Condensed Financial Statements Of Parent Company Condensed Statements Of Comprehensive Income (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Condensed Financial Statements, Captions
Net Income	$ 156	$ 174	$ 176	$ 128	$ 167	$ 183	$ 84	$ 91	$ 634	$ 525	$ 517
Unrealized (losses) and gains on investments available-for-sale									(405)	250	299
Unrealized (losses) and gains on investments available-for-sale, investments held by subsidiaries and other									(612)	388	494
Amortization of pension actuarial losses and (gains) and prior service cost									(6)	(18)	83
Other comprehensive (loss) income before tax									(618)	370	577
Income taxes on above of other comprehensive (loss) income									(218)	130	202
Other comprehensive (loss) income, net of tax									(400)	240	375
Comprehensive Income									234	765	892
Cincinnati Financial Corporation
Condensed Financial Statements, Captions
Net Income									634	525	517
Unrealized (losses) and gains on investments available-for-sale									(111)	150	303
Unrealized (losses) and gains on investments held by subsidiaries									(444)	367	240
Reclassification adjustment for gains and (losses) included in net income									19	(34)	(21)
Reclassification adjustment for (gains) included in net income on subsidiaries									(89)	(99)	(62)
Unrealized gains and (losses) on other									0	7	(1)
Unrealized gains and (losses) on other subsidiaries									$ 13	$ (3)	$ 35