XML 59 R49.htm IDEA: XBRL DOCUMENT
v3.25.3

Life Policy and Investment Contract Reserves (Narrative) (Details) - USD ($) | 9 Months Ended
--- | ---
Sep. 30, 2025 | Sep. 30, 2024
Life policy reserves: |  |
Liability for Future Policy Benefit, after Reinsurance [Abstract] |  |
Discount Rate Assumption Changes included in Impact of flooring at Cohort Level | $ 2,000,000 | $ 3,000,000
Life Insurance Segment |  |
Liability for Future Policy Benefit, after Reinsurance [Abstract] |  |
Liability for Future Policy Benefit, Adverse Development, Expense | $ 0 | $ 0

X
- Definition Discount Rate Assumption Changes included in Impact of flooring at Cohort Level + References No definition available. + Details
Name: | cinf_DiscountRateAssumptionChangesIncludedInImpactOfFlooringAtCohortLevel
Namespace Prefix: | cinf_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Amount of expense for adverse development on liability of future policy benefit from net premium exceeding gross premium. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 944 -SubTopic 40 -Name Accounting Standards Codification -Section 50 -Paragraph 6 -Subparagraph (d) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480081/944-40-50-6 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Topic 944 -SubTopic 40 -Name Accounting Standards Codification -Section 65 -Paragraph 2 -Subparagraph (g)(2)(iii) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480016/944-40-65-2 + Details
Name: | us-gaap_LiabilityForFuturePolicyBenefitAdverseDevelopmentExpense
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- References No definition available. + Details
Name: | us-gaap_LiabilityForFuturePolicyBenefitAfterReinsuranceAbstract
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | us-gaap_EquitySecuritiesByIndustryAxis=cinf_LifePolicyReservesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_EquitySecuritiesByIndustryAxis=cinf_LifeInsuranceMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |