Asbestos and environmental reinsurance retention.

No definition available.

Name:	cinf_AsbestosAndEnvironmentalReinsuranceRetention
Namespace Prefix:	cinf_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Increase in the recovery of liability for unpaid claims and claims adjustment expense, incurred claims, prior years.

+ References

No definition available.

+ Details

Name:	cinf_IncreaseInRecoveryOfLiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseIncurredClaimsPriorYears
Namespace Prefix:	cinf_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Carrying amount as of the balance sheet date of reserves for the costs of settling insured claims and costs incurred in the claims settlement process attributable to environmental claims related to mold.

+ References

No definition available.

+ Details

Name:	cinf_LiabilityForAsbestosAndEnvironmentalClaimsMold
Namespace Prefix:	cinf_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Percentage of reserves for asbestos and environmental claims to total loss and loss expense reserves.

+ References

No definition available.

+ Details

Name:	cinf_PercentageOfReservesForAsbestosAndEnvironmentalClaims
Namespace Prefix:	cinf_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Recovery of Liability for Unpaid Claims and Claims Adjustment Expense, Incurred Claims, Prior Years

+ References

No definition available.

+ Details

Name:	cinf_RecoveryOfLiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseIncurredClaimsPriorYears
Namespace Prefix:	cinf_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Carrying amount as of the balance sheet date of reserves for the costs of settling insured claims and costs incurred in the claims settlement process attributable to asbestos and environmental claims, net of estimated reinsurance recoveries.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 944

-SubTopic 40

-Section 50

-Paragraph 3

-Subparagraph (a)

-URI http://asc.fasb.org/extlink&oid=6482485&loc=d3e14764-158437

+ Details

Name:	us-gaap_LiabilityForAsbestosAndEnvironmentalClaimsNet
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The amount needed to reflect the estimated ultimate cost of settling claims relating to insured events that have occurred on or before the balance sheet date, whether or not reported to the insurer at that date.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 944

-SubTopic 40

-Section 50

-Paragraph 3

-Subparagraph (a),(b),(c)

-URI http://asc.fasb.org/extlink&oid=6482485&loc=d3e14764-158437

+ Details

Name:	us-gaap_LiabilityForClaimsAndClaimsAdjustmentExpense
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Details

Name:	us-gaap_SupplementalInformationForPropertyCasualtyInsuranceUnderwritersLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

Property Casualty Loss And Loss Expenses (Narrative) (Details) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Supplemental Information for Property, Casualty Insurance Underwriters [Line Items]
Favorable reserve development on prior accident years	$ 147,000,000	$ 396,000,000	$ 285,000,000
Net loss and loss expense reserves for asbestos and environmental claims	77,000,000	67,000,000
Environmental claims related to mold	51,000,000	54,000,000
Percentage of reserves for asbestos and environmental claims	1.90%	1.80%
Maximum [Member]
Supplemental Information for Property, Casualty Insurance Underwriters [Line Items]
Reinsurance retention	500,000
Life and Health Loss Reserves [Member]
Supplemental Information for Property, Casualty Insurance Underwriters [Line Items]
Reserve for loss and loss expenses	70,000,000	61,000,000	59,000,000
Homeowner [Member]
Supplemental Information for Property, Casualty Insurance Underwriters [Line Items]
Favorable reserve development on prior accident years	19,000,000	52,000,000
Commercial Lines [Member]
Supplemental Information for Property, Casualty Insurance Underwriters [Line Items]
Favorable reserve development on prior accident years	95,000,000	292,000,000	234,000,000
Increase in favorable reserve developement on prior accident	249,000,000	111,000,000
Commercial Lines [Member] \| Workers' Compensation [Member]
Supplemental Information for Property, Casualty Insurance Underwriters [Line Items]
Favorable reserve development on prior accident years	14,000,000	74,000,000	97,000,000
Commercial Lines [Member] \| Catastrophe Development [Member]
Supplemental Information for Property, Casualty Insurance Underwriters [Line Items]
Favorable reserve development on prior accident years		39,000,000
Commercial Lines [Member] \| Commerical Casualty Business [Member]
Supplemental Information for Property, Casualty Insurance Underwriters [Line Items]
Favorable reserve development on prior accident years	70,000,000	177,000,000	132,000,000
Commercial Lines [Member] \| Commercial Property Segment [Member]
Supplemental Information for Property, Casualty Insurance Underwriters [Line Items]
Favorable reserve development on prior accident years	$ 22,000,000