Schedule II (Details) - Condensed Balance Sheet - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Condensed Balance Sheet
Fixed maturities, at fair value	$ 68,134	$ 63,464
Equity securities, at fair value	425	368
Short-term securities	4,943	3,985
Investment in subsidiaries	0	0
Total assets	110,122	104,233
Debt	6,558	6,564
Total liabilities	84,179	81,339
Common stock (1,750.0 shares authorized; 255.5 and 263.7 shares issued, 255.5 and 263.6 shares outstanding)	23,469	23,144
Retained earnings	36,977	35,204
Accumulated other comprehensive income (loss)	640	(1,859)
Treasury stock, at cost (522.1 and 510.9 shares)	(35,143)	(33,595)
Total shareholders’ equity	25,943	22,894	$ 23,731
Total liabilities and shareholders’ equity	$ 110,122	$ 104,233
Common stock, shares authorized (in shares)	1,750,000,000	1,750,000,000
Common stock, shares issued (in shares)	255,500,000	263,700,000
Common stock, shares outstanding (in shares)	255,500,000	263,600,000
Treasury stock, at cost, shares (in shares)	522,100,000	510,900,000
Travelers [Member]
Condensed Balance Sheet
Fixed maturities, at fair value	$ 91	$ 84
Equity securities, at fair value	209	171
Short-term securities	1,390	1,371
Investment in subsidiaries	30,028	26,993
Other assets	336	649
Total assets	32,054	29,268
Debt	5,865	5,871
Other liabilities	239	496
Total liabilities	6,104	6,367
Common stock (1,750.0 shares authorized; 255.5 and 263.7 shares issued, 255.5 and 263.6 shares outstanding)	23,469	23,144
Retained earnings	36,984	35,211
Accumulated other comprehensive income (loss)	640	(1,859)
Treasury stock, at cost (522.1 and 510.9 shares)	(35,143)	(33,595)
Total shareholders’ equity	25,950	22,901
Total liabilities and shareholders’ equity	$ 32,054	$ 29,268
Common stock, shares authorized (in shares)	1,750,000,000	1,750,000,000
Common stock, shares issued (in shares)	255,500,000	263,700,000
Common stock, shares outstanding (in shares)	255,500,000	263,600,000
Treasury stock, at cost, shares (in shares)	522,100,000	510,900,000