XML 47 R36.htm IDEA: XBRL DOCUMENT
v3.21.2

Investments (Credit quality indicator) (Details) - Mortgage loans $ in Millions | Sep. 30, 2021 USD ($)
--- | ---
Debt Securities, Available-for-sale [Line Items] |
2021 | $ 63
2020 | 161
2019 | 282
2018 | 86
2017 | 169
Prior | 296
Total | 1,057
DSCR ≥1.6x | LTV less than 55% |
Debt Securities, Available-for-sale [Line Items] |
2021 | 8
2020 | 75
2019 | 16
2018 | 37
2017 | 116
Prior | 203
Total | 455
DSCR ≥1.6x | LTV 55% to 65% |
Debt Securities, Available-for-sale [Line Items] |
2021 | 0
2020 | 38
2019 | 15
2018 | 18
2017 | 0
Prior | 1
Total | 72
DSCR ≥1.6x | LTV greater than 65% |
Debt Securities, Available-for-sale [Line Items] |
2021 | 17
2020 | 0
2019 | 14
2018 | 7
2017 | 0
Prior | 23
Total | 61
DSCR 1.2x - 1.6x | LTV less than 55% |
Debt Securities, Available-for-sale [Line Items] |
2021 | 13
2020 | 15
2019 | 95
2018 | 0
2017 | 5
Prior | 58
Total | 186
DSCR 1.2x - 1.6x | LTV 55% to 65% |
Debt Securities, Available-for-sale [Line Items] |
2021 | 25
2020 | 0
2019 | 0
2018 | 24
2017 | 10
Prior | 4
Total | 63
DSCR 1.2x - 1.6x | LTV greater than 65% |
Debt Securities, Available-for-sale [Line Items] |
2021 | 0
2020 | 24
2019 | 9
2018 | 0
2017 | 8
Prior | 0
Total | 41
DSCR ≤1.2 | LTV less than 55% |
Debt Securities, Available-for-sale [Line Items] |
2021 | 0
2020 | 0
2019 | 35
2018 | 0
2017 | 30
Prior | 0
Total | 65
DSCR ≤1.2 | LTV 55% to 65% |
Debt Securities, Available-for-sale [Line Items] |
2021 | 0
2020 | 0
2019 | 42
2018 | 0
2017 | 0
Prior | 0
Total | 42
DSCR ≤1.2 | LTV greater than 65% |
Debt Securities, Available-for-sale [Line Items] |
2021 | 0
2020 | 9
2019 | 56
2018 | 0
2017 | 0
Prior | 7
Total | $ 72

X
- Definition Amount excluding accrued interest, before allowance for credit loss, of financing receivable. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 20 -Section 50 -Paragraph 5 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=124255953&loc=SL82919230-210447 Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 20 -Section 45 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=124255206&loc=SL82895884-210446 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 20 -Section 50 -Paragraph 3B -URI http://asc.fasb.org/extlink&oid=124255953&loc=SL120267963-210447 + Details
Name: | us-gaap_FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLoss
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amount excluding accrued interest of financing receivable originated more than five years prior to current fiscal year. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 20 -Section 50 -Paragraph 3B -URI http://asc.fasb.org/extlink&oid=124255953&loc=SL120267963-210447 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 20 -Section 50 -Paragraph 6 -URI http://asc.fasb.org/extlink&oid=124255953&loc=SL82919232-210447 Reference 3: http://www.xbrl.org/2003/role/exampleRef -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 20 -Section 55 -Paragraph 79 -URI http://asc.fasb.org/extlink&oid=124267575&loc=SL82922352-210448 + Details
Name: | us-gaap_FinancingReceivableExcludingAccruedInterestOriginatedMoreThanFiveYearsBeforeCurrentFiscalYear
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amount excluding accrued interest of financing receivable originated four years prior to current fiscal year. + References Reference 1: http://www.xbrl.org/2003/role/exampleRef -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 20 -Section 55 -Paragraph 79 -URI http://asc.fasb.org/extlink&oid=124267575&loc=SL82922352-210448 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 20 -Section 50 -Paragraph 6 -URI http://asc.fasb.org/extlink&oid=124255953&loc=SL82919232-210447 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 20 -Section 50 -Paragraph 3B -URI http://asc.fasb.org/extlink&oid=124255953&loc=SL120267963-210447 + Details
Name: | us-gaap_FinancingReceivableExcludingAccruedInterestYearFiveOriginatedFourYearsBeforeCurrentFiscalYear
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amount excluding accrued interest of financing receivable originated three years prior to current fiscal year. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 20 -Section 50 -Paragraph 6 -URI http://asc.fasb.org/extlink&oid=124255953&loc=SL82919232-210447 Reference 2: http://www.xbrl.org/2003/role/exampleRef -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 20 -Section 55 -Paragraph 79 -URI http://asc.fasb.org/extlink&oid=124267575&loc=SL82922352-210448 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 20 -Section 50 -Paragraph 3B -URI http://asc.fasb.org/extlink&oid=124255953&loc=SL120267963-210447 + Details
Name: | us-gaap_FinancingReceivableExcludingAccruedInterestYearFourOriginatedThreeYearsBeforeCurrentFiscalYear
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amount excluding accrued interest of financing receivable originated in current fiscal year. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 20 -Section 50 -Paragraph 6 -URI http://asc.fasb.org/extlink&oid=124255953&loc=SL82919232-210447 Reference 2: http://www.xbrl.org/2003/role/exampleRef -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 20 -Section 55 -Paragraph 79 -URI http://asc.fasb.org/extlink&oid=124267575&loc=SL82922352-210448 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 20 -Section 50 -Paragraph 3B -URI http://asc.fasb.org/extlink&oid=124255953&loc=SL120267963-210447 + Details
Name: | us-gaap_FinancingReceivableExcludingAccruedInterestYearOneOriginatedCurrentFiscalYear
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amount excluding accrued interest of financing receivable originated two years prior to current fiscal year. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 20 -Section 50 -Paragraph 3B -URI http://asc.fasb.org/extlink&oid=124255953&loc=SL120267963-210447 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 20 -Section 50 -Paragraph 6 -URI http://asc.fasb.org/extlink&oid=124255953&loc=SL82919232-210447 Reference 3: http://www.xbrl.org/2003/role/exampleRef -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 20 -Section 55 -Paragraph 79 -URI http://asc.fasb.org/extlink&oid=124267575&loc=SL82922352-210448 + Details
Name: | us-gaap_FinancingReceivableExcludingAccruedInterestYearThreeOriginatedTwoYearsBeforeCurrentFiscalYear
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amount excluding accrued interest of financing receivable originated in fiscal year prior to current fiscal year. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 20 -Section 50 -Paragraph 3B -URI http://asc.fasb.org/extlink&oid=124255953&loc=SL120267963-210447 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 20 -Section 50 -Paragraph 6 -URI http://asc.fasb.org/extlink&oid=124255953&loc=SL82919232-210447 Reference 3: http://www.xbrl.org/2003/role/exampleRef -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 20 -Section 55 -Paragraph 79 -URI http://asc.fasb.org/extlink&oid=124267575&loc=SL82922352-210448 + Details
Name: | us-gaap_FinancingReceivableExcludingAccruedInterestYearTwoOriginatedFiscalYearBeforeCurrentFiscalYear
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

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_ScheduleOfAvailableForSaleSecuritiesLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | us-gaap_FinancialInstrumentAxis=us-gaap_MortgagesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | cna_DebtServiceCoverageAxis=cna_DebtServiceCoverageRatioGreaterThanOrEqualto1.6Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_LoanToValueAxis=cna_DebtToValueRatioLessThan55PercentMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_LoanToValueAxis=cna_DebtToValueRatioEqualTo55To65PercentMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_LoanToValueAxis=cna_DebtToValueRatioGreaterThan65PercentMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | cna_DebtServiceCoverageAxis=cna_DebtServiceCoverageRatioBetween1.2And1.6Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | cna_DebtServiceCoverageAxis=cna_DebtServiceCoverageRatioLessThanOrEqualTo1.2Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |