INVESTMENTS - Fair Value of AFS Securities (Details) - USD ($) $ in Millions	Jun. 30, 2024	Dec. 31, 2023
Fair value
Less than 12 months	$ 80,780	$ 68,298
12 months or longer	92,135	98,800
Total	172,915	167,098
Gross unrealized losses
Less than 12 months	755	861
12 months or longer	2,687	2,933
Total	3,442	3,794
U.S. government-sponsored agency guaranteed
Fair value
Less than 12 months	12,369	8,602
12 months or longer	8,991	9,734
Total	21,360	18,336
Gross unrealized losses
Less than 12 months	126	86
12 months or longer	706	648
Total	832	734
Residential
Fair value
Less than 12 months	288	352
12 months or longer	227	34
Total	515	386
Gross unrealized losses
Less than 12 months	0	1
12 months or longer	2	2
Total	2	3
Mortgage-backed securities
Fair value
Less than 12 months	12,657	8,954
12 months or longer	9,218	9,768
Total	21,875	18,722
Gross unrealized losses
Less than 12 months	126	87
12 months or longer	708	650
Total	834	737
U.S. Treasury
Fair value
Less than 12 months	18,190	11,851
12 months or longer	45,988	57,669
Total	64,178	69,520
Gross unrealized losses
Less than 12 months	178	113
12 months or longer	801	1,269
Total	979	1,382
U.S. Treasury and federal agency securities
Fair value
Less than 12 months	18,190	11,851
12 months or longer	45,988	57,669
Total	64,178	69,520
Gross unrealized losses
Less than 12 months	178	113
12 months or longer	801	1,269
Total	979	1,382
State and municipal
Fair value
Less than 12 months	342	906
12 months or longer	807	324
Total	1,149	1,230
Gross unrealized losses
Less than 12 months	13	17
12 months or longer	82	74
Total	95	91
Foreign government
Fair value
Less than 12 months	44,441	42,250
12 months or longer	34,321	29,176
Total	78,762	71,426
Gross unrealized losses
Less than 12 months	368	540
12 months or longer	986	835
Total	1,354	1,375
Corporate
Fair value
Less than 12 months	2,345	2,319
12 months or longer	1,801	1,619
Total	4,146	3,938
Gross unrealized losses
Less than 12 months	66	103
12 months or longer	110	105
Total	176	208
Asset-backed securities
Fair value
Less than 12 months	2	154
12 months or longer	0	16
Total	2	170
Gross unrealized losses
Less than 12 months	0	0
12 months or longer	0	0
Total	0	0
Other debt securities
Fair value
Less than 12 months	2,803	1,864
12 months or longer	0	228
Total	2,803	2,092
Gross unrealized losses
Less than 12 months	4	1
12 months or longer	0	0
Total	$ 4	$ 1