Income NoninterestIncome	1010000000	USD
CY2018	us-gaap	Revenue From Contract With Customer Excluding Assessed Tax RevenueFromContractWithCustomerExcludingAssessedTax	755000000	USD
CY2018	cma	Othersourcesofnoninterestincome Othersourcesofnoninterestincome	221000000	USD
CY2018	us-gaap	Noninterest Income NoninterestIncome	976000000	USD
CY2020	us-gaap	Operating Lease Expense OperatingLeaseExpense	64000000	USD
CY2019	us-gaap	Operating Lease Expense OperatingLeaseExpense	64000000	USD
CY2020	us-gaap	Variable Lease Cost VariableLeaseCost	16000000	USD
CY2019	us-gaap	Variable Lease Cost VariableLeaseCost	19000000	USD
CY2020	us-gaap	Sublease Income SubleaseIncome	1000000	USD
CY2019	us-gaap	Sublease Income SubleaseIncome	2000000	USD
CY2020	us-gaap	Lease Cost LeaseCost	79000000	USD
CY2019	us-gaap	Lease Cost LeaseCost	81000000	USD
CY2020Q4	us-gaap	Operating Lease Right Of Use Asset OperatingLeaseRightOfUseAsset	306000000	USD
CY2020Q4	us-gaap	Operating Lease Liability OperatingLeaseLiability	344000000	USD
CY2019Q4	us-gaap	Operating Lease Right Of Use Asset OperatingLeaseRightOfUseAsset	329000000	USD
CY2019Q4	us-gaap	Operating Lease Liability OperatingLeaseLiability	367000000	USD
CY2020	cma	New Rightof Use Assets NewRightofUseAssets	28000000	USD
CY2019	cma	New Rightof Use Assets NewRightofUseAssets	49000000	USD
CY2020	us-gaap	Operating Lease Payments OperatingLeasePayments	65000000	USD
CY2019	us-gaap	Operating Lease Payments OperatingLeasePayments	67000000	USD
CY2020Q4	us-gaap	Lessee Operating Lease Discount Rate LesseeOperatingLeaseDiscountRate	0.0361
CY2019Q4	us-gaap	Lessee Operating Lease Discount Rate LesseeOperatingLeaseDiscountRate	0.0378
CY2020Q4	us-gaap	Lessee Operating Lease Liability Payments Due Next Rolling Twelve Months LesseeOperatingLeaseLiabilityPaymentsDueNextRollingTwelveMonths	60000000	USD
CY2020Q4	us-gaap	Lessee Operating Lease Liability Payments Due In Rolling Year Two LesseeOperatingLeaseLiabilityPaymentsDueInRollingYearTwo	57000000	USD
CY2020Q4	us-gaap	Lessee Operating Lease Liability Payments Due In Rolling Year Three LesseeOperatingLeaseLiabilityPaymentsDueInRollingYearThree	51000000	USD
CY2020Q4	us-gaap	Lessee Operating Lease Liability Payments Due In Rolling Year Four LesseeOperatingLeaseLiabilityPaymentsDueInRollingYearFour	46000000	USD
CY2020Q4	us-gaap	Lessee Operating Lease Liability Payments Due In Rolling Year Five LesseeOperatingLeaseLiabilityPaymentsDueInRollingYearFive	40000000	USD
CY2020Q4	us-gaap	Lessee Operating Lease Liability Payments Due After Rolling Year Five LesseeOperatingLeaseLiabilityPaymentsDueAfterRollingYearFive	149000000	USD
CY2020Q4	us-gaap	Lessee Operating Lease Liability Payments Due LesseeOperatingLeaseLiabilityPaymentsDue	403000000	USD
CY2020	cma	Operatingleaseimputedinterest Operatingleaseimputedinterest	-59000000	USD
CY2020Q4	us-gaap	Operating Lease Liability OperatingLeaseLiability	344000000	USD
CY2020	us-gaap	Sales Type Lease Lease Income SalesTypeLeaseLeaseIncome	13000000	USD
CY2019	us-gaap	Sales Type Lease Lease Income SalesTypeLeaseLeaseIncome	14000000	USD
CY2020Q4	us-gaap	Sales Type And Direct Financing Leases Lease Receivable SalesTypeAndDirectFinancingLeasesLeaseReceivable	391000000	USD
CY2019Q4	us-gaap	Sales Type And Direct Financing Leases Lease Receivable SalesTypeAndDirectFinancingLeasesLeaseReceivable	369000000	USD
CY2020Q4	us-gaap	Sales Type And Direct Financing Leases Lease Receivable Payments To Be Received Next Rolling Twelve Months SalesTypeAndDirectFinancingLeasesLeaseReceivablePaymentsToBeReceivedNextRollingTwelveMonths	69000000	USD
CY2020Q4	us-gaap	Sales Type And Direct Financing Leases Lease Receivable Lease Payments To Be Received Rolling Year Two SalesTypeAndDirectFinancingLeasesLeaseReceivableLeasePaymentsToBeReceivedRollingYearTwo	101000000	USD
CY2020Q4	us-gaap	Sales Type And Direct Financing Leases Lease Receivable Lease Payments To Be Received Rolling Year Three SalesTypeAndDirectFinancingLeasesLeaseReceivableLeasePaymentsToBeReceivedRollingYearThree	54000000	USD
CY2020Q4	us-gaap	Sales Type And Direct Financing Leases Lease Receivable Payments To Be Received Rolling Year Four SalesTypeAndDirectFinancingLeasesLeaseReceivablePaymentsToBeReceivedRollingYearFour	64000000	USD
CY2020Q4	us-gaap	Sales Type And Direct Financing Leases Lease Receivable Lease Payments To Be Received Rolling Year Five SalesTypeAndDirectFinancingLeasesLeaseReceivableLeasePaymentsToBeReceivedRollingYearFive	33000000	USD
CY2020Q4	us-gaap	Sales Type And Direct Financing Leases Lease Receivable Lease Payments To Be Received After Rolling Year Five SalesTypeAndDirectFinancingLeasesLeaseReceivableLeasePaymentsToBeReceivedAfterRollingYearFive	18000000	USD
CY2020Q4	us-gaap	Sales Type And Direct Financing Leases Lease Receivable Payments To Be Received SalesTypeAndDirectFinancingLeasesLeaseReceivablePaymentsToBeReceived	339000000	USD
CY2020Q4	cma	Sales Typeand Direct Financing Leases Unguaranteed Residual Asset SalesTypeandDirectFinancingLeasesUnguaranteedResidualAsset	72000000	USD
CY2020Q4	us-gaap	Deferred Discounts Finance Charges And Interest Included In Receivables DeferredDiscountsFinanceChargesAndInterestIncludedInReceivables	20000000	USD
CY2020Q4	us-gaap	Sales Type And Direct Financing Leases Lease Receivable SalesTypeAndDirectFinancingLeasesLeaseReceivable	391000000	USD
CY2020Q4	us-gaap	Financing Receivable Allowance For Credit Losses FinancingReceivableAllowanceForCreditLosses	992000000	USD

Files In Submission

Name	View Source	Status
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$CMA
Comerica Inc Stock $cma

2020 Q4 Form 10-K Financial Statement

#000002841221000054 Filed on February 09, 2021

Income Statement

Balance Sheet

Cashflow Statement

Facts In Submission

Files In Submission

$CMA Comerica Inc Stock $cma

2020 Q4 Form 10-K Financial Statement

#000002841221000054 Filed on February 09, 2021

Income Statement

Balance Sheet

Cashflow Statement

Facts In Submission

Files In Submission

$CMA
Comerica Inc Stock $cma