Investments - Fair Value and Gross Unrealized Losses in a Continuous Unrealized Loss Position (Details) $ in Millions	3 Months Ended	12 Months Ended
	Mar. 31, 2024 USD ($) security	Dec. 31, 2023 USD ($) security
Fair Value
Less Than or Equal to Twelve Months	$ 18,261	$ 16,851
Greater Than Twelve Months	41,476	43,082
Total	59,737	59,933
Gross Unrealized Losses
Less Than or Equal to Twelve Months	2,180	1,999
Greater Than Twelve Months	5,455	4,967
Total	$ 7,635	$ 6,966
Total number of fixed maturity AFS securities in an unrealized loss position | security	7,093	7,167
Unrealized holding losses arising during the period	$ 11	$ 7
Corporate bonds
Fair Value
Less Than or Equal to Twelve Months	14,754	13,439
Greater Than Twelve Months	32,673	33,285
Total	47,427	46,724
Gross Unrealized Losses
Less Than or Equal to Twelve Months	1,913	1,744
Greater Than Twelve Months	4,457	4,013
Total	6,370	5,757
U.S. government bonds
Fair Value
Less Than or Equal to Twelve Months	102	65
Greater Than Twelve Months	188	194
Total	290	259
Gross Unrealized Losses
Less Than or Equal to Twelve Months	9	6
Greater Than Twelve Months	26	22
Total	35	28
State and municipal bonds
Fair Value
Less Than or Equal to Twelve Months	396	371
Greater Than Twelve Months	844	814
Total	1,240	1,185
Gross Unrealized Losses
Less Than or Equal to Twelve Months	75	72
Greater Than Twelve Months	168	158
Total	243	230
Foreign government bonds
Fair Value
Less Than or Equal to Twelve Months	100	108
Greater Than Twelve Months	66	57
Total	166	165
Gross Unrealized Losses
Less Than or Equal to Twelve Months	28	31
Greater Than Twelve Months	23	15
Total	51	46
RMBS
Fair Value
Less Than or Equal to Twelve Months	452	355
Greater Than Twelve Months	866	840
Total	1,318	1,195
Gross Unrealized Losses
Less Than or Equal to Twelve Months	27	20
Greater Than Twelve Months	133	118
Total	160	138
CMBS
Fair Value
Less Than or Equal to Twelve Months	571	583
Greater Than Twelve Months	621	586
Total	1,192	1,169
Gross Unrealized Losses
Less Than or Equal to Twelve Months	51	56
Greater Than Twelve Months	108	125
Total	159	181
ABS
Fair Value
Less Than or Equal to Twelve Months	1,874	1,898
Greater Than Twelve Months	6,117	7,212
Total	7,991	9,110
Gross Unrealized Losses
Less Than or Equal to Twelve Months	76	68
Greater Than Twelve Months	530	503
Total	606	571
Hybrid and redeemable preferred securities
Fair Value
Less Than or Equal to Twelve Months	12	32
Greater Than Twelve Months	101	94
Total	113	126
Gross Unrealized Losses
Less Than or Equal to Twelve Months	1	2
Greater Than Twelve Months	10	13
Total	$ 11	$ 15