Condensed Financial Statements Of Parent Company Condensed Statements Of Cash Flows (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
Cash Flows From Operating Activities
Net Income	$ 156	$ 174	$ 176	$ 128	$ 167	$ 183	$ 84	$ 91	$ 634	$ 525	$ 517
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization									52	51	50
Realized investment gains, net									(70)	(133)	(83)
Changes in:
Investment income receivable									(6)	(2)	(6)
Current income tax receivable/payable									(18)	2	(49)
Other assets									(39)	19	(32)
Other liabilities									44	(11)	77
Net cash provided by operating activities									1,064	873	796
Cash Flows From Investing Activities
Sale of fixed maturities									43	26	40
Call or maturity of fixed maturities									1,199	1,019	930
Sale of equity securities									342	335	178
Purchase of fixed maturities									(1,722)	(1,312)	(1,381)
Purchase of equity securities									(493)	(392)	(265)
Investment in buildings and equipment, net									(10)	(9)	(7)
Change in other invested assets, net									1	9	5
Net cash used by investing activities									(624)	(311)	(509)
Cash Flows From Financing Activities
Payments of note payable									(14)	(55)	0
Payment of cash dividends to shareholders									(366)	(278)	(263)
Shares acquired - share repurchase authorization									(53)	(21)	(52)
Proceeds from stock options exercised									24	22	25
Other									(17)	(17)	(14)
Net cash used in financing activities									(487)	(404)	(341)
Net change in cash and cash equivalents									(47)	158	(54)
Cash and cash equivalents at beginning of year				591				433	591	433	487
Cash and cash equivalents at end of year	544				591				544	591	433
Cincinnati Financial Corporation
Cash Flows From Operating Activities
Net Income									634	525	517
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization									7	7	7
Realized investment gains, net									19	(34)	(21)
Dividends from subsidiaries									447	400	378
Changes in:
Increase in equity of subsidiaries									(642)	(504)	(511)
Investment income receivable									0	(1)	(2)
Current federal income taxes									(7)	3	12
Current income tax receivable/payable									(10)	(6)	(6)
Other assets									(3)	20	(30)
Other liabilities									13	(14)	39
Intercompany receivable for operations									16	22	(39)
Net cash provided by operating activities									474	418	344
Cash Flows From Investing Activities
Call or maturity of fixed maturities									8	4	23
Sale of equity securities									54	112	75
Purchase of equity securities									(110)	(225)	(179)
Investment in buildings and equipment, net									0	(2)	(1)
Change in other invested assets, net									1	4	4
Return of capital from subsidiaries									0	0	22
Net cash used by investing activities									(47)	(107)	(56)
Cash Flows From Financing Activities
Payments of note payable									0	(55)	0
Payment of cash dividends to shareholders									(366)	(278)	(263)
Shares acquired - share repurchase authorization									(53)	(21)	(52)
Proceeds from stock options exercised									24	22	25
Other									2	2	3
Net cash used in financing activities									(393)	(330)	(287)
Net change in cash and cash equivalents									34	(19)	1
Cash and cash equivalents at beginning of year				$ 72				$ 91	72	91	90
Cash and cash equivalents at end of year	$ 106				$ 72				$ 106	$ 72	$ 91