Condensed Financial Statements Of Parent Company Condensed Statements Of Cash Flows (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Cash Flows From Operating Activities
Net Income	$ 525	$ 517	$ 421
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	51	50	44
Realized investment gains, net	(133)	(83)	(42)
Changes in:
Investment income receivable	(2)	(6)	4
Current income tax receivable/payable	2	(49)	79
Other assets	19	(32)	(4)
Other liabilities	(11)	77	78
Net cash provided by operating activities	873	796	638
Cash Flows From Investing Activities
Sale of fixed maturities	26	40	144
Call or maturity of fixed maturities	1,019	930	927
Sale of equity securities	335	178	216
Purchase of fixed maturities	(1,312)	(1,381)	(1,166)
Purchase of equity securities	(392)	(265)	(425)
Investment in buildings and equipment, net	(9)	(7)	(6)
Change in other invested assets, net	9	5	5
Net cash (used) provided by investing activities	(311)	(509)	(304)
Cash Flows From Financing Activities
Payments on note payable	(55)	0	0
Payment of cash dividends to shareholders	(278)	(263)	(256)
Purchase of treasury shares	(21)	(52)	0
Proceeds from stock options exercised	22	25	10
Other	(17)	(14)	(13)
Net cash used in financing activities	(404)	(341)	(285)
Net change in cash and cash equivalents	158	(54)	49
Cash and cash equivalents at beginning of year	433	487	438
Cash and cash equivalents at end of year	591	433	487
Cincinnati Financial Corporation
Cash Flows From Operating Activities
Net Income	525	517	421
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	7	7	7
Realized investment gains, net	(34)	(21)	(34)
Dividends from subsidiaries	400	378	300
Changes in:
Increase in equity of subsidiaries	(504)	(511)	(406)
Investment income receivable	(1)	(2)	1
Current federal income taxes	3	12	(24)
Current income tax receivable/payable	(6)	(6)	18
Other assets	20	(30)	(2)
Other liabilities	(14)	39	7
Intercompany receivable for operations	22	(39)	0
Net cash provided by operating activities	418	344	288
Cash Flows From Investing Activities
Sale of fixed maturities	0	0	114
Call or maturity of fixed maturities	4	23	13
Sale of equity securities	112	75	111
Purchase of fixed maturities	0	0	(1)
Purchase of equity securities	(225)	(179)	(212)
Investment in buildings and equipment, net	(2)	(1)	(1)
Change in other invested assets, net	4	4	4
Return of capital from subsidiaries	0	22	0
Net cash (used) provided by investing activities	(107)	(56)	28
Cash Flows From Financing Activities
Payments on note payable	(55)	0	0
Payment of cash dividends to shareholders	(278)	(263)	(256)
Purchase of treasury shares	(21)	(52)	0
Proceeds from stock options exercised	22	25	9
Net transfers to subsidiaries	0	0	(2)
Other	2	3	3
Net cash used in financing activities	(330)	(287)	(246)
Net change in cash and cash equivalents	(19)	1	70
Cash and cash equivalents at beginning of year	91	90	20
Cash and cash equivalents at end of year	$ 72	$ 91	$ 90