|**Valuation And Qualifying Accounts**             | 12 Months Ended                                                                                                                                                                                                                                                                                                
|------------------------------------------------- | ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
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|**Valuation and Qualifying Accounts [Abstract]**  |                                                                                                                                                                                                                                                                                                                
|Valuation And Qualifying Accounts                 | Schedule VCincinnati Financial Corporation and SubsidiariesValuation and Qualifying Accounts(Dollars in millions)At December 31,201720162015Allowance for doubtful receivables:Beginning balance, January 1$5$4$3Additions charged to costs and expenses653Deductions(5)(4)(2)Ending balance, December 31$6$5$4
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|                                                  |                                                                                                                                                                                                                                                                                                                
|Cincinnati Financial Corporation and Subsidiaries
|Valuation and Qualifying Accounts                
|(Dollars in millions)                             |                                                                                                                                                                                                                                                                                                                
|                                                  |                                                                                                                                                                                                                                                                                                                
|Allowance for doubtful receivables:               |                                                                                                                                                                                                                                                                                                                
|Beginning balance, January 1                      |                                                                                                                                                                                                                                                                                                                
|Additions charged to costs and expenses           |                                                                                                                                                                                                                                                                                                                
|Deductions                                        |                                                                                                                                                                                                                                                                                                                
|Ending balance, December 31                       |                                                                                                                                                                                                                                                                                                                
|                                                  |                                                                                                                                                                                                                                                                                                                

X- DefinitionThe entire disclosure for any allowance and reserve accounts (their beginning and ending balances, as well as a reconciliation by type of activity during the period). Alternatively, disclosure of the required information may be within the footnotes to the financial statements or a supplemental schedule to the financial statements.
+ ReferencesReference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 235 -URI http://asc.fasb.org/topic&trid=2122369
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