Schedule of Benefit Obligations Weighted Average Assumptions [Line Items]

No definition available.

Name:	cinf_ScheduleOfBenefitObligationsWeightedAverageAssumptionsLineItems
Namespace Prefix:	cinf_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

The interest rate used to adjust for the time value of money.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (k)(1)
-URI http://asc.fasb.org/extlink&oid=65897934&loc=d3e1928-114920

+ Details

Name:	us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingNetPeriodicBenefitCostDiscountRate
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

An assumption as to the rate of return on plan assets reflecting the average rate of earnings expected on the funds invested or to be invested to provide for the benefits included in the benefit obligation.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Expected Long-Term Rate of Return on Plan Assets
-URI http://asc.fasb.org/extlink&oid=6512046

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (k)(3)
-URI http://asc.fasb.org/extlink&oid=65897934&loc=d3e1928-114920

+ Details

Name:	us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingNetPeriodicBenefitCostExpectedLongTermReturnOnAssets
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Expected rate of compensation increases (for pay-related plans).

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (k)(2)
-URI http://asc.fasb.org/extlink&oid=65897934&loc=d3e1928-114920

+ Details

Name:	us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingNetPeriodicBenefitCostRateOfCompensationIncrease
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	cinf_DefinedBenefitPlanByBenefitPlanCategoriesAxis=cinf_BenefitObligationsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis=us-gaap_PensionPlansDefinedBenefitMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RangeAxis=us-gaap_MinimumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RangeAxis=us-gaap_MaximumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis=us-gaap_SupplementalEmployeeRetirementPlanDefinedBenefitMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	cinf_DefinedBenefitPlanByBenefitPlanCategoriesAxis=cinf_NetPeriodicBenefitCostMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Employee Retirement Benefits (Weighted-Average Assumptions Used) (Details)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Benefit Obligations \| Pension Plan
Schedule of Benefit Obligations Weighted Average Assumptions
Discount rate	4.30%	4.55%
Benefit Obligations \| Pension Plan \| Minimum
Schedule of Benefit Obligations Weighted Average Assumptions
Rate of compensation increase	2.75%	2.75%
Benefit Obligations \| Pension Plan \| Maximum
Schedule of Benefit Obligations Weighted Average Assumptions
Rate of compensation increase	3.25%	3.25%
Benefit Obligations \| Supplemental Employee Retirement Plan
Schedule of Benefit Obligations Weighted Average Assumptions
Discount rate	4.10%	4.30%
Benefit Obligations \| Supplemental Employee Retirement Plan \| Minimum
Schedule of Benefit Obligations Weighted Average Assumptions
Rate of compensation increase	2.75%	2.75%
Benefit Obligations \| Supplemental Employee Retirement Plan \| Maximum
Schedule of Benefit Obligations Weighted Average Assumptions
Rate of compensation increase	3.25%	3.25%
Net Periodic Benefit Cost \| Pension Plan
Schedule of Benefit Obligations Weighted Average Assumptions
Discount rate	4.55%	4.25%	5.15%
Expected return on plan assets	7.25%	7.25%	7.25%
Net Periodic Benefit Cost \| Pension Plan \| Minimum
Schedule of Benefit Obligations Weighted Average Assumptions
Rate of compensation increase	2.75%	2.75%	2.75%
Net Periodic Benefit Cost \| Pension Plan \| Maximum
Schedule of Benefit Obligations Weighted Average Assumptions
Rate of compensation increase	3.25%	3.25%	3.25%
Net Periodic Benefit Cost \| Supplemental Employee Retirement Plan
Schedule of Benefit Obligations Weighted Average Assumptions
Discount rate	4.30%	4.05%	4.80%
Net Periodic Benefit Cost \| Supplemental Employee Retirement Plan \| Minimum
Schedule of Benefit Obligations Weighted Average Assumptions
Rate of compensation increase	2.75%	2.75%	2.75%
Net Periodic Benefit Cost \| Supplemental Employee Retirement Plan \| Maximum
Schedule of Benefit Obligations Weighted Average Assumptions
Rate of compensation increase	3.25%	3.25%	3.25%