SECURITIES BORROWED, LOANED AND SUBJECT TO REPURCHASE AGREEMENTS - Repurchase Agreements (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Assets Sold under Agreements to Repurchase
Repurchase agreements	$ 338,564	$ 266,564
Securities lending agreements	24,689	19,774
Total	363,253	286,338
U.S. Treasury and federal agency securities
Assets Sold under Agreements to Repurchase
Repurchase agreements	112,437	100,781
Securities lending agreements	0	27
Total	112,437	100,808
State and municipal
Assets Sold under Agreements to Repurchase
Repurchase agreements	664	1,938
Securities lending agreements	2	5
Total	666	1,943
Foreign government
Assets Sold under Agreements to Repurchase
Repurchase agreements	130,017	95,880
Securities lending agreements	194	272
Total	130,211	96,152
Corporate bonds
Assets Sold under Agreements to Repurchase
Repurchase agreements	20,149	18,761
Securities lending agreements	78	249
Total	20,227	19,010
Equity securities
Assets Sold under Agreements to Repurchase
Repurchase agreements	21,497	12,010
Securities lending agreements	24,149	19,069
Total	45,646	31,079
Mortgage-backed securities
Assets Sold under Agreements to Repurchase
Repurchase agreements	45,566	28,458
Securities lending agreements	0	0
Total	45,566	28,458
Asset-backed securities
Assets Sold under Agreements to Repurchase
Repurchase agreements	3,307	4,873
Securities lending agreements	0	0
Total	3,307	4,873
Other debt securities
Assets Sold under Agreements to Repurchase
Repurchase agreements	4,927	3,863
Securities lending agreements	266	152
Total	5,193	4,015
Open and overnight
Assets Sold under Agreements to Repurchase
Repurchase agreements	160,754	108,534
Securities lending agreements	17,038	15,758
Total	177,792	124,292
Up to 30 days
Assets Sold under Agreements to Repurchase
Repurchase agreements	98,226	82,749
Securities lending agreements	3	208
Total	98,229	82,957
31–90 days
Assets Sold under Agreements to Repurchase
Repurchase agreements	41,679	35,108
Securities lending agreements	2,770	1,789
Total	44,449	36,897
Greater than 90 days
Assets Sold under Agreements to Repurchase
Repurchase agreements	37,905	40,173
Securities lending agreements	4,878	2,019
Total	$ 42,783	$ 42,192