Statutory Accounting Information (Schedule Of Statutory Net Income And Statutory Surplus (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Cincinnati Insurance Company [Member]
Statutory Accounting Practices [Line Items]
SAP Net Income (Loss)	$ 418	$ 334	$ 120
Capital and Surplus	4,326	3,914
Cincinnati Casualty Company [Member]
Statutory Accounting Practices [Line Items]
SAP Net Income (Loss)	10	10	15
Capital and Surplus	317	293
Cincinnati Indemnity Company [Member]
Statutory Accounting Practices [Line Items]
SAP Net Income (Loss)	2	2	2
Capital and Surplus	82	76
Cincinnati Specialty Underwriters Insurance Company [Member]
Statutory Accounting Practices [Line Items]
SAP Net Income (Loss)	18	6	11
Capital and Surplus	228	199
Cincinnati Life Insurance Company [Member]
Statutory Accounting Practices [Line Items]
SAP Net Income (Loss)	(20)	5	(13)
Capital and Surplus	$ 247	$ 276