Condensed Financial Statements Of Parent Company Condensed Statements Of 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
Revenues
Investment income, net of expenses									$ 572	$ 549	$ 529
Total									70	133	83
Other revenues									7	8	9
Total revenues	$ 1,263	$ 1,278	$ 1,316	$ 1,285	$ 1,262	$ 1,280	$ 1,214	$ 1,189	5,142	4,945	4,531
Expenses
Interest expense									53	53	54
Other expenses									13	14	15
Total expenses									4,261	4,224	3,817
Income (Loss) Before Income Taxes and Earnings of Subsidiaries	216	243	248	174	236	259	107	119	881	721	714
Benefit for income taxes									247	196	197
Net Income	$ 156	$ 174	$ 176	$ 128	$ 167	$ 183	$ 84	$ 91	634	525	517
Cincinnati Financial Corporation
Revenues
Investment income, net of expenses									53	46	41
Total									(19)	34	21
Other revenues									15	16	15
Total revenues									49	96	77
Expenses
Interest expense									52	52	53
Other expenses									28	28	29
Total expenses									80	80	82
Income (Loss) Before Income Taxes and Earnings of Subsidiaries									(31)	16	(5)
Benefit for income taxes									(23)	(5)	(11)
Net Income (Loss) Before Earnings of Subsidiaries									(8)	21	6
Increase in equity of subsidiaries									642	504	511
Net Income									$ 634	$ 525	$ 517