Schedule II (Details) - Condensed Income Statement - USD ($) $ in Millions		3 Months Ended								12 Months Ended
		Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Condensed Statement of Income
Net investment income										$ 2,468	$ 2,474	$ 2,397
Net realized investment gains (losses)	[1]									113	114	216
Total revenues		$ 8,063	$ 8,013	$ 7,834	$ 7,671	$ 7,796	$ 7,723	$ 7,477	$ 7,286	31,581	30,282	28,902
Interest expense										344	352	369
Other										4,365	4,297	4,170
Total claims and expenses		6,989	7,581	7,169	6,704	7,050	6,917	6,846	6,508	28,443	27,321	26,172
Income before income taxes		1,074	432	665	967	746	806	631	778	3,138	2,961	2,730
Income tax expense (benefit)		201	36	108	171	125	97	107	109	516	438	674
Net income of subsidiaries										0	0	0
Net income		$ 873	$ 396	$ 557	$ 796	$ 621	$ 709	$ 524	$ 669	2,622	2,523	2,056
Other-than-temporary impairment losses recognized in net realized investment gains (losses)										(4)	(1)
Other-than-temporary impairment losses recognized in net realized investment gains (losses)												(14)
Other-than-temporary impairment losses recognized in other comprehensive income (loss)											0
Other-than-temporary impairment gains recognized in other comprehensive income (loss)										1		1
Travelers [Member]
Condensed Statement of Income
Net investment income										41	32	24
Net realized investment gains (losses)										33	(13)	66
Total revenues										74	19	90
Interest expense										297	304	321
Other										21	20	25
Total claims and expenses										318	324	346
Income before income taxes										(244)	(305)	(256)
Income tax expense (benefit)										(77)	(114)	(130)
Loss before net income of subsidiaries										(167)	(191)	(126)
Net income of subsidiaries										2,789	2,714	2,190
Net income										2,622	2,523	2,064
Other-than-temporary impairment losses recognized in net realized investment gains (losses)										0	0
Other-than-temporary impairment losses recognized in net realized investment gains (losses)												0
Other-than-temporary impairment losses recognized in other comprehensive income (loss)											$ 0
Other-than-temporary impairment gains recognized in other comprehensive income (loss)										$ 0		$ 0

[1] Total other-than-temporary impairment (OTTI) losses were $(3) million, $(1) million and $(13) million for the years ended December 31, 2019, 2018 and 2017, respectively.  Of total OTTI, credit losses of $(4) million, $(1) million and $(14) million for the years ended December 31, 2019, 2018 and 2017, respectively, were recognized in net realized investment gains.  In addition, unrealized gains (losses) from other changes in total OTTI of $1 million, $0 million and $1 million for the years ended December 31, 2019, 2018 and 2017, respectively, were recognized in other comprehensive income (loss) as part of changes in net unrealized gains (losses) on investment securities having credit losses recognized in the consolidated statement of income.