Condensed Financial Statements Of Parent Company Condensed Balance Sheets (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Investments
Fixed maturities, at fair value (amortized cost: 2020—$69; 2019—$49)	$ 12,338	$ 11,698
Equity securities, at fair value (cost: 2020—$1,607; 2019—$1,427)	8,856	7,752
Other invested assets	348	296
Total investments	21,542	19,746
Cash and cash equivalents	900	767	$ 784	$ 657
Investment income receivable	136	133
Land, building and equipment, net, for company use (accumulated depreciation: 2020—$138; 2019—$129)	213	207
Other assets	438	381
Total assets	27,542	25,408
Liabilities
Deferred federal income tax	1,555	1,311
Long-term debt	788	788
Other liabilities	982	928
Total liabilities	16,753	15,544
Shareholders' Equity
Common stock	397	397
Paid-in capital	1,328	1,306
Retained earnings	10,085	9,257
Accumulated other comprehensive income	769	448
Treasury stock at cost	(1,790)	(1,544)
Total shareholders' equity	10,789	9,864	7,833
Total liabilities and shareholders' equity	27,542	25,408
Cincinnati Financial Corporation
Investments
Fixed maturities, at fair value (amortized cost: 2020—$69; 2019—$49)	68	49
Equity securities, at fair value (cost: 2020—$1,607; 2019—$1,427)	3,687	3,069
Other invested assets	145	103
Total investments	3,900	3,221
Cash and cash equivalents	16	197	$ 209	$ 199
Equity in net assets of subsidiaries	7,982	7,424
Investment income receivable	8	7
Land, building and equipment, net, for company use (accumulated depreciation: 2020—$138; 2019—$129)	143	141
Income tax receivable	5	2
Other assets	53	61
Due from subsidiaries	110	107
Total assets	12,217	11,160
Liabilities
Dividends declared but unpaid	97	91
Deferred federal income tax	429	345
Long-term debt	788	788
Other liabilities	114	72
Total liabilities	1,428	1,296
Shareholders' Equity
Common stock	397	397
Paid-in capital	1,328	1,306
Retained earnings	10,085	9,257
Accumulated other comprehensive income	769	448
Treasury stock at cost	(1,790)	(1,544)
Total shareholders' equity	10,789	9,864
Total liabilities and shareholders' equity	$ 12,217	$ 11,160