Investments (Details) - Fixed Maturities - USD ($) $ in Millions	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Investment disclosure details
Fixed maturities, amortized cost	$ 88,277	$ 81,781
Allowance for expected credit losses	2	5
Gross unrealized gains	223	471
Gross unrealized losses	4,832	4,440
Fixed maturities, at fair value	83,666	77,807
U.S. Treasury securities and obligations of U.S. government and government agencies and authorities [Member]
Investment disclosure details
Fixed maturities, amortized cost	5,735	6,591
Allowance for expected credit losses	0	0
Gross unrealized gains	4	8
Gross unrealized losses	169	231
Fixed maturities, at fair value	5,570	6,368
Obligations of U.S. states, municipalities and political subdivisions [Member]
Investment disclosure details
Fixed maturities, amortized cost	29,526	30,294
Allowance for expected credit losses	0	0
Gross unrealized gains	43	154
Gross unrealized losses	2,384	1,942
Fixed maturities, at fair value	27,185	28,506
Obligations of U.S. states, municipalities and political subdivisions, local general obligation [Member]
Investment disclosure details
Fixed maturities, amortized cost	18,604	18,374
Allowance for expected credit losses	0	0
Gross unrealized gains	23	90
Gross unrealized losses	1,604	1,265
Fixed maturities, at fair value	17,023	17,199
Obligations of U.S. states, municipalities and political subdivisions, revenue [Member]
Investment disclosure details
Fixed maturities, amortized cost	9,268	9,748
Allowance for expected credit losses	0	0
Gross unrealized gains	16	52
Gross unrealized losses	704	616
Fixed maturities, at fair value	8,580	9,184
Obligations of U.S. states, municipalities and political subdivisions, state general obligation [Member]
Investment disclosure details
Fixed maturities, amortized cost	1,081	1,209
Allowance for expected credit losses	0	0
Gross unrealized gains	2	7
Gross unrealized losses	73	59
Fixed maturities, at fair value	1,010	1,157
Obligations of U.S. states, municipalities and political subdivisions, pre-refunded [Member]
Investment disclosure details
Fixed maturities, amortized cost	573	963
Allowance for expected credit losses	0	0
Gross unrealized gains	2	5
Gross unrealized losses	3	2
Fixed maturities, at fair value	572	966
Debt securities issued by foreign governments [Member]
Investment disclosure details
Fixed maturities, amortized cost	917	1,035
Allowance for expected credit losses	0	0
Gross unrealized gains	5	2
Gross unrealized losses	13	31
Fixed maturities, at fair value	909	1,006
Mortgage-backed securities, collateralized mortgage obligations and pass-through securities [Member]
Investment disclosure details
Fixed maturities, amortized cost	12,888	7,874
Allowance for expected credit losses	0	0
Gross unrealized gains	53	120
Gross unrealized losses	336	176
Fixed maturities, at fair value	12,605	7,818
Corporate and all other bonds [Member]
Investment disclosure details
Fixed maturities, amortized cost	39,211	35,987
Allowance for expected credit losses	2	5	$ 3
Gross unrealized gains	118	187
Gross unrealized losses	1,930	2,060
Fixed maturities, at fair value	$ 37,397	$ 34,109