INVESTMENTS - Fair Value of AFS Securities (Details) - USD ($) $ in Millions	Mar. 31, 2025	Dec. 31, 2024
Fair value
Less than 12 months	$ 75,808	$ 82,905
12 months or longer	33,000	33,848
Total	108,808	116,753
Gross unrealized losses
Less than 12 months	729	1,037
12 months or longer	1,246	1,495
Total	1,975	2,532
Commercial and other
Fair value
Less than 12 months	1	0
12 months or longer	0	1
Total	1	1
Gross unrealized losses
Less than 12 months	0	0
12 months or longer	0	0
Total	0	0
U.S. government-sponsored agency guaranteed
Fair value
Less than 12 months	21,178	16,690
12 months or longer	8,595	8,484
Total	29,773	25,174
Gross unrealized losses
Less than 12 months	228	255
12 months or longer	613	687
Total	841	942
Residential
Fair value
Less than 12 months	457	375
12 months or longer	197	216
Total	654	591
Gross unrealized losses
Less than 12 months	2	1
12 months or longer	1	1
Total	3	2
Mortgage-backed securities
Fair value
Less than 12 months	21,636	17,065
12 months or longer	8,792	8,701
Total	30,428	25,766
Gross unrealized losses
Less than 12 months	230	256
12 months or longer	614	688
Total	844	944
U.S. Treasury
Fair value
Less than 12 months	17,690	13,660
12 months or longer	4,790	1,710
Total	22,480	15,370
Gross unrealized losses
Less than 12 months	117	166
12 months or longer	83	98
Total	200	264
U.S. Treasury and federal agency securities
Fair value
Less than 12 months	17,690	13,660
12 months or longer	4,790	1,710
Total	22,480	15,370
Gross unrealized losses
Less than 12 months	117	166
12 months or longer	83	98
Total	200	264
State and municipal
Fair value
Less than 12 months	920	855
12 months or longer	451	335
Total	1,371	1,190
Gross unrealized losses
Less than 12 months	53	72
12 months or longer	37	31
Total	90	103
Foreign government
Fair value
Less than 12 months	34,294	49,384
12 months or longer	16,215	19,719
Total	50,509	69,103
Gross unrealized losses
Less than 12 months	297	487
12 months or longer	450	600
Total	747	1,087
Corporate
Fair value
Less than 12 months	501	455
12 months or longer	1,909	2,444
Total	2,410	2,899
Gross unrealized losses
Less than 12 months	25	45
12 months or longer	61	77
Total	86	122
Asset-backed securities
Fair value
Less than 12 months	445	388
12 months or longer	0	0
Total	445	388
Gross unrealized losses
Less than 12 months	7	11
12 months or longer	0	0
Total	7	11
Other debt securities
Fair value
Less than 12 months	322	1,098
12 months or longer	843	939
Total	1,165	2,037
Gross unrealized losses
Less than 12 months	0	0
12 months or longer	1	1
Total	$ 1	$ 1