XML 121 R108.htm IDEA: XBRL DOCUMENT v3.22.4

Reinsurance (Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020	Feb. 05, 2021
Ceded Credit Risk [Line Items]
Funds held under reinsurance agreements, liability	$ 3,700	$ 4,000		$ 690
Largest recoverable from single reinsurer	5,416	5,463
Reinsurance recoveries reported in insurance claims and policyholders' benefits reported on the Consolidated Statement of Operations	2,631	3,058	$ 3,158
Subsidiaries of Berkshire Hathaway Group
Ceded Credit Risk [Line Items]
Largest recoverable from single reinsurer	1,900
Cavello Bay Reinsurance Limited
Ceded Credit Risk [Line Items]
Largest recoverable from single reinsurer	598
Gateway Rivers Insurance Company
Ceded Credit Risk [Line Items]
Largest recoverable from single reinsurer	446
Significant Captive Program
Ceded Credit Risk [Line Items]
Direct and ceded earned premiums	3,270	3,638	3,543
Reinsurance recoveries reported in insurance claims and policyholders' benefits reported on the Consolidated Statement of Operations	$ 1,796	$ 2,003	$ 2,375

X

- Definition

Direct and ceded earned premiums related to business that is one hundred percent reinsured as a result of a significant captive program

+ References

No definition available.

+ Details

Name:	cna_DirectAndCededEarnedPremiumsRelatedToBusinessThatIsOneHundredPercentReinsuredAsResultOfSignificantCaptiveProgram
Namespace Prefix:	cna_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

X

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

Name:	us-gaap_CededCreditRiskLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

X

- Definition

Amount of funds held as security for payments to be received under reinsurance contracts.

+ References

No definition available.

+ Details

Name:	us-gaap_FundsHeldUnderReinsuranceAgreementsLiability
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

X

- Definition

Amount of reduction of provision for policy benefits and costs incurred for policies ceded.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 20
-Section 50
-Paragraph 3
-URI https://asc.fasb.org/extlink&oid=99397103&loc=d3e6811-158387

+ Details

Name:	us-gaap_ReinsuranceEffectOnClaimsAndBenefitsIncurredAmountCeded
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

X

- Definition

Amount, after valuation allowance, recoverable under reinsurance contracts including premium paid under reinsurance contracts. Examples include, but are not limited to, settled and unsettled claims, incurred but not reported losses, loss adjustment expense, premium paid, policy benefits and policy reserves.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03(a)(6))
-URI https://asc.fasb.org/extlink&oid=126734703&loc=d3e572229-122910

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 20
-Section 50
-Paragraph 5
-URI https://asc.fasb.org/extlink&oid=99397103&loc=d3e6824-158387

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 310
-Section 45
-Paragraph 5
-URI https://asc.fasb.org/extlink&oid=99404803&loc=d3e21409-158489

+ Details

Name:	us-gaap_ReinsuranceRecoverables
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

X

- Details

Name:	us-gaap_CededCreditRiskAxis=cna_SubsidiariesOfBerkshireHathawayGroupMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_CededCreditRiskAxis=cna_CavelloBayReinsuranceLimitedMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_CededCreditRiskAxis=cna_GatewayRiversInsuranceCompanyMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_CededCreditRiskAxis=cna_SignificantCaptiveProgramMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: