Schedule II (Details) - Condensed Balance Sheet - USD ($) shares in Millions, $ in Millions	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Condensed Balance Sheet
Fixed maturities, at fair value	$ 74,003	$ 68,134
Equity securities, at fair value	453	425
Short-term securities	5,511	4,943
Total assets	116,764	110,122
Debt	6,550	6,558
Total liabilities	87,563	84,179
Common stock (1,750.0 shares authorized; 252.4 and 255.5 shares issued and outstanding)	23,743	23,469
Retained earnings	38,771	36,977
Accumulated other comprehensive income	2,502	640
Treasury stock, at cost (527.3 and 522.1 shares)	(35,815)	(35,143)
Total shareholders’ equity	29,201	25,943	$ 22,894
Total liabilities and shareholders’ equity	$ 116,764	$ 110,122
Common stock, shares authorized (in shares)	1,750.0	1,750.0
Common stock, shares issued (in shares)	252.4	255.5
Common stock, shares outstanding (in shares)	252.4	255.5
Treasury stock, at cost (in shares)	527.3	522.1
Travelers [Member]
Condensed Balance Sheet
Fixed maturities, at fair value	$ 94	$ 91
Equity securities, at fair value	241	209
Short-term securities	1,646	1,390
Investment in subsidiaries	33,015	30,028
Other assets	330	336
Total assets	35,326	32,054
Debt	5,856	5,865
Other liabilities	262	239
Total liabilities	6,118	6,104
Common stock (1,750.0 shares authorized; 252.4 and 255.5 shares issued and outstanding)	23,743	23,469
Retained earnings	38,778	36,984
Accumulated other comprehensive income	2,502	640
Treasury stock, at cost (527.3 and 522.1 shares)	(35,815)	(35,143)
Total shareholders’ equity	29,208	25,950
Total liabilities and shareholders’ equity	$ 35,326	$ 32,054
Common stock, shares authorized (in shares)	1,750.0	1,750.0
Common stock, shares issued (in shares)	252.4	255.5
Common stock, shares outstanding (in shares)	252.4	255.5
Treasury stock, at cost (in shares)	527.3	522.1