Investments (Details) - Unrealized Losses - USD ($) $ in Millions	Dec. 31, 2022	Dec. 31, 2021
Investment disclosure details
Continuous unrealized loss position, less than 12 months, fair value	$ 48,184	$ 14,495
Continuous unrealized loss position, less than 12 months, gross unrealized losses	3,860	266
Continuous unrealized loss position, 12 months or longer, fair value	11,592	602
Continuous unrealized loss position, 12 months or longer, gross unrealized losses	2,492	28
Continuous unrealized loss position, total, fair value	59,776	15,097
Continuous unrealized loss position, total, gross unrealized losses	6,352	294
Unrealized investment losses on fixed maturity investments for which fair value is less than 80% of amortized cost, 3 months or less	175
Unrealized investment losses on fixed maturity investments for which fair value is less than 80% of amortized cost greater than 3 months, 6 months or less	1,350
Unrealized investment losses on fixed maturity investments for which fair value is less than 80% of amortized cost, greater than 6 months, 12 months or less	651
Unrealized investment losses on fixed maturity investments for which fair value is less than 80% of amortized cost, greater than 12 months	0
Unrealized investment losses on fixed maturity investments for which fair value is less than 80% of amortized cost, total	2,176	0
U.S. Treasury securities and obligations of U.S. government and government agencies and authorities [Member]
Investment disclosure details
Continuous unrealized loss position, less than 12 months, fair value	2,835	2,438
Continuous unrealized loss position, less than 12 months, gross unrealized losses	100	32
Continuous unrealized loss position, 12 months or longer, fair value	1,679	5
Continuous unrealized loss position, 12 months or longer, gross unrealized losses	263	0
Continuous unrealized loss position, total, fair value	4,514	2,443
Continuous unrealized loss position, total, gross unrealized losses	363	32
Unrealized investment losses on fixed maturity investments for which fair value is less than 80% of amortized cost, 3 months or less	0
Unrealized investment losses on fixed maturity investments for which fair value is less than 80% of amortized cost greater than 3 months, 6 months or less	0
Unrealized investment losses on fixed maturity investments for which fair value is less than 80% of amortized cost, greater than 6 months, 12 months or less	0
Unrealized investment losses on fixed maturity investments for which fair value is less than 80% of amortized cost, greater than 12 months	0
Unrealized investment losses on fixed maturity investments for which fair value is less than 80% of amortized cost, total	0
Obligations of U.S. states, municipalities and political subdivisions [Member]
Investment disclosure details
Continuous unrealized loss position, less than 12 months, fair value	19,251	3,873
Continuous unrealized loss position, less than 12 months, gross unrealized losses	1,975	69
Continuous unrealized loss position, 12 months or longer, fair value	3,134	153
Continuous unrealized loss position, 12 months or longer, gross unrealized losses	846	6
Continuous unrealized loss position, total, fair value	22,385	4,026
Continuous unrealized loss position, total, gross unrealized losses	2,821	75
Unrealized investment losses on fixed maturity investments for which fair value is less than 80% of amortized cost, 3 months or less	81
Unrealized investment losses on fixed maturity investments for which fair value is less than 80% of amortized cost greater than 3 months, 6 months or less	776
Unrealized investment losses on fixed maturity investments for which fair value is less than 80% of amortized cost, greater than 6 months, 12 months or less	643
Unrealized investment losses on fixed maturity investments for which fair value is less than 80% of amortized cost, greater than 12 months	0
Unrealized investment losses on fixed maturity investments for which fair value is less than 80% of amortized cost, total	1,500
Debt securities issued by foreign governments [Member]
Investment disclosure details
Continuous unrealized loss position, less than 12 months, fair value	604	452
Continuous unrealized loss position, less than 12 months, gross unrealized losses	22	7
Continuous unrealized loss position, 12 months or longer, fair value	367	7
Continuous unrealized loss position, 12 months or longer, gross unrealized losses	33	0
Continuous unrealized loss position, total, fair value	971	459
Continuous unrealized loss position, total, gross unrealized losses	55	7
Unrealized investment losses on fixed maturity investments for which fair value is less than 80% of amortized cost, 3 months or less	1
Unrealized investment losses on fixed maturity investments for which fair value is less than 80% of amortized cost greater than 3 months, 6 months or less	0
Unrealized investment losses on fixed maturity investments for which fair value is less than 80% of amortized cost, greater than 6 months, 12 months or less	0
Unrealized investment losses on fixed maturity investments for which fair value is less than 80% of amortized cost, greater than 12 months	0
Unrealized investment losses on fixed maturity investments for which fair value is less than 80% of amortized cost, total	1
Mortgage-backed securities, collateralized mortgage obligations and pass-through securities [Member]
Investment disclosure details
Continuous unrealized loss position, less than 12 months, fair value	1,414	426
Continuous unrealized loss position, less than 12 months, gross unrealized losses	128	5
Continuous unrealized loss position, 12 months or longer, fair value	316	1
Continuous unrealized loss position, 12 months or longer, gross unrealized losses	72	0
Continuous unrealized loss position, total, fair value	1,730	427
Continuous unrealized loss position, total, gross unrealized losses	200	5
Unrealized investment losses on fixed maturity investments for which fair value is less than 80% of amortized cost, 3 months or less	4
Unrealized investment losses on fixed maturity investments for which fair value is less than 80% of amortized cost greater than 3 months, 6 months or less	48
Unrealized investment losses on fixed maturity investments for which fair value is less than 80% of amortized cost, greater than 6 months, 12 months or less	0
Unrealized investment losses on fixed maturity investments for which fair value is less than 80% of amortized cost, greater than 12 months	0
Unrealized investment losses on fixed maturity investments for which fair value is less than 80% of amortized cost, total	52
Corporate and all other bonds [Member]
Investment disclosure details
Continuous unrealized loss position, less than 12 months, fair value	24,080	7,306
Continuous unrealized loss position, less than 12 months, gross unrealized losses	1,635	153
Continuous unrealized loss position, 12 months or longer, fair value	6,096	436
Continuous unrealized loss position, 12 months or longer, gross unrealized losses	1,278	22
Continuous unrealized loss position, total, fair value	30,176	7,742
Continuous unrealized loss position, total, gross unrealized losses	2,913	$ 175
Unrealized investment losses on fixed maturity investments for which fair value is less than 80% of amortized cost, 3 months or less	89
Unrealized investment losses on fixed maturity investments for which fair value is less than 80% of amortized cost greater than 3 months, 6 months or less	526
Unrealized investment losses on fixed maturity investments for which fair value is less than 80% of amortized cost, greater than 6 months, 12 months or less	8
Unrealized investment losses on fixed maturity investments for which fair value is less than 80% of amortized cost, greater than 12 months	0
Unrealized investment losses on fixed maturity investments for which fair value is less than 80% of amortized cost, total	$ 623