Investments - Unrealized Capital Losses (Details) $ in Millions	Jun. 30, 2022 USD ($) securities	Dec. 31, 2021 USD ($) securities
Available-for-sale Securities Including Securities Pledged [Line Items]
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Number of Positions | securities	3,326	989
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	$ 1,847	$ 111
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	$ 1,613	$ 72
Debt Securities, Available-for-sale, Unrealized Loss Position, Number of Positions | securities	3,823	1,326
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Number of Positions | securities	497	337
Debt Securities, Available-for-sale, Unrealized Loss Position	$ 1,099	$ 708
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Fair Value	16,176	3,838
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	234	39
Debt Securities, Available-for-sale, Unrealized Loss Position, Fair Value	$ 17,275	$ 4,546
U.S. Treasuries
Available-for-sale Securities Including Securities Pledged [Line Items]
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Number of Positions | securities	11	4
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	$ 14	$ 0
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	$ 14	$ 0
Debt Securities, Available-for-sale, Unrealized Loss Position, Number of Positions | securities	14	6
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Number of Positions | securities	3	2
Debt Securities, Available-for-sale, Unrealized Loss Position	$ 8	$ 7
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Fair Value	82	7
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	0	0
Debt Securities, Available-for-sale, Unrealized Loss Position, Fair Value	$ 90	$ 14
State, municipalities and political subdivisions
Available-for-sale Securities Including Securities Pledged [Line Items]
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Number of Positions | securities	250	21
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	$ 47	$ 1
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	$ 47	$ 1
Debt Securities, Available-for-sale, Unrealized Loss Position, Number of Positions | securities	250	21
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Number of Positions | securities	0	0
Debt Securities, Available-for-sale, Unrealized Loss Position	$ 0	$ 0
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Fair Value	519	33
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	0	0
Debt Securities, Available-for-sale, Unrealized Loss Position, Fair Value	$ 519	$ 33
U.S. corporate public securities
Available-for-sale Securities Including Securities Pledged [Line Items]
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Number of Positions | securities	978	290
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	$ 776	$ 39
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	$ 656	$ 32
Debt Securities, Available-for-sale, Unrealized Loss Position, Number of Positions | securities	1,165	428
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Number of Positions | securities	187	138
Debt Securities, Available-for-sale, Unrealized Loss Position	$ 323	$ 110
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Fair Value	4,598	1,237
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	120	7
Debt Securities, Available-for-sale, Unrealized Loss Position, Fair Value	$ 4,921	$ 1,347
U.S. corporate private securities
Available-for-sale Securities Including Securities Pledged [Line Items]
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Number of Positions | securities	309	35
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	$ 231	$ 15
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	$ 213	$ 2
Debt Securities, Available-for-sale, Unrealized Loss Position, Number of Positions | securities	317	43
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Number of Positions | securities	8	8
Debt Securities, Available-for-sale, Unrealized Loss Position	$ 81	$ 94
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Fair Value	2,702	325
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	18	13
Debt Securities, Available-for-sale, Unrealized Loss Position, Fair Value	$ 2,783	$ 419
Foreign corporate public securities and foreign governments
Available-for-sale Securities Including Securities Pledged [Line Items]
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Number of Positions | securities	364	90
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	$ 244	$ 14
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	$ 202	$ 13
Debt Securities, Available-for-sale, Unrealized Loss Position, Number of Positions | securities	408	107
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Number of Positions | securities	44	17
Debt Securities, Available-for-sale, Unrealized Loss Position	$ 129	$ 21
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Fair Value	1,504	425
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	42	1
Debt Securities, Available-for-sale, Unrealized Loss Position, Fair Value	$ 1,633	$ 446
Foreign corporate private securities
Available-for-sale Securities Including Securities Pledged [Line Items]
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Number of Positions | securities	186	7
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	$ 136	$ 1
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	$ 134	$ 1
Debt Securities, Available-for-sale, Unrealized Loss Position, Number of Positions | securities	189	8
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Number of Positions | securities	3	1
Debt Securities, Available-for-sale, Unrealized Loss Position	$ 11	$ 10
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Fair Value	1,990	54
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	2	0
Debt Securities, Available-for-sale, Unrealized Loss Position, Fair Value	$ 2,001	$ 64
Residential mortgage-backed
Available-for-sale Securities Including Securities Pledged [Line Items]
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Number of Positions | securities	391	181
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	$ 107	$ 20
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	$ 84	$ 11
Debt Securities, Available-for-sale, Unrealized Loss Position, Number of Positions | securities	540	277
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Number of Positions | securities	149	96
Debt Securities, Available-for-sale, Unrealized Loss Position	$ 281	$ 241
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Fair Value	1,279	400
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	23	9
Debt Securities, Available-for-sale, Unrealized Loss Position, Fair Value	$ 1,560	$ 641
Commercial mortgage-backed
Available-for-sale Securities Including Securities Pledged [Line Items]
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Number of Positions | securities	486	178
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	$ 200	$ 15
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	$ 181	$ 8
Debt Securities, Available-for-sale, Unrealized Loss Position, Number of Positions | securities	524	205
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Number of Positions | securities	38	27
Debt Securities, Available-for-sale, Unrealized Loss Position	$ 168	$ 155
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Fair Value	2,344	780
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	19	7
Debt Securities, Available-for-sale, Unrealized Loss Position, Fair Value	$ 2,512	$ 935
Other asset-backed securities
Available-for-sale Securities Including Securities Pledged [Line Items]
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Number of Positions | securities	349	183
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	$ 90	$ 6
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	$ 80	$ 4
Debt Securities, Available-for-sale, Unrealized Loss Position, Number of Positions | securities	414	231
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Number of Positions | securities	65	48
Debt Securities, Available-for-sale, Unrealized Loss Position	$ 98	$ 70
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Fair Value	1,140	577
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	10	2
Debt Securities, Available-for-sale, Unrealized Loss Position, Fair Value	$ 1,238	$ 647
US Government Corporations and Agencies Securities
Available-for-sale Securities Including Securities Pledged [Line Items]
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Number of Positions | securities	2
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	$ 2
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	$ 2
Debt Securities, Available-for-sale, Unrealized Loss Position, Number of Positions | securities	2
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Number of Positions | securities	0
Debt Securities, Available-for-sale, Unrealized Loss Position	$ 0
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Fair Value	18
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	0
Debt Securities, Available-for-sale, Unrealized Loss Position, Fair Value	$ 18