Investments (Details) - Investment Information, Losses - USD ($) $ in Millions	Mar. 31, 2022	Dec. 31, 2021
Investment disclosure details
Continuous unrealized loss position, less than 12 months, fair value	$ 30,406	$ 14,495
Continuous unrealized loss position, less than 12 months, gross unrealized losses	2,177	266
Continuous unrealized loss position, 12 months or longer, fair value	3,535	602
Continuous unrealized loss position, 12 months or longer, gross unrealized losses	437	28
Continuous unrealized loss position, total, fair value	33,941	15,097
Continuous unrealized loss position, total, gross unrealized losses	2,614	294
Unrealized investment losses on fixed maturity investments for which fair value is less than 80% of amortized cost, total	142
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	2,344	2,438
Continuous unrealized loss position, less than 12 months, gross unrealized losses	167	32
Continuous unrealized loss position, 12 months or longer, fair value	228	5
Continuous unrealized loss position, 12 months or longer, gross unrealized losses	23	0
Continuous unrealized loss position, total, fair value	2,572	2,443
Continuous unrealized loss position, total, gross unrealized losses	190	32
Obligations of U.S. states, municipalities and political subdivisions [Member]
Investment disclosure details
Continuous unrealized loss position, less than 12 months, fair value	10,923	3,873
Continuous unrealized loss position, less than 12 months, gross unrealized losses	1,100	69
Continuous unrealized loss position, 12 months or longer, fair value	1,177	153
Continuous unrealized loss position, 12 months or longer, gross unrealized losses	163	6
Continuous unrealized loss position, total, fair value	12,100	4,026
Continuous unrealized loss position, total, gross unrealized losses	1,263	75
Debt securities issued by foreign governments [Member]
Investment disclosure details
Continuous unrealized loss position, less than 12 months, fair value	633	452
Continuous unrealized loss position, less than 12 months, gross unrealized losses	21	7
Continuous unrealized loss position, 12 months or longer, fair value	145	7
Continuous unrealized loss position, 12 months or longer, gross unrealized losses	11	0
Continuous unrealized loss position, total, fair value	778	459
Continuous unrealized loss position, total, gross unrealized losses	32	7
Mortgage-backed securities, collateralized mortgage obligations and pass-through securities [Member]
Investment disclosure details
Continuous unrealized loss position, less than 12 months, fair value	1,336	426
Continuous unrealized loss position, less than 12 months, gross unrealized losses	53	5
Continuous unrealized loss position, 12 months or longer, fair value	21	1
Continuous unrealized loss position, 12 months or longer, gross unrealized losses	1	0
Continuous unrealized loss position, total, fair value	1,357	427
Continuous unrealized loss position, total, gross unrealized losses	54	5
Corporate and all other bonds [Member]
Investment disclosure details
Continuous unrealized loss position, less than 12 months, fair value	15,170	7,306
Continuous unrealized loss position, less than 12 months, gross unrealized losses	836	153
Continuous unrealized loss position, 12 months or longer, fair value	1,964	436
Continuous unrealized loss position, 12 months or longer, gross unrealized losses	239	22
Continuous unrealized loss position, total, fair value	17,134	7,742
Continuous unrealized loss position, total, gross unrealized losses	$ 1,075	$ 175