Investments (Details) - Investment Information, Losses - USD ($) $ in Millions	Sep. 30, 2022	Dec. 31, 2021
Investment disclosure details
Continuous unrealized loss position, less than 12 months, fair value	$ 55,662	$ 14,495
Continuous unrealized loss position, less than 12 months, gross unrealized losses	5,859	266
Continuous unrealized loss position, 12 months or longer, fair value	8,825	602
Continuous unrealized loss position, 12 months or longer, gross unrealized losses	2,215	28
Continuous unrealized loss position, total, fair value	64,487	15,097
Continuous unrealized loss position, total, gross unrealized losses	8,074	294
Unrealized investment losses on fixed maturity investments for which fair value is less than 80% of amortized cost, 3 months or less	2,865
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	524
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	239
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	3,628	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	2,641	2,438
Continuous unrealized loss position, less than 12 months, gross unrealized losses	179	32
Continuous unrealized loss position, 12 months or longer, fair value	1,389	5
Continuous unrealized loss position, 12 months or longer, gross unrealized losses	240	0
Continuous unrealized loss position, total, fair value	4,030	2,443
Continuous unrealized loss position, total, gross unrealized losses	419	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	25,138	3,873
Continuous unrealized loss position, less than 12 months, gross unrealized losses	3,245	69
Continuous unrealized loss position, 12 months or longer, fair value	2,526	153
Continuous unrealized loss position, 12 months or longer, gross unrealized losses	798	6
Continuous unrealized loss position, total, fair value	27,664	4,026
Continuous unrealized loss position, total, gross unrealized losses	4,043	75
Unrealized investment losses on fixed maturity investments for which fair value is less than 80% of amortized cost, 3 months or less	1,523
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	514
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	239
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	2,276
Debt securities issued by foreign governments [Member]
Investment disclosure details
Continuous unrealized loss position, less than 12 months, fair value	614	452
Continuous unrealized loss position, less than 12 months, gross unrealized losses	24	7
Continuous unrealized loss position, 12 months or longer, fair value	305	7
Continuous unrealized loss position, 12 months or longer, gross unrealized losses	31	0
Continuous unrealized loss position, total, fair value	919	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	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	1,532	426
Continuous unrealized loss position, less than 12 months, gross unrealized losses	171	5
Continuous unrealized loss position, 12 months or longer, fair value	168	1
Continuous unrealized loss position, 12 months or longer, gross unrealized losses	39	0
Continuous unrealized loss position, total, fair value	1,700	427
Continuous unrealized loss position, total, gross unrealized losses	210	5
Unrealized investment losses on fixed maturity investments for which fair value is less than 80% of amortized cost, 3 months or less	69
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	69
Corporate and all other bonds [Member]
Investment disclosure details
Continuous unrealized loss position, less than 12 months, fair value	25,737	7,306
Continuous unrealized loss position, less than 12 months, gross unrealized losses	2,240	153
Continuous unrealized loss position, 12 months or longer, fair value	4,437	436
Continuous unrealized loss position, 12 months or longer, gross unrealized losses	1,107	22
Continuous unrealized loss position, total, fair value	30,174	7,742
Continuous unrealized loss position, total, gross unrealized losses	3,347	$ 175
Unrealized investment losses on fixed maturity investments for which fair value is less than 80% of amortized cost, 3 months or less	1,273
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	10
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	$ 1,283