| **Share-Based Associate Compensation Plans (Options Outstanding And Exercisable) (Details) (USD $)In Thousands, except Per Share data, unless otherwise specified** | 12 Months Ended                                                                                                                                                                                                                        |                                                                                                                        |
|---------------------------------------------------------------------------------------------------------------------------------------------------------------------|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|------------------------------------------------------------------------------------------------------------------------|
||
| **Options Outstanding [Abstract]**                                                                                                                                  |                                                                                                                                                                                                                                   |                                                                                                                   |
| Shares                                                                                                                                                              | 4,958us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber                                                                                                                                         | 6,332us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber                         |
| Weighted-average remaining contractual life                                                                                                                         | 4 years 1 month 30 days                                                                                                                                                                                                                |                                                                                                                   |
| Weighted-average exercise price                                                                                                                                     | $ 39.10us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice                                                                                                                 | $ 38.39us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice |
| **Options Exercisable [Abstract]**                                                                                                                                  |                                                                                                                                                                                                                                   |                                                                                                                   |
| Shares                                                                                                                                                              | 4,165us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableNumber                                                                                                                                         |                                                                                                                   |
| Weighted-average exercise price                                                                                                                                     | $ 38.17us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableWeightedAverageExercisePrice                                                                                                                 |                                                                                                                   |
| Range 1                                                                                                                                                             |                                                                                                                                                                                                                                   |                                                                                                                   |
| **Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range**                                                                      |                                                                                                                                                                                                                                   |                                                                                                                   |
| Range of per-share exercise prices, lower limit                                                                                                                     | $ 25.00us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLowerRangeLimit/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis= cinf_Range1Member            |                                                                                                                   |
| Range of per-share exercise prices, upper limit                                                                                                                     | $ 29.99us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeUpperRangeLimit/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis= cinf_Range1Member            |                                                                                                                   |
| **Options Outstanding [Abstract]**                                                                                                                                  |                                                                                                                                                                                                                                   |                                                                                                                   |
| Shares                                                                                                                                                              | 731us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis= cinf_Range1Member                           |                                                                                                                   |
| Weighted-average remaining contractual life                                                                                                                         | 4 years 6 months 28 days                                                                                                                                                                                                               |                                                                                                                   |
| Weighted-average exercise price                                                                                                                                     | $ 26.58us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis= cinf_Range1Member |                                                                                                                   |
| **Options Exercisable [Abstract]**                                                                                                                                  |                                                                                                                                                                                                                                   |                                                                                                                   |
| Shares                                                                                                                                                              | 731us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableNumber/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis= cinf_Range1Member                           |                                                                                                                   |
| Weighted-average exercise price                                                                                                                                     | $ 26.58us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableWeightedAverageExercisePrice/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis= cinf_Range1Member |                                                                                                                   |
| Range 2                                                                                                                                                             |                                                                                                                                                                                                                                   |                                                                                                                   |
| **Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range**                                                                      |                                                                                                                                                                                                                                   |                                                                                                                   |
| Range of per-share exercise prices, lower limit                                                                                                                     | $ 30.00us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLowerRangeLimit/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis= cinf_Range2Member            |                                                                                                                   |
| Range of per-share exercise prices, upper limit                                                                                                                     | $ 34.99us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeUpperRangeLimit/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis= cinf_Range2Member            |                                                                                                                   |
| **Options Outstanding [Abstract]**                                                                                                                                  |                                                                                                                                                                                                                                   |                                                                                                                   |
| Shares                                                                                                                                                              | 675us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis= cinf_Range2Member                           |                                                                                                                   |
| Weighted-average remaining contractual life                                                                                                                         | 6 years 5 days                                                                                                                                                                                                                         |                                                                                                                   |
| Weighted-average exercise price                                                                                                                                     | $ 33.96us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis= cinf_Range2Member |                                                                                                                   |
| **Options Exercisable [Abstract]**                                                                                                                                  |                                                                                                                                                                                                                                   |                                                                                                                   |
| Shares                                                                                                                                                              | 675us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableNumber/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis= cinf_Range2Member                           |                                                                                                                   |
| Weighted-average exercise price                                                                                                                                     | $ 33.96us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableWeightedAverageExercisePrice/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis= cinf_Range2Member |                                                                                                                   |
| Range 3                                                                                                                                                             |                                                                                                                                                                                                                                   |                                                                                                                   |
| **Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range**                                                                      |                                                                                                                                                                                                                                   |                                                                                                                   |
| Range of per-share exercise prices, lower limit                                                                                                                     | $ 35.00us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLowerRangeLimit/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis= cinf_Range3Member            |                                                                                                                   |
| Range of per-share exercise prices, upper limit                                                                                                                     | $ 39.99us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeUpperRangeLimit/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis= cinf_Range3Member            |                                                                                                                   |
| **Options Outstanding [Abstract]**                                                                                                                                  |                                                                                                                                                                                                                                   |                                                                                                                   |
| Shares                                                                                                                                                              | 981us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis= cinf_Range3Member                           |                                                                                                                   |
| Weighted-average remaining contractual life                                                                                                                         | 4 years 10 months 24 days                                                                                                                                                                                                              |                                                                                                                   |
| Weighted-average exercise price                                                                                                                                     | $ 37.31us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis= cinf_Range3Member |                                                                                                                   |
| **Options Exercisable [Abstract]**                                                                                                                                  |                                                                                                                                                                                                                                   |                                                                                                                   |
| Shares                                                                                                                                                              | 824us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableNumber/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis= cinf_Range3Member                           |                                                                                                                   |
| Weighted-average exercise price                                                                                                                                     | $ 37.63us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableWeightedAverageExercisePrice/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis= cinf_Range3Member |                                                                                                                   |
| Range 4                                                                                                                                                             |                                                                                                                                                                                                                                   |                                                                                                                   |
| **Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range**                                                                      |                                                                                                                                                                                                                                   |                                                                                                                   |
| Range of per-share exercise prices, lower limit                                                                                                                     | $ 40.00us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLowerRangeLimit/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis= cinf_Range4Member            |                                                                                                                   |
| Range of per-share exercise prices, upper limit                                                                                                                     | $ 44.99us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeUpperRangeLimit/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis= cinf_Range4Member            |                                                                                                                   |
| **Options Outstanding [Abstract]**                                                                                                                                  |                                                                                                                                                                                                                                   |                                                                                                                   |
| Shares                                                                                                                                                              | 1,258us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis= cinf_Range4Member                         |                                                                                                                   |
| Weighted-average remaining contractual life                                                                                                                         | 3 years 1 month 2 days                                                                                                                                                                                                                 |                                                                                                                   |
| Weighted-average exercise price                                                                                                                                     | $ 43.58us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis= cinf_Range4Member |                                                                                                                   |
| **Options Exercisable [Abstract]**                                                                                                                                  |                                                                                                                                                                                                                                   |                                                                                                                   |
| Shares                                                                                                                                                              | 1,015us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableNumber/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis= cinf_Range4Member                         |                                                                                                                   |
| Weighted-average exercise price                                                                                                                                     | $ 43.32us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableWeightedAverageExercisePrice/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis= cinf_Range4Member |                                                                                                                   |
| Range 5                                                                                                                                                             |                                                                                                                                                                                                                                   |                                                                                                                   |
| **Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range**                                                                      |                                                                                                                                                                                                                                   |                                                                                                                   |
| Range of per-share exercise prices, lower limit                                                                                                                     | $ 45.00us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLowerRangeLimit/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis= cinf_Range5Member            |                                                                                                                   |
| Range of per-share exercise prices, upper limit                                                                                                                     | $ 49.99us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeUpperRangeLimit/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis= cinf_Range5Member            |                                                                                                                   |
| **Options Outstanding [Abstract]**                                                                                                                                  |                                                                                                                                                                                                                                   |                                                                                                                   |
| Shares                                                                                                                                                              | 1,313us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis= cinf_Range5Member                         |                                                                                                                   |
| Weighted-average remaining contractual life                                                                                                                         | 3 years 6 months 1 day                                                                                                                                                                                                                 |                                                                                                                   |
| Weighted-average exercise price                                                                                                                                     | $ 45.73us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis= cinf_Range5Member |                                                                                                                   |
| **Options Exercisable [Abstract]**                                                                                                                                  |                                                                                                                                                                                                                                   |                                                                                                                   |
| Shares                                                                                                                                                              | 920us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableNumber/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis= cinf_Range5Member                           |                                                                                                                   |
| Weighted-average exercise price                                                                                                                                     | $ 45.26us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableWeightedAverageExercisePrice/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis= cinf_Range5Member |                                                                                                                   |

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| - Definition
The number of shares into which fully or partially vested stock options outstanding as of the balance sheet date can be currently converted under the option plan.
+ References
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|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
The weighted-average price as of the balance sheet date at which grantees can acquire the shares reserved for issuance on vested portions of options outstanding and currently exercisable under the stock option plan.
+ References
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|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Number of options outstanding, including both vested and non-vested options.
+ References
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|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Weighted average price at which grantees can acquire the shares reserved for issuance under the stock option plan.
+ References
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|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Weighted average remaining contractual term for option awards outstanding, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.
+ References
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|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
The floor of a customized range of exercise prices for purposes of disclosing shares potentially issuable under outstanding stock option awards on all stock option plans and other required information pertaining to awards in the customized range.
+ References
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|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
The ceiling of a customized range of exercise prices for purposes of disclosing shares potentially issuable under outstanding stock option awards on all stock option plans and other required information pertaining to awards in the customized range.
+ References
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