XML 90 R77.htm IDEA: XBRL DOCUMENT
v3.22.4

Claim and Claim Adjustment Expense Reserves and Future Policy Benefit Reserves (Specialty - Other Professional Liability and Management Liability - Net Incurred Claims and Allocated Claim Adjustment Expenses) (Details) - Other Professional Liability and Management Liability - Specialty $ in Millions | Dec. 31, 2022 USD ($) claim | Dec. 31, 2021 USD ($) | Dec. 31, 2020 USD ($) | Dec. 31, 2019 USD ($) | Dec. 31, 2018 USD ($) | Dec. 31, 2017 USD ($) | Dec. 31, 2016 USD ($) | Dec. 31, 2015 USD ($) | Dec. 31, 2014 USD ($) | Dec. 31, 2013 USD ($)
--- | --- | --- | --- | --- | --- | --- | --- | --- | --- | ---
Short-duration Insurance Contracts, Net Incurred Claim and Claim Adjustment Expenses [Line Items] |  |  |  |  |  |  |  |  |  |
Incurred claims and allocated claim adjustment expense, net | $ 9,080 |  |  |  |  |  |  |  |  |
IBNR | 2,673 |  |  |  |  |  |  |  |  |
2013 |  |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Net Incurred Claim and Claim Adjustment Expenses [Line Items] |  |  |  |  |  |  |  |  |  |
Incurred claims and allocated claim adjustment expense, net | 829 | $ 833 | $ 846 | $ 850 | $ 863 | $ 866 | $ 885 | $ 926 | $ 894 | $ 884
IBNR | $ 21 |  |  |  |  |  |  |  |  |
Cumulative Number of Claims | claim | 17,953 |  |  |  |  |  |  |  |  |
2014 |  |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Net Incurred Claim and Claim Adjustment Expenses [Line Items] |  |  |  |  |  |  |  |  |  |
Incurred claims and allocated claim adjustment expense, net | $ 842 | 841 | 845 | 854 | 835 | 831 | 885 | 898 | $ 878 |
IBNR | $ 29 |  |  |  |  |  |  |  |  |
Cumulative Number of Claims | claim | 17,583 |  |  |  |  |  |  |  |  |
2015 |  |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Net Incurred Claim and Claim Adjustment Expenses [Line Items] |  |  |  |  |  |  |  |  |  |
Incurred claims and allocated claim adjustment expense, net | $ 855 | 836 | 813 | 807 | 832 | 877 | 892 | $ 888 |  |
IBNR | $ 30 |  |  |  |  |  |  |  |  |
Cumulative Number of Claims | claim | 17,452 |  |  |  |  |  |  |  |  |
2016 |  |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Net Incurred Claim and Claim Adjustment Expenses [Line Items] |  |  |  |  |  |  |  |  |  |
Incurred claims and allocated claim adjustment expense, net | $ 888 | 891 | 907 | 904 | 900 | 900 | $ 901 |  |  |
IBNR | $ 57 |  |  |  |  |  |  |  |  |
Cumulative Number of Claims | claim | 17,976 |  |  |  |  |  |  |  |  |
2017 |  |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Net Incurred Claim and Claim Adjustment Expenses [Line Items] |  |  |  |  |  |  |  |  |  |
Incurred claims and allocated claim adjustment expense, net | $ 758 | 775 | 791 | 813 | 845 | $ 847 |  |  |  |
IBNR | $ 107 |  |  |  |  |  |  |  |  |
Cumulative Number of Claims | claim | 18,181 |  |  |  |  |  |  |  |  |
2018 |  |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Net Incurred Claim and Claim Adjustment Expenses [Line Items] |  |  |  |  |  |  |  |  |  |
Incurred claims and allocated claim adjustment expense, net | $ 923 | 906 | 869 | 864 | $ 850 |  |  |  |  |
IBNR | $ 142 |  |  |  |  |  |  |  |  |
Cumulative Number of Claims | claim | 19,995 |  |  |  |  |  |  |  |  |
2019 |  |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Net Incurred Claim and Claim Adjustment Expenses [Line Items] |  |  |  |  |  |  |  |  |  |
Incurred claims and allocated claim adjustment expense, net | $ 876 | 856 | 845 | $ 837 |  |  |  |  |  |
IBNR | $ 173 |  |  |  |  |  |  |  |  |
Cumulative Number of Claims | claim | 19,447 |  |  |  |  |  |  |  |  |
2020 |  |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Net Incurred Claim and Claim Adjustment Expenses [Line Items] |  |  |  |  |  |  |  |  |  |
Incurred claims and allocated claim adjustment expense, net | $ 951 | 944 | $ 930 |  |  |  |  |  |  |
IBNR | $ 408 |  |  |  |  |  |  |  |  |
Cumulative Number of Claims | claim | 19,333 |  |  |  |  |  |  |  |  |
2021 |  |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Net Incurred Claim and Claim Adjustment Expenses [Line Items] |  |  |  |  |  |  |  |  |  |
Incurred claims and allocated claim adjustment expense, net | $ 1,038 | $ 1,037 |  |  |  |  |  |  |  |
IBNR | $ 706 |  |  |  |  |  |  |  |  |
Cumulative Number of Claims | claim | 17,983 |  |  |  |  |  |  |  |  |
2022 |  |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Net Incurred Claim and Claim Adjustment Expenses [Line Items] |  |  |  |  |  |  |  |  |  |
Incurred claims and allocated claim adjustment expense, net | $ 1,120 |  |  |  |  |  |  |  |  |
IBNR | $ 1,000 |  |  |  |  |  |  |  |  |
Cumulative Number of Claims | claim | 15,327 |  |  |  |  |  |  |  |  |

X
- Definition [Line Items] for Net Incurred Claim and Claim Adjustment Expense [Table] + References No definition available. + Details
Name: | cna_NetIncurredClaimandClaimAdjustmentExpenseLineItems
Namespace Prefix: | cna_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Undiscounted amount, after reinsurance, of incurred-but-not-reported (IBNR) liabilities plus expected development on reported claims, for claims and allocated claim adjustment expense for short-duration insurance contracts. Excludes unallocated claim adjustment expense. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 40 -Section 50 -Paragraph 4E -URI https://asc.fasb.org/extlink&oid=116884468&loc=SL65671321-158438 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 40 -Section 50 -Paragraph 4D -Subparagraph (a) -URI https://asc.fasb.org/extlink&oid=116884468&loc=SL65671317-158438 + Details
Name: | us-gaap_ShortdurationInsuranceContractsIncurredButNotReportedIbnrClaimsLiabilityNet
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Undiscounted amount, after reinsurance, of incurred claims and allocated claim adjustment expense used in claims development for short-duration insurance contracts. Excludes unallocated claim adjustment expense. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 40 -Section 50 -Paragraph 4B -Subparagraph (a) -URI https://asc.fasb.org/extlink&oid=116884468&loc=SL65671311-158438 + Details
Name: | us-gaap_ShortdurationInsuranceContractsIncurredClaimsAndAllocatedClaimAdjustmentExpenseNet
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Cumulative number of reported claims for short-duration insurance contracts. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 40 -Section 50 -Paragraph 4D -Subparagraph (b) -URI https://asc.fasb.org/extlink&oid=116884468&loc=SL65671317-158438 + Details
Name: | us-gaap_ShortdurationInsuranceContractsNumberOfReportedClaims
Namespace Prefix: | us-gaap_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | instant

X
- Details
Name: | srt_ProductOrServiceAxis=cna_OtherProfessionalLiabilityandManagementLiabilityMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_StatementBusinessSegmentsAxis=cna_SpecialtySegmentMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_ShortdurationInsuranceContractsAccidentYearAxis=us-gaap_ShortdurationInsuranceContractsAccidentYear2013Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_ShortdurationInsuranceContractsAccidentYearAxis=us-gaap_ShortdurationInsuranceContractsAccidentYear2014Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_ShortdurationInsuranceContractsAccidentYearAxis=us-gaap_ShortdurationInsuranceContractsAccidentYear2015Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_ShortdurationInsuranceContractsAccidentYearAxis=us-gaap_ShortdurationInsuranceContractsAccidentYear2016Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_ShortdurationInsuranceContractsAccidentYearAxis=us-gaap_ShortDurationInsuranceContractsAccidentYear2017Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_ShortdurationInsuranceContractsAccidentYearAxis=us-gaap_ShortDurationInsuranceContractsAccidentYear2018Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_ShortdurationInsuranceContractsAccidentYearAxis=us-gaap_ShortDurationInsuranceContractAccidentYear2019Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_ShortdurationInsuranceContractsAccidentYearAxis=us-gaap_ShortDurationInsuranceContractAccidentYear2020Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_ShortdurationInsuranceContractsAccidentYearAxis=us-gaap_ShortDurationInsuranceContractAccidentYear2021Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_ShortdurationInsuranceContractsAccidentYearAxis=us-gaap_ShortDurationInsuranceContractAccidentYear2022Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |