Condensed Financial Statements Of Parent Company Condensed Statements Of Income (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Revenues
Investment income, net of expenses									$ 595	$ 572	$ 549
Total									124	70	133
Other revenues									5	7	8
Total revenues	$ 1,312	$ 1,402	$ 1,371	$ 1,364	$ 1,263	$ 1,278	$ 1,316	$ 1,285	5,449	5,142	4,945
Expenses
Interest expense									53	53	53
Other expenses									12	13	14
Total expenses									4,637	4,261	4,224
Income (Loss) Before Income Taxes and Earnings of Subsidiaries	128	253	166	265	216	243	248	174	812	881	721
Benefit for income taxes									221	247	196
Net Income	$ 100	$ 180	$ 123	$ 188	$ 156	$ 174	$ 176	$ 128	591	634	525
Cincinnati Financial Corporation
Revenues
Investment income, net of expenses									56	53	46
Total									27	(19)	34
Other revenues									15	15	16
Total revenues									98	49	96
Expenses
Interest expense									52	52	52
Other expenses									27	28	28
Total expenses									79	80	80
Income (Loss) Before Income Taxes and Earnings of Subsidiaries									19	(31)	16
Benefit for income taxes									(6)	(23)	(5)
Net Income (Loss) Before Earnings of Subsidiaries									25	(8)	21
Increase in equity of subsidiaries									566	642	504
Net Income									$ 591	$ 634	$ 525