$CNA
CNA FINANCIAL CORP Stock $cna

$cna Overview Financials Valuation SEC Filings Company Website

2021 Q4 Form 10-K Financial Statement

#000002117522000016 Filed on February 08, 2022

Income Statement

Concept	2021 Q4	2021	2020 Q4
Revenue	$3.054B	$11.91B	$2.931B
YoY Change	4.2%	10.18%	5.55%
Cost Of Revenue		$6.327B
YoY Change		2.89%
Gross Profit		$5.581B
YoY Change		19.79%
Gross Profit Margin		46.87%
Selling, General & Admin
YoY Change
% of Gross Profit
Research & Development
YoY Change
% of Gross Profit
Depreciation & Amortization	$13.00M	$54.00M	$14.00M
YoY Change	-7.14%	-10.0%	-12.5%
% of Gross Profit		0.97%
Operating Expenses	$2.696B	$10.31B	$2.425B
YoY Change	11.18%	4.52%	0.58%
Operating Profit		-$4.730B
YoY Change		-9.14%
Interest Expense	-$28.00M	$113.0M	-$28.00M
YoY Change	0.0%	-7.38%	-9.68%
% of Operating Profit
Other Income/Expense, Net		$242.0M
YoY Change		10.0%
Pretax Income	$330.0M	$1.484B	$478.0M
YoY Change	-30.96%	80.76%	42.69%
Income Tax	$64.00M	$282.0M	$91.00M
% Of Pretax Income	19.39%	19.0%	19.04%
Net Earnings	$266.0M	$1.202B	$387.0M
YoY Change	-31.27%	74.2%	41.76%
Net Earnings / Revenue	8.71%	10.09%	13.2%
Basic Earnings Per Share		$4.42	$1.42
Diluted Earnings Per Share	$975.1K	$4.41	$1.42
COMMON SHARES
Basic Shares Outstanding	271.4M shares	271.8M shares	271.4M shares
Diluted Shares Outstanding		272.8M shares

Balance Sheet

Concept	2021 Q4	2021	2020 Q4
SHORT-TERM ASSETS
Cash & Short-Term Investments
YoY Change
Cash & Equivalents	$536.0M		$419.0M
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	$226.0M	$401.0M	$252.0M
YoY Change	-10.32%	-11.09%	-10.64%
Goodwill	$148.0M		$148.0M
YoY Change	0.0%		0.68%
Intangibles
YoY Change
Long-Term Investments	$50.33B	$50.33B	$50.29B
YoY Change	0.07%	0.07%	5.34%
Other Assets	$142.0M	$142.0M	$66.00M
YoY Change	115.15%	115.15%	-66.83%
Total Long-Term Assets
YoY Change
TOTAL ASSETS
Total Short-Term Assets
Total Long-Term Assets
Total Assets	$66.64B	$66.64B	$64.03B
YoY Change	4.08%	4.08%	5.63%
SHORT-TERM LIABILITIES
YoY Change
Accounts Payable
YoY Change
Accrued Expenses	$248.0M	$248.0M	$279.0M
YoY Change	-11.11%	-11.11%	-7.31%
Deferred Revenue
YoY Change
Short-Term Debt	$0.00	$0.00	$0.00
YoY Change
Long-Term Debt Due		$0.00
YoY Change
Total Short-Term Liabilities	$248.0M	$248.0M	$279.0M
YoY Change	-11.11%	-11.11%	-7.31%
LONG-TERM LIABILITIES
Long-Term Debt	$2.779B	$2.779B	$2.776B
YoY Change	0.11%	0.11%	3.62%
Other Long-Term Liabilities	$7.632B	$7.632B	$7.121B
YoY Change	7.18%	7.18%	4.67%
Total Long-Term Liabilities	$2.779B	$10.41B	$2.776B
YoY Change	0.11%	5.19%	3.62%
TOTAL LIABILITIES
Total Short-Term Liabilities	$248.0M	$248.0M	$279.0M
Total Long-Term Liabilities	$2.779B	$10.41B	$2.776B
Total Liabilities	$53.83B	$53.83B	$51.32B
YoY Change	4.89%	4.89%	6.04%
SHAREHOLDERS EQUITY
Retained Earnings	$9.663B		$9.081B
YoY Change	6.41%		-2.86%
Common Stock	$2.898B		$2.894B
YoY Change	0.14%		0.28%
Preferred Stock
YoY Change
Treasury Stock (at cost)	$72.00M		$71.00M
YoY Change	1.41%		1.43%
Treasury Stock Shares	1.676M shares		1.649M shares
Shareholders Equity	$12.81B	$12.81B	$12.71B
YoY Change
Total Liabilities & Shareholders Equity	$66.64B	$66.64B	$64.03B
YoY Change	4.08%	4.08%	5.63%

Cashflow Statement

Concept	2021 Q4	2021	2020 Q4
OPERATING ACTIVITIES
Net Income	$266.0M	$1.202B	$387.0M
YoY Change	-31.27%	74.2%	41.76%
Depreciation, Depletion And Amortization	$13.00M	$54.00M	$14.00M
YoY Change	-7.14%	-10.0%	-12.5%
Cash From Operating Activities	$643.0M	$1.997B	$367.0M
YoY Change	75.2%	12.51%	129.38%
INVESTING ACTIVITIES
Capital Expenditures	-$10.00M	$26.00M	-$7.000M
YoY Change	42.86%	13.04%	16.67%
Acquisitions
YoY Change
Other Investing Activities	-$621.0M	-$1.000M	-$291.0M
YoY Change	113.4%	-93.75%	83.02%
Cash From Investing Activities	-$631.0M	-$1.228B	-$298.0M
YoY Change	111.74%	74.18%	80.61%
FINANCING ACTIVITIES
Cash Dividend Paid
YoY Change
Common Stock Issuance & Retirement, Net		$18.00M
YoY Change		0.0%
Debt Paid & Issued, Net		$0.00
YoY Change		-100.0%
Cash From Financing Activities	-103.0M	-$648.0M	-101.0M
YoY Change	1.98%	-28.16%	0.0%
NET CHANGE
Cash From Operating Activities	643.0M	$1.997B	367.0M
Cash From Investing Activities	-631.0M	-$1.228B	-298.0M
Cash From Financing Activities	-103.0M	-$648.0M	-101.0M
Net Change In Cash	-91.00M	$117.0M	-32.00M
YoY Change	184.38%	-33.9%	-69.81%
FREE CASH FLOW
Cash From Operating Activities	$643.0M	$1.997B	$367.0M
Capital Expenditures	-$10.00M	$26.00M	-$7.000M
Free Cash Flow	$653.0M	$1.971B	$374.0M
YoY Change	74.6%	12.5%	125.3%

Facts In Submission

Frame	Concept Type	Concept / XBRL Key	Value	Unit
CY2021	dei	Entity Central Index Key EntityCentralIndexKey	0000021175
CY2021	dei	Document Fiscal Year Focus DocumentFiscalYearFocus	2021
CY2021	dei	Document Fiscal Period Focus DocumentFiscalPeriodFocus	FY
CY2021	dei	Amendment Flag AmendmentFlag	false
CY2020Q4	us-gaap	Operating Lease Right Of Use Asset Statement Of Financial Position Extensible List OperatingLeaseRightOfUseAssetStatementOfFinancialPositionExtensibleList	http://fasb.org/us-gaap/2021-01-31#OtherAssets
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CY2021Q4	us-gaap	Revenue Remaining Performance Obligation Expected Timing Of Satisfaction Period1 RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionPeriod1	P1Y
CY2021Q4	us-gaap	Revenue Remaining Performance Obligation Expected Timing Of Satisfaction Period1 RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionPeriod1
CY2021	dei	Document Type DocumentType	10-K
CY2021	dei	Document Annual Report DocumentAnnualReport	true
CY2021	dei	Document Period End Date DocumentPeriodEndDate	2021-12-31
CY2021	dei	Current Fiscal Year End Date CurrentFiscalYearEndDate	--12-31
CY2021	dei	Document Transition Report DocumentTransitionReport	false
CY2021	dei	Entity File Number EntityFileNumber	1-5823
CY2021	dei	Entity Registrant Name EntityRegistrantName	CNA FINANCIAL CORPORATION
CY2021	dei	Entity Incorporation State Country Code EntityIncorporationStateCountryCode	DE
CY2021	dei	Entity Tax Identification Number EntityTaxIdentificationNumber	36-6169860
CY2021	dei	Entity Address Address Line1 EntityAddressAddressLine1	151 N. Franklin
CY2021	dei	Entity Address Postal Zip Code EntityAddressPostalZipCode	60606
CY2021	dei	Entity Address City Or Town EntityAddressCityOrTown	Chicago,
CY2021	dei	Entity Address State Or Province EntityAddressStateOrProvince	IL
CY2021	dei	City Area Code CityAreaCode	312
CY2021	dei	Local Phone Number LocalPhoneNumber	822-5000
CY2021	dei	Security12b Title Security12bTitle	Common Stock, Par value $2.50
CY2021	dei	Trading Symbol TradingSymbol	"CNA"
CY2021	dei	Entity Well Known Seasoned Issuer EntityWellKnownSeasonedIssuer	Yes
CY2021	dei	Entity Voluntary Filers EntityVoluntaryFilers	No
CY2021	dei	Entity Current Reporting Status EntityCurrentReportingStatus	Yes
CY2021	dei	Entity Interactive Data Current EntityInteractiveDataCurrent	Yes
CY2021	dei	Entity Filer Category EntityFilerCategory	Large Accelerated Filer
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CY2021	dei	Entity Emerging Growth Company EntityEmergingGrowthCompany	false
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CY2020Q4	us-gaap	Due To Related Parties Current And Noncurrent DueToRelatedPartiesCurrentAndNoncurrent	89000000	USD
CY2021Q4	us-gaap	Other Liabilities OtherLiabilities	3377000000	USD
CY2020Q4	us-gaap	Other Liabilities OtherLiabilities	3377000000	USD
CY2021Q4	us-gaap	Liabilities Liabilities	53830000000	USD
CY2020Q4	us-gaap	Liabilities Liabilities	51319000000	USD
CY2020Q4	us-gaap	Commitments And Contingencies CommitmentsAndContingencies		USD
CY2020Q4	us-gaap	Common Stock Par Or Stated Value Per Share CommonStockParOrStatedValuePerShare	2.50
CY2021Q4	us-gaap	Common Stock Par Or Stated Value Per Share CommonStockParOrStatedValuePerShare	2.50
CY2021Q4	us-gaap	Common Stock Shares Authorized CommonStockSharesAuthorized	500000000	shares
CY2020Q4	us-gaap	Common Stock Shares Authorized CommonStockSharesAuthorized	500000000	shares
CY2020Q4	us-gaap	Common Stock Shares Issued CommonStockSharesIssued	273040243	shares
CY2021Q4	us-gaap	Common Stock Shares Issued CommonStockSharesIssued	273040243	shares
CY2021Q4	us-gaap	Common Stock Shares Outstanding CommonStockSharesOutstanding	271363999	shares
CY2020Q4	us-gaap	Common Stock Shares Outstanding CommonStockSharesOutstanding	271391603	shares
CY2021Q4	us-gaap	Common Stock Value CommonStockValue	683000000	USD
CY2020Q4	us-gaap	Common Stock Value CommonStockValue	683000000	USD
CY2021Q4	us-gaap	Additional Paid In Capital Common Stock AdditionalPaidInCapitalCommonStock	2215000000	USD
CY2020Q4	us-gaap	Additional Paid In Capital Common Stock AdditionalPaidInCapitalCommonStock	2211000000	USD
CY2021Q4	us-gaap	Retained Earnings Accumulated Deficit RetainedEarningsAccumulatedDeficit	9663000000	USD
CY2020Q4	us-gaap	Retained Earnings Accumulated Deficit RetainedEarningsAccumulatedDeficit	9081000000	USD
CY2021Q4	us-gaap	Accumulated Other Comprehensive Income Loss Net Of Tax AccumulatedOtherComprehensiveIncomeLossNetOfTax	320000000	USD
CY2020Q4	us-gaap	Accumulated Other Comprehensive Income Loss Net Of Tax AccumulatedOtherComprehensiveIncomeLossNetOfTax	803000000	USD
CY2021Q4	us-gaap	Treasury Stock Shares TreasuryStockShares	1676244	shares
CY2020Q4	us-gaap	Treasury Stock Shares TreasuryStockShares	1648640	shares
CY2021Q4	us-gaap	Treasury Stock Value TreasuryStockValue	72000000	USD
CY2020Q4	us-gaap	Treasury Stock Value TreasuryStockValue	71000000	USD
CY2021Q4	us-gaap	Stockholders Equity StockholdersEquity	12809000000	USD
CY2020Q4	us-gaap	Stockholders Equity StockholdersEquity	12707000000	USD
CY2021Q4	us-gaap	Liabilities And Stockholders Equity LiabilitiesAndStockholdersEquity	66639000000	USD
CY2020Q4	us-gaap	Liabilities And Stockholders Equity LiabilitiesAndStockholdersEquity	64026000000	USD
CY2021	us-gaap	Net Income Loss NetIncomeLoss	1202000000	USD
CY2020	us-gaap	Net Income Loss NetIncomeLoss	690000000	USD
CY2019	us-gaap	Net Income Loss NetIncomeLoss	1000000000	USD
CY2021	us-gaap	Deferred Income Tax Expense Benefit DeferredIncomeTaxExpenseBenefit	47000000	USD
CY2020	us-gaap	Deferred Income Tax Expense Benefit DeferredIncomeTaxExpenseBenefit	-49000000	USD
CY2019	us-gaap	Deferred Income Tax Expense Benefit DeferredIncomeTaxExpenseBenefit	-46000000	USD
CY2021	us-gaap	Increase Decrease In Financial Instruments Used In Operating Activities IncreaseDecreaseInFinancialInstrumentsUsedInOperatingActivities	-20000000	USD
CY2020	us-gaap	Increase Decrease In Financial Instruments Used In Operating Activities IncreaseDecreaseInFinancialInstrumentsUsedInOperatingActivities	5000000	USD
CY2019	us-gaap	Increase Decrease In Financial Instruments Used In Operating Activities IncreaseDecreaseInFinancialInstrumentsUsedInOperatingActivities	16000000	USD
CY2021	cna	Net Realized Investment Gains Losses Continuing And Discontinuing Operations NetRealizedInvestmentGainsLossesContinuingAndDiscontinuingOperations	120000000	USD
CY2020	cna	Net Realized Investment Gains Losses Continuing And Discontinuing Operations NetRealizedInvestmentGainsLossesContinuingAndDiscontinuingOperations	-54000000	USD
CY2019	cna	Net Realized Investment Gains Losses Continuing And Discontinuing Operations NetRealizedInvestmentGainsLossesContinuingAndDiscontinuingOperations	29000000	USD
CY2021	us-gaap	Income Loss From Equity Method Investments Net Of Dividends Or Distributions IncomeLossFromEquityMethodInvestmentsNetOfDividendsOrDistributions	127000000	USD
CY2020	us-gaap	Income Loss From Equity Method Investments Net Of Dividends Or Distributions IncomeLossFromEquityMethodInvestmentsNetOfDividendsOrDistributions	8000000	USD
CY2019	us-gaap	Income Loss From Equity Method Investments Net Of Dividends Or Distributions IncomeLossFromEquityMethodInvestmentsNetOfDividendsOrDistributions	-11000000	USD
CY2021	us-gaap	Accretion Amortization Of Discounts And Premiums Investments AccretionAmortizationOfDiscountsAndPremiumsInvestments	81000000	USD
CY2020	us-gaap	Accretion Amortization Of Discounts And Premiums Investments AccretionAmortizationOfDiscountsAndPremiumsInvestments	67000000	USD
CY2019	us-gaap	Accretion Amortization Of Discounts And Premiums Investments AccretionAmortizationOfDiscountsAndPremiumsInvestments	89000000	USD
CY2021	us-gaap	Depreciation Depletion And Amortization DepreciationDepletionAndAmortization	54000000	USD
CY2020	us-gaap	Depreciation Depletion And Amortization DepreciationDepletionAndAmortization	60000000	USD
CY2019	us-gaap	Depreciation Depletion And Amortization DepreciationDepletionAndAmortization	68000000	USD
CY2021	us-gaap	Increase Decrease In Other Receivables IncreaseDecreaseInOtherReceivables	1358000000	USD
CY2020	us-gaap	Increase Decrease In Other Receivables IncreaseDecreaseInOtherReceivables	409000000	USD
CY2019	us-gaap	Increase Decrease In Other Receivables IncreaseDecreaseInOtherReceivables	-137000000	USD
CY2021	us-gaap	Increase Decrease In Accrued Investment Income Receivable IncreaseDecreaseInAccruedInvestmentIncomeReceivable	-3000000	USD
CY2020	us-gaap	Increase Decrease In Accrued Investment Income Receivable IncreaseDecreaseInAccruedInvestmentIncomeReceivable	-16000000	USD
CY2019	us-gaap	Increase Decrease In Accrued Investment Income Receivable IncreaseDecreaseInAccruedInvestmentIncomeReceivable	3000000	USD
CY2021	us-gaap	Increase Decrease In Deferred Policy Acquisition Costs IncreaseDecreaseInDeferredPolicyAcquisitionCosts	30000000	USD
CY2020	us-gaap	Increase Decrease In Deferred Policy Acquisition Costs IncreaseDecreaseInDeferredPolicyAcquisitionCosts	43000000	USD
CY2019	us-gaap	Increase Decrease In Deferred Policy Acquisition Costs IncreaseDecreaseInDeferredPolicyAcquisitionCosts	26000000	USD
CY2021	us-gaap	Increase Decrease In Insurance Liabilities IncreaseDecreaseInInsuranceLiabilities	2463000000	USD
CY2020	us-gaap	Increase Decrease In Insurance Liabilities IncreaseDecreaseInInsuranceLiabilities	1681000000	USD
CY2019	us-gaap	Increase Decrease In Insurance Liabilities IncreaseDecreaseInInsuranceLiabilities	358000000	USD
CY2021	us-gaap	Other Operating Activities Cash Flow Statement OtherOperatingActivitiesCashFlowStatement	-76000000	USD
CY2020	us-gaap	Other Operating Activities Cash Flow Statement OtherOperatingActivitiesCashFlowStatement	-145000000	USD
CY2019	us-gaap	Other Operating Activities Cash Flow Statement OtherOperatingActivitiesCashFlowStatement	-225000000	USD
CY2021	us-gaap	Net Cash Provided By Used In Operating Activities NetCashProvidedByUsedInOperatingActivities	1997000000	USD
CY2020	us-gaap	Net Cash Provided By Used In Operating Activities NetCashProvidedByUsedInOperatingActivities	1775000000	USD
CY2020	us-gaap	Proceeds From Sale Of Available For Sale Securities Debt ProceedsFromSaleOfAvailableForSaleSecuritiesDebt	5904000000	USD
CY2019	us-gaap	Net Cash Provided By Used In Operating Activities NetCashProvidedByUsedInOperatingActivities	1140000000	USD
CY2021	us-gaap	Proceeds From Sale Of Available For Sale Securities Debt ProceedsFromSaleOfAvailableForSaleSecuritiesDebt	3816000000	USD
CY2019	us-gaap	Proceeds From Sale Of Available For Sale Securities Debt ProceedsFromSaleOfAvailableForSaleSecuritiesDebt	5842000000	USD
CY2021	us-gaap	Proceeds From Maturities Prepayments And Calls Of Available For Sale Securities ProceedsFromMaturitiesPrepaymentsAndCallsOfAvailableForSaleSecurities	4464000000	USD
CY2020	us-gaap	Proceeds From Maturities Prepayments And Calls Of Available For Sale Securities ProceedsFromMaturitiesPrepaymentsAndCallsOfAvailableForSaleSecurities	3760000000	USD
CY2019	us-gaap	Proceeds From Maturities Prepayments And Calls Of Available For Sale Securities ProceedsFromMaturitiesPrepaymentsAndCallsOfAvailableForSaleSecurities	2997000000	USD
CY2021	us-gaap	Proceeds From Sale Of Equity Securities Fv Ni ProceedsFromSaleOfEquitySecuritiesFvNi	316000000	USD
CY2020	us-gaap	Proceeds From Sale Of Equity Securities Fv Ni ProceedsFromSaleOfEquitySecuritiesFvNi	355000000	USD
CY2019	us-gaap	Proceeds From Sale Of Equity Securities Fv Ni ProceedsFromSaleOfEquitySecuritiesFvNi	214000000	USD
CY2021	us-gaap	Proceeds From Limited Partnership Investments ProceedsFromLimitedPartnershipInvestments	246000000	USD
CY2020	us-gaap	Proceeds From Limited Partnership Investments ProceedsFromLimitedPartnershipInvestments	373000000	USD
CY2019	us-gaap	Proceeds From Limited Partnership Investments ProceedsFromLimitedPartnershipInvestments	479000000	USD
CY2021	us-gaap	Proceeds From Sale And Collection Of Mortgage Notes Receivable ProceedsFromSaleAndCollectionOfMortgageNotesReceivable	190000000	USD
CY2020	us-gaap	Proceeds From Sale And Collection Of Mortgage Notes Receivable ProceedsFromSaleAndCollectionOfMortgageNotesReceivable	74000000	USD
CY2019	us-gaap	Proceeds From Sale And Collection Of Mortgage Notes Receivable ProceedsFromSaleAndCollectionOfMortgageNotesReceivable	143000000	USD
CY2021	us-gaap	Payments To Acquire Available For Sale Securities Debt PaymentsToAcquireAvailableForSaleSecuritiesDebt	9307000000	USD
CY2020	us-gaap	Payments To Acquire Available For Sale Securities Debt PaymentsToAcquireAvailableForSaleSecuritiesDebt	10269000000	USD
CY2019	us-gaap	Payments To Acquire Available For Sale Securities Debt PaymentsToAcquireAvailableForSaleSecuritiesDebt	8661000000	USD
CY2021	us-gaap	Payments To Acquire Equity Securities Fv Ni PaymentsToAcquireEquitySecuritiesFvNi	304000000	USD
CY2020	us-gaap	Payments To Acquire Equity Securities Fv Ni PaymentsToAcquireEquitySecuritiesFvNi	452000000	USD
CY2019	us-gaap	Payments To Acquire Equity Securities Fv Ni PaymentsToAcquireEquitySecuritiesFvNi	186000000	USD
CY2021	us-gaap	Payments To Acquire Limited Partnership Interests PaymentsToAcquireLimitedPartnershipInterests	440000000	USD
CY2020	us-gaap	Payments To Acquire Limited Partnership Interests PaymentsToAcquireLimitedPartnershipInterests	224000000	USD
CY2019	us-gaap	Payments To Acquire Limited Partnership Interests PaymentsToAcquireLimitedPartnershipInterests	198000000	USD
CY2021	us-gaap	Payments To Acquire Mortgage Notes Receivable PaymentsToAcquireMortgageNotesReceivable	95000000	USD
CY2020	us-gaap	Payments To Acquire Mortgage Notes Receivable PaymentsToAcquireMortgageNotesReceivable	172000000	USD
CY2019	us-gaap	Payments To Acquire Mortgage Notes Receivable PaymentsToAcquireMortgageNotesReceivable	298000000	USD
CY2021	cna	Change In Other Investments ChangeInOtherInvestments	-6000000	USD
CY2020	cna	Change In Other Investments ChangeInOtherInvestments	-8000000	USD
CY2019	cna	Change In Other Investments ChangeInOtherInvestments	-11000000	USD
CY2021	cna	Change In Short Term Investments ChangeInShortTermInvestments	-83000000	USD
CY2020	cna	Change In Short Term Investments ChangeInShortTermInvestments	-39000000	USD
CY2019	cna	Change In Short Term Investments ChangeInShortTermInvestments	-535000000	USD
CY2021	us-gaap	Payments To Acquire Property Plant And Equipment PaymentsToAcquirePropertyPlantAndEquipment	26000000	USD
CY2020	us-gaap	Payments To Acquire Property Plant And Equipment PaymentsToAcquirePropertyPlantAndEquipment	23000000	USD
CY2019	us-gaap	Payments To Acquire Property Plant And Equipment PaymentsToAcquirePropertyPlantAndEquipment	26000000	USD
CY2021	us-gaap	Payments For Proceeds From Other Investing Activities PaymentsForProceedsFromOtherInvestingActivities	-1000000	USD
CY2020	us-gaap	Payments For Proceeds From Other Investing Activities PaymentsForProceedsFromOtherInvestingActivities	-16000000	USD
CY2019	us-gaap	Payments For Proceeds From Other Investing Activities PaymentsForProceedsFromOtherInvestingActivities	-15000000	USD
CY2021	us-gaap	Net Cash Provided By Used In Investing Activities NetCashProvidedByUsedInInvestingActivities	-1228000000	USD
CY2020	us-gaap	Net Cash Provided By Used In Investing Activities NetCashProvidedByUsedInInvestingActivities	-705000000	USD
CY2019	us-gaap	Net Cash Provided By Used In Investing Activities NetCashProvidedByUsedInInvestingActivities	-225000000	USD
CY2021	us-gaap	Payments Of Dividends Common Stock PaymentsOfDividendsCommonStock	621000000	USD
CY2020	us-gaap	Payments Of Dividends Common Stock PaymentsOfDividendsCommonStock	950000000	USD
CY2019	us-gaap	Payments Of Dividends Common Stock PaymentsOfDividendsCommonStock	929000000	USD
CY2021	us-gaap	Proceeds From Issuance Of Long Term Debt ProceedsFromIssuanceOfLongTermDebt	0	USD
CY2020	us-gaap	Proceeds From Issuance Of Long Term Debt ProceedsFromIssuanceOfLongTermDebt	495000000	USD
CY2019	us-gaap	Proceeds From Issuance Of Long Term Debt ProceedsFromIssuanceOfLongTermDebt	496000000	USD
CY2021	us-gaap	Repayments Of Long Term Debt RepaymentsOfLongTermDebt	0	USD
CY2020	us-gaap	Repayments Of Long Term Debt RepaymentsOfLongTermDebt	419000000	USD
CY2019	us-gaap	Repayments Of Long Term Debt RepaymentsOfLongTermDebt	520000000	USD
CY2021	us-gaap	Payments For Repurchase Of Common Stock PaymentsForRepurchaseOfCommonStock	18000000	USD
CY2020	us-gaap	Payments For Repurchase Of Common Stock PaymentsForRepurchaseOfCommonStock	18000000	USD
CY2019	us-gaap	Payments For Repurchase Of Common Stock PaymentsForRepurchaseOfCommonStock	23000000	USD
CY2021	us-gaap	Proceeds From Payments For Other Financing Activities ProceedsFromPaymentsForOtherFinancingActivities	-9000000	USD
CY2020	us-gaap	Proceeds From Payments For Other Financing Activities ProceedsFromPaymentsForOtherFinancingActivities	-10000000	USD
CY2019	us-gaap	Proceeds From Payments For Other Financing Activities ProceedsFromPaymentsForOtherFinancingActivities	-12000000	USD
CY2021	us-gaap	Net Cash Provided By Used In Financing Activities NetCashProvidedByUsedInFinancingActivities	-648000000	USD
CY2020	us-gaap	Net Cash Provided By Used In Financing Activities NetCashProvidedByUsedInFinancingActivities	-902000000	USD
CY2019	us-gaap	Net Cash Provided By Used In Financing Activities NetCashProvidedByUsedInFinancingActivities	-988000000	USD
CY2021	us-gaap	Effect Of Exchange Rate On Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents EffectOfExchangeRateOnCashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	-4000000	USD
CY2020	us-gaap	Effect Of Exchange Rate On Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents EffectOfExchangeRateOnCashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	9000000	USD
CY2019	us-gaap	Effect Of Exchange Rate On Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents EffectOfExchangeRateOnCashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	5000000	USD
CY2021	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents Period Increase Decrease Including Exchange Rate Effect CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect	117000000	USD
CY2020	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents Period Increase Decrease Including Exchange Rate Effect CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect	177000000	USD
CY2019	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents Period Increase Decrease Including Exchange Rate Effect CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect	-68000000	USD
CY2020Q4	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	419000000	USD
CY2019Q4	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	242000000	USD
CY2018Q4	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	310000000	USD
CY2021Q4	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	536000000	USD
CY2020Q4	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	419000000	USD
CY2019Q4	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	242000000	USD
CY2021	us-gaap	Common Stock Dividends Per Share Declared CommonStockDividendsPerShareDeclared	2.27
CY2020	us-gaap	Common Stock Dividends Per Share Declared CommonStockDividendsPerShareDeclared	3.48
CY2019	us-gaap	Common Stock Dividends Per Share Declared CommonStockDividendsPerShareDeclared	3.40
CY2021Q4	us-gaap	Stockholders Equity StockholdersEquity	12809000000	USD
CY2020Q4	us-gaap	Stockholders Equity StockholdersEquity	12707000000	USD
CY2019Q4	us-gaap	Stockholders Equity StockholdersEquity	12215000000	USD
CY2021	us-gaap	Use Of Estimates UseOfEstimates	The preparation of Consolidated Financial Statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and the disclosure of contingent assets and liabilities at the date of the Consolidated Financial Statements and the reported amounts of revenues and expenses during the reporting period. Actual results may differ from those estimates.
CY2021Q4	cna	Anticipated Amounts Due From Insureds Related To Losses Under Deductible Policies AnticipatedAmountsDueFromInsuredsRelatedToLossesUnderDeductiblePolicies	1100000000	USD
CY2020Q4	cna	Anticipated Amounts Due From Insureds Related To Losses Under Deductible Policies AnticipatedAmountsDueFromInsuredsRelatedToLossesUnderDeductiblePolicies	1200000000	USD
CY2021	cna	Structured Settlement Annuities Interest Rates Low End StructuredSettlementAnnuitiesInterestRatesLowEnd	0.064
CY2020	cna	Structured Settlement Annuities Interest Rates High End StructuredSettlementAnnuitiesInterestRatesHighEnd	0.065
CY2021Q4	cna	Discounted Reserves For Unfunded Structured Settlements DiscountedReservesForUnfundedStructuredSettlements	503000000	USD
CY2020Q4	cna	Discounted Reserves For Unfunded Structured Settlements DiscountedReservesForUnfundedStructuredSettlements	520000000	USD
CY2021Q4	cna	Discounted Reserves For Unfunded Structure Settlements Discount Amount DiscountedReservesForUnfundedStructureSettlementsDiscountAmount	621000000	USD
CY2020Q4	cna	Discounted Reserves For Unfunded Structure Settlements Discount Amount DiscountedReservesForUnfundedStructureSettlementsDiscountAmount	657000000	USD
CY2021Q4	cna	Amountofinterestrecognizedonthediscountedreservesofunfundedstructuredsettlements Amountofinterestrecognizedonthediscountedreservesofunfundedstructuredsettlements	36000000	USD
CY2020Q4	cna	Amountofinterestrecognizedonthediscountedreservesofunfundedstructuredsettlements Amountofinterestrecognizedonthediscountedreservesofunfundedstructuredsettlements	35000000	USD
CY2019Q4	cna	Amountofinterestrecognizedonthediscountedreservesofunfundedstructuredsettlements Amountofinterestrecognizedonthediscountedreservesofunfundedstructuredsettlements	36000000	USD
CY2021	us-gaap	Workers Compensation Discount Percent WorkersCompensationDiscountPercent	0.035
CY2020	us-gaap	Workers Compensation Discount Percent WorkersCompensationDiscountPercent	0.035
CY2021Q4	us-gaap	Workers Compensation Liability Current And Noncurrent WorkersCompensationLiabilityCurrentAndNoncurrent	228000000	USD
CY2020Q4	us-gaap	Workers Compensation Liability Current And Noncurrent WorkersCompensationLiabilityCurrentAndNoncurrent	258000000	USD
CY2021Q4	us-gaap	Workers Compensation Discount Amount WorkersCompensationDiscountAmount	97000000	USD
CY2020Q4	us-gaap	Workers Compensation Discount Amount WorkersCompensationDiscountAmount	113000000	USD
CY2021Q4	cna	Amountofinterestaccretionrecognizedonthediscountedreservesofworkerscompensationlifetimeclaimreserves Amountofinterestaccretionrecognizedonthediscountedreservesofworkerscompensationlifetimeclaimreserves	12000000	USD
CY2020Q4	cna	Amountofinterestaccretionrecognizedonthediscountedreservesofworkerscompensationlifetimeclaimreserves Amountofinterestaccretionrecognizedonthediscountedreservesofworkerscompensationlifetimeclaimreserves	15000000	USD
CY2019Q4	cna	Amountofinterestaccretionrecognizedonthediscountedreservesofworkerscompensationlifetimeclaimreserves Amountofinterestaccretionrecognizedonthediscountedreservesofworkerscompensationlifetimeclaimreserves	21000000	USD
CY2021	cna	Longterm Care Claim Reserves Weighted Average Discounted Interest Rate LongtermCareClaimReservesWeightedAverageDiscountedInterestRate	0.058
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CY2021Q4	cna	Discountedreservesforlongtermcareclaimreserves Discountedreservesforlongtermcareclaimreserves	2700000000	USD
CY2020Q4	cna	Discountedreservesforlongtermcareclaimreserves Discountedreservesforlongtermcareclaimreserves	2700000000	USD
CY2021Q4	cna	Discountedreservesforlongtermcareclaimreservesdiscountamount Discountedreservesforlongtermcareclaimreservesdiscountamount	428000000	USD
CY2020Q4	cna	Discountedreservesforlongtermcareclaimreservesdiscountamount Discountedreservesforlongtermcareclaimreservesdiscountamount	439000000	USD
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CY2021	us-gaap	Liability For Future Policy Benefit By Product Segment Interest Rate Year Of Issue LiabilityForFuturePolicyBenefitByProductSegmentInterestRateYearOfIssue	0.053
CY2020	us-gaap	Liability For Future Policy Benefit By Product Segment Interest Rate Year Of Issue LiabilityForFuturePolicyBenefitByProductSegmentInterestRateYearOfIssue	0.054
CY2021	us-gaap	Loss Contingency Undiscounted Amount Of Insurance Related Assessment Liability LossContingencyUndiscountedAmountOfInsuranceRelatedAssessmentLiability	79000000	USD
CY2020	us-gaap	Loss Contingency Undiscounted Amount Of Insurance Related Assessment Liability LossContingencyUndiscountedAmountOfInsuranceRelatedAssessmentLiability	82000000	USD
CY2021	cna	Percentage Of Billed Receivables Compared To Total Reinsurance Receivable PercentageOfBilledReceivablesComparedToTotalReinsuranceReceivable	0.05
CY2019	us-gaap	Policyholder Dividends Rate On Policy Earnings PolicyholderDividendsRateOnPolicyEarnings	0.01
CY2020	us-gaap	Policyholder Dividends Rate On Policy Earnings PolicyholderDividendsRateOnPolicyEarnings	0.01
CY2021	us-gaap	Policyholder Dividends Rate On Policy Earnings PolicyholderDividendsRateOnPolicyEarnings	0.01
CY2021	cna	Increasedecreaseinshadowadjustmentnetoftax Increasedecreaseinshadowadjustmentnetoftax	-296000000	USD
CY2020	cna	Increasedecreaseinshadowadjustmentnetoftax Increasedecreaseinshadowadjustmentnetoftax	575000000	USD
CY2021Q4	cna	Reduction Of Net Unrealized Gains On Investments Included In Aoci Due To Shadow Adjustments ReductionOfNetUnrealizedGainsOnInvestmentsIncludedInAOCIDueToShadowAdjustments	2477000000	USD
CY2020Q4	cna	Reduction Of Net Unrealized Gains On Investments Included In Aoci Due To Shadow Adjustments ReductionOfNetUnrealizedGainsOnInvestmentsIncludedInAOCIDueToShadowAdjustments	2773000000	USD
CY2021	us-gaap	Foreign Currency Transaction Gain Loss Before Tax ForeignCurrencyTransactionGainLossBeforeTax	-1000000	USD
CY2020	us-gaap	Foreign Currency Transaction Gain Loss Before Tax ForeignCurrencyTransactionGainLossBeforeTax	13000000	USD
CY2019	us-gaap	Foreign Currency Transaction Gain Loss Before Tax ForeignCurrencyTransactionGainLossBeforeTax	1000000	USD
CY2021	us-gaap	Weighted Average Number Diluted Shares Outstanding Adjustment WeightedAverageNumberDilutedSharesOutstandingAdjustment	1000000	shares
CY2020	us-gaap	Weighted Average Number Diluted Shares Outstanding Adjustment WeightedAverageNumberDilutedSharesOutstandingAdjustment	770000	shares
CY2019	us-gaap	Weighted Average Number Diluted Shares Outstanding Adjustment WeightedAverageNumberDilutedSharesOutstandingAdjustment	960000	shares
CY2021	us-gaap	Antidilutive Securities Excluded From Computation Of Earnings Per Share Amount AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount	1000	shares
CY2020	us-gaap	Antidilutive Securities Excluded From Computation Of Earnings Per Share Amount AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount	8000	shares
CY2019	us-gaap	Antidilutive Securities Excluded From Computation Of Earnings Per Share Amount AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount	1000	shares
CY2021	us-gaap	Interest Paid Net InterestPaidNet	110000000	USD
CY2020	us-gaap	Interest Paid Net InterestPaidNet	124000000	USD
CY2019	us-gaap	Interest Paid Net InterestPaidNet	136000000	USD
CY2021	us-gaap	Income Taxes Paid IncomeTaxesPaid	278000000	USD
CY2020	us-gaap	Income Taxes Paid IncomeTaxesPaid	108000000	USD
CY2019	us-gaap	Income Taxes Paid IncomeTaxesPaid	255000000	USD
CY2021	us-gaap	Gross Investment Income Operating GrossInvestmentIncomeOperating	2223000000	USD
CY2020	us-gaap	Gross Investment Income Operating GrossInvestmentIncomeOperating	1999000000	USD
CY2019	us-gaap	Gross Investment Income Operating GrossInvestmentIncomeOperating	2181000000	USD
CY2021	us-gaap	Investment Income Investment Expense InvestmentIncomeInvestmentExpense	64000000	USD
CY2020	us-gaap	Investment Income Investment Expense InvestmentIncomeInvestmentExpense	64000000	USD
CY2019	us-gaap	Investment Income Investment Expense InvestmentIncomeInvestmentExpense	63000000	USD
CY2021	us-gaap	Net Investment Income NetInvestmentIncome	2159000000	USD
CY2020	us-gaap	Net Investment Income NetInvestmentIncome	1935000000	USD
CY2019	us-gaap	Net Investment Income NetInvestmentIncome	2118000000	USD
CY2020Q4	cna	Non Income Producing Fixed Maturity Securities NonIncomeProducingFixedMaturitySecurities	1000000	USD
CY2021Q4	cna	Non Income Producing Fixed Maturity Securities NonIncomeProducingFixedMaturitySecurities	1000000	USD
CY2021Q4	cna	Non Income Producing Mortgage Loans NonIncomeProducingMortgageLoans	7000000	USD
CY2020Q4	cna	Non Income Producing Mortgage Loans NonIncomeProducingMortgageLoans	0	USD
CY2021Q4	cna	Investmentsthat Exceed Ten Percentof Stockholders Equity InvestmentsthatExceedTenPercentofStockholdersEquity	0	USD
CY2020Q4	cna	Investmentsthat Exceed Ten Percentof Stockholders Equity InvestmentsthatExceedTenPercentofStockholdersEquity	0	USD
CY2021	us-gaap	Debt Securities Available For Sale Realized Gain DebtSecuritiesAvailableForSaleRealizedGain	186000000	USD
CY2020	us-gaap	Debt Securities Available For Sale Realized Gain DebtSecuritiesAvailableForSaleRealizedGain	220000000	USD
CY2019	us-gaap	Debt Securities Available For Sale Realized Gain DebtSecuritiesAvailableForSaleRealizedGain	125000000	USD
CY2021	us-gaap	Debt Securities Available For Sale Realized Loss DebtSecuritiesAvailableForSaleRealizedLoss	90000000	USD
CY2020	us-gaap	Debt Securities Available For Sale Realized Loss DebtSecuritiesAvailableForSaleRealizedLoss	220000000	USD
CY2019	us-gaap	Debt Securities Available For Sale Realized Loss DebtSecuritiesAvailableForSaleRealizedLoss	131000000	USD
CY2021	us-gaap	Debt Securities Available For Sale Realized Gain Loss DebtSecuritiesAvailableForSaleRealizedGainLoss	96000000	USD
CY2020	us-gaap	Debt Securities Available For Sale Realized Gain Loss DebtSecuritiesAvailableForSaleRealizedGainLoss	0	USD
CY2019	us-gaap	Debt Securities Available For Sale Realized Gain Loss DebtSecuritiesAvailableForSaleRealizedGainLoss	-6000000	USD
CY2021	us-gaap	Equity Securities Fv Ni Realized Gain Loss EquitySecuritiesFvNiRealizedGainLoss	4000000	USD
CY2020	us-gaap	Equity Securities Fv Ni Realized Gain Loss EquitySecuritiesFvNiRealizedGainLoss	-3000000	USD
CY2019	us-gaap	Equity Securities Fv Ni Realized Gain Loss EquitySecuritiesFvNiRealizedGainLoss	66000000	USD
CY2021	us-gaap	Gain Loss On Sale Of Derivatives GainLossOnSaleOfDerivatives	6000000	USD
CY2020	us-gaap	Gain Loss On Sale Of Derivatives GainLossOnSaleOfDerivatives	-10000000	USD
CY2019	us-gaap	Gain Loss On Sale Of Derivatives GainLossOnSaleOfDerivatives	-11000000	USD
CY2021	us-gaap	Provision For Loan Losses Expensed ProvisionForLoanLossesExpensed	-10000000	USD
CY2020	us-gaap	Provision For Loan Losses Expensed ProvisionForLoanLossesExpensed	21000000	USD
CY2019	us-gaap	Provision For Loan Losses Expensed ProvisionForLoanLossesExpensed	0	USD
CY2021	cna	Realized Gain Losson Short Term Investments RealizedGainLossonShortTermInvestments	4000000	USD
CY2020	cna	Realized Gain Losson Short Term Investments RealizedGainLossonShortTermInvestments	-20000000	USD
CY2019	cna	Realized Gain Losson Short Term Investments RealizedGainLossonShortTermInvestments	-20000000	USD
CY2021	cna	Investmentsand Derivatives Realized Gain Loss InvestmentsandDerivativesRealizedGainLoss	120000000	USD
CY2020	cna	Investmentsand Derivatives Realized Gain Loss InvestmentsandDerivativesRealizedGainLoss	-54000000	USD
CY2019	cna	Investmentsand Derivatives Realized Gain Loss InvestmentsandDerivativesRealizedGainLoss	29000000	USD
CY2020Q4	us-gaap	Debt Securities Available For Sale Amortized Cost Allowance For Credit Loss Excluding Accrued Interest DebtSecuritiesAvailableForSaleAmortizedCostAllowanceForCreditLossExcludingAccruedInterest	40000000	USD
CY2021	us-gaap	Debt Securities Available For Sale Allowance For Credit Loss Not Previously Recorded DebtSecuritiesAvailableForSaleAllowanceForCreditLossNotPreviouslyRecorded	14000000	USD
CY2021	us-gaap	Debt Securities Available For Sale Allowance For Credit Loss Purchased With Credit Deterioration Increase DebtSecuritiesAvailableForSaleAllowanceForCreditLossPurchasedWithCreditDeteriorationIncrease	11000000	USD
CY2021	us-gaap	Debt Securities Available For Sale Allowance For Credit Loss Securities Sold DebtSecuritiesAvailableForSaleAllowanceForCreditLossSecuritiesSold	24000000	USD
CY2021	us-gaap	Debt Securities Available For Sale Allowance For Credit Loss Sell Before Recovery DebtSecuritiesAvailableForSaleAllowanceForCreditLossSellBeforeRecovery	0	USD
CY2021	us-gaap	Debt Securities Available For Sale Allowance For Credit Loss Writeoff DebtSecuritiesAvailableForSaleAllowanceForCreditLossWriteoff	16000000	USD
CY2021	us-gaap	Debt Securities Available For Sale Allowance For Credit Loss Recovery DebtSecuritiesAvailableForSaleAllowanceForCreditLossRecovery	0	USD
CY2021	us-gaap	Debt Securities Available For Sale Allowance For Credit Loss Not To Sell Before Recovery Credit Loss Previously Recorded Expense Reversal DebtSecuritiesAvailableForSaleAllowanceForCreditLossNotToSellBeforeRecoveryCreditLossPreviouslyRecordedExpenseReversal	-7000000	USD
CY2021Q4	us-gaap	Debt Securities Available For Sale Amortized Cost Allowance For Credit Loss Excluding Accrued Interest DebtSecuritiesAvailableForSaleAmortizedCostAllowanceForCreditLossExcludingAccruedInterest	18000000	USD
CY2019Q4	us-gaap	Debt Securities Available For Sale Amortized Cost Allowance For Credit Loss Excluding Accrued Interest DebtSecuritiesAvailableForSaleAmortizedCostAllowanceForCreditLossExcludingAccruedInterest	0	USD
CY2020	us-gaap	Debt Securities Available For Sale Allowance For Credit Loss Not Previously Recorded DebtSecuritiesAvailableForSaleAllowanceForCreditLossNotPreviouslyRecorded	79000000	USD
CY2020	us-gaap	Debt Securities Available For Sale Allowance For Credit Loss Purchased With Credit Deterioration Increase DebtSecuritiesAvailableForSaleAllowanceForCreditLossPurchasedWithCreditDeteriorationIncrease	5000000	USD
CY2020	us-gaap	Debt Securities Available For Sale Allowance For Credit Loss Securities Sold DebtSecuritiesAvailableForSaleAllowanceForCreditLossSecuritiesSold	22000000	USD
CY2020	us-gaap	Debt Securities Available For Sale Allowance For Credit Loss Sell Before Recovery DebtSecuritiesAvailableForSaleAllowanceForCreditLossSellBeforeRecovery	1000000	USD
CY2020	us-gaap	Debt Securities Available For Sale Allowance For Credit Loss Writeoff DebtSecuritiesAvailableForSaleAllowanceForCreditLossWriteoff	0	USD
CY2020	us-gaap	Debt Securities Available For Sale Allowance For Credit Loss Recovery DebtSecuritiesAvailableForSaleAllowanceForCreditLossRecovery	0	USD
CY2020	us-gaap	Debt Securities Available For Sale Allowance For Credit Loss Not To Sell Before Recovery Credit Loss Previously Recorded Expense Reversal DebtSecuritiesAvailableForSaleAllowanceForCreditLossNotToSellBeforeRecoveryCreditLossPreviouslyRecordedExpenseReversal	-27000000	USD
CY2020Q4	us-gaap	Debt Securities Available For Sale Amortized Cost Allowance For Credit Loss Excluding Accrued Interest DebtSecuritiesAvailableForSaleAmortizedCostAllowanceForCreditLossExcludingAccruedInterest	40000000	USD
CY2021	us-gaap	Other Than Temporary Impairment Loss Debt Securities Portion Recognized In Earnings OtherThanTemporaryImpairmentLossDebtSecuritiesPortionRecognizedInEarnings	31000000	USD
CY2020	us-gaap	Other Than Temporary Impairment Loss Debt Securities Portion Recognized In Earnings OtherThanTemporaryImpairmentLossDebtSecuritiesPortionRecognizedInEarnings	111000000	USD
CY2019	us-gaap	Other Than Temporary Impairment Loss Debt Securities Portion Recognized In Earnings OtherThanTemporaryImpairmentLossDebtSecuritiesPortionRecognizedInEarnings	44000000	USD
CY2021	us-gaap	Provision For Loan Losses Expensed ProvisionForLoanLossesExpensed	-10000000	USD
CY2020	us-gaap	Provision For Loan Losses Expensed ProvisionForLoanLossesExpensed	21000000	USD
CY2021Q4	cna	Debt Securities Amortized Cost DebtSecuritiesAmortizedCost	39952000000	USD
CY2021Q4	us-gaap	Available For Sale Debt Securities Accumulated Gross Unrealized Gain Before Tax AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedGainBeforeTax	4558000000	USD
CY2021Q4	us-gaap	Available For Sale Debt Securities Accumulated Gross Unrealized Loss Before Tax AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedLossBeforeTax	112000000	USD
CY2021Q4	us-gaap	Debt Securities Available For Sale Amortized Cost Allowance For Credit Loss Excluding Accrued Interest DebtSecuritiesAvailableForSaleAmortizedCostAllowanceForCreditLossExcludingAccruedInterest	18000000	USD
CY2021Q4	us-gaap	Debt Securities DebtSecurities	44380000000	USD
CY2020Q4	cna	Debt Securities Amortized Cost DebtSecuritiesAmortizedCost	38953000000	USD
CY2020Q4	us-gaap	Available For Sale Debt Securities Accumulated Gross Unrealized Gain Before Tax AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedGainBeforeTax	5795000000	USD
CY2020Q4	us-gaap	Available For Sale Debt Securities Accumulated Gross Unrealized Loss Before Tax AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedLossBeforeTax	77000000	USD
CY2020Q4	us-gaap	Debt Securities Available For Sale Amortized Cost Allowance For Credit Loss Excluding Accrued Interest DebtSecuritiesAvailableForSaleAmortizedCostAllowanceForCreditLossExcludingAccruedInterest	40000000	USD
CY2020Q4	us-gaap	Debt Securities DebtSecurities	44631000000	USD
CY2021Q4	us-gaap	Debt Securities Available For Sale Continuous Unrealized Loss Position Less Than12 Months DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12Months	5695000000	USD
CY2021Q4	us-gaap	Debt Securities Available For Sale Continuous Unrealized Loss Position Less Than12 Months Accumulated Loss DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12MonthsAccumulatedLoss	92000000	USD
CY2021Q4	us-gaap	Debt Securities Available For Sale Continuous Unrealized Loss Position12 Months Or Longer DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLonger	370000000	USD
CY2021Q4	us-gaap	Debt Securities Available For Sale Continuous Unrealized Loss Position12 Months Or Longer Accumulated Loss DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLongerAccumulatedLoss	20000000	USD
CY2021Q4	us-gaap	Debt Securities Available For Sale Unrealized Loss Position DebtSecuritiesAvailableForSaleUnrealizedLossPosition	6065000000	USD
CY2020Q4	us-gaap	Retained Earnings Undistributed Earnings From Equity Method Investees RetainedEarningsUndistributedEarningsFromEquityMethodInvestees	235000000	USD
CY2021Q4	us-gaap	Debt Securities Available For Sale Unrealized Loss Position Accumulated Loss DebtSecuritiesAvailableForSaleUnrealizedLossPositionAccumulatedLoss	112000000	USD
CY2020Q4	us-gaap	Debt Securities Available For Sale Continuous Unrealized Loss Position Less Than12 Months DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12Months	1666000000	USD
CY2020Q4	us-gaap	Debt Securities Available For Sale Continuous Unrealized Loss Position Less Than12 Months Accumulated Loss DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12MonthsAccumulatedLoss	74000000	USD
CY2020Q4	us-gaap	Debt Securities Available For Sale Continuous Unrealized Loss Position12 Months Or Longer DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLonger	64000000	USD
CY2020Q4	us-gaap	Debt Securities Available For Sale Continuous Unrealized Loss Position12 Months Or Longer Accumulated Loss DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLongerAccumulatedLoss	3000000	USD
CY2020Q4	us-gaap	Debt Securities Available For Sale Unrealized Loss Position DebtSecuritiesAvailableForSaleUnrealizedLossPosition	1730000000	USD
CY2020Q4	us-gaap	Debt Securities Available For Sale Unrealized Loss Position Accumulated Loss DebtSecuritiesAvailableForSaleUnrealizedLossPositionAccumulatedLoss	77000000	USD
CY2021Q4	us-gaap	Available For Sale Securities Debt Maturities Within One Year Amortized Cost AvailableForSaleSecuritiesDebtMaturitiesWithinOneYearAmortizedCost	1603000000	USD
CY2021Q4	us-gaap	Available For Sale Securities Debt Maturities Within One Year Fair Value AvailableForSaleSecuritiesDebtMaturitiesWithinOneYearFairValue	1624000000	USD
CY2020Q4	us-gaap	Available For Sale Securities Debt Maturities Within One Year Amortized Cost AvailableForSaleSecuritiesDebtMaturitiesWithinOneYearAmortizedCost	1456000000	USD
CY2020Q4	us-gaap	Available For Sale Securities Debt Maturities Within One Year Fair Value AvailableForSaleSecuritiesDebtMaturitiesWithinOneYearFairValue	1458000000	USD
CY2021Q4	us-gaap	Available For Sale Securities Debt Maturities After One Through Five Years Amortized Cost AvailableForSaleSecuritiesDebtMaturitiesAfterOneThroughFiveYearsAmortizedCost	10637000000	USD
CY2021Q4	us-gaap	Available For Sale Securities Debt Maturities After One Through Five Years Fair Value AvailableForSaleSecuritiesDebtMaturitiesAfterOneThroughFiveYearsFairValue	11229000000	USD
CY2020Q4	us-gaap	Available For Sale Securities Debt Maturities After One Through Five Years Amortized Cost AvailableForSaleSecuritiesDebtMaturitiesAfterOneThroughFiveYearsAmortizedCost	12304000000	USD
CY2020Q4	us-gaap	Available For Sale Securities Debt Maturities After One Through Five Years Fair Value AvailableForSaleSecuritiesDebtMaturitiesAfterOneThroughFiveYearsFairValue	13098000000	USD
CY2021Q4	us-gaap	Available For Sale Securities Debt Maturities After Five Through Ten Years Amortized Cost AvailableForSaleSecuritiesDebtMaturitiesAfterFiveThroughTenYearsAmortizedCost	13294000000	USD
CY2021Q4	us-gaap	Available For Sale Securities Debt Maturities After Five Through Ten Years Fair Value AvailableForSaleSecuritiesDebtMaturitiesAfterFiveThroughTenYearsFairValue	14338000000	USD
CY2020Q4	us-gaap	Available For Sale Securities Debt Maturities After Five Through Ten Years Amortized Cost AvailableForSaleSecuritiesDebtMaturitiesAfterFiveThroughTenYearsAmortizedCost	12319000000	USD
CY2020Q4	us-gaap	Available For Sale Securities Debt Maturities After Five Through Ten Years Fair Value AvailableForSaleSecuritiesDebtMaturitiesAfterFiveThroughTenYearsFairValue	13878000000	USD
CY2021Q4	us-gaap	Available For Sale Securities Debt Maturities After Ten Years Amortized Cost AvailableForSaleSecuritiesDebtMaturitiesAfterTenYearsAmortizedCost	14411000000	USD
CY2021Q4	us-gaap	Available For Sale Securities Debt Maturities After Ten Years Fair Value AvailableForSaleSecuritiesDebtMaturitiesAfterTenYearsFairValue	17182000000	USD
CY2020Q4	us-gaap	Available For Sale Securities Debt Maturities After Ten Years Amortized Cost AvailableForSaleSecuritiesDebtMaturitiesAfterTenYearsAmortizedCost	12847000000	USD
CY2020Q4	us-gaap	Available For Sale Securities Debt Maturities After Ten Years Fair Value AvailableForSaleSecuritiesDebtMaturitiesAfterTenYearsFairValue	16170000000	USD
CY2021Q4	us-gaap	Debt Securities Available For Sale Amortized Cost Excluding Accrued Interest After Allowance For Credit Loss DebtSecuritiesAvailableForSaleAmortizedCostExcludingAccruedInterestAfterAllowanceForCreditLoss	39945000000	USD
CY2021Q4	us-gaap	Debt Securities Available For Sale Excluding Accrued Interest DebtSecuritiesAvailableForSaleExcludingAccruedInterest	44373000000	USD
CY2020Q4	us-gaap	Debt Securities Available For Sale Amortized Cost Excluding Accrued Interest After Allowance For Credit Loss DebtSecuritiesAvailableForSaleAmortizedCostExcludingAccruedInterestAfterAllowanceForCreditLoss	38926000000	USD
CY2020Q4	us-gaap	Debt Securities Available For Sale Excluding Accrued Interest DebtSecuritiesAvailableForSaleExcludingAccruedInterest	44604000000	USD
CY2021Q4	cna	Limited Partnership Investments LimitedPartnershipInvestments	1859000000	USD
CY2020Q4	cna	Limited Partnership Investments LimitedPartnershipInvestments	1619000000	USD
CY2021Q4	us-gaap	Retained Earnings Undistributed Earnings From Equity Method Investees RetainedEarningsUndistributedEarningsFromEquityMethodInvestees	266000000	USD
CY2021Q4	us-gaap	Deferred Tax Assets Tax Deferred Expense Compensation And Benefits Employee Benefits DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefitsEmployeeBenefits	46000000	USD
CY2021Q4	cna	Percentage Of Limited Partnerships Reported On Current Basis PercentageOfLimitedPartnershipsReportedOnCurrentBasis	0.32
CY2021Q4	cna	Percentage Of Limited Partnerships Reported On One Month Lag PercentageOfLimitedPartnershipsReportedOnOneMonthLag	0.06
CY2021Q4	cna	Limited Partnerships Invested In Private Debt And Equity LimitedPartnershipsInvestedInPrivateDebtAndEquity	0.68
CY2020Q4	cna	Limited Partnerships Invested In Private Debt And Equity LimitedPartnershipsInvestedInPrivateDebtAndEquity	0.49
CY2021Q4	cna	Percentage Of Limited Partnerships Employing Hedge Fund Strategies Focused On Fixed Income And Equity Investments PercentageOfLimitedPartnershipsEmployingHedgeFundStrategiesFocusedOnFixedIncomeAndEquityInvestments	0.32
CY2020Q4	cna	Percentage Of Limited Partnerships Employing Hedge Fund Strategies Focused On Fixed Income And Equity Investments PercentageOfLimitedPartnershipsEmployingHedgeFundStrategiesFocusedOnFixedIncomeAndEquityInvestments	0.51
CY2021Q4	cna	Carrying Value Of Ten Largest Limited Partnerships CarryingValueOfTenLargestLimitedPartnerships	665000000	USD
CY2020Q4	cna	Carrying Value Of Ten Largest Limited Partnerships CarryingValueOfTenLargestLimitedPartnerships	775000000	USD
CY2021Q4	cna	Carrying Value Of Limited Partnerships As Percentage Of Aggregate Partnership Equity CarryingValueOfLimitedPartnershipsAsPercentageOfAggregatePartnershipEquity	0.01
CY2020Q4	cna	Carrying Value Of Limited Partnerships As Percentage Of Aggregate Partnership Equity CarryingValueOfLimitedPartnershipsAsPercentageOfAggregatePartnershipEquity	0.02
CY2021Q4	cna	Income As Percentage Of Change In Partnership Equity For All Limited Partnerships IncomeAsPercentageOfChangeInPartnershipEquityForAllLimitedPartnerships	0.02
CY2020Q4	cna	Income As Percentage Of Change In Partnership Equity For All Limited Partnerships IncomeAsPercentageOfChangeInPartnershipEquityForAllLimitedPartnerships	0.02
CY2019Q4	cna	Income As Percentage Of Change In Partnership Equity For All Limited Partnerships IncomeAsPercentageOfChangeInPartnershipEquityForAllLimitedPartnerships	0.02
CY2021Q4	us-gaap	Derivative Collateral Obligation To Return Cash DerivativeCollateralObligationToReturnCash	0	USD
CY2020Q4	us-gaap	Derivative Collateral Obligation To Return Cash DerivativeCollateralObligationToReturnCash	0	USD
CY2021Q4	us-gaap	Derivative Notional Amount DerivativeNotionalAmount	270000000	USD
CY2020Q4	us-gaap	Derivative Notional Amount DerivativeNotionalAmount	190000000	USD
CY2021Q4	us-gaap	Derivative Fair Value Of Derivative Liability DerivativeFairValueOfDerivativeLiability	12000000	USD
CY2020Q4	us-gaap	Derivative Fair Value Of Derivative Liability DerivativeFairValueOfDerivativeLiability	19000000	USD
CY2021Q4	cna	Commitments To Purchase Or Fund Additional Amounts CommitmentsToPurchaseOrFundAdditionalAmounts	1230000000	USD
CY2021Q4	cna	Commitments To Sell Various Privately Placed Debt Securities CommitmentsToSellVariousPrivatelyPlacedDebtSecurities	90000000	USD
CY2021Q4	cna	Carrying Value Of Securities Deposited Under Requirements Of Regulatory Authorities CarryingValueOfSecuritiesDepositedUnderRequirementsOfRegulatoryAuthorities	3000000000	USD
CY2020Q4	cna	Carrying Value Of Securities Deposited Under Requirements Of Regulatory Authorities CarryingValueOfSecuritiesDepositedUnderRequirementsOfRegulatoryAuthorities	3000000000	USD
CY2021Q4	cna	Cash And Securities Deposited As Collateral For Letters Of Credit CashAndSecuritiesDepositedAsCollateralForLettersOfCredit	1200000000	USD
CY2020Q4	cna	Cash And Securities Deposited As Collateral For Letters Of Credit CashAndSecuritiesDepositedAsCollateralForLettersOfCredit	1100000000	USD
CY2021Q4	us-gaap	Debt Securities DebtSecurities	44380000000	USD
CY2021Q4	us-gaap	Equity Securities Fv Ni EquitySecuritiesFvNi	1035000000	USD
CY2021Q4	cna	Shortterm Investmentsand Other ShorttermInvestmentsandOther	1872000000	USD
CY2021Q4	us-gaap	Assets Fair Value Disclosure AssetsFairValueDisclosure	47287000000	USD
CY2021Q4	us-gaap	Other Liabilities Fair Value Disclosure OtherLiabilitiesFairValueDisclosure	12000000	USD
CY2021Q4	us-gaap	Liabilities Fair Value Disclosure LiabilitiesFairValueDisclosure	12000000	USD
CY2020Q4	us-gaap	Debt Securities DebtSecurities	44631000000	USD
CY2020Q4	us-gaap	Equity Securities Fv Ni EquitySecuritiesFvNi	992000000	USD
CY2020Q4	cna	Shortterm Investmentsand Other ShorttermInvestmentsandOther	1789000000	USD
CY2020Q4	us-gaap	Assets Fair Value Disclosure AssetsFairValueDisclosure	47412000000	USD
CY2020Q4	us-gaap	Other Liabilities Fair Value Disclosure OtherLiabilitiesFairValueDisclosure	19000000	USD
CY2020Q4	us-gaap	Liabilities Fair Value Disclosure LiabilitiesFairValueDisclosure	19000000	USD
CY2020Q4	us-gaap	Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Value FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetValue	1151000000	USD
CY2021	us-gaap	Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Gain Loss Included In Other Comprehensive Income Loss FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInOtherComprehensiveIncomeLoss	-43000000	USD
CY2021	cna	Fair Value Measurementwith Unobservable Inputs Reconciliation Recurring Basis Asset Gain Loss Included In Earnings And Other Comprehensive Income Loss FairValueMeasurementwithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInEarningsAndOtherComprehensiveIncomeLoss	-46000000	USD
CY2021	us-gaap	Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Purchases FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetPurchases	612000000	USD
CY2021	us-gaap	Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Sales FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetSales	32000000	USD
CY2021	us-gaap	Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Settlements FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetSettlements	130000000	USD
CY2021	us-gaap	Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Transfers Into Level3 FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetTransfersIntoLevel3	150000000	USD
CY2021	us-gaap	Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Transfers Out Of Level3 FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetTransfersOutOfLevel3	127000000	USD
CY2021Q4	us-gaap	Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Value FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetValue	1578000000	USD
CY2021	us-gaap	Fair Value Assets Measured On Recurring Basis Change In Unrealized Gain Loss FairValueAssetsMeasuredOnRecurringBasisChangeInUnrealizedGainLoss	-2000000	USD
CY2021	cna	Fair Value Measurementwith Unobservable Inputs Reconciliation Recurring Basis Asset Unrealized Gain Loss Includedin Other Comprehensive Income Loss FairValueMeasurementwithUnobservableInputsReconciliationRecurringBasisAssetUnrealizedGainLossIncludedinOtherComprehensiveIncomeLoss	-44000000	USD
CY2019Q4	us-gaap	Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Value FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetValue	651000000	USD
CY2020	us-gaap	Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Gain Loss Included In Other Comprehensive Income Loss FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInOtherComprehensiveIncomeLoss	60000000	USD
CY2020	cna	Fair Value Measurementwith Unobservable Inputs Reconciliation Recurring Basis Asset Gain Loss Included In Earnings And Other Comprehensive Income Loss FairValueMeasurementwithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInEarningsAndOtherComprehensiveIncomeLoss	56000000	USD
CY2020	us-gaap	Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Purchases FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetPurchases	478000000	USD
CY2020	us-gaap	Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Sales FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetSales	12000000	USD
CY2020	us-gaap	Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Settlements FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetSettlements	45000000	USD
CY2020	us-gaap	Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Transfers Into Level3 FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetTransfersIntoLevel3	40000000	USD
CY2020	us-gaap	Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Transfers Out Of Level3 FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetTransfersOutOfLevel3	17000000	USD
CY2020Q4	us-gaap	Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Value FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetValue	1151000000	USD
CY2020	us-gaap	Fair Value Assets Measured On Recurring Basis Change In Unrealized Gain Loss FairValueAssetsMeasuredOnRecurringBasisChangeInUnrealizedGainLoss	-6000000	USD
CY2020	cna	Fair Value Measurementwith Unobservable Inputs Reconciliation Recurring Basis Asset Unrealized Gain Loss Includedin Other Comprehensive Income Loss FairValueMeasurementwithUnobservableInputsReconciliationRecurringBasisAssetUnrealizedGainLossIncludedinOtherComprehensiveIncomeLoss	62000000	USD
CY2021Q4	cna	Other Invested Assets Overseas Deposit OtherInvestedAssetsOverseasDeposit	74000000	USD
CY2020Q4	cna	Other Invested Assets Overseas Deposit OtherInvestedAssetsOverseasDeposit	71000000	USD
CY2021Q4	us-gaap	Unrecognized Tax Benefits UnrecognizedTaxBenefits	0	USD
CY2020Q4	us-gaap	Unrecognized Tax Benefits UnrecognizedTaxBenefits	0	USD
CY2020	us-gaap	Interest Income Expense Net InterestIncomeExpenseNet	0	USD
CY2019	us-gaap	Interest Income Expense Net InterestIncomeExpenseNet	0	USD
CY2021	us-gaap	Interest Income Expense Net InterestIncomeExpenseNet	0	USD
CY2021	us-gaap	Unrecognized Tax Benefits Income Tax Penalties Expense UnrecognizedTaxBenefitsIncomeTaxPenaltiesExpense	0	USD
CY2019	us-gaap	Unrecognized Tax Benefits Income Tax Penalties Expense UnrecognizedTaxBenefitsIncomeTaxPenaltiesExpense	0	USD
CY2020	us-gaap	Unrecognized Tax Benefits Income Tax Penalties Expense UnrecognizedTaxBenefitsIncomeTaxPenaltiesExpense	0	USD
CY2020Q4	us-gaap	Unrecognized Tax Benefits Income Tax Penalties And Interest Accrued UnrecognizedTaxBenefitsIncomeTaxPenaltiesAndInterestAccrued	0	USD
CY2021Q4	us-gaap	Unrecognized Tax Benefits Income Tax Penalties And Interest Accrued UnrecognizedTaxBenefitsIncomeTaxPenaltiesAndInterestAccrued	0	USD
CY2019	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	223000000	USD
CY2021	us-gaap	Foreign Income Tax Expense Benefit Continuing Operations ForeignIncomeTaxExpenseBenefitContinuingOperations	18000000	USD
CY2020	us-gaap	Foreign Income Tax Expense Benefit Continuing Operations ForeignIncomeTaxExpenseBenefitContinuingOperations	16000000	USD
CY2019	us-gaap	Foreign Income Tax Expense Benefit Continuing Operations ForeignIncomeTaxExpenseBenefitContinuingOperations	19000000	USD
CY2021	us-gaap	Income Loss From Continuing Operations Before Income Taxes Foreign IncomeLossFromContinuingOperationsBeforeIncomeTaxesForeign	124000000	USD
CY2020	us-gaap	Income Loss From Continuing Operations Before Income Taxes Foreign IncomeLossFromContinuingOperationsBeforeIncomeTaxesForeign	45000000	USD
CY2019	us-gaap	Income Loss From Continuing Operations Before Income Taxes Foreign IncomeLossFromContinuingOperationsBeforeIncomeTaxesForeign	43000000	USD
CY2021Q4	us-gaap	Deferred Tax Assets Tax Deferred Expense Reserves And Accruals Loss Reserves DeferredTaxAssetsTaxDeferredExpenseReservesAndAccrualsLossReserves	173000000	USD
CY2020Q4	us-gaap	Deferred Tax Assets Tax Deferred Expense Reserves And Accruals Loss Reserves DeferredTaxAssetsTaxDeferredExpenseReservesAndAccrualsLossReserves	157000000	USD
CY2021	us-gaap	Income Tax Reconciliation Income Tax Expense Benefit At Federal Statutory Income Tax Rate IncomeTaxReconciliationIncomeTaxExpenseBenefitAtFederalStatutoryIncomeTaxRate	312000000	USD
CY2020	us-gaap	Income Tax Reconciliation Income Tax Expense Benefit At Federal Statutory Income Tax Rate IncomeTaxReconciliationIncomeTaxExpenseBenefitAtFederalStatutoryIncomeTaxRate	172000000	USD
CY2019	us-gaap	Income Tax Reconciliation Income Tax Expense Benefit At Federal Statutory Income Tax Rate IncomeTaxReconciliationIncomeTaxExpenseBenefitAtFederalStatutoryIncomeTaxRate	257000000	USD
CY2021	us-gaap	Income Tax Reconciliation Tax Exempt Income IncomeTaxReconciliationTaxExemptIncome	51000000	USD
CY2020	us-gaap	Income Tax Reconciliation Tax Exempt Income IncomeTaxReconciliationTaxExemptIncome	52000000	USD
CY2019	us-gaap	Income Tax Reconciliation Tax Exempt Income IncomeTaxReconciliationTaxExemptIncome	53000000	USD
CY2021	us-gaap	Income Tax Reconciliation Foreign Income Tax Rate Differential IncomeTaxReconciliationForeignIncomeTaxRateDifferential	3000000	USD
CY2020	us-gaap	Income Tax Reconciliation Foreign Income Tax Rate Differential IncomeTaxReconciliationForeignIncomeTaxRateDifferential	-2000000	USD
CY2019	us-gaap	Income Tax Reconciliation Foreign Income Tax Rate Differential IncomeTaxReconciliationForeignIncomeTaxRateDifferential	1000000	USD
CY2021	us-gaap	Income Tax Reconciliation State And Local Income Taxes IncomeTaxReconciliationStateAndLocalIncomeTaxes	13000000	USD
CY2020	us-gaap	Income Tax Reconciliation State And Local Income Taxes IncomeTaxReconciliationStateAndLocalIncomeTaxes	6000000	USD
CY2019	us-gaap	Income Tax Reconciliation State And Local Income Taxes IncomeTaxReconciliationStateAndLocalIncomeTaxes	14000000	USD
CY2021	us-gaap	Income Tax Reconciliation Other Adjustments IncomeTaxReconciliationOtherAdjustments	5000000	USD
CY2020Q4	us-gaap	Deferred Tax Assets Tax Deferred Expense Compensation And Benefits Employee Benefits DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefitsEmployeeBenefits	122000000	USD
CY2021Q4	cna	Deferred Tax Assets Deferred Retroactive Reinsurance Benefit DeferredTaxAssetsDeferredRetroactiveReinsuranceBenefit	90000000	USD
CY2020	us-gaap	Income Tax Reconciliation Other Adjustments IncomeTaxReconciliationOtherAdjustments	7000000	USD
CY2019	us-gaap	Income Tax Reconciliation Other Adjustments IncomeTaxReconciliationOtherAdjustments	4000000	USD
CY2021	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	282000000	USD
CY2020	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	131000000	USD
CY2019	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	223000000	USD
CY2021Q4	us-gaap	Deferred Tax Liability Not Recognized Amount Of Unrecognized Deferred Tax Liability Undistributed Earnings Of Foreign Subsidiaries DeferredTaxLiabilityNotRecognizedAmountOfUnrecognizedDeferredTaxLiabilityUndistributedEarningsOfForeignSubsidiaries	0	USD
CY2021	us-gaap	Current Income Tax Expense Benefit CurrentIncomeTaxExpenseBenefit	235000000	USD
CY2020	us-gaap	Current Income Tax Expense Benefit CurrentIncomeTaxExpenseBenefit	180000000	USD
CY2019	us-gaap	Current Income Tax Expense Benefit CurrentIncomeTaxExpenseBenefit	269000000	USD
CY2021	us-gaap	Deferred Income Tax Expense Benefit DeferredIncomeTaxExpenseBenefit	47000000	USD
CY2020	us-gaap	Deferred Income Tax Expense Benefit DeferredIncomeTaxExpenseBenefit	-49000000	USD
CY2019	us-gaap	Deferred Income Tax Expense Benefit DeferredIncomeTaxExpenseBenefit	-46000000	USD
CY2021	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	282000000	USD
CY2020	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	131000000	USD
CY2021Q4	us-gaap	Deferred Tax Assets Tax Deferred Expense Reserves And Accruals Unearned Premiums Reserve DeferredTaxAssetsTaxDeferredExpenseReservesAndAccrualsUnearnedPremiumsReserve	193000000	USD
CY2020Q4	us-gaap	Deferred Tax Assets Tax Deferred Expense Reserves And Accruals Unearned Premiums Reserve DeferredTaxAssetsTaxDeferredExpenseReservesAndAccrualsUnearnedPremiumsReserve	174000000	USD
CY2021Q4	us-gaap	Deferred Tax Assets Deferred Income DeferredTaxAssetsDeferredIncome	64000000	USD
CY2020Q4	us-gaap	Deferred Tax Assets Deferred Income DeferredTaxAssetsDeferredIncome	62000000	USD
CY2020Q4	cna	Deferred Tax Assets Deferred Retroactive Reinsurance Benefit DeferredTaxAssetsDeferredRetroactiveReinsuranceBenefit	83000000	USD
CY2021Q4	us-gaap	Deferred Tax Assets Other DeferredTaxAssetsOther	88000000	USD
CY2020Q4	us-gaap	Deferred Tax Assets Other DeferredTaxAssetsOther	92000000	USD
CY2021Q4	us-gaap	Deferred Tax Assets Gross DeferredTaxAssetsGross	654000000	USD
CY2020Q4	us-gaap	Deferred Tax Assets Gross DeferredTaxAssetsGross	690000000	USD
CY2021Q4	us-gaap	Deferred Tax Liabilities Investments DeferredTaxLiabilitiesInvestments	93000000	USD
CY2020Q4	us-gaap	Deferred Tax Liabilities Investments DeferredTaxLiabilitiesInvestments	28000000	USD
CY2021Q4	us-gaap	Deferred Tax Liabilities Deferred Expense Deferred Policy Acquisition Cost DeferredTaxLiabilitiesDeferredExpenseDeferredPolicyAcquisitionCost	99000000	USD
CY2020Q4	us-gaap	Deferred Tax Liabilities Deferred Expense Deferred Policy Acquisition Cost DeferredTaxLiabilitiesDeferredExpenseDeferredPolicyAcquisitionCost	93000000	USD
CY2021Q4	us-gaap	Deferred Tax Liabilities Other Comprehensive Income DeferredTaxLiabilitiesOtherComprehensiveIncome	272000000	USD
CY2020Q4	us-gaap	Deferred Tax Liabilities Other Comprehensive Income DeferredTaxLiabilitiesOtherComprehensiveIncome	453000000	USD
CY2021Q4	cna	Deferred Tax Liabilities Deferred Expense Softwareand Hardware DeferredTaxLiabilitiesDeferredExpenseSoftwareandHardware	27000000	USD
CY2020Q4	cna	Deferred Tax Liabilities Deferred Expense Softwareand Hardware DeferredTaxLiabilitiesDeferredExpenseSoftwareandHardware	31000000	USD
CY2021Q4	us-gaap	Deferred Tax Liabilities Other DeferredTaxLiabilitiesOther	21000000	USD
CY2020Q4	us-gaap	Deferred Tax Liabilities Other DeferredTaxLiabilitiesOther	19000000	USD
CY2021Q4	us-gaap	Deferred Income Tax Liabilities DeferredIncomeTaxLiabilities	512000000	USD
CY2020Q4	us-gaap	Deferred Income Tax Liabilities DeferredIncomeTaxLiabilities	624000000	USD
CY2021Q4	us-gaap	Deferred Tax Assets Liabilities Net DeferredTaxAssetsLiabilitiesNet	142000000	USD
CY2020Q4	us-gaap	Deferred Tax Assets Liabilities Net DeferredTaxAssetsLiabilitiesNet	66000000	USD
CY2021Q4	us-gaap	Operating Loss Carryforwards OperatingLossCarryforwards	0	USD
CY2021Q4	us-gaap	Tax Credit Carryforward Amount TaxCreditCarryforwardAmount	0	USD
CY2021Q4	us-gaap	Deferred Tax Assets Valuation Allowance DeferredTaxAssetsValuationAllowance	0	USD
CY2020Q4	us-gaap	Deferred Tax Assets Valuation Allowance DeferredTaxAssetsValuationAllowance	0	USD
CY2021Q4	us-gaap	Liability For Unpaid Claims And Claims Adjustment Expense Net LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseNet	19205000000	USD
CY2021Q4	us-gaap	Reinsurance Recoverables On Unpaid Losses Gross ReinsuranceRecoverablesOnUnpaidLossesGross	4969000000	USD
CY2021Q4	us-gaap	Liability For Claims And Claims Adjustment Expense LiabilityForClaimsAndClaimsAdjustmentExpense	24174000000	USD
CY2021	us-gaap	Schedule Of Liability For Unpaid Claims And Claims Adjustment Expense ScheduleOfLiabilityForUnpaidClaimsAndClaimsAdjustmentExpense	<div style="margin-top:6pt;text-align:justify"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%">The following table presents a reconciliation between beginning and ending claim and claim adjustment expense reserves, including claim and claim adjustment expense reserves of the Life & Group segment.</span></div><div style="margin-top:5pt"><table style="border-collapse:collapse;display:inline-table;margin-bottom:5pt;vertical-align:text-bottom;width:100.000%"><tr><td style="width:1.0%"/><td style="width:64.066%"/><td style="width:0.1%"/><td style="width:1.0%"/><td style="width:9.733%"/><td style="width:0.1%"/><td style="width:0.1%"/><td style="width:0.966%"/><td style="width:0.1%"/><td style="width:1.0%"/><td style="width:9.733%"/><td style="width:0.1%"/><td style="width:0.1%"/><td style="width:0.966%"/><td style="width:0.1%"/><td style="width:1.0%"/><td style="width:9.736%"/><td style="width:0.1%"/></tr><tr><td colspan="3" style="padding:2px 1pt;text-align:left;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:700;line-height:100%">As of or for the years ended December 31</span></td><td colspan="3" style="padding:0 1pt"/><td colspan="3" style="padding:0 1pt"/><td colspan="3" style="padding:0 1pt"/><td colspan="3" style="padding:0 1pt"/><td colspan="3" style="padding:0 1pt"/></tr><tr><td colspan="3" style="background-color:#ffffff;padding:2px 1pt;text-align:left;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:100%">(In millions)</span></td><td colspan="3" style="padding:2px 1pt;text-align:center;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:700;line-height:100%">2021</span></td><td colspan="3" style="padding:0 1pt"/><td colspan="3" style="padding:2px 1pt;text-align:center;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:700;line-height:100%">2020</span></td><td colspan="3" style="padding:0 1pt"/><td colspan="3" style="padding:2px 1pt;text-align:center;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:700;line-height:100%">2019</span></td></tr><tr><td colspan="3" style="background-color:#cceeff;padding:2px 1pt;text-align:left;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:100%">Reserves, beginning of year:</span></td><td colspan="3" style="background-color:#cceeff;border-top:1pt solid #000000;padding:0 1pt"/><td colspan="3" style="background-color:#cceeff;padding:0 1pt"/><td colspan="3" style="background-color:#cceeff;border-top:1pt solid #000000;padding:0 1pt"/><td colspan="3" style="background-color:#cceeff;padding:0 1pt"/><td colspan="3" style="background-color:#cceeff;border-top:1pt solid #000000;padding:0 1pt"/></tr><tr><td colspan="3" style="background-color:#ffffff;padding:2px 1pt 2px 7.75pt;text-align:left;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:100%">Gross</span></td><td style="background-color:#ffffff;padding:2px 0 2px 1pt;text-align:left;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:100%">$</span></td><td style="background-color:#ffffff;padding:2px 0;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:100%">22,706 </span></td><td style="background-color:#ffffff;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"/><td colspan="3" style="background-color:#ffffff;padding:0 1pt"/><td style="background-color:#ffffff;padding:2px 0 2px 1pt;text-align:left;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:100%">$</span></td><td style="background-color:#ffffff;padding:2px 0;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:100%">21,720 </span></td><td style="background-color:#ffffff;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"/><td colspan="3" style="background-color:#ffffff;padding:0 1pt"/><td style="background-color:#ffffff;padding:2px 0 2px 1pt;text-align:left;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:100%">$</span></td><td style="background-color:#ffffff;padding:2px 0;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:100%">21,984 </span></td><td style="background-color:#ffffff;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"/></tr><tr><td colspan="3" style="background-color:#cceeff;padding:2px 1pt 2px 7.75pt;text-align:left;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:100%">Ceded</span></td><td colspan="2" style="background-color:#cceeff;padding:2px 0 2px 1pt;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:100%">4,005 </span></td><td style="background-color:#cceeff;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"/><td colspan="3" style="background-color:#cceeff;padding:0 1pt"/><td colspan="2" style="background-color:#cceeff;padding:2px 0 2px 1pt;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:100%">3,835 </span></td><td style="background-color:#cceeff;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"/><td colspan="3" style="background-color:#cceeff;padding:0 1pt"/><td colspan="2" style="background-color:#cceeff;padding:2px 0 2px 1pt;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:100%">4,019 </span></td><td style="background-color:#cceeff;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"/></tr><tr><td colspan="3" style="background-color:#ffffff;padding:2px 1pt;text-align:left;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:100%">Net reserves, beginning of year</span></td><td colspan="2" style="background-color:#ffffff;border-top:1pt solid #000000;padding:2px 0 2px 1pt;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:100%">18,701 </span></td><td style="background-color:#ffffff;border-top:1pt solid #000000;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"/><td colspan="3" style="background-color:#ffffff;padding:0 1pt"/><td colspan="2" style="background-color:#ffffff;border-top:1pt solid #000000;padding:2px 0 2px 1pt;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:100%">17,885 </span></td><td style="background-color:#ffffff;border-top:1pt solid #000000;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"/><td colspan="3" style="background-color:#ffffff;padding:0 1pt"/><td colspan="2" style="background-color:#ffffff;border-top:1pt solid #000000;padding:2px 0 2px 1pt;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:100%">17,965 </span></td><td style="background-color:#ffffff;border-top:1pt solid #000000;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"/></tr><tr><td colspan="3" style="background-color:#cceeff;padding:2px 1pt;text-align:left;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:100%">Reduction of net reserves due to Excess Workers' Compensation Loss Portfolio Transfer</span></td><td colspan="2" style="background-color:#cceeff;padding:2px 0 2px 1pt;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:100%">(632)</span></td><td style="background-color:#cceeff;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"/><td colspan="3" style="background-color:#cceeff;padding:0 1pt"/><td colspan="2" style="background-color:#cceeff;padding:2px 0 2px 1pt;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:100%">— </span></td><td style="background-color:#cceeff;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"/><td colspan="3" style="background-color:#cceeff;padding:0 1pt"/><td colspan="2" style="background-color:#cceeff;padding:2px 0 2px 1pt;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:100%">— </span></td><td style="background-color:#cceeff;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"/></tr><tr><td colspan="3" style="background-color:#ffffff;padding:2px 1pt;text-align:left;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:100%">Net incurred claim and claim adjustment expenses:</span></td><td colspan="3" style="background-color:#ffffff;padding:0 1pt"/><td colspan="3" style="background-color:#ffffff;padding:0 1pt"/><td colspan="3" style="background-color:#ffffff;padding:0 1pt"/><td colspan="3" style="background-color:#ffffff;padding:0 1pt"/><td colspan="3" style="background-color:#ffffff;padding:0 1pt"/></tr><tr><td colspan="3" style="background-color:#cceeff;padding:2px 1pt 2px 7.75pt;text-align:left;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:100%">Provision for insured events of current year</span></td><td colspan="2" style="background-color:#cceeff;padding:2px 0 2px 1pt;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:100%">5,970 </span></td><td style="background-color:#cceeff;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"/><td colspan="3" style="background-color:#cceeff;padding:0 1pt"/><td colspan="2" style="background-color:#cceeff;padding:2px 0 2px 1pt;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:100%">5,793 </span></td><td style="background-color:#cceeff;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"/><td colspan="3" style="background-color:#cceeff;padding:0 1pt"/><td colspan="2" style="background-color:#cceeff;padding:2px 0 2px 1pt;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:100%">5,356 </span></td><td style="background-color:#cceeff;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"/></tr><tr><td colspan="3" style="background-color:#ffffff;padding:2px 1pt 2px 7.75pt;text-align:left;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:100%">Increase (decrease) in provision for insured events of prior years</span></td><td colspan="2" style="background-color:#ffffff;padding:2px 0 2px 1pt;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:100%">(104)</span></td><td style="background-color:#ffffff;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"/><td colspan="3" style="background-color:#ffffff;padding:0 1pt"/><td colspan="2" style="background-color:#ffffff;padding:2px 0 2px 1pt;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:100%">(119)</span></td><td style="background-color:#ffffff;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"/><td colspan="3" style="background-color:#ffffff;padding:0 1pt"/><td colspan="2" style="background-color:#ffffff;padding:2px 0 2px 1pt;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:100%">(127)</span></td><td style="background-color:#ffffff;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"/></tr><tr><td colspan="3" style="background-color:#cceeff;padding:2px 1pt 2px 7.75pt;text-align:left;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:100%">Amortization of discount</span></td><td colspan="2" style="background-color:#cceeff;padding:2px 0 2px 1pt;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:100%">174 </span></td><td style="background-color:#cceeff;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"/><td colspan="3" style="background-color:#cceeff;padding:0 1pt"/><td colspan="2" style="background-color:#cceeff;padding:2px 0 2px 1pt;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:100%">183 </span></td><td style="background-color:#cceeff;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"/><td colspan="3" style="background-color:#cceeff;padding:0 1pt"/><td colspan="2" style="background-color:#cceeff;padding:2px 0 2px 1pt;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:100%">184 </span></td><td style="background-color:#cceeff;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"/></tr><tr><td colspan="3" style="background-color:#ffffff;padding:2px 1pt;text-align:left;vertical-align:bottom"><div><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:100%">Total net incurred </span><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:5.2pt;font-weight:400;line-height:100%;position:relative;top:-2.8pt;vertical-align:baseline">(1)</span></div></td><td colspan="2" style="background-color:#ffffff;border-top:1pt solid #000000;padding:2px 0 2px 1pt;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:100%">6,040 </span></td><td style="background-color:#ffffff;border-top:1pt solid #000000;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"/><td colspan="3" style="background-color:#ffffff;padding:0 1pt"/><td colspan="2" style="background-color:#ffffff;border-top:1pt solid #000000;padding:2px 0 2px 1pt;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:100%">5,857 </span></td><td style="background-color:#ffffff;border-top:1pt solid #000000;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"/><td colspan="3" style="background-color:#ffffff;padding:0 1pt"/><td colspan="2" style="background-color:#ffffff;border-top:1pt solid #000000;padding:2px 0 2px 1pt;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:100%">5,413 </span></td><td style="background-color:#ffffff;border-top:1pt solid #000000;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"/></tr><tr><td colspan="3" style="background-color:#cceeff;padding:2px 1pt;text-align:left;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:100%">Net payments attributable to:</span></td><td colspan="3" style="background-color:#cceeff;padding:0 1pt"/><td colspan="3" style="background-color:#cceeff;padding:0 1pt"/><td colspan="3" style="background-color:#cceeff;padding:0 1pt"/><td colspan="3" style="background-color:#cceeff;padding:0 1pt"/><td colspan="3" style="background-color:#cceeff;padding:0 1pt"/></tr><tr><td colspan="3" style="background-color:#ffffff;padding:2px 1pt 2px 7.75pt;text-align:left;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:100%">Current year events</span></td><td colspan="2" style="background-color:#ffffff;padding:2px 0 2px 1pt;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:100%">(1,014)</span></td><td style="background-color:#ffffff;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"/><td colspan="3" style="background-color:#ffffff;padding:0 1pt"/><td colspan="2" style="background-color:#ffffff;padding:2px 0 2px 1pt;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:100%">(948)</span></td><td style="background-color:#ffffff;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"/><td colspan="3" style="background-color:#ffffff;padding:0 1pt"/><td colspan="2" style="background-color:#ffffff;padding:2px 0 2px 1pt;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:100%">(992)</span></td><td style="background-color:#ffffff;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"/></tr><tr><td colspan="3" style="background-color:#cceeff;padding:2px 1pt 2px 7.75pt;text-align:left;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:100%">Prior year events</span></td><td colspan="2" style="background-color:#cceeff;padding:2px 0 2px 1pt;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:100%">(3,830)</span></td><td style="background-color:#cceeff;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"/><td colspan="3" style="background-color:#cceeff;padding:0 1pt"/><td colspan="2" style="background-color:#cceeff;padding:2px 0 2px 1pt;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:100%">(4,216)</span></td><td style="background-color:#cceeff;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"/><td colspan="3" style="background-color:#cceeff;padding:0 1pt"/><td colspan="2" style="background-color:#cceeff;padding:2px 0 2px 1pt;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:100%">(4,584)</span></td><td style="background-color:#cceeff;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"/></tr><tr><td colspan="3" style="background-color:#ffffff;padding:2px 1pt;text-align:left;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:100%">Total net payments</span></td><td colspan="2" style="background-color:#ffffff;border-top:1pt solid #000000;padding:2px 0 2px 1pt;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:100%">(4,844)</span></td><td style="background-color:#ffffff;border-top:1pt solid #000000;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"/><td colspan="3" style="background-color:#ffffff;padding:0 1pt"/><td colspan="2" style="background-color:#ffffff;border-top:1pt solid #000000;padding:2px 0 2px 1pt;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:100%">(5,164)</span></td><td style="background-color:#ffffff;border-top:1pt solid #000000;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"/><td colspan="3" style="background-color:#ffffff;padding:0 1pt"/><td colspan="2" style="background-color:#ffffff;border-top:1pt solid #000000;padding:2px 0 2px 1pt;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:100%">(5,576)</span></td><td style="background-color:#ffffff;border-top:1pt solid #000000;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"/></tr><tr><td colspan="3" style="background-color:#cceeff;padding:2px 1pt;text-align:left;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:100%">Foreign currency translation adjustment and other</span></td><td colspan="2" style="background-color:#cceeff;padding:2px 0 2px 1pt;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:100%">(60)</span></td><td style="background-color:#cceeff;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"/><td colspan="3" style="background-color:#cceeff;padding:0 1pt"/><td colspan="2" style="background-color:#cceeff;padding:2px 0 2px 1pt;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:100%">123 </span></td><td style="background-color:#cceeff;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"/><td colspan="3" style="background-color:#cceeff;padding:0 1pt"/><td colspan="2" style="background-color:#cceeff;padding:2px 0 2px 1pt;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:100%">83 </span></td><td style="background-color:#cceeff;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"/></tr><tr><td colspan="3" style="background-color:#ffffff;padding:2px 1pt;text-align:left;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:100%">Net reserves, end of year</span></td><td colspan="2" style="background-color:#ffffff;border-top:1pt solid #000000;padding:2px 0 2px 1pt;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:100%">19,205 </span></td><td style="background-color:#ffffff;border-top:1pt solid #000000;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"/><td colspan="3" style="background-color:#ffffff;padding:0 1pt"/><td colspan="2" style="background-color:#ffffff;border-top:1pt solid #000000;padding:2px 0 2px 1pt;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:100%">18,701 </span></td><td style="background-color:#ffffff;border-top:1pt solid #000000;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"/><td colspan="3" style="background-color:#ffffff;padding:0 1pt"/><td colspan="2" style="background-color:#ffffff;border-top:1pt solid #000000;padding:2px 0 2px 1pt;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:100%">17,885 </span></td><td style="background-color:#ffffff;border-top:1pt solid #000000;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"/></tr><tr><td colspan="3" style="background-color:#cceeff;padding:2px 1pt;text-align:left;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:100%">Ceded reserves, end of year</span></td><td colspan="2" style="background-color:#cceeff;padding:2px 0 2px 1pt;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:100%">4,969 </span></td><td style="background-color:#cceeff;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"/><td colspan="3" style="background-color:#cceeff;padding:0 1pt"/><td colspan="2" style="background-color:#cceeff;padding:2px 0 2px 1pt;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:100%">4,005 </span></td><td style="background-color:#cceeff;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"/><td colspan="3" style="background-color:#cceeff;padding:0 1pt"/><td colspan="2" style="background-color:#cceeff;padding:2px 0 2px 1pt;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:100%">3,835 </span></td><td style="background-color:#cceeff;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"/></tr><tr><td colspan="3" style="background-color:#ffffff;padding:2px 1pt;text-align:left;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:700;line-height:100%">Gross reserves, end of year</span></td><td style="background-color:#ffffff;border-bottom:3pt double #000000;border-top:1pt solid #000000;padding:2px 0 2px 1pt;text-align:left;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:100%">$</span></td><td style="background-color:#ffffff;border-bottom:3pt double #000000;border-top:1pt solid #000000;padding:2px 0;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:100%">24,174 </span></td><td style="background-color:#ffffff;border-bottom:3pt double #000000;border-top:1pt solid #000000;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"/><td colspan="3" style="background-color:#ffffff;padding:0 1pt"/><td style="background-color:#ffffff;border-bottom:3pt double #000000;border-top:1pt solid #000000;padding:2px 0 2px 1pt;text-align:left;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:100%">$</span></td><td style="background-color:#ffffff;border-bottom:3pt double #000000;border-top:1pt solid #000000;padding:2px 0;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:100%">22,706 </span></td><td style="background-color:#ffffff;border-bottom:3pt double #000000;border-top:1pt solid #000000;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"/><td colspan="3" style="background-color:#ffffff;padding:0 1pt"/><td style="background-color:#ffffff;border-bottom:3pt double #000000;border-top:1pt solid #000000;padding:2px 0 2px 1pt;text-align:left;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:100%">$</span></td><td style="background-color:#ffffff;border-bottom:3pt double #000000;border-top:1pt solid #000000;padding:2px 0;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:100%">21,720 </span></td><td style="background-color:#ffffff;border-bottom:3pt double #000000;border-top:1pt solid #000000;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"/></tr></table></div><div style="margin-top:1pt;padding-left:13.5pt;text-align:justify;text-indent:-13.5pt"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:120%">(1) Total net incurred above does not agree to Insurance claims and policyholders' benefits as reflected on the Consolidated Statements of Operations due to amounts related to retroactive reinsurance deferred gain accounting, the loss on the Excess Workers' Compensation LPT, uncollectible reinsurance and benefit expenses related to future policy benefits, which are not reflected in the table above.</span></div>
CY2020Q4	cna	Liabilityforunpaidclaimandclaimadjustmentexpensegross Liabilityforunpaidclaimandclaimadjustmentexpensegross	22706000000	USD
CY2019Q4	cna	Liabilityforunpaidclaimandclaimadjustmentexpensegross Liabilityforunpaidclaimandclaimadjustmentexpensegross	21720000000	USD
CY2018Q4	cna	Liabilityforunpaidclaimandclaimadjustmentexpensegross Liabilityforunpaidclaimandclaimadjustmentexpensegross	21984000000	USD
CY2020Q4	cna	Ceded Claim And Claim Adjustment Expenses CededClaimAndClaimAdjustmentExpenses	4005000000	USD
CY2019	cna	Liability For Unpaid Claims And Claims Adjustment Expense Incurred Claims Amortization Of Discount LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseIncurredClaimsAmortizationOfDiscount	184000000	USD
CY2019Q4	cna	Ceded Claim And Claim Adjustment Expenses CededClaimAndClaimAdjustmentExpenses	3835000000	USD
CY2018Q4	cna	Ceded Claim And Claim Adjustment Expenses CededClaimAndClaimAdjustmentExpenses	4019000000	USD
CY2020Q4	us-gaap	Liability For Unpaid Claims And Claims Adjustment Expense Net LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseNet	18701000000	USD
CY2019Q4	us-gaap	Liability For Unpaid Claims And Claims Adjustment Expense Net LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseNet	17885000000	USD
CY2018Q4	us-gaap	Liability For Unpaid Claims And Claims Adjustment Expense Net LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseNet	17965000000	USD
CY2021Q4	us-gaap	Liability For Unpaid Claims And Claims Adjustment Expense Opening Balance Adjustments LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseOpeningBalanceAdjustments	-632000000	USD
CY2020Q4	us-gaap	Liability For Unpaid Claims And Claims Adjustment Expense Opening Balance Adjustments LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseOpeningBalanceAdjustments	0	USD
CY2019Q4	us-gaap	Liability For Unpaid Claims And Claims Adjustment Expense Opening Balance Adjustments LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseOpeningBalanceAdjustments	0	USD
CY2021	us-gaap	Supplemental Information For Property Casualty Insurance Underwriters Current Year Claims And Claims Adjustment Expense SupplementalInformationForPropertyCasualtyInsuranceUnderwritersCurrentYearClaimsAndClaimsAdjustmentExpense	5970000000	USD
CY2020	us-gaap	Supplemental Information For Property Casualty Insurance Underwriters Current Year Claims And Claims Adjustment Expense SupplementalInformationForPropertyCasualtyInsuranceUnderwritersCurrentYearClaimsAndClaimsAdjustmentExpense	5793000000	USD
CY2019	us-gaap	Supplemental Information For Property Casualty Insurance Underwriters Current Year Claims And Claims Adjustment Expense SupplementalInformationForPropertyCasualtyInsuranceUnderwritersCurrentYearClaimsAndClaimsAdjustmentExpense	5356000000	USD
CY2021	us-gaap	Supplemental Information For Property Casualty Insurance Underwriters Prior Year Claims And Claims Adjustment Expense SupplementalInformationForPropertyCasualtyInsuranceUnderwritersPriorYearClaimsAndClaimsAdjustmentExpense	-104000000	USD
CY2020	us-gaap	Supplemental Information For Property Casualty Insurance Underwriters Prior Year Claims And Claims Adjustment Expense SupplementalInformationForPropertyCasualtyInsuranceUnderwritersPriorYearClaimsAndClaimsAdjustmentExpense	-119000000	USD
CY2019	us-gaap	Supplemental Information For Property Casualty Insurance Underwriters Prior Year Claims And Claims Adjustment Expense SupplementalInformationForPropertyCasualtyInsuranceUnderwritersPriorYearClaimsAndClaimsAdjustmentExpense	-127000000	USD
CY2021	cna	Liability For Unpaid Claims And Claims Adjustment Expense Incurred Claims Amortization Of Discount LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseIncurredClaimsAmortizationOfDiscount	174000000	USD
CY2020	cna	Liability For Unpaid Claims And Claims Adjustment Expense Incurred Claims Amortization Of Discount LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseIncurredClaimsAmortizationOfDiscount	183000000	USD
CY2021	us-gaap	Liability For Unpaid Claims And Claims Adjustment Expense Incurred Claims1 LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseIncurredClaims1	6040000000	USD
CY2020	us-gaap	Liability For Unpaid Claims And Claims Adjustment Expense Incurred Claims1 LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseIncurredClaims1	5857000000	USD
CY2019	us-gaap	Liability For Unpaid Claims And Claims Adjustment Expense Incurred Claims1 LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseIncurredClaims1	5413000000	USD
CY2021	us-gaap	Liability For Unpaid Claims And Claims Adjustment Expense Claims Paid Current Year1 LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseClaimsPaidCurrentYear1	1014000000	USD
CY2020	us-gaap	Liability For Unpaid Claims And Claims Adjustment Expense Claims Paid Current Year1 LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseClaimsPaidCurrentYear1	948000000	USD
CY2019	us-gaap	Liability For Unpaid Claims And Claims Adjustment Expense Claims Paid Current Year1 LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseClaimsPaidCurrentYear1	992000000	USD
CY2021	us-gaap	Liability For Unpaid Claims And Claims Adjustment Expense Claims Paid Prior Years1 LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseClaimsPaidPriorYears1	3830000000	USD
CY2020	us-gaap	Liability For Unpaid Claims And Claims Adjustment Expense Claims Paid Prior Years1 LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseClaimsPaidPriorYears1	4216000000	USD
CY2019	us-gaap	Liability For Unpaid Claims And Claims Adjustment Expense Claims Paid Prior Years1 LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseClaimsPaidPriorYears1	4584000000	USD
CY2021	us-gaap	Payments For Losses And Loss Adjustment Expense PaymentsForLossesAndLossAdjustmentExpense	4844000000	USD
CY2020	us-gaap	Payments For Losses And Loss Adjustment Expense PaymentsForLossesAndLossAdjustmentExpense	5164000000	USD
CY2019	us-gaap	Payments For Losses And Loss Adjustment Expense PaymentsForLossesAndLossAdjustmentExpense	5576000000	USD
CY2021	cna	Liability For Unpaid Claims And Claims Adjustment Expense Foreign Cta And Other LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseForeignCtaAndOther	-60000000	USD
CY2020	cna	Liability For Unpaid Claims And Claims Adjustment Expense Foreign Cta And Other LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseForeignCtaAndOther	123000000	USD
CY2019	cna	Liability For Unpaid Claims And Claims Adjustment Expense Foreign Cta And Other LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseForeignCtaAndOther	83000000	USD
CY2021Q4	us-gaap	Liability For Unpaid Claims And Claims Adjustment Expense Net LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseNet	19205000000	USD
CY2020Q4	us-gaap	Liability For Unpaid Claims And Claims Adjustment Expense Net LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseNet	18701000000	USD
CY2019Q4	us-gaap	Liability For Unpaid Claims And Claims Adjustment Expense Net LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseNet	17885000000	USD
CY2021Q4	cna	Ceded Claim And Claim Adjustment Expenses CededClaimAndClaimAdjustmentExpenses	4969000000	USD
CY2020Q4	cna	Ceded Claim And Claim Adjustment Expenses CededClaimAndClaimAdjustmentExpenses	4005000000	USD
CY2019Q4	cna	Ceded Claim And Claim Adjustment Expenses CededClaimAndClaimAdjustmentExpenses	3835000000	USD
CY2021Q4	cna	Liabilityforunpaidclaimandclaimadjustmentexpensegross Liabilityforunpaidclaimandclaimadjustmentexpensegross	24174000000	USD
CY2020Q4	cna	Liabilityforunpaidclaimandclaimadjustmentexpensegross Liabilityforunpaidclaimandclaimadjustmentexpensegross	22706000000	USD
CY2019Q4	cna	Liabilityforunpaidclaimandclaimadjustmentexpensegross Liabilityforunpaidclaimandclaimadjustmentexpensegross	21720000000	USD
CY2021Q4	us-gaap	Liability For Unpaid Claims And Claims Adjustment Expense Reported Claims Amount LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseReportedClaimsAmount	10555000000	USD
CY2021Q4	us-gaap	Liability For Unpaid Claims And Claims Adjustment Expense Incurred But Not Reported Ibnr Claims Amount LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseIncurredButNotReportedIBNRClaimsAmount	13619000000	USD
CY2021Q4	cna	Liabilityforunpaidclaimandclaimadjustmentexpensegross Liabilityforunpaidclaimandclaimadjustmentexpensegross	24174000000	USD
CY2021Q4	cna	Net Case Reserves NetCaseReserves	8369000000	USD
CY2021Q4	cna	Net Ibnr Reserves NetIbnrReserves	10836000000	USD
CY2021Q4	us-gaap	Liability For Unpaid Claims And Claims Adjustment Expense Net LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseNet	19205000000	USD
CY2020Q4	us-gaap	Liability For Unpaid Claims And Claims Adjustment Expense Reported Claims Amount LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseReportedClaimsAmount	10694000000	USD
CY2020Q4	us-gaap	Liability For Unpaid Claims And Claims Adjustment Expense Incurred But Not Reported Ibnr Claims Amount LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseIncurredButNotReportedIBNRClaimsAmount	12012000000	USD
CY2020Q4	cna	Liabilityforunpaidclaimandclaimadjustmentexpensegross Liabilityforunpaidclaimandclaimadjustmentexpensegross	22706000000	USD
CY2020Q4	cna	Net Case Reserves NetCaseReserves	8930000000	USD
CY2020Q4	cna	Net Ibnr Reserves NetIbnrReserves	9771000000	USD
CY2020Q4	us-gaap	Liability For Unpaid Claims And Claims Adjustment Expense Net LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseNet	18701000000	USD
CY2021	cna	Pretax Favorable Unfavorable Premium Development Excluding Life Group PretaxFavorableUnfavorablePremiumDevelopmentExcludingLifeGroup	11000000	USD
CY2020	cna	Pretax Favorable Unfavorable Premium Development Excluding Life Group PretaxFavorableUnfavorablePremiumDevelopmentExcludingLifeGroup	-20000000	USD
CY2019	cna	Pretax Favorable Unfavorable Premium Development Excluding Life Group PretaxFavorableUnfavorablePremiumDevelopmentExcludingLifeGroup	-73000000	USD
CY2021Q1	us-gaap	Funds Held Under Reinsurance Agreements Liability FundsHeldUnderReinsuranceAgreementsLiability	690000000	USD
CY2021Q1	cna	Retroactive Reinsurance Agreement Maximum RetroactiveReinsuranceAgreementMaximum	1000000000	USD
CY2021Q1	cna	Reinsurance Premiums Paid ReinsurancePremiumsPaid	697000000	USD
	cna	Reinsurance Premiums Paid ReinsurancePremiumsPaid	64000000	USD
CY2021Q1	us-gaap	Reinsurance Loss On Uncollectible Accounts In Period Amount ReinsuranceLossOnUncollectibleAccountsInPeriodAmount	12000000	USD
CY2021Q4	us-gaap	Securities Held As Collateral At Fair Value SecuritiesHeldAsCollateralAtFairValue	634000000	USD
CY2021Q3	cna	Liability For Unpaid Claims And Claims Adjustment Expense Long Term Care Policies Period Increase Decrease LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseLongTermCarePoliciesPeriodIncreaseDecrease	-40000000	USD
CY2020Q3	cna	Liability For Unpaid Claims And Claims Adjustment Expense Long Term Care Policies Period Increase Decrease LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseLongTermCarePoliciesPeriodIncreaseDecrease	-37000000	USD
CY2019Q3	cna	Liability For Unpaid Claims And Claims Adjustment Expense Long Term Care Policies Period Increase Decrease LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseLongTermCarePoliciesPeriodIncreaseDecrease	-56000000	USD
CY2021Q3	cna	Liability For Unpaid Claims And Claims Adjustment Expense Structured Settlement Obligations Period Increase Decrease LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseStructuredSettlementObligationsPeriodIncreaseDecrease	2000000	USD
CY2020Q3	cna	Liability For Unpaid Claims And Claims Adjustment Expense Structured Settlement Obligations Period Increase Decrease LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseStructuredSettlementObligationsPeriodIncreaseDecrease	46000000	USD
CY2021Q3	cna	Liability For Future Policy Benefits Gross Premium Valuation Pretax Margin LiabilityForFuturePolicyBenefitsGrossPremiumValuationPretaxMargin	72000000	USD
CY2020Q3	us-gaap	Liability For Future Policy Benefits Period Expense LiabilityForFuturePolicyBenefitsPeriodExpense	74000000	USD
CY2019Q3	us-gaap	Liability For Future Policy Benefits Period Expense LiabilityForFuturePolicyBenefitsPeriodExpense	216000000	USD
CY2021Q4	cna	Ceded Claim And Claim Adjustment Expenses CededClaimAndClaimAdjustmentExpenses	4969000000	USD
CY2020Q4	cna	Ceded Claim And Claim Adjustment Expenses CededClaimAndClaimAdjustmentExpenses	4005000000	USD
CY2021Q4	cna	Ceded Future Policy Benefits CededFuturePolicyBenefits	288000000	USD
CY2020Q4	cna	Ceded Future Policy Benefits CededFuturePolicyBenefits	263000000	USD
CY2021Q4	us-gaap	Reinsurance Recoverables On Paid Losses Gross ReinsuranceRecoverablesOnPaidLossesGross	227000000	USD
CY2020Q4	us-gaap	Reinsurance Recoverables On Paid Losses Gross ReinsuranceRecoverablesOnPaidLossesGross	210000000	USD
CY2021Q4	us-gaap	Reinsurance Recoverables Gross ReinsuranceRecoverablesGross	5484000000	USD
CY2020Q4	us-gaap	Reinsurance Recoverables Gross ReinsuranceRecoverablesGross	4478000000	USD
CY2021Q4	us-gaap	Reinsurance Recoverables Allowance ReinsuranceRecoverablesAllowance	21000000	USD
CY2020Q4	us-gaap	Reinsurance Recoverables Allowance ReinsuranceRecoverablesAllowance	21000000	USD
CY2021Q4	us-gaap	Reinsurance Recoverables ReinsuranceRecoverables	5463000000	USD
CY2020Q4	us-gaap	Reinsurance Recoverables ReinsuranceRecoverables	4457000000	USD
CY2021Q4	cna	Voluntary Reinsurance Recoverable Gross VoluntaryReinsuranceRecoverableGross	4802000000	USD
CY2021Q4	us-gaap	Funds Held Under Reinsurance Agreements Liability FundsHeldUnderReinsuranceAgreementsLiability	4000000000	USD
CY2020Q4	us-gaap	Funds Held Under Reinsurance Agreements Liability FundsHeldUnderReinsuranceAgreementsLiability	3300000000	USD
CY2021	us-gaap	Direct Premiums Earned DirectPremiumsEarned	12997000000	USD
CY2021	us-gaap	Assumed Premiums Earned AssumedPremiumsEarned	288000000	USD
CY2021	us-gaap	Ceded Premiums Earned CededPremiumsEarned	5110000000	USD
CY2021	us-gaap	Premiums Earned Net PremiumsEarnedNet	8175000000	USD
CY2020	us-gaap	Direct Premiums Earned DirectPremiumsEarned	12001000000	USD
CY2020	us-gaap	Assumed Premiums Earned AssumedPremiumsEarned	288000000	USD
CY2020	us-gaap	Ceded Premiums Earned CededPremiumsEarned	4640000000	USD
CY2020	us-gaap	Premiums Earned Net PremiumsEarnedNet	7649000000	USD
CY2019	us-gaap	Direct Premiums Earned DirectPremiumsEarned	11491000000	USD
CY2019	us-gaap	Assumed Premiums Earned AssumedPremiumsEarned	338000000	USD
CY2019	us-gaap	Ceded Premiums Earned CededPremiumsEarned	4401000000	USD
CY2019	us-gaap	Premiums Earned Net PremiumsEarnedNet	7428000000	USD
CY2021	us-gaap	Direct Premiums Written DirectPremiumsWritten	13587000000	USD
CY2021	us-gaap	Assumed Premiums Written AssumedPremiumsWritten	303000000	USD
CY2021	us-gaap	Ceded Premiums Written CededPremiumsWritten	5485000000	USD
CY2021	us-gaap	Premiums Written Net PremiumsWrittenNet	8405000000	USD
CY2020	us-gaap	Direct Premiums Written DirectPremiumsWritten	12612000000	USD
CY2020	us-gaap	Assumed Premiums Written AssumedPremiumsWritten	279000000	USD
CY2020	us-gaap	Ceded Premiums Written CededPremiumsWritten	4832000000	USD
CY2020	us-gaap	Premiums Written Net PremiumsWrittenNet	8059000000	USD
CY2019	us-gaap	Direct Premiums Written DirectPremiumsWritten	11894000000	USD
CY2019	us-gaap	Assumed Premiums Written AssumedPremiumsWritten	331000000	USD
CY2019	us-gaap	Ceded Premiums Written CededPremiumsWritten	4569000000	USD
CY2019	us-gaap	Premiums Written Net PremiumsWrittenNet	7656000000	USD
CY2021	us-gaap	Reinsurance Effect On Claims And Benefits Incurred Amount Ceded ReinsuranceEffectOnClaimsAndBenefitsIncurredAmountCeded	3058000000	USD
CY2020	us-gaap	Reinsurance Effect On Claims And Benefits Incurred Amount Ceded ReinsuranceEffectOnClaimsAndBenefitsIncurredAmountCeded	3158000000	USD
CY2019	us-gaap	Reinsurance Effect On Claims And Benefits Incurred Amount Ceded ReinsuranceEffectOnClaimsAndBenefitsIncurredAmountCeded	2733000000	USD
CY2021Q4	us-gaap	Long Term Debt LongTermDebt	2779000000	USD
CY2020Q4	us-gaap	Long Term Debt LongTermDebt	2776000000	USD
CY2021Q4	us-gaap	Federal Home Loan Bank Stock FederalHomeLoanBankStock	5000000	USD
CY2021Q4	us-gaap	Federal Home Loan Bank Advances General Debt Obligations Disclosures Maximum Amount Available FederalHomeLoanBankAdvancesGeneralDebtObligationsDisclosuresMaximumAmountAvailable	106000000	USD
CY2020Q4	us-gaap	Federal Home Loan Bank Advances Branch Of Fhlb Bank Amount Of Advances By Branch FederalHomeLoanBankAdvancesBranchOfFHLBBankAmountOfAdvancesByBranch	0	USD
CY2021Q4	us-gaap	Federal Home Loan Bank Advances Branch Of Fhlb Bank Amount Of Advances By Branch FederalHomeLoanBankAdvancesBranchOfFHLBBankAmountOfAdvancesByBranch	0	USD
CY2019	us-gaap	Debt Instrument Term DebtInstrumentTerm	P5Y
CY2019Q4	us-gaap	Line Of Credit Facility Current Borrowing Capacity LineOfCreditFacilityCurrentBorrowingCapacity	250000000	USD
CY2019Q4	cna	Line Of Credit Facility Additional Borrowing Capacity LineOfCreditFacilityAdditionalBorrowingCapacity	100000000	USD
CY2019Q4	cna	Lineof Credit Facility Numberof Extension Options LineofCreditFacilityNumberofExtensionOptions	2	extensionTerm
CY2019	cna	Line Of Credit Facility Extension Term LineOfCreditFacilityExtensionTerm	P1Y
CY2021Q4	us-gaap	Minimum Net Worth Required For Compliance MinimumNetWorthRequiredForCompliance	8700000000	USD
CY2021Q4	us-gaap	Line Of Credit LineOfCredit	0	USD
CY2020Q4	us-gaap	Line Of Credit LineOfCredit	0	USD
CY2021Q4	us-gaap	Long Term Debt Maturities Repayments Of Principal In Next Twelve Months LongTermDebtMaturitiesRepaymentsOfPrincipalInNextTwelveMonths	0	USD
CY2021Q4	us-gaap	Long Term Debt Maturities Repayments Of Principal In Year Two LongTermDebtMaturitiesRepaymentsOfPrincipalInYearTwo	243000000	USD
CY2021Q4	us-gaap	Long Term Debt Maturities Repayments Of Principal In Year Three LongTermDebtMaturitiesRepaymentsOfPrincipalInYearThree	550000000	USD
CY2021Q4	us-gaap	Long Term Debt Maturities Repayments Of Principal In Year Four LongTermDebtMaturitiesRepaymentsOfPrincipalInYearFour	0	USD
CY2021Q4	us-gaap	Long Term Debt Maturities Repayments Of Principal In Year Five LongTermDebtMaturitiesRepaymentsOfPrincipalInYearFive	500000000	USD
CY2021Q4	us-gaap	Long Term Debt Maturities Repayments Of Principal After Year Five LongTermDebtMaturitiesRepaymentsOfPrincipalAfterYearFive	1500000000	USD
CY2021Q4	us-gaap	Debt Instrument Unamortized Discount DebtInstrumentUnamortizedDiscount	14000000	USD
CY2021Q4	us-gaap	Long Term Debt LongTermDebt	2779000000	USD
CY2021	us-gaap	Defined Benefit Plan Actuarial Gain Loss DefinedBenefitPlanActuarialGainLoss	84000000	USD
CY2020	us-gaap	Defined Benefit Plan Actuarial Gain Loss DefinedBenefitPlanActuarialGainLoss	-205000000	USD
CY2021Q4	us-gaap	Defined Benefit Plan Pension Plans With Accumulated Benefit Obligations In Excess Of Plan Assets Aggregate Accumulated Benefit Obligation DefinedBenefitPlanPensionPlansWithAccumulatedBenefitObligationsInExcessOfPlanAssetsAggregateAccumulatedBenefitObligation	61000000	USD
CY2021Q4	us-gaap	Defined Benefit Plan Pension Plans With Accumulated Benefit Obligations In Excess Of Plan Assets Aggregate Fair Value Of Plan Assets DefinedBenefitPlanPensionPlansWithAccumulatedBenefitObligationsInExcessOfPlanAssetsAggregateFairValueOfPlanAssets	0	USD
CY2021	us-gaap	Other Comprehensive Income Loss Pension And Other Postretirement Benefit Plans Net Unamortized Gain Loss Arising During Period Before Tax OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansNetUnamortizedGainLossArisingDuringPeriodBeforeTax	262000000	USD
CY2020	us-gaap	Other Comprehensive Income Loss Pension And Other Postretirement Benefit Plans Net Unamortized Gain Loss Arising During Period Before Tax OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansNetUnamortizedGainLossArisingDuringPeriodBeforeTax	-67000000	USD
CY2019	us-gaap	Other Comprehensive Income Loss Pension And Other Postretirement Benefit Plans Net Unamortized Gain Loss Arising During Period Before Tax OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansNetUnamortizedGainLossArisingDuringPeriodBeforeTax	-112000000	USD
CY2021	cna	Other Comprehensive Income Loss Pensionand Other Postretirement Benefit Plans Settlementsbefore Tax OtherComprehensiveIncomeLossPensionandOtherPostretirementBenefitPlansSettlementsbeforeTax	1000000	USD
CY2020	cna	Other Comprehensive Income Loss Pensionand Other Postretirement Benefit Plans Settlementsbefore Tax OtherComprehensiveIncomeLossPensionandOtherPostretirementBenefitPlansSettlementsbeforeTax	3000000	USD
CY2019	cna	Other Comprehensive Income Loss Pensionand Other Postretirement Benefit Plans Settlementsbefore Tax OtherComprehensiveIncomeLossPensionandOtherPostretirementBenefitPlansSettlementsbeforeTax	0	USD
CY2021	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	0	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	0	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	0	USD
CY2021	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci Pension And Other Postretirement Benefit Plans For Net Gain Loss Before Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetGainLossBeforeTax	-46000000	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	-45000000	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	-39000000	USD
CY2021	us-gaap	Other Comprehensive Income Loss Pension And Other Postretirement Benefit Plans Adjustment Before Tax OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansAdjustmentBeforeTax	-309000000	USD
CY2020	us-gaap	Other Comprehensive Income Loss Pension And Other Postretirement Benefit Plans Adjustment Before Tax OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansAdjustmentBeforeTax	19000000	USD
CY2019	us-gaap	Other Comprehensive Income Loss Pension And Other Postretirement Benefit Plans Adjustment Before Tax OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansAdjustmentBeforeTax	73000000	USD
CY2021	cna	Assumptionsusedincalculatingassumedhealthcarecosttrendrate Assumptionsusedincalculatingassumedhealthcarecosttrendrate	0.04
CY2021	cna	Assumptionsusedincalculatingassumedhealthcarecosttrendrate Assumptionsusedincalculatingassumedhealthcarecosttrendrate	0.04
CY2021Q4	cna	Future Capital Call Commitments FutureCapitalCallCommitments	160000000	USD
CY2021	us-gaap	Defined Contribution Plan Maximum Annual Contributions Per Employee Percent DefinedContributionPlanMaximumAnnualContributionsPerEmployeePercent	0.50
CY2021	us-gaap	Defined Contribution Plan Employer Matching Contribution Percent Of Match DefinedContributionPlanEmployerMatchingContributionPercentOfMatch	1
CY2021	us-gaap	Defined Contribution Plan Employer Matching Contribution Percent DefinedContributionPlanEmployerMatchingContributionPercent	0.06
CY2021	cna	Company Contributionof Eligible Compensation Dependingon Age Percent CompanyContributionofEligibleCompensationDependingonAgePercent	0.05
CY2021	cna	Defined Contribution Plan Employers Matching Contribution Vesting Periodin Years DefinedContributionPlanEmployersMatchingContributionVestingPeriodinYears	P5Y
CY2021	us-gaap	Defined Contribution Plan Cost Recognized DefinedContributionPlanCostRecognized	65000000	USD
CY2020	us-gaap	Defined Contribution Plan Cost Recognized DefinedContributionPlanCostRecognized	70000000	USD
CY2019	us-gaap	Defined Contribution Plan Cost Recognized DefinedContributionPlanCostRecognized	71000000	USD
CY2021Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Number Of Shares Authorized ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized	16000000	shares
CY2021Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Number Of Shares Available For Grant ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant	5600000	shares
CY2021	cna	Measurement Periodof Specific Annual Performance Goalsin Years MeasurementPeriodofSpecificAnnualPerformanceGoalsinYears	P1Y
CY2021	cna	Cliff Vesting Period Following Dateof Grant CliffVestingPeriodFollowingDateofGrant	P2Y
CY2021	us-gaap	Allocated Share Based Compensation Expense AllocatedShareBasedCompensationExpense	32000000	USD
CY2020	us-gaap	Allocated Share Based Compensation Expense AllocatedShareBasedCompensationExpense	37000000	USD
CY2019	us-gaap	Allocated Share Based Compensation Expense AllocatedShareBasedCompensationExpense	34000000	USD
CY2021	us-gaap	Employee Service Share Based Compensation Tax Benefit From Compensation Expense EmployeeServiceShareBasedCompensationTaxBenefitFromCompensationExpense	6000000	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	8000000	USD
CY2021Q4	us-gaap	Employee Service Share Based Compensation Nonvested Awards Total Compensation Cost Not Yet Recognized EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized	41000000	USD
CY2021	us-gaap	Employee Service Share Based Compensation Nonvested Awards Total Compensation Cost Not Yet Recognized Period For Recognition1 EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1	P1Y8M12D
CY2021	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Vested In Period Total Fair Value ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodTotalFairValue	36000000	USD
CY2020	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Vested In Period Total Fair Value ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodTotalFairValue	35000000	USD
CY2019	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Vested In Period Total Fair Value ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodTotalFairValue	31000000	USD
CY2021	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Grants In Period Weighted Average Grant Date Fair Value ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue	45.82
CY2020	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Grants In Period Weighted Average Grant Date Fair Value ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue	34.36
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CY2020Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Nonvested Weighted Average Grant Date Fair Value ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue	40.56
CY2021	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Grants In Period ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod	1044772	shares
CY2021	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Grants In Period Weighted Average Grant Date Fair Value ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue	45.82
CY2021	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Vested In Period ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod	789495	shares
CY2021	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Vested In Period Weighted Average Grant Date Fair Value ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue	46.13
CY2021	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Forfeited In Period ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod	355881	shares
CY2021	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Forfeitures Weighted Average Grant Date Fair Value ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue	40.19
CY2021	cna	Performance Based Adjustment Share Based Compensation Equity Instruments Other Than Options PerformanceBasedAdjustmentShareBasedCompensationEquityInstrumentsOtherThanOptions	37061	shares
CY2021	cna	Performance Based Adjustment Share Based Compensation Equity Instruments Other Than Options Weighted Average Grant Date Fair Value PerformanceBasedAdjustmentShareBasedCompensationEquityInstrumentsOtherThanOptionsWeightedAverageGrantDateFairValue	43.70
CY2021Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Nonvested Number ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber	2375598	shares
CY2021Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Nonvested Weighted Average Grant Date Fair Value ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue	41.21
CY2021Q4	us-gaap	Finite Lived Intangible Assets Gross FiniteLivedIntangibleAssetsGross	18000000	USD
CY2021Q4	us-gaap	Finite Lived Intangible Assets Accumulated Amortization FiniteLivedIntangibleAssetsAccumulatedAmortization	14000000	USD
CY2020Q4	us-gaap	Finite Lived Intangible Assets Gross FiniteLivedIntangibleAssetsGross	18000000	USD
CY2020Q4	us-gaap	Finite Lived Intangible Assets Accumulated Amortization FiniteLivedIntangibleAssetsAccumulatedAmortization	13000000	USD
CY2021Q4	us-gaap	Indefinite Lived Intangible Assets Excluding Goodwill IndefiniteLivedIntangibleAssetsExcludingGoodwill	63000000	USD
CY2020Q4	us-gaap	Indefinite Lived Intangible Assets Excluding Goodwill IndefiniteLivedIntangibleAssetsExcludingGoodwill	64000000	USD
CY2021Q4	us-gaap	Intangible Assets Gross Excluding Goodwill IntangibleAssetsGrossExcludingGoodwill	81000000	USD
CY2021Q4	us-gaap	Finite Lived Intangible Assets Accumulated Amortization FiniteLivedIntangibleAssetsAccumulatedAmortization	14000000	USD
CY2020Q4	us-gaap	Intangible Assets Gross Excluding Goodwill IntangibleAssetsGrossExcludingGoodwill	82000000	USD
CY2020Q4	us-gaap	Finite Lived Intangible Assets Accumulated Amortization FiniteLivedIntangibleAssetsAccumulatedAmortization	13000000	USD
CY2021Q4	us-gaap	Finite Lived Intangible Assets Amortization Expense Year Three FiniteLivedIntangibleAssetsAmortizationExpenseYearThree	1000000	USD
CY2021Q4	us-gaap	Finite Lived Intangible Assets Amortization Expense Year Five FiniteLivedIntangibleAssetsAmortizationExpenseYearFive	1000000	USD
CY2021Q4	us-gaap	Finite Lived Intangible Assets Amortization Expense Year Two FiniteLivedIntangibleAssetsAmortizationExpenseYearTwo	1000000	USD
CY2021Q4	us-gaap	Finite Lived Intangible Assets Amortization Expense Year Four FiniteLivedIntangibleAssetsAmortizationExpenseYearFour	1000000	USD
CY2021Q4	us-gaap	Finite Lived Intangible Assets Amortization Expense Next Twelve Months FiniteLivedIntangibleAssetsAmortizationExpenseNextTwelveMonths	1000000	USD
CY2021	us-gaap	Operating Lease Expense OperatingLeaseExpense	57000000	USD
CY2020	us-gaap	Operating Lease Expense OperatingLeaseExpense	57000000	USD
CY2019	us-gaap	Operating Lease Expense OperatingLeaseExpense	55000000	USD
CY2021	us-gaap	Operating Lease Cost OperatingLeaseCost	38000000	USD
CY2020	us-gaap	Operating Lease Cost OperatingLeaseCost	38000000	USD
CY2019	us-gaap	Operating Lease Cost OperatingLeaseCost	37000000	USD
CY2021	us-gaap	Variable Lease Cost VariableLeaseCost	19000000	USD
CY2020	us-gaap	Variable Lease Cost VariableLeaseCost	19000000	USD
CY2019	us-gaap	Variable Lease Cost VariableLeaseCost	18000000	USD
CY2021	us-gaap	Operating Lease Payments OperatingLeasePayments	44000000	USD
CY2020	us-gaap	Operating Lease Payments OperatingLeasePayments	41000000	USD
CY2019	us-gaap	Operating Lease Payments OperatingLeasePayments	34000000	USD
CY2021	us-gaap	Right Of Use Asset Obtained In Exchange For Operating Lease Liability RightOfUseAssetObtainedInExchangeForOperatingLeaseLiability	11000000	USD
CY2020	us-gaap	Right Of Use Asset Obtained In Exchange For Operating Lease Liability RightOfUseAssetObtainedInExchangeForOperatingLeaseLiability	6000000	USD
CY2019	us-gaap	Right Of Use Asset Obtained In Exchange For Operating Lease Liability RightOfUseAssetObtainedInExchangeForOperatingLeaseLiability	12000000	USD
CY2021Q4	us-gaap	Operating Lease Right Of Use Asset OperatingLeaseRightOfUseAsset	175000000	USD
CY2020Q4	us-gaap	Operating Lease Right Of Use Asset OperatingLeaseRightOfUseAsset	199000000	USD
CY2021Q4	us-gaap	Operating Lease Liability OperatingLeaseLiability	248000000	USD
CY2020Q4	us-gaap	Operating Lease Liability OperatingLeaseLiability	279000000	USD
CY2021Q4	us-gaap	Lessee Operating Lease Liability Payments Due Next Twelve Months LesseeOperatingLeaseLiabilityPaymentsDueNextTwelveMonths	42000000	USD
CY2021Q4	us-gaap	Lessee Operating Lease Liability Payments Due Year Two LesseeOperatingLeaseLiabilityPaymentsDueYearTwo	37000000	USD
CY2021Q4	us-gaap	Lessee Operating Lease Liability Payments Due Year Three LesseeOperatingLeaseLiabilityPaymentsDueYearThree	30000000	USD
CY2021Q4	us-gaap	Lessee Operating Lease Liability Payments Due Year Four LesseeOperatingLeaseLiabilityPaymentsDueYearFour	25000000	USD
CY2021Q4	us-gaap	Lessee Operating Lease Liability Payments Due Year Five LesseeOperatingLeaseLiabilityPaymentsDueYearFive	22000000	USD
CY2021Q4	us-gaap	Lessee Operating Lease Liability Payments Due After Year Five LesseeOperatingLeaseLiabilityPaymentsDueAfterYearFive	141000000	USD
CY2021Q4	us-gaap	Lessee Operating Lease Liability Payments Due LesseeOperatingLeaseLiabilityPaymentsDue	297000000	USD
CY2021Q4	us-gaap	Lessee Operating Lease Liability Undiscounted Excess Amount LesseeOperatingLeaseLiabilityUndiscountedExcessAmount	49000000	USD
CY2021Q4	us-gaap	Operating Lease Liability OperatingLeaseLiability	248000000	USD
CY2021Q4	us-gaap	Operating Lease Weighted Average Remaining Lease Term1 OperatingLeaseWeightedAverageRemainingLeaseTerm1	P9Y9M18D
CY2020Q4	us-gaap	Operating Lease Weighted Average Remaining Lease Term1 OperatingLeaseWeightedAverageRemainingLeaseTerm1	P10Y3M18D
CY2021Q4	us-gaap	Operating Lease Weighted Average Discount Rate Percent OperatingLeaseWeightedAverageDiscountRatePercent	0.034
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CY2021	us-gaap	Statutory Accounting Practices Prescribed Practice Amount StatutoryAccountingPracticesPrescribedPracticeAmount	67000000	USD
CY2020	us-gaap	Statutory Accounting Practices Prescribed Practice Amount StatutoryAccountingPracticesPrescribedPracticeAmount	91000000	USD
CY2021Q4	cna	Statutory Accounting Practices Statutory Amount Availablefor Dividend Payments Before Considerationof Statutory Dividends Paidintheprecedingtwelvemonths StatutoryAccountingPracticesStatutoryAmountAvailableforDividendPaymentsBeforeConsiderationofStatutoryDividendsPaidintheprecedingtwelvemonths	1201000000	USD
CY2021	cna	Statutory Accounting Practices Dividends Paidintheprecedingtwelvemonths StatutoryAccountingPracticesDividendsPaidintheprecedingtwelvemonths	880000000	USD
CY2021Q4	us-gaap	Capital Required For Capital Adequacy To Risk Weighted Assets CapitalRequiredForCapitalAdequacyToRiskWeightedAssets	2.64
CY2020Q4	us-gaap	Capital Required For Capital Adequacy To Risk Weighted Assets CapitalRequiredForCapitalAdequacyToRiskWeightedAssets	2.66
CY2021	us-gaap	Oci Before Reclassifications Net Of Tax Attributable To Parent OciBeforeReclassificationsNetOfTaxAttributableToParent	-444000000	USD
CY2021	us-gaap	Reclassification From Aoci Current Period Tax ReclassificationFromAociCurrentPeriodTax	10000000	USD
CY2021	us-gaap	Reclassification From Aoci Current Period Net Of Tax Attributable To Parent ReclassificationFromAociCurrentPeriodNetOfTaxAttributableToParent	39000000	USD
CY2021	us-gaap	Other Comprehensive Income Loss Tax Portion Attributable To Parent1 OtherComprehensiveIncomeLossTaxPortionAttributableToParent1	-124000000	USD
CY2021	us-gaap	Other Comprehensive Income Loss Net Of Tax Portion Attributable To Parent OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent	-483000000	USD
CY2020	us-gaap	Oci Before Reclassifications Net Of Tax Attributable To Parent OciBeforeReclassificationsNetOfTaxAttributableToParent	714000000	USD
CY2020	us-gaap	Reclassification From Aoci Current Period Tax ReclassificationFromAociCurrentPeriodTax	-10000000	USD
CY2020	us-gaap	Reclassification From Aoci Current Period Net Of Tax Attributable To Parent ReclassificationFromAociCurrentPeriodNetOfTaxAttributableToParent	-38000000	USD
CY2020	us-gaap	Other Comprehensive Income Loss Tax Portion Attributable To Parent1 OtherComprehensiveIncomeLossTaxPortionAttributableToParent1	185000000	USD
CY2020	us-gaap	Other Comprehensive Income Loss Net Of Tax Portion Attributable To Parent OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent	752000000	USD
CY2021	cna	Percentageofforeigndirectwrittenpremiums Percentageofforeigndirectwrittenpremiums	0.10
CY2020	cna	Percentageofforeigndirectwrittenpremiums Percentageofforeigndirectwrittenpremiums	0.09
CY2019	cna	Percentageofforeigndirectwrittenpremiums Percentageofforeigndirectwrittenpremiums	0.09
CY2021	us-gaap	Premiums Written Net PremiumsWrittenNet	8405000000	USD
CY2021	us-gaap	Premiums Earned Net PremiumsEarnedNet	8175000000	USD
CY2021	cna	Net Investment Income And Gains Losses On Trading Securities NetInvestmentIncomeAndGainsLossesOnTradingSecurities	2159000000	USD
CY2021	us-gaap	Revenue From Contract With Customer Excluding Assessed Tax RevenueFromContractWithCustomerExcludingAssessedTax	1430000000	USD
CY2021	us-gaap	Other Income OtherIncome	24000000	USD
CY2021	cna	Operating Revenues OperatingRevenues	11788000000	USD
CY2021	us-gaap	Policyholder Benefits And Claims Incurred Net PolicyholderBenefitsAndClaimsIncurredNet	6327000000	USD
CY2021	us-gaap	Policyholder Dividends PolicyholderDividends	22000000	USD
CY2021	us-gaap	Deferred Policy Acquisition Cost Amortization Expense DeferredPolicyAcquisitionCostAmortizationExpense	1443000000	USD
CY2021	cna	Costs From Contract With Customers CostsFromContractWithCustomers	1328000000	USD
CY2021	cna	Other Insurance Related Expenses OtherInsuranceRelatedExpenses	1062000000	USD
CY2021	us-gaap	Other Expenses OtherExpenses	242000000	USD
CY2021	us-gaap	Benefits Losses And Expenses BenefitsLossesAndExpenses	10424000000	USD
CY2021	cna	Operating Income Loss From Continuing Operations Before Income Tax OperatingIncomeLossFromContinuingOperationsBeforeIncomeTax	1364000000	USD
CY2021	cna	Income Tax Expense Benefit On Operating Income Loss IncomeTaxExpenseBenefitOnOperatingIncomeLoss	258000000	USD
CY2021	cna	Net Operating Income Loss From Continuing Operations Attributableto Parent NetOperatingIncomeLossFromContinuingOperationsAttributabletoParent	1106000000	USD
CY2021	us-gaap	Debt Securities Realized Gain Loss DebtSecuritiesRealizedGainLoss	120000000	USD
CY2020Q4	us-gaap	Reinsurance Recoverables Gross ReinsuranceRecoverablesGross	4478000000	USD
CY2021	cna	Income Tax Expense Benefit On Net Realized Investment Gains Losses IncomeTaxExpenseBenefitOnNetRealizedInvestmentGainsLosses	24000000	USD
CY2021	cna	Net Realized Investment Gains Losses NetRealizedInvestmentGainsLosses	96000000	USD
CY2021	us-gaap	Income Loss From Continuing Operations IncomeLossFromContinuingOperations	1202000000	USD
CY2021Q4	us-gaap	Reinsurance Recoverables Gross ReinsuranceRecoverablesGross	5484000000	USD
CY2021Q4	us-gaap	Premiums Receivable Gross PremiumsReceivableGross	2974000000	USD
CY2021Q4	us-gaap	Deferred Policy Acquisition Costs DeferredPolicyAcquisitionCosts	737000000	USD
CY2021Q4	us-gaap	Goodwill Goodwill	148000000	USD
CY2021Q4	us-gaap	Contract With Customer Asset Net ContractWithCustomerAssetNet	3476000000	USD
CY2021Q4	us-gaap	Liability For Claims And Claims Adjustment Expense LiabilityForClaimsAndClaimsAdjustmentExpense	24174000000	USD
CY2021Q4	us-gaap	Unearned Premiums UnearnedPremiums	5761000000	USD
CY2021Q4	us-gaap	Liability For Future Policy Benefits LiabilityForFuturePolicyBenefits	13236000000	USD
CY2021Q4	us-gaap	Contract With Customer Liability ContractWithCustomerLiability	4503000000	USD
CY2020	us-gaap	Premiums Written Net PremiumsWrittenNet	8059000000	USD
CY2020	us-gaap	Premiums Earned Net PremiumsEarnedNet	7649000000	USD
CY2020	cna	Net Investment Income And Gains Losses On Trading Securities NetInvestmentIncomeAndGainsLossesOnTradingSecurities	1935000000	USD
CY2020	us-gaap	Revenue From Contract With Customer Excluding Assessed Tax RevenueFromContractWithCustomerExcludingAssessedTax	1252000000	USD
CY2020	us-gaap	Other Income OtherIncome	26000000	USD
CY2020	cna	Operating Revenues OperatingRevenues	10862000000	USD
CY2020	us-gaap	Policyholder Benefits And Claims Incurred Net PolicyholderBenefitsAndClaimsIncurredNet	6149000000	USD
CY2020	us-gaap	Policyholder Dividends PolicyholderDividends	21000000	USD
CY2020	us-gaap	Deferred Policy Acquisition Cost Amortization Expense DeferredPolicyAcquisitionCostAmortizationExpense	1410000000	USD
CY2020	cna	Costs From Contract With Customers CostsFromContractWithCustomers	1159000000	USD
CY2020	cna	Other Insurance Related Expenses OtherInsuranceRelatedExpenses	1028000000	USD
CY2020	us-gaap	Other Expenses OtherExpenses	220000000	USD
CY2020	us-gaap	Benefits Losses And Expenses BenefitsLossesAndExpenses	9987000000	USD
CY2020	cna	Operating Income Loss From Continuing Operations Before Income Tax OperatingIncomeLossFromContinuingOperationsBeforeIncomeTax	875000000	USD
CY2020	cna	Income Tax Expense Benefit On Operating Income Loss IncomeTaxExpenseBenefitOnOperatingIncomeLoss	140000000	USD
CY2020	cna	Net Operating Income Loss From Continuing Operations Attributableto Parent NetOperatingIncomeLossFromContinuingOperationsAttributabletoParent	735000000	USD
CY2020	us-gaap	Debt Securities Realized Gain Loss DebtSecuritiesRealizedGainLoss	-54000000	USD
CY2020	cna	Income Tax Expense Benefit On Net Realized Investment Gains Losses IncomeTaxExpenseBenefitOnNetRealizedInvestmentGainsLosses	-9000000	USD
CY2020	cna	Net Realized Investment Gains Losses NetRealizedInvestmentGainsLosses	-45000000	USD
CY2020	us-gaap	Income Loss From Continuing Operations IncomeLossFromContinuingOperations	690000000	USD
CY2020Q4	us-gaap	Premiums Receivable Gross PremiumsReceivableGross	2640000000	USD
CY2020Q4	us-gaap	Deferred Policy Acquisition Costs DeferredPolicyAcquisitionCosts	708000000	USD
CY2020Q4	us-gaap	Goodwill Goodwill	148000000	USD
CY2020Q4	us-gaap	Contract With Customer Asset Net ContractWithCustomerAssetNet	3068000000	USD
CY2020Q4	us-gaap	Liability For Claims And Claims Adjustment Expense LiabilityForClaimsAndClaimsAdjustmentExpense	22706000000	USD
CY2020Q4	us-gaap	Unearned Premiums UnearnedPremiums	5119000000	USD
CY2020Q4	us-gaap	Liability For Future Policy Benefits LiabilityForFuturePolicyBenefits	13318000000	USD
CY2020Q4	us-gaap	Contract With Customer Liability ContractWithCustomerLiability	4023000000	USD
CY2019	us-gaap	Premiums Written Net PremiumsWrittenNet	7656000000	USD
CY2019	us-gaap	Premiums Earned Net PremiumsEarnedNet	7428000000	USD
CY2019	cna	Net Investment Income And Gains Losses On Trading Securities NetInvestmentIncomeAndGainsLossesOnTradingSecurities	2118000000	USD
CY2019	us-gaap	Revenue From Contract With Customer Excluding Assessed Tax RevenueFromContractWithCustomerExcludingAssessedTax	1161000000	USD
CY2019	us-gaap	Other Income OtherIncome	31000000	USD
CY2019	cna	Operating Revenues OperatingRevenues	10738000000	USD
CY2019	us-gaap	Policyholder Benefits And Claims Incurred Net PolicyholderBenefitsAndClaimsIncurredNet	5783000000	USD
CY2019	us-gaap	Policyholder Dividends PolicyholderDividends	23000000	USD
CY2019	us-gaap	Deferred Policy Acquisition Cost Amortization Expense DeferredPolicyAcquisitionCostAmortizationExpense	1383000000	USD
CY2019	cna	Costs From Contract With Customers CostsFromContractWithCustomers	1082000000	USD
CY2019	cna	Other Insurance Related Expenses OtherInsuranceRelatedExpenses	1038000000	USD
CY2019	us-gaap	Other Expenses OtherExpenses	235000000	USD
CY2019	us-gaap	Benefits Losses And Expenses BenefitsLossesAndExpenses	9544000000	USD
CY2019	cna	Operating Income Loss From Continuing Operations Before Income Tax OperatingIncomeLossFromContinuingOperationsBeforeIncomeTax	1194000000	USD
CY2019	cna	Income Tax Expense Benefit On Operating Income Loss IncomeTaxExpenseBenefitOnOperatingIncomeLoss	215000000	USD
CY2019	cna	Net Operating Income Loss From Continuing Operations Attributableto Parent NetOperatingIncomeLossFromContinuingOperationsAttributabletoParent	979000000	USD
CY2019	us-gaap	Debt Securities Realized Gain Loss DebtSecuritiesRealizedGainLoss	29000000	USD
CY2019	cna	Income Tax Expense Benefit On Net Realized Investment Gains Losses IncomeTaxExpenseBenefitOnNetRealizedInvestmentGainsLosses	8000000	USD
CY2019	cna	Net Realized Investment Gains Losses NetRealizedInvestmentGainsLosses	21000000	USD
CY2019	us-gaap	Income Loss From Continuing Operations IncomeLossFromContinuingOperations	1000000000	USD
CY2021	cna	Revenues Excluding Investments And Derivatives Realized Gain Loss RevenuesExcludingInvestmentsAndDerivativesRealizedGainLoss	11788000000	USD
CY2020	cna	Revenues Excluding Investments And Derivatives Realized Gain Loss RevenuesExcludingInvestmentsAndDerivativesRealizedGainLoss	10862000000	USD
CY2019	cna	Revenues Excluding Investments And Derivatives Realized Gain Loss RevenuesExcludingInvestmentsAndDerivativesRealizedGainLoss	10738000000	USD
CY2021	cna	Investmentsand Derivatives Realized Gain Loss InvestmentsandDerivativesRealizedGainLoss	120000000	USD
CY2020	cna	Investmentsand Derivatives Realized Gain Loss InvestmentsandDerivativesRealizedGainLoss	-54000000	USD
CY2019	cna	Investmentsand Derivatives Realized Gain Loss InvestmentsandDerivativesRealizedGainLoss	29000000	USD
CY2021	us-gaap	Revenues Revenues	11908000000	USD
CY2020	us-gaap	Revenues Revenues	10808000000	USD
CY2019	us-gaap	Revenues Revenues	10767000000	USD
CY2021Q4	us-gaap	Contract With Customer Liability ContractWithCustomerLiability	4500000000	USD
CY2020Q4	us-gaap	Contract With Customer Liability ContractWithCustomerLiability	4000000000	USD
CY2021	us-gaap	Contract With Customer Liability Revenue Recognized ContractWithCustomerLiabilityRevenueRecognized	1200000000	USD
CY2020	us-gaap	Contract With Customer Liability Revenue Recognized ContractWithCustomerLiabilityRevenueRecognized	1100000000	USD
CY2021Q4	us-gaap	Revenue Remaining Performance Obligation RevenueRemainingPerformanceObligation	1300000000	USD
CY2021Q4	us-gaap	Common Stock Shares Outstanding CommonStockSharesOutstanding	271363999	shares
CY2021Q4	us-gaap	Revenue Remaining Performance Obligation RevenueRemainingPerformanceObligation	1000000000	USD
CY2021Q4	us-gaap	Revenue Remaining Performance Obligation RevenueRemainingPerformanceObligation	800000000	USD
CY2021Q4	us-gaap	Revenue Remaining Performance Obligation RevenueRemainingPerformanceObligation	1300000000	USD
CY2021	us-gaap	Amortization Of Deferred Sales Commissions AmortizationOfDeferredSalesCommissions	1100000000	USD
CY2020	us-gaap	Amortization Of Deferred Sales Commissions AmortizationOfDeferredSalesCommissions	900000000	USD
CY2021	dei	Auditor Name AuditorName	DELOITTE & TOUCHE LLP
CY2021	dei	Auditor Location AuditorLocation	Chicago, Illinois
CY2021	dei	Auditor Firm AuditorFirmId	34
CY2020Q4	us-gaap	Common Stock Par Or Stated Value Per Share CommonStockParOrStatedValuePerShare	2.50
CY2021Q4	us-gaap	Common Stock Par Or Stated Value Per Share CommonStockParOrStatedValuePerShare	2.50
CY2021Q4	us-gaap	Common Stock Shares Authorized CommonStockSharesAuthorized	500000000	shares
CY2020Q4	us-gaap	Common Stock Shares Authorized CommonStockSharesAuthorized	500000000	shares
CY2020Q4	us-gaap	Common Stock Shares Issued CommonStockSharesIssued	273040243	shares
CY2021Q4	us-gaap	Common Stock Shares Issued CommonStockSharesIssued	273040243	shares
CY2020Q4	us-gaap	Common Stock Shares Outstanding CommonStockSharesOutstanding	271391603	shares
CY2021Q4	us-gaap	Treasury Stock Shares TreasuryStockShares	1676244	shares
CY2020Q4	us-gaap	Treasury Stock Shares TreasuryStockShares	1648640	shares
CY2021	us-gaap	Supplemental Information For Property Casualty Insurance Underwriters Current Year Claims And Claims Adjustment Expense SupplementalInformationForPropertyCasualtyInsuranceUnderwritersCurrentYearClaimsAndClaimsAdjustmentExpense	5970000000	USD
CY2021	us-gaap	Supplemental Information For Property Casualty Insurance Underwriters Prior Year Claims And Claims Adjustment Expense SupplementalInformationForPropertyCasualtyInsuranceUnderwritersPriorYearClaimsAndClaimsAdjustmentExpense	-104000000	USD

Files In Submission

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$CNA
CNA FINANCIAL CORP Stock $cna

2021 Q4 Form 10-K Financial Statement

#000002117522000016 Filed on February 08, 2022

Income Statement

Balance Sheet

Cashflow Statement

Facts In Submission

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$CNA CNA FINANCIAL CORP Stock $cna

2021 Q4 Form 10-K Financial Statement

#000002117522000016 Filed on February 08, 2022

Income Statement

Balance Sheet

Cashflow Statement

Facts In Submission

Files In Submission

$CNA
CNA FINANCIAL CORP Stock $cna