Schedule II (Details) - Condensed Statement of Cash Flows - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Condensed Statement of Cash Flows
Net income	$ 4,999	$ 2,991	$ 2,842
Deferred federal income tax benefit	(152)	(163)	(186)
Other operating activities	556	647	45
Net cash provided by operating activities	9,074	7,711	6,465
Net sales (purchases) of short-term securities	370	(1,664)	355
Net cash used in investing activities	(7,264)	(6,821)	(3,728)
Treasury stock acquired — share repurchase authorizations	(1,003)	(958)	(2,000)
Treasury stock acquired — net employee share-based compensation	(114)	(64)	(61)
Dividends paid to shareholders	(951)	(908)	(875)
Issuance of debt	0	738	0
Issuance of common stock — employee share options	321	141	267
Net cash used in financing activities	(1,747)	(1,051)	(2,669)
Net increase (decrease) in cash and restricted cash	49	(149)	38
Cash and restricted cash at beginning of year	650	799	761
Cash and restricted cash at end of year	699	650	799
Cash received during the year for taxes	(1,310)	(201)	(817)
Cash paid during the year for interest	390	370	349
Issuance of common stock — net share settlement of employee options	32
Travelers [Member]
Condensed Statement of Cash Flows
Net income	4,999	2,991	2,842
Equity in net income of subsidiaries	(5,132)	(3,114)	(3,080)
Dividends received from consolidated subsidiaries	1,964	1,125	2,860
Capital received from subsidiaries	48	18	0
Deferred federal income tax benefit	9	17	14
Change in income taxes payable	(7)	(2)	(13)
Other operating activities	130	142	7
Net cash provided by operating activities	2,011	1,177	2,630
Net sales (purchases) of short-term securities	(254)	(88)	73
Other investments, net	(8)	(37)	(35)
Net cash used in investing activities	(262)	(125)	38
Treasury stock acquired — share repurchase authorizations	(1,003)	(958)	(2,000)
Treasury stock acquired — net employee share-based compensation	(114)	(64)	(61)
Dividends paid to shareholders	(951)	(908)	(875)
Issuance of debt	0	738	0
Issuance of common stock — employee share options	321	141	267
Net cash used in financing activities	(1,747)	(1,051)	(2,669)
Net increase (decrease) in cash and restricted cash	2	1	(1)
Cash and restricted cash at beginning of year	1	0	1
Cash and restricted cash at end of year	3	1	0
Cash received during the year for taxes	122	73	100
Cash paid during the year for interest	343	322	301
Issuance of common stock — net share settlement of employee options	$ 32	$ 0	$ 0