Investments (Details) - Investment Information, Losses - USD ($) $ in Millions	Jun. 30, 2022	Dec. 31, 2021
Investment disclosure details
Continuous unrealized loss position, less than 12 months, fair value	$ 49,966	$ 14,495
Continuous unrealized loss position, less than 12 months, gross unrealized losses	4,406	266
Continuous unrealized loss position, 12 months or longer, fair value	3,412	602
Continuous unrealized loss position, 12 months or longer, gross unrealized losses	634	28
Continuous unrealized loss position, total, fair value	53,378	15,097
Continuous unrealized loss position, total, gross unrealized losses	5,040	294
Unrealized investment losses on fixed maturity investments for which fair value is less than 80% of amortized cost, 3 months or less	923
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	195
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	$ 1,118	0
Unrealized investment losses for securities for which fair value is less than 80% of amortized cost, as a percentage of the fixed maturity portfolio on a pre-tax basis (less than)	2.00%
Unrealized investment losses for securities for which fair value is less than 80% of amortized cost, as a percentage of shareholders' equity on an after-tax basis (less than)	5.00%
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	$ 2,506	2,438
Continuous unrealized loss position, less than 12 months, gross unrealized losses	235	32
Continuous unrealized loss position, 12 months or longer, fair value	221	5
Continuous unrealized loss position, 12 months or longer, gross unrealized losses	29	0
Continuous unrealized loss position, total, fair value	2,727	2,443
Continuous unrealized loss position, total, gross unrealized losses	264	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	19,690	3,873
Continuous unrealized loss position, less than 12 months, gross unrealized losses	2,201	69
Continuous unrealized loss position, 12 months or longer, fair value	1,117	153
Continuous unrealized loss position, 12 months or longer, gross unrealized losses	230	6
Continuous unrealized loss position, total, fair value	20,807	4,026
Continuous unrealized loss position, total, gross unrealized losses	2,431	75
Unrealized investment losses on fixed maturity investments for which fair value is less than 80% of amortized cost, 3 months or less	807
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	195
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	1,002
Debt securities issued by foreign governments [Member]
Investment disclosure details
Continuous unrealized loss position, less than 12 months, fair value	805	452
Continuous unrealized loss position, less than 12 months, gross unrealized losses	34	7
Continuous unrealized loss position, 12 months or longer, fair value	136	7
Continuous unrealized loss position, 12 months or longer, gross unrealized losses	13	0
Continuous unrealized loss position, total, fair value	941	459
Continuous unrealized loss position, total, gross unrealized losses	47	7
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
Mortgage-backed securities, collateralized mortgage obligations and pass-through securities [Member]
Investment disclosure details
Continuous unrealized loss position, less than 12 months, fair value	1,476	426
Continuous unrealized loss position, less than 12 months, gross unrealized losses	118	5
Continuous unrealized loss position, 12 months or longer, fair value	21	1
Continuous unrealized loss position, 12 months or longer, gross unrealized losses	2	0
Continuous unrealized loss position, total, fair value	1,497	427
Continuous unrealized loss position, total, gross unrealized losses	120	5
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
Corporate and all other bonds [Member]
Investment disclosure details
Continuous unrealized loss position, less than 12 months, fair value	25,489	7,306
Continuous unrealized loss position, less than 12 months, gross unrealized losses	1,818	153
Continuous unrealized loss position, 12 months or longer, fair value	1,917	436
Continuous unrealized loss position, 12 months or longer, gross unrealized losses	360	22
Continuous unrealized loss position, total, fair value	27,406	7,742
Continuous unrealized loss position, total, gross unrealized losses	2,178	$ 175
Unrealized investment losses on fixed maturity investments for which fair value is less than 80% of amortized cost, 3 months or less	116
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	$ 116