$CNA
CNA FINANCIAL CORP Stock $cna

$cna Overview Financials Valuation SEC Filings Company Website

2020 Q4 Form 10-K Financial Statement

#000002117521000022 Filed on February 09, 2021

Income Statement

Concept	2020 Q4	2019 Q4	2019 Q3
Revenue	$2.931B	$2.777B	$2.685B
YoY Change	5.55%	15.56%	2.4%
Cost Of Revenue			$1.607B
YoY Change			23.05%
Gross Profit			$1.078B
YoY Change			-18.09%
Gross Profit Margin			40.15%
Selling, General & Admin
YoY Change
% of Gross Profit
Research & Development
YoY Change
% of Gross Profit
Depreciation & Amortization	$14.00M	$16.00M	$345.0M
YoY Change	-12.5%	-20.0%	2.37%
% of Gross Profit			32.0%
Operating Expenses	$2.425B	$2.411B	$2.526B
YoY Change	0.58%	-2.9%	15.55%
Operating Profit			-$1.448B
YoY Change			66.44%
Interest Expense	-$28.00M	-$31.00M	$32.00M
YoY Change	-9.68%	-8.82%	-5.88%
% of Operating Profit
Other Income/Expense, Net			$64.00M
YoY Change			-8.57%
Pretax Income	$478.0M	$335.0M	$127.0M
YoY Change	42.69%	-393.86%	-68.41%
Income Tax	$91.00M	$62.00M	$20.00M
% Of Pretax Income	19.04%	18.51%	15.75%
Net Earnings	$387.0M	$273.0M	$107.0M
YoY Change	41.76%	-425.0%	-68.15%
Net Earnings / Revenue	13.2%	9.83%	3.99%
Basic Earnings Per Share	$1.42	$1.00	$0.39
Diluted Earnings Per Share	$1.42	$1.00	$0.39
COMMON SHARES
Basic Shares Outstanding	271.4M shares	271.5M shares	271.6M shares
Diluted Shares Outstanding			272.6M shares

Balance Sheet

Concept	2020 Q4	2019 Q4	2019 Q3
SHORT-TERM ASSETS
Cash & Short-Term Investments
YoY Change
Cash & Equivalents	$419.0M	$242.0M	$340.0M
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	$252.0M	$282.0M	$293.0M
YoY Change	-10.64%	-12.96%	-11.75%
Goodwill	$148.0M	$147.0M	$145.0M
YoY Change	0.68%	0.68%	-1.36%
Intangibles
YoY Change
Long-Term Investments	$50.29B	$47.74B	$47.54B
YoY Change	5.34%	7.32%	5.8%
Other Assets	$66.00M	$199.0M	$190.0M
YoY Change	-66.83%	-49.23%	-39.49%
Total Long-Term Assets
YoY Change
TOTAL ASSETS
Total Short-Term Assets
Total Long-Term Assets
Total Assets	$64.03B	$60.61B	$60.45B
YoY Change	5.63%	6.05%	5.57%
SHORT-TERM LIABILITIES
YoY Change
Accounts Payable
YoY Change
Accrued Expenses	$279.0M	$301.0M	$304.0M
YoY Change	-7.31%
Deferred Revenue
YoY Change
Short-Term Debt	$0.00	$0.00	$0.00
YoY Change
Long-Term Debt Due
YoY Change
Total Short-Term Liabilities	$279.0M	$301.0M	$304.0M
YoY Change	-7.31%
LONG-TERM LIABILITIES
Long-Term Debt	$2.776B	$2.679B	$2.678B
YoY Change	3.62%	-0.04%	-0.07%
Other Long-Term Liabilities	$7.121B	$6.803B	$6.836B
YoY Change	4.67%	4.81%	4.03%
Total Long-Term Liabilities	$2.776B	$2.679B	$2.678B
YoY Change	3.62%	-0.04%	-0.07%
TOTAL LIABILITIES
Total Short-Term Liabilities	$279.0M	$301.0M	$304.0M
Total Long-Term Liabilities	$2.776B	$2.679B	$2.678B
Total Liabilities	$51.32B	$48.40B	$48.33B
YoY Change	6.04%	5.36%	5.64%
SHAREHOLDERS EQUITY
Retained Earnings	$9.081B	$9.348B	$9.171B
YoY Change	-2.86%	0.77%	-3.01%
Common Stock	$2.894B	$2.886B	$2.880B
YoY Change	0.28%	0.38%	0.38%
Preferred Stock
YoY Change
Treasury Stock (at cost)	$71.00M	$70.00M	$67.00M
YoY Change	1.43%	22.81%	15.52%
Treasury Stock Shares	1.649M shares	1.628M shares	1.562M shares
Shareholders Equity	$12.71B	$12.22B	$12.12B
YoY Change
Total Liabilities & Shareholders Equity	$64.03B	$60.61B	$60.45B
YoY Change	5.63%	6.05%	5.57%

Cashflow Statement

Concept	2020 Q4	2019 Q4	2019 Q3
OPERATING ACTIVITIES
Net Income	$387.0M	$273.0M	$107.0M
YoY Change	41.76%	-425.0%	-68.15%
Depreciation, Depletion And Amortization	$14.00M	$16.00M	$345.0M
YoY Change	-12.5%	-20.0%	2.37%
Cash From Operating Activities	$367.0M	$160.0M	$466.0M
YoY Change	129.38%	-55.43%	-9.34%
INVESTING ACTIVITIES
Capital Expenditures	-$7.000M	-$6.000M	-$6.000M
YoY Change	16.67%	-50.0%	-45.45%
Acquisitions
YoY Change
Other Investing Activities	-$291.0M	-$159.0M	-$287.0M
YoY Change	83.02%	-35.1%	-17.53%
Cash From Investing Activities	-$298.0M	-$165.0M	-$293.0M
YoY Change	80.61%	-35.8%	-18.38%
FINANCING ACTIVITIES
Cash Dividend Paid
YoY Change
Common Stock Issuance & Retirement, Net
YoY Change
Debt Paid & Issued, Net
YoY Change
Cash From Financing Activities	-101.0M	-101.0M	-99.00M
YoY Change	0.0%	5.21%	-26.12%
NET CHANGE
Cash From Operating Activities	367.0M	160.0M	466.0M
Cash From Investing Activities	-298.0M	-165.0M	-293.0M
Cash From Financing Activities	-101.0M	-101.0M	-99.00M
Net Change In Cash	-32.00M	-106.0M	74.00M
YoY Change	-69.81%	-1866.67%	252.38%
FREE CASH FLOW
Cash From Operating Activities	$367.0M	$160.0M	$466.0M
Capital Expenditures	-$7.000M	-$6.000M	-$6.000M
Free Cash Flow	$374.0M	$166.0M	$472.0M
YoY Change	125.3%	-55.26%	-10.1%

Facts In Submission

Frame	Concept Type	Concept / XBRL Key	Value	Unit
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CY2020	dei	Entity Central Index Key EntityCentralIndexKey	0000021175
CY2020	dei	Document Fiscal Year Focus DocumentFiscalYearFocus	2020
CY2020	dei	Document Fiscal Period Focus DocumentFiscalPeriodFocus	FY
CY2020	dei	Amendment Flag AmendmentFlag	false
CY2019Q4	us-gaap	Operating Lease Right Of Use Asset Statement Of Financial Position Extensible List OperatingLeaseRightOfUseAssetStatementOfFinancialPositionExtensibleList	us-gaap:OtherAssets
CY2020Q4	us-gaap	Operating Lease Right Of Use Asset Statement Of Financial Position Extensible List OperatingLeaseRightOfUseAssetStatementOfFinancialPositionExtensibleList	us-gaap:OtherAssets
CY2019Q4	us-gaap	Operating Lease Liability Statement Of Financial Position Extensible List OperatingLeaseLiabilityStatementOfFinancialPositionExtensibleList	us-gaap:OtherLiabilities
CY2020Q4	us-gaap	Operating Lease Liability Statement Of Financial Position Extensible List OperatingLeaseLiabilityStatementOfFinancialPositionExtensibleList	us-gaap:OtherLiabilities
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CY2020Q4	us-gaap	Revenue Remaining Performance Obligation Expected Timing Of Satisfaction Period1 RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionPeriod1	P1Y
CY2020Q4	us-gaap	Revenue Remaining Performance Obligation Expected Timing Of Satisfaction Period1 RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionPeriod1	P1Y
CY2020Q4	us-gaap	Revenue Remaining Performance Obligation Expected Timing Of Satisfaction Period1 RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionPeriod1
CY2020	dei	Document Type DocumentType	10-K
CY2020	dei	Document Annual Report DocumentAnnualReport	true
CY2020	dei	Document Period End Date DocumentPeriodEndDate	2020-12-31
CY2020	dei	Current Fiscal Year End Date CurrentFiscalYearEndDate	--12-31
CY2020	dei	Document Transition Report DocumentTransitionReport	false
CY2020	dei	Entity File Number EntityFileNumber	1-5823
CY2020	dei	Entity Registrant Name EntityRegistrantName	CNA FINANCIAL CORPORATION
CY2020	dei	Entity Incorporation State Country Code EntityIncorporationStateCountryCode	DE
CY2020	dei	Entity Tax Identification Number EntityTaxIdentificationNumber	36-6169860
CY2020	dei	Entity Address Address Line1 EntityAddressAddressLine1	151 N. Franklin
CY2020	dei	Entity Address Postal Zip Code EntityAddressPostalZipCode	60606
CY2020	dei	Entity Address City Or Town EntityAddressCityOrTown	Chicago,
CY2020	dei	Entity Address State Or Province EntityAddressStateOrProvince	IL
CY2020	dei	City Area Code CityAreaCode	312
CY2020	dei	Local Phone Number LocalPhoneNumber	822-5000
CY2020	dei	Security12b Title Security12bTitle	Common Stock, Par value $2.50
CY2020	dei	Trading Symbol TradingSymbol	"CNA"
CY2020	dei	Entity Well Known Seasoned Issuer EntityWellKnownSeasonedIssuer	Yes
CY2020	dei	Entity Voluntary Filers EntityVoluntaryFilers	No
CY2020	dei	Entity Current Reporting Status EntityCurrentReportingStatus	Yes
CY2020	dei	Entity Interactive Data Current EntityInteractiveDataCurrent	Yes
CY2020	dei	Entity Filer Category EntityFilerCategory	Large Accelerated Filer
CY2020	dei	Entity Small Business EntitySmallBusiness	false
CY2020	dei	Entity Emerging Growth Company EntityEmergingGrowthCompany	false
CY2020	dei	Icfr Auditor Attestation Flag IcfrAuditorAttestationFlag	true
CY2020	dei	Entity Shell Company EntityShellCompany	false
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CY2020Q2	dei	Entity Public Float EntityPublicFloat	889000000	USD
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CY2020Q4	us-gaap	Due To Related Parties Current And Noncurrent DueToRelatedPartiesCurrentAndNoncurrent	89000000	USD
CY2019Q4	us-gaap	Due To Related Parties Current And Noncurrent DueToRelatedPartiesCurrentAndNoncurrent	21000000	USD
CY2020Q4	us-gaap	Other Liabilities OtherLiabilities	3377000000	USD
CY2019Q4	us-gaap	Other Liabilities OtherLiabilities	3325000000	USD
CY2020Q4	us-gaap	Liabilities Liabilities	51319000000	USD
CY2019Q4	us-gaap	Liabilities Liabilities	48397000000	USD
CY2019Q4	us-gaap	Commitments And Contingencies CommitmentsAndContingencies		USD
CY2019Q4	us-gaap	Common Stock Par Or Stated Value Per Share CommonStockParOrStatedValuePerShare	2.50
CY2020Q4	us-gaap	Common Stock Par Or Stated Value Per Share CommonStockParOrStatedValuePerShare	2.50
CY2019Q4	us-gaap	Common Stock Shares Authorized CommonStockSharesAuthorized	500000000	shares
CY2020Q4	us-gaap	Common Stock Shares Authorized CommonStockSharesAuthorized	500000000	shares
CY2019Q4	us-gaap	Common Stock Shares Issued CommonStockSharesIssued	273040243	shares
CY2020Q4	us-gaap	Common Stock Shares Issued CommonStockSharesIssued	273040243	shares
CY2020Q4	us-gaap	Common Stock Shares Outstanding CommonStockSharesOutstanding	271391603	shares
CY2019Q4	us-gaap	Common Stock Shares Outstanding CommonStockSharesOutstanding	271412591	shares
CY2020Q4	us-gaap	Common Stock Value CommonStockValue	683000000	USD
CY2019Q4	us-gaap	Common Stock Value CommonStockValue	683000000	USD
CY2020Q4	us-gaap	Additional Paid In Capital Common Stock AdditionalPaidInCapitalCommonStock	2211000000	USD
CY2019Q4	us-gaap	Additional Paid In Capital Common Stock AdditionalPaidInCapitalCommonStock	2203000000	USD
CY2020Q4	us-gaap	Retained Earnings Accumulated Deficit RetainedEarningsAccumulatedDeficit	9081000000	USD
CY2019Q4	us-gaap	Retained Earnings Accumulated Deficit RetainedEarningsAccumulatedDeficit	9348000000	USD
CY2020Q4	us-gaap	Accumulated Other Comprehensive Income Loss Net Of Tax AccumulatedOtherComprehensiveIncomeLossNetOfTax	803000000	USD
CY2019Q4	us-gaap	Accumulated Other Comprehensive Income Loss Net Of Tax AccumulatedOtherComprehensiveIncomeLossNetOfTax	51000000	USD
CY2020Q4	us-gaap	Treasury Stock Shares TreasuryStockShares	1648640	shares
CY2019Q4	us-gaap	Treasury Stock Shares TreasuryStockShares	1627652	shares
CY2020Q4	us-gaap	Treasury Stock Value TreasuryStockValue	71000000	USD
CY2019Q4	us-gaap	Treasury Stock Value TreasuryStockValue	70000000	USD
CY2020Q4	us-gaap	Stockholders Equity StockholdersEquity	12707000000	USD
CY2019Q4	us-gaap	Stockholders Equity StockholdersEquity	12215000000	USD
CY2020Q4	us-gaap	Liabilities And Stockholders Equity LiabilitiesAndStockholdersEquity	64026000000	USD
CY2019Q4	us-gaap	Liabilities And Stockholders Equity LiabilitiesAndStockholdersEquity	60612000000	USD
CY2020	us-gaap	Net Income Loss NetIncomeLoss	690000000	USD
CY2019	us-gaap	Net Income Loss NetIncomeLoss	1000000000	USD
CY2018	us-gaap	Net Income Loss NetIncomeLoss	813000000	USD
CY2020	us-gaap	Deferred Income Tax Expense Benefit DeferredIncomeTaxExpenseBenefit	-49000000	USD
CY2019	us-gaap	Deferred Income Tax Expense Benefit DeferredIncomeTaxExpenseBenefit	-46000000	USD
CY2018	us-gaap	Deferred Income Tax Expense Benefit DeferredIncomeTaxExpenseBenefit	-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
CY2018	us-gaap	Increase Decrease In Financial Instruments Used In Operating Activities IncreaseDecreaseInFinancialInstrumentsUsedInOperatingActivities	0	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
CY2018	cna	Net Realized Investment Gains Losses Continuing And Discontinuing Operations NetRealizedInvestmentGainsLossesContinuingAndDiscontinuingOperations	-52000000	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
CY2018	us-gaap	Income Loss From Equity Method Investments Net Of Dividends Or Distributions IncomeLossFromEquityMethodInvestmentsNetOfDividendsOrDistributions	-330000000	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
CY2018	us-gaap	Accretion Amortization Of Discounts And Premiums Investments AccretionAmortizationOfDiscountsAndPremiumsInvestments	70000000	USD
CY2020	us-gaap	Depreciation Depletion And Amortization DepreciationDepletionAndAmortization	60000000	USD
CY2019	us-gaap	Depreciation Depletion And Amortization DepreciationDepletionAndAmortization	68000000	USD
CY2018	us-gaap	Depreciation Depletion And Amortization DepreciationDepletionAndAmortization	79000000	USD
CY2020	us-gaap	Increase Decrease In Other Receivables IncreaseDecreaseInOtherReceivables	409000000	USD
CY2019	us-gaap	Increase Decrease In Other Receivables IncreaseDecreaseInOtherReceivables	-137000000	USD
CY2018	us-gaap	Increase Decrease In Other Receivables IncreaseDecreaseInOtherReceivables	229000000	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
CY2018	us-gaap	Increase Decrease In Accrued Investment Income Receivable IncreaseDecreaseInAccruedInvestmentIncomeReceivable	-19000000	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
CY2018	us-gaap	Increase Decrease In Deferred Policy Acquisition Costs IncreaseDecreaseInDeferredPolicyAcquisitionCosts	6000000	USD
CY2020	us-gaap	Increase Decrease In Insurance Liabilities IncreaseDecreaseInInsuranceLiabilities	1681000000	USD
CY2019	us-gaap	Increase Decrease In Insurance Liabilities IncreaseDecreaseInInsuranceLiabilities	358000000	USD
CY2018	us-gaap	Increase Decrease In Insurance Liabilities IncreaseDecreaseInInsuranceLiabilities	482000000	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
CY2018	us-gaap	Other Operating Activities Cash Flow Statement OtherOperatingActivitiesCashFlowStatement	-223000000	USD
CY2020	us-gaap	Net Cash Provided By Used In Operating Activities NetCashProvidedByUsedInOperatingActivities	1775000000	USD
CY2019	us-gaap	Net Cash Provided By Used In Operating Activities NetCashProvidedByUsedInOperatingActivities	1140000000	USD
CY2018	us-gaap	Net Cash Provided By Used In Operating Activities NetCashProvidedByUsedInOperatingActivities	1227000000	USD
CY2020	us-gaap	Proceeds From Sale Of Available For Sale Securities Debt ProceedsFromSaleOfAvailableForSaleSecuritiesDebt	5904000000	USD
CY2019	us-gaap	Proceeds From Sale Of Available For Sale Securities Debt ProceedsFromSaleOfAvailableForSaleSecuritiesDebt	5842000000	USD
CY2018	us-gaap	Proceeds From Sale Of Available For Sale Securities Debt ProceedsFromSaleOfAvailableForSaleSecuritiesDebt	8408000000	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
CY2018	us-gaap	Proceeds From Maturities Prepayments And Calls Of Available For Sale Securities ProceedsFromMaturitiesPrepaymentsAndCallsOfAvailableForSaleSecurities	2370000000	USD
CY2020	cna	Proceedsfrom Saleof Marketable Securities Equity ProceedsfromSaleofMarketableSecuritiesEquity	355000000	USD
CY2019	cna	Proceedsfrom Saleof Marketable Securities Equity ProceedsfromSaleofMarketableSecuritiesEquity	214000000	USD
CY2018	cna	Proceedsfrom Saleof Marketable Securities Equity ProceedsfromSaleofMarketableSecuritiesEquity	89000000	USD
CY2020	us-gaap	Proceeds From Limited Partnership Investments ProceedsFromLimitedPartnershipInvestments	373000000	USD
CY2019	us-gaap	Proceeds From Limited Partnership Investments ProceedsFromLimitedPartnershipInvestments	479000000	USD
CY2018	us-gaap	Proceeds From Limited Partnership Investments ProceedsFromLimitedPartnershipInvestments	343000000	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
CY2018	us-gaap	Proceeds From Sale And Collection Of Mortgage Notes Receivable ProceedsFromSaleAndCollectionOfMortgageNotesReceivable	128000000	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
CY2018	us-gaap	Payments To Acquire Available For Sale Securities Debt PaymentsToAcquireAvailableForSaleSecuritiesDebt	10785000000	USD
CY2020	cna	Paymentsto Acquire Marketable Securities Equity PaymentstoAcquireMarketableSecuritiesEquity	452000000	USD
CY2019	cna	Paymentsto Acquire Marketable Securities Equity PaymentstoAcquireMarketableSecuritiesEquity	186000000	USD
CY2018	cna	Paymentsto Acquire Marketable Securities Equity PaymentstoAcquireMarketableSecuritiesEquity	258000000	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
CY2018	us-gaap	Payments To Acquire Limited Partnership Interests PaymentsToAcquireLimitedPartnershipInterests	419000000	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
CY2018	us-gaap	Payments To Acquire Mortgage Notes Receivable PaymentsToAcquireMortgageNotesReceivable	128000000	USD
CY2020	cna	Change In Other Investments ChangeInOtherInvestments	-8000000	USD
CY2019	cna	Change In Other Investments ChangeInOtherInvestments	-11000000	USD
CY2018	cna	Change In Other Investments ChangeInOtherInvestments	-12000000	USD
CY2020	cna	Change In Short Term Investments ChangeInShortTermInvestments	-39000000	USD
CY2019	cna	Change In Short Term Investments ChangeInShortTermInvestments	-535000000	USD
CY2018	cna	Change In Short Term Investments ChangeInShortTermInvestments	168000000	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
CY2018	us-gaap	Payments To Acquire Property Plant And Equipment PaymentsToAcquirePropertyPlantAndEquipment	99000000	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
CY2018	us-gaap	Payments For Proceeds From Other Investing Activities PaymentsForProceedsFromOtherInvestingActivities	-18000000	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
CY2018	us-gaap	Net Cash Provided By Used In Investing Activities NetCashProvidedByUsedInInvestingActivities	-177000000	USD
CY2020	us-gaap	Payments Of Dividends Common Stock PaymentsOfDividendsCommonStock	950000000	USD
CY2019	us-gaap	Payments Of Dividends Common Stock PaymentsOfDividendsCommonStock	929000000	USD
CY2018	us-gaap	Payments Of Dividends Common Stock PaymentsOfDividendsCommonStock	896000000	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
CY2018	us-gaap	Proceeds From Issuance Of Long Term Debt ProceedsFromIssuanceOfLongTermDebt	0	USD
CY2020	us-gaap	Repayments Of Long Term Debt RepaymentsOfLongTermDebt	419000000	USD
CY2019	us-gaap	Repayments Of Long Term Debt RepaymentsOfLongTermDebt	520000000	USD
CY2018	us-gaap	Repayments Of Long Term Debt RepaymentsOfLongTermDebt	180000000	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
CY2018	us-gaap	Payments For Repurchase Of Common Stock PaymentsForRepurchaseOfCommonStock	0	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
CY2018	us-gaap	Proceeds From Payments For Other Financing Activities ProceedsFromPaymentsForOtherFinancingActivities	-9000000	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
CY2018	us-gaap	Net Cash Provided By Used In Financing Activities NetCashProvidedByUsedInFinancingActivities	-1085000000	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
CY2018	us-gaap	Effect Of Exchange Rate On Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents EffectOfExchangeRateOnCashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	-10000000	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
CY2018	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents Period Increase Decrease Including Exchange Rate Effect CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect	-45000000	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
CY2017Q4	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	355000000	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
CY2020	us-gaap	Common Stock Dividends Per Share Declared CommonStockDividendsPerShareDeclared	3.48
CY2019	us-gaap	Common Stock Dividends Per Share Declared CommonStockDividendsPerShareDeclared	3.40
CY2018	us-gaap	Common Stock Dividends Per Share Declared CommonStockDividendsPerShareDeclared	3.30
CY2020Q4	us-gaap	Stockholders Equity StockholdersEquity	12707000000	USD
CY2019Q4	us-gaap	Stockholders Equity StockholdersEquity	12215000000	USD
CY2018Q4	us-gaap	Stockholders Equity StockholdersEquity	11217000000	USD
CY2020	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.
CY2019Q4	cna	Anticipated Amounts Due From Insureds Related To Losses Under Deductible Policies AnticipatedAmountsDueFromInsuredsRelatedToLossesUnderDeductiblePolicies	1200000000	USD
CY2020Q4	cna	Anticipated Amounts Due From Insureds Related To Losses Under Deductible Policies AnticipatedAmountsDueFromInsuredsRelatedToLossesUnderDeductiblePolicies	1200000000	USD
CY2020	cna	Structured Settlement Annuities Interest Rates Low End StructuredSettlementAnnuitiesInterestRatesLowEnd	0.065
CY2019	cna	Longterm Care Claim Reserves Weighted Average Discounted Interest Rate LongtermCareClaimReservesWeightedAverageDiscountedInterestRate	0.059
CY2019	cna	Structured Settlement Annuities Interest Rates High End StructuredSettlementAnnuitiesInterestRatesHighEnd	0.071
CY2020Q4	cna	Discounted Reserves For Unfunded Structured Settlements DiscountedReservesForUnfundedStructuredSettlements	520000000	USD
CY2019Q4	cna	Discounted Reserves For Unfunded Structured Settlements DiscountedReservesForUnfundedStructuredSettlements	497000000	USD
CY2020Q4	cna	Discounted Reserves For Unfunded Structure Settlements Discount Amount DiscountedReservesForUnfundedStructureSettlementsDiscountAmount	657000000	USD
CY2019Q4	cna	Discounted Reserves For Unfunded Structure Settlements Discount Amount DiscountedReservesForUnfundedStructureSettlementsDiscountAmount	724000000	USD
CY2020Q4	cna	Amountofinterestrecognizedonthediscountedreservesofunfundedstructuredsettlements Amountofinterestrecognizedonthediscountedreservesofunfundedstructuredsettlements	35000000	USD
CY2019Q4	cna	Amountofinterestrecognizedonthediscountedreservesofunfundedstructuredsettlements Amountofinterestrecognizedonthediscountedreservesofunfundedstructuredsettlements	36000000	USD
CY2018Q4	cna	Amountofinterestrecognizedonthediscountedreservesofunfundedstructuredsettlements Amountofinterestrecognizedonthediscountedreservesofunfundedstructuredsettlements	40000000	USD
CY2019	us-gaap	Workers Compensation Discount Percent WorkersCompensationDiscountPercent	0.035
CY2020	us-gaap	Workers Compensation Discount Percent WorkersCompensationDiscountPercent	0.035
CY2020Q4	us-gaap	Workers Compensation Liability Current And Noncurrent WorkersCompensationLiabilityCurrentAndNoncurrent	258000000	USD
CY2019Q4	us-gaap	Workers Compensation Liability Current And Noncurrent WorkersCompensationLiabilityCurrentAndNoncurrent	293000000	USD
CY2020Q4	us-gaap	Workers Compensation Discount Amount WorkersCompensationDiscountAmount	113000000	USD
CY2019Q4	us-gaap	Workers Compensation Discount Amount WorkersCompensationDiscountAmount	135000000	USD
CY2020Q4	cna	Amountofinterestaccretionrecognizedonthediscountedreservesofworkerscompensationlifetimeclaimreserves Amountofinterestaccretionrecognizedonthediscountedreservesofworkerscompensationlifetimeclaimreserves	15000000	USD
CY2019Q4	cna	Amountofinterestaccretionrecognizedonthediscountedreservesofworkerscompensationlifetimeclaimreserves Amountofinterestaccretionrecognizedonthediscountedreservesofworkerscompensationlifetimeclaimreserves	21000000	USD
CY2018Q4	cna	Amountofinterestaccretionrecognizedonthediscountedreservesofworkerscompensationlifetimeclaimreserves Amountofinterestaccretionrecognizedonthediscountedreservesofworkerscompensationlifetimeclaimreserves	16000000	USD
CY2020	cna	Longterm Care Claim Reserves Weighted Average Discounted Interest Rate LongtermCareClaimReservesWeightedAverageDiscountedInterestRate	0.058
CY2020Q4	cna	Discountedreservesforlongtermcareclaimreserves Discountedreservesforlongtermcareclaimreserves	2700000000	USD
CY2019Q4	cna	Discountedreservesforlongtermcareclaimreserves Discountedreservesforlongtermcareclaimreserves	2700000000	USD
CY2020Q4	cna	Discountedreservesforlongtermcareclaimreservesdiscountamount Discountedreservesforlongtermcareclaimreservesdiscountamount	439000000	USD
CY2019Q4	cna	Discountedreservesforlongtermcareclaimreservesdiscountamount Discountedreservesforlongtermcareclaimreservesdiscountamount	462000000	USD
CY2020	us-gaap	Liability For Future Policy Benefits Period Expense LiabilityForFuturePolicyBenefitsPeriodExpense	74000000	USD
CY2020	us-gaap	Liability For Future Policy Benefit By Product Segment Interest Rate Year Of Issue LiabilityForFuturePolicyBenefitByProductSegmentInterestRateYearOfIssue	0.054
CY2019	us-gaap	Liability For Future Policy Benefit By Product Segment Interest Rate Year Of Issue LiabilityForFuturePolicyBenefitByProductSegmentInterestRateYearOfIssue	0.057
CY2020	us-gaap	Loss Contingency Undiscounted Amount Of Insurance Related Assessment Liability LossContingencyUndiscountedAmountOfInsuranceRelatedAssessmentLiability	82000000	USD
CY2019	us-gaap	Loss Contingency Undiscounted Amount Of Insurance Related Assessment Liability LossContingencyUndiscountedAmountOfInsuranceRelatedAssessmentLiability	84000000	USD
CY2020	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
CY2018	us-gaap	Policyholder Dividends Rate On Policy Earnings PolicyholderDividendsRateOnPolicyEarnings	0.01
CY2020	us-gaap	Policyholder Dividends Rate On Policy Earnings PolicyholderDividendsRateOnPolicyEarnings	0.01
CY2020	cna	Increasedecreaseinshadowadjustmentnetoftax Increasedecreaseinshadowadjustmentnetoftax	575000000	USD
CY2019	cna	Increasedecreaseinshadowadjustmentnetoftax Increasedecreaseinshadowadjustmentnetoftax	1120000000	USD
CY2020Q4	cna	Reduction Of Net Unrealized Gains On Investments Included In Aoci Due To Shadow Adjustments ReductionOfNetUnrealizedGainsOnInvestmentsIncludedInAOCIDueToShadowAdjustments	2773000000	USD
CY2019Q4	cna	Reduction Of Net Unrealized Gains On Investments Included In Aoci Due To Shadow Adjustments ReductionOfNetUnrealizedGainsOnInvestmentsIncludedInAOCIDueToShadowAdjustments	2198000000	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
CY2018	us-gaap	Foreign Currency Transaction Gain Loss Before Tax ForeignCurrencyTransactionGainLossBeforeTax	1000000	USD
CY2020	us-gaap	Weighted Average Number Diluted Shares Outstanding Adjustment WeightedAverageNumberDilutedSharesOutstandingAdjustment	772000	shares
CY2019	us-gaap	Weighted Average Number Diluted Shares Outstanding Adjustment WeightedAverageNumberDilutedSharesOutstandingAdjustment	961000	shares
CY2018	us-gaap	Weighted Average Number Diluted Shares Outstanding Adjustment WeightedAverageNumberDilutedSharesOutstandingAdjustment	943000	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
CY2018	us-gaap	Antidilutive Securities Excluded From Computation Of Earnings Per Share Amount AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount	6000	shares
CY2020	us-gaap	Interest Paid Net InterestPaidNet	124000000	USD
CY2019	us-gaap	Interest Paid Net InterestPaidNet	136000000	USD
CY2018	us-gaap	Interest Paid Net InterestPaidNet	145000000	USD
CY2020	us-gaap	Income Taxes Paid IncomeTaxesPaid	108000000	USD
CY2019	us-gaap	Income Taxes Paid IncomeTaxesPaid	255000000	USD
CY2018	us-gaap	Income Taxes Paid IncomeTaxesPaid	308000000	USD
CY2020	us-gaap	Gross Investment Income Operating GrossInvestmentIncomeOperating	1999000000	USD
CY2019	us-gaap	Gross Investment Income Operating GrossInvestmentIncomeOperating	2181000000	USD
CY2018	us-gaap	Gross Investment Income Operating GrossInvestmentIncomeOperating	1878000000	USD
CY2020	us-gaap	Investment Income Investment Expense InvestmentIncomeInvestmentExpense	64000000	USD
CY2019	us-gaap	Investment Income Investment Expense InvestmentIncomeInvestmentExpense	63000000	USD
CY2018	us-gaap	Investment Income Investment Expense InvestmentIncomeInvestmentExpense	61000000	USD
CY2020	us-gaap	Net Investment Income NetInvestmentIncome	1935000000	USD
CY2019	us-gaap	Net Investment Income NetInvestmentIncome	2118000000	USD
CY2018	us-gaap	Net Investment Income NetInvestmentIncome	1817000000	USD
CY2019Q4	cna	Non Income Producing Fixed Maturity Securities NonIncomeProducingFixedMaturitySecurities	1000000	USD
CY2020Q4	cna	Non Income Producing Fixed Maturity Securities NonIncomeProducingFixedMaturitySecurities	1000000	USD
CY2020Q4	cna	Investmentsthat Exceed Ten Percentof Stockholders Equity InvestmentsthatExceedTenPercentofStockholdersEquity	0	USD
CY2019Q4	cna	Investmentsthat Exceed Ten Percentof Stockholders Equity InvestmentsthatExceedTenPercentofStockholdersEquity	0	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
CY2018	us-gaap	Debt Securities Available For Sale Realized Gain DebtSecuritiesAvailableForSaleRealizedGain	168000000	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
CY2018	us-gaap	Debt Securities Available For Sale Realized Loss DebtSecuritiesAvailableForSaleRealizedLoss	164000000	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
CY2018	us-gaap	Debt Securities Available For Sale Realized Gain Loss DebtSecuritiesAvailableForSaleRealizedGainLoss	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
CY2018	us-gaap	Equity Securities Fv Ni Realized Gain Loss EquitySecuritiesFvNiRealizedGainLoss	-74000000	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
CY2018	us-gaap	Gain Loss On Sale Of Derivatives GainLossOnSaleOfDerivatives	9000000	USD
CY2020	us-gaap	Provision For Loan Losses Expensed ProvisionForLoanLossesExpensed	21000000	USD
CY2019	us-gaap	Provision For Loan Losses Expensed ProvisionForLoanLossesExpensed	0	USD
CY2018	us-gaap	Provision For Loan Losses Expensed ProvisionForLoanLossesExpensed	0	USD
CY2020	cna	Realized Gain Losson Short Term Investments RealizedGainLossonShortTermInvestments	-20000000	USD
CY2019	cna	Realized Gain Losson Short Term Investments RealizedGainLossonShortTermInvestments	-20000000	USD
CY2018	cna	Realized Gain Losson Short Term Investments RealizedGainLossonShortTermInvestments	9000000	USD
CY2020	cna	Investmentsand Derivatives Realized Gain Loss InvestmentsandDerivativesRealizedGainLoss	-54000000	USD
CY2019	cna	Investmentsand Derivatives Realized Gain Loss InvestmentsandDerivativesRealizedGainLoss	29000000	USD
CY2018	cna	Investmentsand Derivatives Realized Gain Loss InvestmentsandDerivativesRealizedGainLoss	-52000000	USD
CY2019Q4	us-gaap	Debt Securities Available For Sale Allowance For Credit Loss DebtSecuritiesAvailableForSaleAllowanceForCreditLoss	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 Allowance For Credit Loss DebtSecuritiesAvailableForSaleAllowanceForCreditLoss	40000000	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
CY2018	us-gaap	Other Than Temporary Impairment Loss Debt Securities Portion Recognized In Earnings OtherThanTemporaryImpairmentLossDebtSecuritiesPortionRecognizedInEarnings	21000000	USD
CY2020	us-gaap	Provision For Loan Losses Expensed ProvisionForLoanLossesExpensed	21000000	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 Allowance For Credit Loss DebtSecuritiesAvailableForSaleAllowanceForCreditLoss	40000000	USD
CY2020Q4	us-gaap	Debt Securities DebtSecurities	44631000000	USD
CY2019Q4	cna	Debt Securities Amortized Cost DebtSecuritiesAmortizedCost	38126000000	USD
CY2019Q4	us-gaap	Available For Sale Debt Securities Accumulated Gross Unrealized Gain Before Tax AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedGainBeforeTax	4126000000	USD
CY2019Q4	us-gaap	Available For Sale Debt Securities Accumulated Gross Unrealized Loss Before Tax AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedLossBeforeTax	45000000	USD
CY2019Q4	us-gaap	Debt Securities DebtSecurities	42207000000	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
CY2019Q4	us-gaap	Debt Securities Available For Sale Continuous Unrealized Loss Position Less Than12 Months DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12Months	2148000000	USD
CY2019Q4	us-gaap	Debt Securities Available For Sale Continuous Unrealized Loss Position Less Than12 Months Accumulated Loss DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12MonthsAccumulatedLoss	31000000	USD
CY2019Q4	us-gaap	Debt Securities Available For Sale Continuous Unrealized Loss Position12 Months Or Longer DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLonger	272000000	USD
CY2019Q4	us-gaap	Debt Securities Available For Sale Continuous Unrealized Loss Position12 Months Or Longer Accumulated Loss DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLongerAccumulatedLoss	14000000	USD
CY2019Q4	us-gaap	Debt Securities Available For Sale Unrealized Loss Position DebtSecuritiesAvailableForSaleUnrealizedLossPosition	2420000000	USD
CY2019Q4	us-gaap	Debt Securities Available For Sale Unrealized Loss Position Accumulated Loss DebtSecuritiesAvailableForSaleUnrealizedLossPositionAccumulatedLoss	45000000	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
CY2019Q4	us-gaap	Available For Sale Securities Debt Maturities Within One Year Amortized Cost AvailableForSaleSecuritiesDebtMaturitiesWithinOneYearAmortizedCost	1334000000	USD
CY2019Q4	us-gaap	Available For Sale Securities Debt Maturities Within One Year Fair Value AvailableForSaleSecuritiesDebtMaturitiesWithinOneYearFairValue	1356000000	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
CY2019Q4	us-gaap	Available For Sale Securities Debt Maturities After One Through Five Years Amortized Cost AvailableForSaleSecuritiesDebtMaturitiesAfterOneThroughFiveYearsAmortizedCost	9746000000	USD
CY2019Q4	us-gaap	Available For Sale Securities Debt Maturities After One Through Five Years Fair Value AvailableForSaleSecuritiesDebtMaturitiesAfterOneThroughFiveYearsFairValue	10186000000	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
CY2019Q4	us-gaap	Available For Sale Securities Debt Maturities After Five Through Ten Years Amortized Cost AvailableForSaleSecuritiesDebtMaturitiesAfterFiveThroughTenYearsAmortizedCost	14892000000	USD
CY2019Q4	us-gaap	Available For Sale Securities Debt Maturities After Five Through Ten Years Fair Value AvailableForSaleSecuritiesDebtMaturitiesAfterFiveThroughTenYearsFairValue	15931000000	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
CY2019Q4	us-gaap	Available For Sale Securities Debt Maturities After Ten Years Amortized Cost AvailableForSaleSecuritiesDebtMaturitiesAfterTenYearsAmortizedCost	12134000000	USD
CY2019Q4	us-gaap	Available For Sale Securities Debt Maturities After Ten Years Fair Value AvailableForSaleSecuritiesDebtMaturitiesAfterTenYearsFairValue	14714000000	USD
CY2020Q4	us-gaap	Available For Sale Debt Securities Amortized Cost Basis AvailableForSaleDebtSecuritiesAmortizedCostBasis	38926000000	USD
CY2020Q4	us-gaap	Available For Sale Securities Debt Securities AvailableForSaleSecuritiesDebtSecurities	44604000000	USD
CY2019Q4	us-gaap	Available For Sale Debt Securities Amortized Cost Basis AvailableForSaleDebtSecuritiesAmortizedCostBasis	38106000000	USD
CY2019Q4	us-gaap	Available For Sale Securities Debt Securities AvailableForSaleSecuritiesDebtSecurities	42187000000	USD
CY2020Q4	cna	Limited Partnership Investments LimitedPartnershipInvestments	1619000000	USD
CY2019Q4	cna	Limited Partnership Investments LimitedPartnershipInvestments	1752000000	USD
CY2020Q4	us-gaap	Retained Earnings Undistributed Earnings From Equity Method Investees RetainedEarningsUndistributedEarningsFromEquityMethodInvestees	235000000	USD
CY2019Q4	us-gaap	Retained Earnings Undistributed Earnings From Equity Method Investees RetainedEarningsUndistributedEarningsFromEquityMethodInvestees	229000000	USD
CY2020Q4	cna	Percentage Of Limited Partnerships Reported On Current Basis PercentageOfLimitedPartnershipsReportedOnCurrentBasis	0.49
CY2020Q4	cna	Percentage Of Limited Partnerships Reported On One Month Lag PercentageOfLimitedPartnershipsReportedOnOneMonthLag	0.10
CY2020Q4	cna	Percentage Of Limited Partnerships Employing Hedge Fund Strategies Focused On Fixed Income And Equity Investments PercentageOfLimitedPartnershipsEmployingHedgeFundStrategiesFocusedOnFixedIncomeAndEquityInvestments	0.51
CY2019Q4	cna	Percentage Of Limited Partnerships Employing Hedge Fund Strategies Focused On Fixed Income And Equity Investments PercentageOfLimitedPartnershipsEmployingHedgeFundStrategiesFocusedOnFixedIncomeAndEquityInvestments	0.61
CY2020Q4	cna	Limited Partnerships Invested In Private Debt And Equity LimitedPartnershipsInvestedInPrivateDebtAndEquity	0.40
CY2019Q4	cna	Limited Partnerships Invested In Private Debt And Equity LimitedPartnershipsInvestedInPrivateDebtAndEquity	0.33
CY2020Q4	cna	Percentage Of Equity Related Limited Partnership Hedge Fund Strategies PercentageOfEquityRelatedLimitedPartnershipHedgeFundStrategies	0.55
CY2020Q4	cna	Percentage Of Multistrategy Approach Limited Partnership Hedge Fund Strategies PercentageOfMultistrategyApproachLimitedPartnershipHedgeFundStrategies	0.26
CY2020Q4	cna	Percentage Of Distressed Investments Limited Partnership Hedge Fund Strategies PercentageOfDistressedInvestmentsLimitedPartnershipHedgeFundStrategies	0.14
CY2020Q4	cna	Percentage Of Fixed Income Limited Partnership Hedge Fund Strategies PercentageOfFixedIncomeLimitedPartnershipHedgeFundStrategies	0.05
CY2020Q4	cna	Carrying Value Of Ten Largest Limited Partnerships CarryingValueOfTenLargestLimitedPartnerships	775000000	USD
CY2019Q4	cna	Carrying Value Of Ten Largest Limited Partnerships CarryingValueOfTenLargestLimitedPartnerships	893000000	USD
CY2019Q4	cna	Carrying Value Of Limited Partnerships As Percentage Of Aggregate Partnership Equity CarryingValueOfLimitedPartnershipsAsPercentageOfAggregatePartnershipEquity	0.02
CY2020Q4	cna	Carrying Value Of Limited Partnerships As Percentage Of Aggregate Partnership Equity CarryingValueOfLimitedPartnershipsAsPercentageOfAggregatePartnershipEquity	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
CY2018Q4	cna	Income As Percentage Of Change In Partnership Equity For All Limited Partnerships IncomeAsPercentageOfChangeInPartnershipEquityForAllLimitedPartnerships	0.03
CY2020Q4	us-gaap	Derivative Collateral Obligation To Return Cash DerivativeCollateralObligationToReturnCash	0	USD
CY2019Q4	us-gaap	Derivative Collateral Obligation To Return Cash DerivativeCollateralObligationToReturnCash	0	USD
CY2020Q4	us-gaap	Derivative Notional Amount DerivativeNotionalAmount	190000000	USD
CY2019Q4	us-gaap	Derivative Notional Amount DerivativeNotionalAmount	182000000	USD
CY2020Q4	us-gaap	Derivative Fair Value Of Derivative Liability DerivativeFairValueOfDerivativeLiability	19000000	USD
CY2019Q4	us-gaap	Derivative Fair Value Of Derivative Liability DerivativeFairValueOfDerivativeLiability	7000000	USD
CY2020Q4	cna	Commitments To Purchase Or Fund Additional Amounts CommitmentsToPurchaseOrFundAdditionalAmounts	1210000000	USD
CY2020Q4	cna	Commitments To Sell Various Privately Placed Debt Securities CommitmentsToSellVariousPrivatelyPlacedDebtSecurities	85000000	USD
CY2020Q4	cna	Carrying Value Of Securities Deposited Under Requirements Of Regulatory Authorities CarryingValueOfSecuritiesDepositedUnderRequirementsOfRegulatoryAuthorities	3000000000.0	USD
CY2019Q4	cna	Carrying Value Of Securities Deposited Under Requirements Of Regulatory Authorities CarryingValueOfSecuritiesDepositedUnderRequirementsOfRegulatoryAuthorities	2700000000	USD
CY2020Q4	cna	Cash And Securities Deposited As Collateral For Letters Of Credit CashAndSecuritiesDepositedAsCollateralForLettersOfCredit	1100000000	USD
CY2019Q4	cna	Cash And Securities Deposited As Collateral For Letters Of Credit CashAndSecuritiesDepositedAsCollateralForLettersOfCredit	1100000000	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
CY2019Q4	us-gaap	Debt Securities DebtSecurities	42207000000	USD
CY2019Q4	us-gaap	Equity Securities Fv Ni EquitySecuritiesFvNi	865000000	USD
CY2019Q4	cna	Shortterm Investmentsand Other ShorttermInvestmentsandOther	1741000000	USD
CY2019Q4	us-gaap	Assets Fair Value Disclosure AssetsFairValueDisclosure	44813000000	USD
CY2019Q4	us-gaap	Other Liabilities Fair Value Disclosure OtherLiabilitiesFairValueDisclosure	7000000	USD
CY2019Q4	us-gaap	Liabilities Fair Value Disclosure LiabilitiesFairValueDisclosure	7000000	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
CY2018Q4	us-gaap	Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Value FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetValue	437000000	USD
CY2019	us-gaap	Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Gain Loss Included In Other Comprehensive Income Loss FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInOtherComprehensiveIncomeLoss	41000000	USD
CY2019	cna	Fair Value Measurementwith Unobservable Inputs Reconciliation Recurring Basis Asset Gain Loss Included In Earnings And Other Comprehensive Income Loss FairValueMeasurementwithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInEarningsAndOtherComprehensiveIncomeLoss	39000000	USD
CY2019	us-gaap	Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Purchases FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetPurchases	306000000	USD
CY2019	us-gaap	Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Sales FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetSales	0	USD
CY2019	us-gaap	Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Settlements FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetSettlements	27000000	USD
CY2019	us-gaap	Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Transfers Into Level3 FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetTransfersIntoLevel3	45000000	USD
CY2019	us-gaap	Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Transfers Out Of Level3 FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetTransfersOutOfLevel3	149000000	USD
CY2019Q4	us-gaap	Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Value FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetValue	651000000	USD
CY2019	us-gaap	Fair Value Assets Measured On Recurring Basis Change In Unrealized Gain Loss FairValueAssetsMeasuredOnRecurringBasisChangeInUnrealizedGainLoss	-2000000	USD
CY2019	cna	Fair Value Measurementwith Unobservable Inputs Reconciliation Recurring Basis Asset Unrealized Gain Loss Includedin Other Comprehensive Income Loss FairValueMeasurementwithUnobservableInputsReconciliationRecurringBasisAssetUnrealizedGainLossIncludedinOtherComprehensiveIncomeLoss	35000000	USD
CY2020Q4	cna	Other Invested Assets Overseas Deposit OtherInvestedAssetsOverseasDeposit	71000000	USD
CY2019Q4	cna	Other Invested Assets Overseas Deposit OtherInvestedAssetsOverseasDeposit	60000000	USD
CY2020Q4	us-gaap	Unrecognized Tax Benefits UnrecognizedTaxBenefits	0	USD
CY2019Q4	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
CY2018	us-gaap	Interest Income Expense Net InterestIncomeExpenseNet	0	USD
CY2020	us-gaap	Unrecognized Tax Benefits Income Tax Penalties Expense UnrecognizedTaxBenefitsIncomeTaxPenaltiesExpense	0	USD
CY2018	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
CY2019Q4	us-gaap	Unrecognized Tax Benefits Income Tax Penalties And Interest Accrued UnrecognizedTaxBenefitsIncomeTaxPenaltiesAndInterestAccrued	0	USD
CY2020Q4	us-gaap	Unrecognized Tax Benefits Income Tax Penalties And Interest Accrued UnrecognizedTaxBenefitsIncomeTaxPenaltiesAndInterestAccrued	0	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
CY2018	us-gaap	Income Tax Reconciliation Income Tax Expense Benefit At Federal Statutory Income Tax Rate IncomeTaxReconciliationIncomeTaxExpenseBenefitAtFederalStatutoryIncomeTaxRate	203000000	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
CY2018	us-gaap	Income Tax Reconciliation Tax Exempt Income IncomeTaxReconciliationTaxExemptIncome	63000000	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
CY2018	us-gaap	Income Tax Reconciliation Foreign Income Tax Rate Differential IncomeTaxReconciliationForeignIncomeTaxRateDifferential	1000000	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
CY2018	us-gaap	Income Tax Reconciliation State And Local Income Taxes IncomeTaxReconciliationStateAndLocalIncomeTaxes	13000000	USD
CY2020	us-gaap	Income Tax Reconciliation Other Adjustments IncomeTaxReconciliationOtherAdjustments	7000000	USD
CY2019	us-gaap	Income Tax Reconciliation Other Adjustments IncomeTaxReconciliationOtherAdjustments	4000000	USD
CY2018	us-gaap	Income Tax Reconciliation Other Adjustments IncomeTaxReconciliationOtherAdjustments	-3000000	USD
CY2020	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	131000000	USD
CY2019	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	223000000	USD
CY2018	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	151000000	USD
CY2020Q4	us-gaap	Deferred Tax Liability Not Recognized Amount Of Unrecognized Deferred Tax Liability Undistributed Earnings Of Foreign Subsidiaries DeferredTaxLiabilityNotRecognizedAmountOfUnrecognizedDeferredTaxLiabilityUndistributedEarningsOfForeignSubsidiaries	0	USD
CY2020	us-gaap	Current Income Tax Expense Benefit CurrentIncomeTaxExpenseBenefit	180000000	USD
CY2019	us-gaap	Current Income Tax Expense Benefit CurrentIncomeTaxExpenseBenefit	269000000	USD
CY2018	us-gaap	Current Income Tax Expense Benefit CurrentIncomeTaxExpenseBenefit	171000000	USD
CY2020	us-gaap	Deferred Income Tax Expense Benefit DeferredIncomeTaxExpenseBenefit	-49000000	USD
CY2019	us-gaap	Deferred Income Tax Expense Benefit DeferredIncomeTaxExpenseBenefit	-46000000	USD
CY2018	us-gaap	Deferred Income Tax Expense Benefit DeferredIncomeTaxExpenseBenefit	-20000000	USD
CY2020	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	131000000	USD
CY2019	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	223000000	USD
CY2018	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	151000000	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
CY2018	us-gaap	Foreign Income Tax Expense Benefit Continuing Operations ForeignIncomeTaxExpenseBenefitContinuingOperations	-5000000	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
CY2018	us-gaap	Income Loss From Continuing Operations Before Income Taxes Foreign IncomeLossFromContinuingOperationsBeforeIncomeTaxesForeign	22000000	USD
CY2020Q4	us-gaap	Deferred Tax Assets Tax Deferred Expense Reserves And Accruals Loss Reserves DeferredTaxAssetsTaxDeferredExpenseReservesAndAccrualsLossReserves	157000000	USD
CY2019Q4	us-gaap	Deferred Tax Assets Tax Deferred Expense Reserves And Accruals Loss Reserves DeferredTaxAssetsTaxDeferredExpenseReservesAndAccrualsLossReserves	129000000	USD
CY2020Q4	us-gaap	Deferred Tax Assets Tax Deferred Expense Reserves And Accruals Unearned Premiums Reserve DeferredTaxAssetsTaxDeferredExpenseReservesAndAccrualsUnearnedPremiumsReserve	174000000	USD
CY2019Q4	us-gaap	Deferred Tax Assets Tax Deferred Expense Reserves And Accruals Unearned Premiums Reserve DeferredTaxAssetsTaxDeferredExpenseReservesAndAccrualsUnearnedPremiumsReserve	153000000	USD
CY2020Q4	us-gaap	Deferred Tax Assets Tax Deferred Expense Reserves And Accruals Allowance For Doubtful Accounts DeferredTaxAssetsTaxDeferredExpenseReservesAndAccrualsAllowanceForDoubtfulAccounts	11000000	USD
CY2019Q4	us-gaap	Deferred Tax Assets Tax Deferred Expense Reserves And Accruals Allowance For Doubtful Accounts DeferredTaxAssetsTaxDeferredExpenseReservesAndAccrualsAllowanceForDoubtfulAccounts	11000000	USD
CY2020Q4	us-gaap	Deferred Tax Assets Tax Deferred Expense Compensation And Benefits Employee Benefits DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefitsEmployeeBenefits	122000000	USD
CY2019Q4	us-gaap	Deferred Tax Assets Tax Deferred Expense Compensation And Benefits Employee Benefits DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefitsEmployeeBenefits	127000000	USD
CY2020Q4	cna	Deferred Tax Assets Deferred Retroactive Reinsurance Benefit DeferredTaxAssetsDeferredRetroactiveReinsuranceBenefit	83000000	USD
CY2019Q4	cna	Deferred Tax Assets Deferred Retroactive Reinsurance Benefit DeferredTaxAssetsDeferredRetroactiveReinsuranceBenefit	82000000	USD
CY2020Q4	us-gaap	Deferred Tax Assets Other DeferredTaxAssetsOther	143000000	USD
CY2019Q4	us-gaap	Deferred Tax Assets Other DeferredTaxAssetsOther	132000000	USD
CY2020Q4	us-gaap	Deferred Tax Assets Gross DeferredTaxAssetsGross	690000000	USD
CY2019Q4	us-gaap	Deferred Tax Assets Gross DeferredTaxAssetsGross	634000000	USD
CY2020Q4	us-gaap	Deferred Tax Liabilities Investments DeferredTaxLiabilitiesInvestments	28000000	USD
CY2019Q4	us-gaap	Deferred Tax Liabilities Investments DeferredTaxLiabilitiesInvestments	40000000	USD
CY2020Q4	us-gaap	Deferred Tax Liabilities Deferred Expense Deferred Policy Acquisition Cost DeferredTaxLiabilitiesDeferredExpenseDeferredPolicyAcquisitionCost	93000000	USD
CY2019Q4	us-gaap	Deferred Tax Liabilities Deferred Expense Deferred Policy Acquisition Cost DeferredTaxLiabilitiesDeferredExpenseDeferredPolicyAcquisitionCost	83000000	USD
CY2020Q4	us-gaap	Deferred Tax Liabilities Other Comprehensive Income DeferredTaxLiabilitiesOtherComprehensiveIncome	453000000	USD
CY2019Q4	us-gaap	Deferred Tax Liabilities Other Comprehensive Income DeferredTaxLiabilitiesOtherComprehensiveIncome	264000000	USD
CY2020Q4	cna	Deferred Tax Liabilities Deferred Expense Softwareand Hardware DeferredTaxLiabilitiesDeferredExpenseSoftwareandHardware	31000000	USD
CY2019Q4	cna	Deferred Tax Liabilities Deferred Expense Softwareand Hardware DeferredTaxLiabilitiesDeferredExpenseSoftwareandHardware	34000000	USD
CY2020Q4	us-gaap	Deferred Tax Liabilities Other DeferredTaxLiabilitiesOther	19000000	USD
CY2019Q4	us-gaap	Deferred Tax Liabilities Other DeferredTaxLiabilitiesOther	14000000	USD
CY2020Q4	us-gaap	Deferred Income Tax Liabilities DeferredIncomeTaxLiabilities	624000000	USD
CY2019Q4	us-gaap	Deferred Income Tax Liabilities DeferredIncomeTaxLiabilities	435000000	USD
CY2020Q4	us-gaap	Deferred Tax Assets Liabilities Net DeferredTaxAssetsLiabilitiesNet	66000000	USD
CY2019Q4	us-gaap	Deferred Tax Assets Liabilities Net DeferredTaxAssetsLiabilitiesNet	199000000	USD
CY2020Q4	us-gaap	Operating Loss Carryforwards OperatingLossCarryforwards	0	USD
CY2020Q4	us-gaap	Tax Credit Carryforward Amount TaxCreditCarryforwardAmount	8000000	USD
CY2020Q4	cna	Operating Loss Carryforwards Not Subject To Expiration OperatingLossCarryforwardsNotSubjectToExpiration	46000000	USD
CY2019Q4	us-gaap	Deferred Tax Assets Valuation Allowance DeferredTaxAssetsValuationAllowance	0	USD
CY2020Q4	us-gaap	Deferred Tax Assets Valuation Allowance DeferredTaxAssetsValuationAllowance	0	USD
CY2020Q4	us-gaap	Liability For Unpaid Claims And Claims Adjustment Expense Net LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseNet	18701000000	USD
CY2020Q4	us-gaap	Reinsurance Recoverables On Unpaid Losses Gross ReinsuranceRecoverablesOnUnpaidLossesGross	4005000000	USD
CY2020Q4	us-gaap	Liability For Claims And Claims Adjustment Expense LiabilityForClaimsAndClaimsAdjustmentExpense	22706000000	USD
CY2020	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-bottom:5pt;margin-top:5pt"><table style="border-collapse:collapse;display:inline-table;vertical-align:top;width:100.000%"><tr><td style="width:1.0%"/><td style="width:56.637%"/><td style="width:0.1%"/><td style="width:1.0%"/><td style="width:12.211%"/><td style="width:0.1%"/><td style="width:0.1%"/><td style="width:0.964%"/><td style="width:0.1%"/><td style="width:1.0%"/><td style="width:12.211%"/><td style="width:0.1%"/><td style="width:0.1%"/><td style="width:0.964%"/><td style="width:0.1%"/><td style="width:1.0%"/><td style="width:12.213%"/><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%">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><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%">2018</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%">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%">$</span></td><td style="background-color:#ffffff;padding:2px 0;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:100%">21,984 </span></td><td style="background-color:#ffffff;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"/><td colspan="3" style="background-color:#ffffff;padding:0 1pt"/><td style="background-color:#ffffff;padding:2px 0 2px 1pt;text-align:left;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:100%">$</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%">22,004 </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%">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"/><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%">3,934 </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%">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"/><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%">18,070 </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 incurred claim and claim adjustment expenses:</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%">Provision for insured events of current year</span></td><td colspan="2" style="background-color:#ffffff;padding:2px 0 2px 1pt;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:100%">5,793 </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%">5,356 </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%">5,358 </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%">Increase (decrease) in provision for insured events of prior years</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%">(119)</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%">(127)</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%">(179)</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%">Amortization of discount</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%">183 </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%">184 </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%">176 </span></td><td style="background-color:#ffffff;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"/></tr><tr><td colspan="3" style="background-color:#cceeff;padding:2px 1pt;text-align:left;vertical-align:bottom"><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:#cceeff;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:#cceeff;border-top:1pt solid #000000;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;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:#cceeff;border-top:1pt solid #000000;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;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%">5,355 </span></td><td style="background-color:#cceeff;border-top:1pt solid #000000;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"/></tr><tr><td colspan="3" style="background-color:#ffffff;padding:2px 1pt;text-align:left;vertical-align: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:#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%">Current 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%">(948)</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%">(992)</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%">(1,046)</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%">Prior 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%">(4,216)</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%">(4,584)</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%">(4,285)</span></td><td style="background-color:#ffffff;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"/></tr><tr><td colspan="3" style="background-color:#cceeff;padding:2px 1pt;text-align:left;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:100%">Total net payments</span></td><td colspan="2" style="background-color:#cceeff;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:#cceeff;border-top:1pt solid #000000;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;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:#cceeff;border-top:1pt solid #000000;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;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%">(5,331)</span></td><td style="background-color:#cceeff;border-top:1pt solid #000000;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"/></tr><tr><td colspan="3" style="background-color:#ffffff;padding:2px 1pt;text-align:left;vertical-align: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:#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%">123 </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%">83 </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%">(129)</span></td><td style="background-color:#ffffff;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"/></tr><tr><td colspan="3" style="background-color:#cceeff;padding:2px 1pt;text-align:left;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:100%">Net reserves, end of year</span></td><td colspan="2" style="background-color:#cceeff;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:#cceeff;border-top:1pt solid #000000;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;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:#cceeff;border-top:1pt solid #000000;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;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:#cceeff;border-top:1pt solid #000000;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"/></tr><tr><td colspan="3" style="background-color:#ffffff;padding:2px 1pt;text-align:left;vertical-align: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:#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%">4,005 </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%">3,835 </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%">4,019 </span></td><td style="background-color:#ffffff;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"/></tr><tr><td colspan="3" style="background-color:#cceeff;padding:2px 1pt;text-align:left;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:700;line-height:100%">Gross reserves, end of year</span></td><td style="background-color:#cceeff;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%">$</span></td><td style="background-color:#cceeff;border-bottom:3pt double #000000;border-top:1pt solid #000000;padding:2px 0;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:100%">22,706 </span></td><td style="background-color:#cceeff;border-bottom:3pt double #000000;border-top:1pt solid #000000;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"/><td colspan="3" style="background-color:#cceeff;padding:0 1pt"/><td style="background-color:#cceeff;border-bottom:3pt double #000000;border-top:1pt solid #000000;padding:2px 0 2px 1pt;text-align:left;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:100%">$</span></td><td style="background-color:#cceeff;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:#cceeff;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:#cceeff;padding:0 1pt"/><td style="background-color:#cceeff;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:#cceeff;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%">21,984 </span></td><td style="background-color:#cceeff;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:6pt;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, uncollectible reinsurance and benefit expenses related to future policy benefits, which are not reflected in the table above.</span></div>
CY2019Q4	cna	Liabilityforunpaidclaimandclaimadjustmentexpensegross Liabilityforunpaidclaimandclaimadjustmentexpensegross	21720000000	USD
CY2018Q4	cna	Liabilityforunpaidclaimandclaimadjustmentexpensegross Liabilityforunpaidclaimandclaimadjustmentexpensegross	21984000000	USD
CY2017Q4	cna	Liabilityforunpaidclaimandclaimadjustmentexpensegross Liabilityforunpaidclaimandclaimadjustmentexpensegross	22004000000	USD
CY2019Q4	cna	Ceded Claim And Claim Adjustment Expenses CededClaimAndClaimAdjustmentExpenses	3835000000	USD
CY2018Q4	cna	Ceded Claim And Claim Adjustment Expenses CededClaimAndClaimAdjustmentExpenses	4019000000	USD
CY2017Q4	cna	Ceded Claim And Claim Adjustment Expenses CededClaimAndClaimAdjustmentExpenses	3934000000	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
CY2017Q4	us-gaap	Liability For Unpaid Claims And Claims Adjustment Expense Net LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseNet	18070000000	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
CY2018	us-gaap	Supplemental Information For Property Casualty Insurance Underwriters Current Year Claims And Claims Adjustment Expense SupplementalInformationForPropertyCasualtyInsuranceUnderwritersCurrentYearClaimsAndClaimsAdjustmentExpense	5358000000	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
CY2018	us-gaap	Supplemental Information For Property Casualty Insurance Underwriters Prior Year Claims And Claims Adjustment Expense SupplementalInformationForPropertyCasualtyInsuranceUnderwritersPriorYearClaimsAndClaimsAdjustmentExpense	-179000000	USD
CY2020	cna	Liability For Unpaid Claims And Claims Adjustment Expense Incurred Claims Amortization Of Discount LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseIncurredClaimsAmortizationOfDiscount	183000000	USD
CY2019	cna	Liability For Unpaid Claims And Claims Adjustment Expense Incurred Claims Amortization Of Discount LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseIncurredClaimsAmortizationOfDiscount	184000000	USD
CY2018	cna	Liability For Unpaid Claims And Claims Adjustment Expense Incurred Claims Amortization Of Discount LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseIncurredClaimsAmortizationOfDiscount	176000000	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
CY2018	us-gaap	Liability For Unpaid Claims And Claims Adjustment Expense Incurred Claims1 LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseIncurredClaims1	5355000000	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
CY2018	us-gaap	Liability For Unpaid Claims And Claims Adjustment Expense Claims Paid Current Year1 LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseClaimsPaidCurrentYear1	1046000000	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
CY2018	us-gaap	Liability For Unpaid Claims And Claims Adjustment Expense Claims Paid Prior Years1 LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseClaimsPaidPriorYears1	4285000000	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
CY2018	us-gaap	Payments For Losses And Loss Adjustment Expense PaymentsForLossesAndLossAdjustmentExpense	5331000000	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
CY2018	cna	Liability For Unpaid Claims And Claims Adjustment Expense Foreign Cta And Other LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseForeignCtaAndOther	-129000000	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
CY2020Q4	cna	Ceded Claim And Claim Adjustment Expenses CededClaimAndClaimAdjustmentExpenses	4005000000	USD
CY2019Q4	cna	Ceded Claim And Claim Adjustment Expenses CededClaimAndClaimAdjustmentExpenses	3835000000	USD
CY2018Q4	cna	Ceded Claim And Claim Adjustment Expenses CededClaimAndClaimAdjustmentExpenses	4019000000	USD
CY2020Q4	cna	Liabilityforunpaidclaimandclaimadjustmentexpensegross Liabilityforunpaidclaimandclaimadjustmentexpensegross	22706000000	USD
CY2019Q4	cna	Liabilityforunpaidclaimandclaimadjustmentexpensegross Liabilityforunpaidclaimandclaimadjustmentexpensegross	21720000000	USD
CY2018Q4	cna	Liabilityforunpaidclaimandclaimadjustmentexpensegross Liabilityforunpaidclaimandclaimadjustmentexpensegross	21984000000	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
CY2019Q4	us-gaap	Liability For Unpaid Claims And Claims Adjustment Expense Reported Claims Amount LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseReportedClaimsAmount	10989000000	USD
CY2019Q4	us-gaap	Liability For Unpaid Claims And Claims Adjustment Expense Incurred But Not Reported Ibnr Claims Amount LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseIncurredButNotReportedIBNRClaimsAmount	10731000000	USD
CY2019Q4	cna	Liabilityforunpaidclaimandclaimadjustmentexpensegross Liabilityforunpaidclaimandclaimadjustmentexpensegross	21720000000	USD
CY2019Q4	cna	Net Case Reserves NetCaseReserves	9178000000	USD
CY2019Q4	cna	Net Ibnr Reserves NetIbnrReserves	8707000000	USD
CY2019Q4	us-gaap	Liability For Unpaid Claims And Claims Adjustment Expense Net LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseNet	17885000000	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
CY2018	cna	Pretax Favorable Unfavorable Premium Development Excluding Life Group PretaxFavorableUnfavorablePremiumDevelopmentExcludingLifeGroup	-181000000	USD
CY2020Q3	cna	Liability For Unpaid Claims And Claims Adjustment Expense Structured Settlement Obligations Period Increase Decrease LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseStructuredSettlementObligationsPeriodIncreaseDecrease	46000000	USD
CY2020Q3	cna	Liability For Unpaid Claims And Claims Adjustment Expense Long Term Care Policies Period Increase Decrease LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseLongTermCarePoliciesPeriodIncreaseDecrease	-37000000	USD
CY2019Q3	us-gaap	Liability For Unpaid Claims And Claims Adjustment Expense Period Increase Decrease LiabilityForUnpaidClaimsAndClaimsAdjustmentExpensePeriodIncreaseDecrease	-56000000	USD
CY2018Q3	us-gaap	Liability For Unpaid Claims And Claims Adjustment Expense Period Increase Decrease LiabilityForUnpaidClaimsAndClaimsAdjustmentExpensePeriodIncreaseDecrease	-31000000	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
CY2020Q4	cna	Increase Decrease Earned Premiums IncreaseDecreaseEarnedPremiums	-14000000	USD
CY2020Q4	cna	Ceded Claim And Claim Adjustment Expenses CededClaimAndClaimAdjustmentExpenses	4005000000	USD
CY2019Q4	cna	Ceded Claim And Claim Adjustment Expenses CededClaimAndClaimAdjustmentExpenses	3835000000	USD
CY2020Q4	cna	Ceded Future Policy Benefits CededFuturePolicyBenefits	263000000	USD
CY2019Q4	cna	Ceded Future Policy Benefits CededFuturePolicyBenefits	226000000	USD
CY2020Q4	us-gaap	Reinsurance Recoverables On Paid Losses Gross ReinsuranceRecoverablesOnPaidLossesGross	210000000	USD
CY2019Q4	us-gaap	Reinsurance Recoverables On Paid Losses Gross ReinsuranceRecoverablesOnPaidLossesGross	143000000	USD
CY2020Q4	us-gaap	Reinsurance Recoverables Gross ReinsuranceRecoverablesGross	4478000000	USD
CY2019Q4	us-gaap	Reinsurance Recoverables Gross ReinsuranceRecoverablesGross	4204000000	USD
CY2020Q4	us-gaap	Reinsurance Recoverables Allowance ReinsuranceRecoverablesAllowance	21000000	USD
CY2019Q4	us-gaap	Reinsurance Recoverables Allowance ReinsuranceRecoverablesAllowance	25000000	USD
CY2020Q4	us-gaap	Reinsurance Recoverables ReinsuranceRecoverables	4457000000	USD
CY2019Q4	us-gaap	Reinsurance Recoverables ReinsuranceRecoverables	4179000000	USD
CY2020Q4	cna	Voluntary Reinsurance Recoverable Gross VoluntaryReinsuranceRecoverableGross	3727000000	USD
CY2020Q4	us-gaap	Funds Held Under Reinsurance Agreements Liability FundsHeldUnderReinsuranceAgreementsLiability	3300000000	USD
CY2019Q4	us-gaap	Funds Held Under Reinsurance Agreements Liability FundsHeldUnderReinsuranceAgreementsLiability	3200000000	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
CY2018	us-gaap	Direct Premiums Earned DirectPremiumsEarned	11337000000	USD
CY2018	us-gaap	Assumed Premiums Earned AssumedPremiumsEarned	355000000	USD
CY2018	us-gaap	Ceded Premiums Earned CededPremiumsEarned	4380000000	USD
CY2018	us-gaap	Premiums Earned Net PremiumsEarnedNet	7312000000	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
CY2018	us-gaap	Direct Premiums Written DirectPremiumsWritten	11568000000	USD
CY2018	us-gaap	Assumed Premiums Written AssumedPremiumsWritten	360000000	USD
CY2018	us-gaap	Ceded Premiums Written CededPremiumsWritten	4583000000	USD
CY2018	us-gaap	Premiums Written Net PremiumsWrittenNet	7345000000	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
CY2018	us-gaap	Reinsurance Effect On Claims And Benefits Incurred Amount Ceded ReinsuranceEffectOnClaimsAndBenefitsIncurredAmountCeded	2836000000	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
CY2020Q4	us-gaap	Long Term Debt LongTermDebt	2776000000	USD
CY2020Q4	us-gaap	Long Term Debt Maturities Repayments Of Principal In Year Three LongTermDebtMaturitiesRepaymentsOfPrincipalInYearThree	243000000	USD
CY2019Q4	us-gaap	Long Term Debt LongTermDebt	2679000000	USD
CY2020Q4	us-gaap	Federal Home Loan Bank Stock FederalHomeLoanBankStock	5000000	USD
CY2020Q4	us-gaap	Federal Home Loan Bank Advances General Debt Obligations Disclosures Maximum Amount Available FederalHomeLoanBankAdvancesGeneralDebtObligationsDisclosuresMaximumAmountAvailable	111000000	USD
CY2020Q4	us-gaap	Federal Home Loan Bank Advances Branch Of Fhlb Bank Amount Of Advances By Branch FederalHomeLoanBankAdvancesBranchOfFHLBBankAmountOfAdvancesByBranch	0	USD
CY2019Q4	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
CY2020Q4	us-gaap	Minimum Net Worth Required For Compliance MinimumNetWorthRequiredForCompliance	8700000000	USD
CY2019Q4	us-gaap	Line Of Credit LineOfCredit	0	USD
CY2020Q4	us-gaap	Line Of Credit LineOfCredit	0	USD
CY2020Q4	us-gaap	Long Term Debt Maturities Repayments Of Principal In Next Twelve Months LongTermDebtMaturitiesRepaymentsOfPrincipalInNextTwelveMonths	0	USD
CY2020Q4	us-gaap	Long Term Debt Maturities Repayments Of Principal In Year Two LongTermDebtMaturitiesRepaymentsOfPrincipalInYearTwo	0	USD
CY2020	cna	Assumptionsusedincalculatingassumedhealthcarecosttrendrate Assumptionsusedincalculatingassumedhealthcarecosttrendrate	0.04
CY2020Q4	us-gaap	Long Term Debt Maturities Repayments Of Principal In Year Four LongTermDebtMaturitiesRepaymentsOfPrincipalInYearFour	550000000	USD
CY2020Q4	us-gaap	Long Term Debt Maturities Repayments Of Principal In Year Five LongTermDebtMaturitiesRepaymentsOfPrincipalInYearFive	0	USD
CY2020Q4	us-gaap	Long Term Debt Maturities Repayments Of Principal After Year Five LongTermDebtMaturitiesRepaymentsOfPrincipalAfterYearFive	2000000000	USD
CY2020Q4	us-gaap	Debt Instrument Unamortized Discount DebtInstrumentUnamortizedDiscount	17000000	USD
CY2020Q4	us-gaap	Long Term Debt LongTermDebt	2776000000	USD
CY2020	us-gaap	Defined Benefit Plan Actuarial Gain Loss DefinedBenefitPlanActuarialGainLoss	-205000000	USD
CY2019	us-gaap	Defined Benefit Plan Actuarial Gain Loss DefinedBenefitPlanActuarialGainLoss	-261000000	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
CY2018	us-gaap	Other Comprehensive Income Loss Pension And Other Postretirement Benefit Plans Net Unamortized Gain Loss Arising During Period Before Tax OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansNetUnamortizedGainLossArisingDuringPeriodBeforeTax	-41000000	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
CY2018	cna	Other Comprehensive Income Loss Pensionand Other Postretirement Benefit Plans Settlementsbefore Tax OtherComprehensiveIncomeLossPensionandOtherPostretirementBenefitPlansSettlementsbeforeTax	6000000	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
CY2018	us-gaap	Other Comprehensive Income Loss Amortization Adjustment From Aoci Pension And Other Postretirement Benefit Plans For Net Prior Service Cost Credit Before Tax OtherComprehensiveIncomeLossAmortizationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetPriorServiceCostCreditBeforeTax	-2000000	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
CY2018	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci Pension And Other Postretirement Benefit Plans For Net Gain Loss Before Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetGainLossBeforeTax	-36000000	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
CY2018	us-gaap	Other Comprehensive Income Loss Pension And Other Postretirement Benefit Plans Adjustment Before Tax OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansAdjustmentBeforeTax	1000000	USD
CY2020	us-gaap	Defined Benefit Plan Assumptions Used Calculating Net Periodic Benefit Cost Rate Of Compensation Increase DefinedBenefitPlanAssumptionsUsedCalculatingNetPeriodicBenefitCostRateOfCompensationIncrease	0.03000
CY2019	us-gaap	Defined Benefit Plan Assumptions Used Calculating Net Periodic Benefit Cost Rate Of Compensation Increase DefinedBenefitPlanAssumptionsUsedCalculatingNetPeriodicBenefitCostRateOfCompensationIncrease	0.05000
CY2020	cna	Assumptionsusedincalculatingassumedhealthcarecosttrendrate Assumptionsusedincalculatingassumedhealthcarecosttrendrate	0.04
CY2020	us-gaap	Defined Contribution Plan Maximum Annual Contributions Per Employee Percent DefinedContributionPlanMaximumAnnualContributionsPerEmployeePercent	0.50
CY2020	us-gaap	Defined Contribution Plan Employer Matching Contribution Percent Of Match DefinedContributionPlanEmployerMatchingContributionPercentOfMatch	1
CY2020	us-gaap	Defined Contribution Plan Employer Matching Contribution Percent DefinedContributionPlanEmployerMatchingContributionPercent	0.06
CY2020	cna	Company Contributionof Eligible Compensation Dependingon Age Percent CompanyContributionofEligibleCompensationDependingonAgePercent	0.05
CY2020	cna	Defined Contribution Plan Employers Matching Contribution Vesting Periodin Years DefinedContributionPlanEmployersMatchingContributionVestingPeriodinYears	P5Y
CY2019	us-gaap	Defined Contribution Plan Employer Matching Contribution Percent Of Match DefinedContributionPlanEmployerMatchingContributionPercentOfMatch	0.70
CY2019	cna	Defined Contribution Plan Employer Matching Contribution First Year Of Employment Percent Of Match DefinedContributionPlanEmployerMatchingContributionFirstYearOfEmploymentPercentOfMatch	0.35
CY2019	us-gaap	Defined Contribution Plan Employer Matching Contribution Percent DefinedContributionPlanEmployerMatchingContributionPercent	0.06
CY2020	us-gaap	Defined Contribution Plan Cost Recognized DefinedContributionPlanCostRecognized	70000000	USD
CY2019	us-gaap	Defined Contribution Plan Cost Recognized DefinedContributionPlanCostRecognized	71000000	USD
CY2018	us-gaap	Defined Contribution Plan Cost Recognized DefinedContributionPlanCostRecognized	71000000	USD
CY2020Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Number Of Shares Authorized ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized	16000000	shares
CY2020Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Number Of Shares Available For Grant ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant	5900000	shares
CY2020	cna	Measurement Periodof Specific Annual Performance Goalsin Years MeasurementPeriodofSpecificAnnualPerformanceGoalsinYears	P1Y
CY2020	cna	Cliff Vesting Period Following Dateof Grant CliffVestingPeriodFollowingDateofGrant	P2Y
CY2018	cna	Measurement Periodof Specific Annual Performance Goalsin Years MeasurementPeriodofSpecificAnnualPerformanceGoalsinYears	P3Y
CY2020	us-gaap	Allocated Share Based Compensation Expense AllocatedShareBasedCompensationExpense	37000000	USD
CY2019	us-gaap	Allocated Share Based Compensation Expense AllocatedShareBasedCompensationExpense	34000000	USD
CY2018	us-gaap	Allocated Share Based Compensation Expense AllocatedShareBasedCompensationExpense	32000000	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
CY2018	us-gaap	Employee Service Share Based Compensation Tax Benefit From Compensation Expense EmployeeServiceShareBasedCompensationTaxBenefitFromCompensationExpense	8000000	USD
CY2020Q4	us-gaap	Employee Service Share Based Compensation Nonvested Awards Total Compensation Cost Not Yet Recognized EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized	39000000	USD
CY2020	us-gaap	Employee Service Share Based Compensation Nonvested Awards Total Compensation Cost Not Yet Recognized Period For Recognition1 EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1	P1Y9M18D
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
CY2018	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Vested In Period Total Fair Value ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodTotalFairValue	16000000	USD
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
CY2019	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	43.86
CY2018	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	51.64
CY2019Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Nonvested Number ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber	2115186	shares
CY2019Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Nonvested Weighted Average Grant Date Fair Value ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue	46.25
CY2020	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Grants In Period ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod	1316407	shares
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
CY2020	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Vested In Period ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod	806589	shares
CY2020	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	44.31
CY2020	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Forfeited In Period ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod	248760	shares
CY2020	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Forfeitures Weighted Average Grant Date Fair Value ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue	42.57
CY2020	cna	Performance Based Adjustment Share Based Compensation Equity Instruments Other Than Options PerformanceBasedAdjustmentShareBasedCompensationEquityInstrumentsOtherThanOptions	62897	shares
CY2020	cna	Performance Based Adjustment Share Based Compensation Equity Instruments Other Than Options Weighted Average Grant Date Fair Value PerformanceBasedAdjustmentShareBasedCompensationEquityInstrumentsOtherThanOptionsWeightedAverageGrantDateFairValue	34.45
CY2020Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Nonvested Number ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber	2439141	shares
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
CY2020Q4	us-gaap	Finite Lived Intangible Assets Gross FiniteLivedIntangibleAssetsGross	18000000	USD
CY2020Q4	us-gaap	Finite Lived Intangible Assets Accumulated Amortization FiniteLivedIntangibleAssetsAccumulatedAmortization	13000000	USD
CY2019Q4	us-gaap	Finite Lived Intangible Assets Gross FiniteLivedIntangibleAssetsGross	18000000	USD
CY2019Q4	us-gaap	Finite Lived Intangible Assets Accumulated Amortization FiniteLivedIntangibleAssetsAccumulatedAmortization	11000000	USD
CY2020Q4	us-gaap	Indefinite Lived Intangible Assets Excluding Goodwill IndefiniteLivedIntangibleAssetsExcludingGoodwill	64000000	USD
CY2019Q4	us-gaap	Indefinite Lived Intangible Assets Excluding Goodwill IndefiniteLivedIntangibleAssetsExcludingGoodwill	62000000	USD
CY2020Q4	us-gaap	Intangible Assets Gross Excluding Goodwill IntangibleAssetsGrossExcludingGoodwill	82000000	USD
CY2020Q4	us-gaap	Finite Lived Intangible Assets Accumulated Amortization FiniteLivedIntangibleAssetsAccumulatedAmortization	13000000	USD
CY2019Q4	us-gaap	Intangible Assets Gross Excluding Goodwill IntangibleAssetsGrossExcludingGoodwill	80000000	USD
CY2019Q4	us-gaap	Finite Lived Intangible Assets Accumulated Amortization FiniteLivedIntangibleAssetsAccumulatedAmortization	11000000	USD
CY2020Q4	us-gaap	Finite Lived Intangible Assets Amortization Expense Year Four FiniteLivedIntangibleAssetsAmortizationExpenseYearFour	1000000	USD
CY2020Q4	us-gaap	Finite Lived Intangible Assets Amortization Expense Year Three FiniteLivedIntangibleAssetsAmortizationExpenseYearThree	1000000	USD
CY2020Q4	us-gaap	Finite Lived Intangible Assets Amortization Expense Year Two FiniteLivedIntangibleAssetsAmortizationExpenseYearTwo	1000000	USD
CY2020Q4	us-gaap	Finite Lived Intangible Assets Amortization Expense Next Twelve Months FiniteLivedIntangibleAssetsAmortizationExpenseNextTwelveMonths	1000000	USD
CY2020Q4	us-gaap	Finite Lived Intangible Assets Amortization Expense Year Five FiniteLivedIntangibleAssetsAmortizationExpenseYearFive	1000000	USD
CY2020	us-gaap	Operating Lease Expense OperatingLeaseExpense	57000000	USD
CY2019	us-gaap	Operating Lease Expense OperatingLeaseExpense	55000000	USD
CY2020	us-gaap	Operating Lease Cost OperatingLeaseCost	38000000	USD
CY2019	us-gaap	Operating Lease Cost OperatingLeaseCost	37000000	USD
CY2020	us-gaap	Variable Lease Cost VariableLeaseCost	19000000	USD
CY2019	us-gaap	Variable Lease Cost VariableLeaseCost	18000000	USD
CY2018Q4	us-gaap	Capital Lease Obligations CapitalLeaseObligations	62000000	USD
CY2020	us-gaap	Operating Lease Payments OperatingLeasePayments	41000000	USD
CY2019	us-gaap	Operating Lease Payments OperatingLeasePayments	34000000	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
CY2020Q4	us-gaap	Operating Lease Right Of Use Asset OperatingLeaseRightOfUseAsset	199000000	USD
CY2019Q4	us-gaap	Operating Lease Right Of Use Asset OperatingLeaseRightOfUseAsset	220000000	USD
CY2019Q4	us-gaap	Operating Lease Weighted Average Remaining Lease Term1 OperatingLeaseWeightedAverageRemainingLeaseTerm1	P10Y9M18D
CY2020Q4	us-gaap	Operating Lease Weighted Average Discount Rate Percent OperatingLeaseWeightedAverageDiscountRatePercent	0.034
CY2020Q4	us-gaap	Operating Lease Liability OperatingLeaseLiability	279000000	USD
CY2019Q4	us-gaap	Operating Lease Liability OperatingLeaseLiability	301000000	USD
CY2020Q4	us-gaap	Lessee Operating Lease Liability Payments Due Next Twelve Months LesseeOperatingLeaseLiabilityPaymentsDueNextTwelveMonths	44000000	USD
CY2020Q4	us-gaap	Lessee Operating Lease Liability Payments Due Year Two LesseeOperatingLeaseLiabilityPaymentsDueYearTwo	41000000	USD
CY2020Q4	us-gaap	Lessee Operating Lease Liability Payments Due Year Three LesseeOperatingLeaseLiabilityPaymentsDueYearThree	36000000	USD
CY2020Q4	us-gaap	Lessee Operating Lease Liability Payments Due Year Four LesseeOperatingLeaseLiabilityPaymentsDueYearFour	29000000	USD
CY2020Q4	us-gaap	Lessee Operating Lease Liability Payments Due Year Five LesseeOperatingLeaseLiabilityPaymentsDueYearFive	24000000	USD
CY2020Q4	us-gaap	Lessee Operating Lease Liability Payments Due After Year Five LesseeOperatingLeaseLiabilityPaymentsDueAfterYearFive	163000000	USD
CY2020Q4	us-gaap	Lessee Operating Lease Liability Payments Due LesseeOperatingLeaseLiabilityPaymentsDue	337000000	USD
CY2020Q4	us-gaap	Lessee Operating Lease Liability Undiscounted Excess Amount LesseeOperatingLeaseLiabilityUndiscountedExcessAmount	58000000	USD
CY2020Q4	us-gaap	Operating Lease Liability OperatingLeaseLiability	279000000	USD
CY2019Q4	us-gaap	Operating Lease Weighted Average Discount Rate Percent OperatingLeaseWeightedAverageDiscountRatePercent	0.034
CY2019	us-gaap	Statutory Accounting Practices Prescribed Practice Amount StatutoryAccountingPracticesPrescribedPracticeAmount	91000000	USD
CY2020	us-gaap	Statutory Accounting Practices Prescribed Practice Amount StatutoryAccountingPracticesPrescribedPracticeAmount	91000000	USD
CY2020Q4	cna	Statutory Accounting Practices Statutory Amount Availablefor Dividend Payments Before Considerationof Statutory Dividends Paidintheprecedingtwelvemonths StatutoryAccountingPracticesStatutoryAmountAvailableforDividendPaymentsBeforeConsiderationofStatutoryDividendsPaidintheprecedingtwelvemonths	1070000000	USD
CY2020	cna	Statutory Accounting Practices Dividends Paidintheprecedingtwelvemonths StatutoryAccountingPracticesDividendsPaidintheprecedingtwelvemonths	975000000	USD
CY2020Q4	us-gaap	Capital Required For Capital Adequacy To Risk Weighted Assets CapitalRequiredForCapitalAdequacyToRiskWeightedAssets	2.66
CY2019Q4	us-gaap	Capital Required For Capital Adequacy To Risk Weighted Assets CapitalRequiredForCapitalAdequacyToRiskWeightedAssets	2.91
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
CY2019	us-gaap	Oci Before Reclassifications Net Of Tax Attributable To Parent OciBeforeReclassificationsNetOfTaxAttributableToParent	894000000	USD
CY2019	us-gaap	Reclassification From Aoci Current Period Tax ReclassificationFromAociCurrentPeriodTax	-10000000	USD
CY2019	us-gaap	Reclassification From Aoci Current Period Net Of Tax Attributable To Parent ReclassificationFromAociCurrentPeriodNetOfTaxAttributableToParent	-35000000	USD
CY2019	us-gaap	Other Comprehensive Income Loss Tax Portion Attributable To Parent1 OtherComprehensiveIncomeLossTaxPortionAttributableToParent1	240000000	USD
CY2019	us-gaap	Other Comprehensive Income Loss Net Of Tax Portion Attributable To Parent OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent	929000000	USD
CY2019	cna	Percentageofforeigndirectwrittenpremiums Percentageofforeigndirectwrittenpremiums	0.09
CY2020	cna	Percentageofforeigndirectwrittenpremiums Percentageofforeigndirectwrittenpremiums	0.09
CY2018	cna	Percentageofforeigndirectwrittenpremiums Percentageofforeigndirectwrittenpremiums	0.09
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	Income Loss From Continuing Operations IncomeLossFromContinuingOperations	690000000	USD
CY2020Q4	us-gaap	Reinsurance Recoverables Gross ReinsuranceRecoverablesGross	4478000000	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	Contract With Customer Liability ContractWithCustomerLiability	4023000000	USD
CY2019	us-gaap	Premiums Written Net PremiumsWrittenNet	7656000000	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
CY2019	cna	Net Investment Income And Gains Losses On Trading Securities NetInvestmentIncomeAndGainsLossesOnTradingSecurities	2118000000	USD
CY2019	us-gaap	Premiums Earned Net PremiumsEarnedNet	7428000000	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
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
CY2019Q4	us-gaap	Reinsurance Recoverables Gross ReinsuranceRecoverablesGross	4204000000	USD
CY2019Q4	us-gaap	Premiums Receivable Gross PremiumsReceivableGross	2481000000	USD
CY2019Q4	us-gaap	Deferred Policy Acquisition Costs DeferredPolicyAcquisitionCosts	662000000	USD
CY2019Q4	us-gaap	Goodwill Goodwill	147000000	USD
CY2019Q4	us-gaap	Contract With Customer Asset Net ContractWithCustomerAssetNet	2840000000	USD
CY2019Q4	us-gaap	Liability For Claims And Claims Adjustment Expense LiabilityForClaimsAndClaimsAdjustmentExpense	21720000000	USD
CY2019Q4	us-gaap	Unearned Premiums UnearnedPremiums	4583000000	USD
CY2019Q4	us-gaap	Liability For Future Policy Benefits LiabilityForFuturePolicyBenefits	12311000000	USD
CY2019Q4	us-gaap	Contract With Customer Liability ContractWithCustomerLiability	3779000000	USD
CY2018	us-gaap	Premiums Written Net PremiumsWrittenNet	7345000000	USD
CY2018	us-gaap	Premiums Earned Net PremiumsEarnedNet	7312000000	USD
CY2018	cna	Net Investment Income And Gains Losses On Trading Securities NetInvestmentIncomeAndGainsLossesOnTradingSecurities	1817000000	USD
CY2018	us-gaap	Revenue From Contract With Customer Excluding Assessed Tax RevenueFromContractWithCustomerExcludingAssessedTax	1007000000	USD
CY2018	us-gaap	Other Income OtherIncome	50000000	USD
CY2018	cna	Operating Revenues OperatingRevenues	10186000000	USD
CY2018	us-gaap	Policyholder Benefits And Claims Incurred Net PolicyholderBenefitsAndClaimsIncurredNet	5547000000	USD
CY2018	us-gaap	Policyholder Dividends PolicyholderDividends	25000000	USD
CY2018	us-gaap	Deferred Policy Acquisition Cost Amortization Expense DeferredPolicyAcquisitionCostAmortizationExpense	1335000000	USD
CY2018	cna	Costs From Contract With Customers CostsFromContractWithCustomers	923000000	USD
CY2018	cna	Other Insurance Related Expenses OtherInsuranceRelatedExpenses	1039000000	USD
CY2018	us-gaap	Other Expenses OtherExpenses	301000000	USD
CY2018	us-gaap	Benefits Losses And Expenses BenefitsLossesAndExpenses	9170000000	USD
CY2018	cna	Operating Income Loss From Continuing Operations Before Income Tax OperatingIncomeLossFromContinuingOperationsBeforeIncomeTax	1016000000	USD
CY2018	cna	Income Tax Expense Benefit On Operating Income Loss IncomeTaxExpenseBenefitOnOperatingIncomeLoss	171000000	USD
CY2018	cna	Net Operating Income Loss From Continuing Operations Attributableto Parent NetOperatingIncomeLossFromContinuingOperationsAttributabletoParent	845000000	USD
CY2018	us-gaap	Debt Securities Realized Gain Loss DebtSecuritiesRealizedGainLoss	-52000000	USD
CY2018	cna	Income Tax Expense Benefit On Net Realized Investment Gains Losses IncomeTaxExpenseBenefitOnNetRealizedInvestmentGainsLosses	-14000000	USD
CY2018	cna	Net Realized Investment Gains Losses NetRealizedInvestmentGainsLosses	-38000000	USD
CY2018	cna	Deferred Income Tax Expense Benefit Remeasurementof Deferred Tax Asset DeferredIncomeTaxExpenseBenefitRemeasurementofDeferredTaxAsset	-6000000	USD
CY2018	us-gaap	Income Loss From Continuing Operations IncomeLossFromContinuingOperations	813000000	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
CY2018	cna	Revenues Excluding Investments And Derivatives Realized Gain Loss RevenuesExcludingInvestmentsAndDerivativesRealizedGainLoss	10186000000	USD
CY2020	cna	Investmentsand Derivatives Realized Gain Loss InvestmentsandDerivativesRealizedGainLoss	-54000000	USD
CY2019	cna	Investmentsand Derivatives Realized Gain Loss InvestmentsandDerivativesRealizedGainLoss	29000000	USD
CY2018	cna	Investmentsand Derivatives Realized Gain Loss InvestmentsandDerivativesRealizedGainLoss	-52000000	USD
CY2020	us-gaap	Revenues Revenues	10808000000	USD
CY2019	us-gaap	Revenues Revenues	10767000000	USD
CY2018	us-gaap	Revenues Revenues	10134000000	USD
CY2020Q1	us-gaap	Revenues Revenues	2291000000	USD
CY2020Q2	us-gaap	Revenues Revenues	2766000000	USD
CY2020Q3	us-gaap	Revenues Revenues	2820000000	USD
CY2020Q4	us-gaap	Revenues Revenues	2931000000	USD
CY2020	us-gaap	Revenues Revenues	10808000000	USD
CY2020Q1	us-gaap	Net Income Loss NetIncomeLoss	-61000000	USD
CY2019Q4	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	1.00
CY2019	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	3.67
CY2020Q1	cna	Net Realized Investment Gains Losses NetRealizedInvestmentGainsLosses	-216000000	USD
CY2020Q2	us-gaap	Net Income Loss NetIncomeLoss	151000000	USD
CY2020Q3	us-gaap	Net Income Loss NetIncomeLoss	213000000	USD
CY2020Q4	us-gaap	Net Income Loss NetIncomeLoss	387000000	USD
CY2020	us-gaap	Net Income Loss NetIncomeLoss	690000000	USD
CY2020Q1	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	-0.23
CY2020Q2	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	0.56
CY2020Q3	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	0.79
CY2020Q4	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	1.42
CY2020	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	2.54
CY2020Q1	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	-0.23
CY2020Q2	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	0.55
CY2020Q3	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	0.79
CY2020Q4	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	1.42
CY2020	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	2.53
CY2019Q1	us-gaap	Revenues Revenues	2695000000	USD
CY2019Q2	us-gaap	Revenues Revenues	2610000000	USD
CY2019Q3	us-gaap	Revenues Revenues	2685000000	USD
CY2019Q4	us-gaap	Revenues Revenues	2777000000	USD
CY2019	us-gaap	Revenues Revenues	10767000000	USD
CY2019Q1	us-gaap	Net Income Loss NetIncomeLoss	342000000	USD
CY2019Q2	us-gaap	Net Income Loss NetIncomeLoss	278000000	USD
CY2019Q3	us-gaap	Net Income Loss NetIncomeLoss	107000000	USD
CY2019Q4	us-gaap	Net Income Loss NetIncomeLoss	273000000	USD
CY2019	us-gaap	Net Income Loss NetIncomeLoss	1000000000	USD
CY2019Q1	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	1.26
CY2019Q2	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	1.03
CY2019Q3	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	0.39
CY2019Q4	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	1.00
CY2019	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	3.68
CY2019Q1	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	1.25
CY2019Q2	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	1.02
CY2019Q3	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	0.39
CY2020Q2	us-gaap	Loss From Catastrophes LossFromCatastrophes	301000000	USD
CY2020Q3	us-gaap	Loss From Catastrophes LossFromCatastrophes	160000000	USD
CY2020Q3	us-gaap	Premium Deficiency Testing Expense Long Duration Contract Amount PremiumDeficiencyTestingExpenseLongDurationContractAmount	74000000	USD
CY2019Q3	us-gaap	Premium Deficiency Testing Expense Long Duration Contract Amount PremiumDeficiencyTestingExpenseLongDurationContractAmount	216000000	USD
CY2020Q4	us-gaap	Contract With Customer Liability ContractWithCustomerLiability	4000000000.0	USD
CY2019Q4	us-gaap	Contract With Customer Liability ContractWithCustomerLiability	3800000000	USD
CY2020	us-gaap	Contract With Customer Liability Revenue Recognized ContractWithCustomerLiabilityRevenueRecognized	1100000000	USD
CY2019	us-gaap	Contract With Customer Liability Revenue Recognized ContractWithCustomerLiabilityRevenueRecognized	971000000	USD
CY2020Q4	us-gaap	Revenue Remaining Performance Obligation RevenueRemainingPerformanceObligation	1200000000	USD
CY2020Q4	us-gaap	Revenue Remaining Performance Obligation RevenueRemainingPerformanceObligation	900000000	USD
CY2020Q4	us-gaap	Revenue Remaining Performance Obligation RevenueRemainingPerformanceObligation	800000000	USD
CY2020Q4	us-gaap	Revenue Remaining Performance Obligation RevenueRemainingPerformanceObligation	1200000000	USD
CY2020	us-gaap	Amortization Of Deferred Sales Commissions AmortizationOfDeferredSalesCommissions	897000000	USD
CY2019	us-gaap	Amortization Of Deferred Sales Commissions AmortizationOfDeferredSalesCommissions	813000000	USD
CY2019Q4	us-gaap	Common Stock Par Or Stated Value Per Share CommonStockParOrStatedValuePerShare	2.50
CY2020Q4	us-gaap	Common Stock Par Or Stated Value Per Share CommonStockParOrStatedValuePerShare	2.50
CY2019Q4	us-gaap	Common Stock Shares Authorized CommonStockSharesAuthorized	500000000	shares
CY2020Q4	us-gaap	Common Stock Shares Authorized CommonStockSharesAuthorized	500000000	shares
CY2019Q4	us-gaap	Common Stock Shares Issued CommonStockSharesIssued	273040243	shares
CY2020Q4	us-gaap	Common Stock Shares Issued CommonStockSharesIssued	273040243	shares
CY2020Q4	us-gaap	Common Stock Shares Outstanding CommonStockSharesOutstanding	271391603	shares
CY2019Q4	us-gaap	Common Stock Shares Outstanding CommonStockSharesOutstanding	271412591	shares
CY2020Q4	us-gaap	Treasury Stock Shares TreasuryStockShares	1648640	shares
CY2019Q4	us-gaap	Treasury Stock Shares TreasuryStockShares	1627652	shares
CY2020	us-gaap	Supplemental Information For Property Casualty Insurance Underwriters Current Year Claims And Claims Adjustment Expense SupplementalInformationForPropertyCasualtyInsuranceUnderwritersCurrentYearClaimsAndClaimsAdjustmentExpense	5793000000	USD
CY2020	us-gaap	Supplemental Information For Property Casualty Insurance Underwriters Prior Year Claims And Claims Adjustment Expense SupplementalInformationForPropertyCasualtyInsuranceUnderwritersPriorYearClaimsAndClaimsAdjustmentExpense	-119000000	USD

Files In Submission

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$CNA
CNA FINANCIAL CORP Stock $cna

2020 Q4 Form 10-K Financial Statement

#000002117521000022 Filed on February 09, 2021

Income Statement

Balance Sheet

Cashflow Statement

Facts In Submission

Files In Submission

$CNA CNA FINANCIAL CORP Stock $cna

2020 Q4 Form 10-K Financial Statement

#000002117521000022 Filed on February 09, 2021

Income Statement

Balance Sheet

Cashflow Statement

Facts In Submission

Files In Submission

$CNA
CNA FINANCIAL CORP Stock $cna