Investments - Unrealized Capital Losses (Details) $ in Millions	12 Months Ended
	Dec. 31, 2022 USD ($) securities	Dec. 31, 2021 USD ($) securities
Debt Securities, Available-for-sale, Unrealized Loss Position [Line Items]
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months		$ 3,838
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss		$ 72
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Number of Positions | securities	3,153	989
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer		$ 708
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	$ 861	$ 39
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Number of Positions | securities	1,069	337
Debt Securities, Available-for-sale, Unrealized Loss Position	$ 18,531	$ 4,546
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	$ 2,628	$ 111
Debt Securities, Available-for-sale, Unrealized Loss Position, Number of Positions | securities	4,222	1,326
Available For Sale Securities Change in Loss Position	$ 2,517
More Than Twelve Months Below Amortized Cost, Fair Value	3,143
Debt Securities, Available-for-sale, Including Securities Pledged, Continuous Unrealized Loss Position Twelve Months or Less, Fair Value	15,388
Available-for-Sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	$ 1,767
U.S. Treasuries
Debt Securities, Available-for-sale, Unrealized Loss Position [Line Items]
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months		$ 7
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss		$ 0
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Number of Positions | securities	18	4
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer		$ 7
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	$ 1	$ 0
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	$ 225	$ 14
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	$ 31	$ 0
Debt Securities, Available-for-sale, Unrealized Loss Position, Number of Positions | securities	21	6
More Than Twelve Months Below Amortized Cost, Fair Value	$ 2
Debt Securities, Available-for-sale, Including Securities Pledged, Continuous Unrealized Loss Position Twelve Months or Less, Fair Value	223
Available-for-Sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	$ 30
State, municipalities and political subdivisions
Debt Securities, Available-for-sale, Unrealized Loss Position [Line Items]
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months		$ 33
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss		$ 1
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Number of Positions | securities	276	21
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer		$ 0
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	$ 7	$ 0
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Number of Positions | securities	16	0
Debt Securities, Available-for-sale, Unrealized Loss Position	$ 560	$ 33
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	$ 92	$ 1
Debt Securities, Available-for-sale, Unrealized Loss Position, Number of Positions | securities	292	21
More Than Twelve Months Below Amortized Cost, Fair Value	$ 15
Debt Securities, Available-for-sale, Including Securities Pledged, Continuous Unrealized Loss Position Twelve Months or Less, Fair Value	545
Available-for-Sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	$ 85
U.S. corporate public securities
Debt Securities, Available-for-sale, Unrealized Loss Position [Line Items]
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months		$ 1,237
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss		$ 32
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Number of Positions | securities	901	290
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer		$ 110
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	$ 419	$ 7
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Number of Positions | securities	360	138
Debt Securities, Available-for-sale, Unrealized Loss Position	$ 5,288	$ 1,347
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	$ 1,032	$ 39
Debt Securities, Available-for-sale, Unrealized Loss Position, Number of Positions | securities	1,261	428
More Than Twelve Months Below Amortized Cost, Fair Value	$ 998
Debt Securities, Available-for-sale, Including Securities Pledged, Continuous Unrealized Loss Position Twelve Months or Less, Fair Value	4,290
Available-for-Sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	$ 613
U.S. corporate private securities
Debt Securities, Available-for-sale, Unrealized Loss Position [Line Items]
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months		$ 325
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss		$ 2
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Number of Positions | securities	312	35
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer		$ 94
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	$ 64	$ 13
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Number of Positions | securities	32	8
Debt Securities, Available-for-sale, Unrealized Loss Position	$ 3,150	$ 419
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	$ 328	$ 15
Debt Securities, Available-for-sale, Unrealized Loss Position, Number of Positions | securities	344	43
More Than Twelve Months Below Amortized Cost, Fair Value	$ 331
Debt Securities, Available-for-sale, Including Securities Pledged, Continuous Unrealized Loss Position Twelve Months or Less, Fair Value	2,819
Available-for-Sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	$ 264
Foreign corporate public securities and foreign governments
Debt Securities, Available-for-sale, Unrealized Loss Position [Line Items]
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months		$ 425
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss		$ 13
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Number of Positions | securities	348	90
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer		$ 21
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	$ 116	$ 1
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Number of Positions | securities	93	17
Debt Securities, Available-for-sale, Unrealized Loss Position	$ 1,807	$ 446
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	$ 317	$ 14
Debt Securities, Available-for-sale, Unrealized Loss Position, Number of Positions | securities	441	107
More Than Twelve Months Below Amortized Cost, Fair Value	$ 298
Debt Securities, Available-for-sale, Including Securities Pledged, Continuous Unrealized Loss Position Twelve Months or Less, Fair Value	1,509
Available-for-Sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	$ 201
Foreign corporate private securities
Debt Securities, Available-for-sale, Unrealized Loss Position [Line Items]
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months		$ 54
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss		$ 1
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Number of Positions | securities	200	7
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer		$ 10
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	$ 11	$ 0
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Number of Positions | securities	6	1
Debt Securities, Available-for-sale, Unrealized Loss Position	$ 2,255	$ 64
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	$ 184	$ 1
Debt Securities, Available-for-sale, Unrealized Loss Position, Number of Positions | securities	206	8
More Than Twelve Months Below Amortized Cost, Fair Value	$ 52
Debt Securities, Available-for-sale, Including Securities Pledged, Continuous Unrealized Loss Position Twelve Months or Less, Fair Value	2,203
Available-for-Sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	$ 173
Residential mortgage-backed securities
Debt Securities, Available-for-sale, Unrealized Loss Position [Line Items]
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months		$ 400
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss		$ 11
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Number of Positions | securities	441	181
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer		$ 241
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	$ 75	$ 9
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Number of Positions | securities	215	96
Debt Securities, Available-for-sale, Unrealized Loss Position	$ 1,393	$ 641
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	$ 153	$ 20
Debt Securities, Available-for-sale, Unrealized Loss Position, Number of Positions | securities	656	277
More Than Twelve Months Below Amortized Cost, Fair Value	$ 328
Debt Securities, Available-for-sale, Including Securities Pledged, Continuous Unrealized Loss Position Twelve Months or Less, Fair Value	1,065
Available-for-Sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	$ 78
Commercial mortgage-backed securities
Debt Securities, Available-for-sale, Unrealized Loss Position [Line Items]
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months		$ 780
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss		$ 8
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Number of Positions | securities	373	178
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer		$ 155
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	$ 127	$ 7
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Number of Positions | securities	189	27
Debt Securities, Available-for-sale, Unrealized Loss Position	$ 2,551	$ 935
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	$ 379	$ 15
Debt Securities, Available-for-sale, Unrealized Loss Position, Number of Positions | securities	562	205
More Than Twelve Months Below Amortized Cost, Fair Value	$ 759
Debt Securities, Available-for-sale, Including Securities Pledged, Continuous Unrealized Loss Position Twelve Months or Less, Fair Value	1,792
Available-for-Sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	$ 252
Other asset-backed securities
Debt Securities, Available-for-sale, Unrealized Loss Position [Line Items]
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months		$ 577
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss		$ 4
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Number of Positions | securities	281	183
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer		$ 70
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	$ 41	$ 2
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Number of Positions | securities	155	48
Debt Securities, Available-for-sale, Unrealized Loss Position	$ 1,272	$ 647
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	$ 109	$ 6
Debt Securities, Available-for-sale, Unrealized Loss Position, Number of Positions | securities	436	231
More Than Twelve Months Below Amortized Cost, Fair Value	$ 360
Debt Securities, Available-for-sale, Including Securities Pledged, Continuous Unrealized Loss Position Twelve Months or Less, Fair Value	912
Available-for-Sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	$ 68
U.S. Government agencies and authorities
Debt Securities, Available-for-sale, Unrealized Loss Position [Line Items]
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Number of Positions | securities	3
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	$ 0
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	$ 30
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	$ 3
Debt Securities, Available-for-sale, Unrealized Loss Position, Number of Positions | securities	3
More Than Twelve Months Below Amortized Cost, Fair Value	$ 0
Debt Securities, Available-for-sale, Including Securities Pledged, Continuous Unrealized Loss Position Twelve Months or Less, Fair Value	30
Available-for-Sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	3
Fair value decline below amortized cost greater than 20%
Debt Securities, Available-for-sale, Unrealized Loss Position [Line Items]
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	$ 6
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Number of Positions | securities	9