INVESTMENTS - Fair Value of AFS Securities (Details) - USD ($) $ in Millions	Mar. 31, 2022	Dec. 31, 2021
Fair value
Less than 12 months	$ 163,137	$ 144,333
12 months or longer	48,318	17,829
Total	211,455	162,162
Gross unrealized losses
Less than 12 months	4,055	1,895
12 months or longer	2,825	457
Total	6,880	2,352
Mortgage-backed securities - U.S. government-sponsored agency guaranteed
Fair value
Less than 12 months	26,134	17,039
12 months or longer	6,722	698
Total	32,856	17,737
Gross unrealized losses
Less than 12 months	1,066	270
12 months or longer	554	31
Total	1,620	301
Mortgage-backed securities - Non-U.S. residential
Fair value
Less than 12 months	76	96
12 months or longer	0	1
Total	76	97
Gross unrealized losses
Less than 12 months	2	1
12 months or longer	0	0
Total	2	1
Commercial
Fair value
Less than 12 months	15	0
12 months or longer	1	0
Total	16	0
Gross unrealized losses
Less than 12 months	0	0
12 months or longer	0	0
Total	0	0
Mortgage-backed securities
Fair value
Less than 12 months	26,225	17,135
12 months or longer	6,723	699
Total	32,948	17,834
Gross unrealized losses
Less than 12 months	1,068	271
12 months or longer	554	31
Total	1,622	302
U.S. Treasury
Fair value
Less than 12 months	55,233	56,448
12 months or longer	26,403	6,310
Total	81,636	62,758
Gross unrealized losses
Less than 12 months	1,271	713
12 months or longer	1,672	131
Total	2,943	844
Agency obligations
Fair value
Less than 12 months		0
12 months or longer		0
Total		0
Gross unrealized losses
Less than 12 months		0
12 months or longer		0
Total		0
U.S. Treasury and federal agency securities
Fair value
Less than 12 months		56,448
12 months or longer		6,310
Total		62,758
Gross unrealized losses
Less than 12 months		713
12 months or longer		131
Total		844
State and municipal
Fair value
Less than 12 months	688	229
12 months or longer	1,083	874
Total	1,771	1,103
Gross unrealized losses
Less than 12 months	27	3
12 months or longer	127	98
Total	154	101
Foreign government
Fair value
Less than 12 months	74,927	64,319
12 months or longer	13,965	9,924
Total	88,892	74,243
Gross unrealized losses
Less than 12 months	1,598	826
12 months or longer	461	197
Total	2,059	1,023
Corporate
Fair value
Less than 12 months	2,166	2,655
12 months or longer	144	22
Total	2,310	2,677
Gross unrealized losses
Less than 12 months	80	77
12 months or longer	11	0
Total	91	77
Asset-backed securities
Fair value
Less than 12 months	4	108
12 months or longer	0	0
Total	4	108
Gross unrealized losses
Less than 12 months	1	1
12 months or longer	0	0
Total	1	1
Other debt securities
Fair value
Less than 12 months	3,894	3,439
12 months or longer	0	0
Total	3,894	3,439
Gross unrealized losses
Less than 12 months	10	4
12 months or longer	0	0
Total	$ 10	$ 4