SECURITIES BORROWED, LOANED AND SUBJECT TO REPURCHASE AGREEMENTS - Repurchase Agreements (Details) - USD ($) $ in Millions	Sep. 30, 2020	Dec. 31, 2019
Assets Sold under Agreements to Repurchase
Securities sold under agreements to repurchase	$ 309,749	$ 266,564
Deposits received for securities loaned	18,336	19,774
Total	328,085	286,338
U.S. Treasury and federal agency securities
Assets Sold under Agreements to Repurchase
Securities sold under agreements to repurchase	109,674	100,781
Deposits received for securities loaned	2	27
Total	109,676	100,808
State and municipal securities
Assets Sold under Agreements to Repurchase
Securities sold under agreements to repurchase	896	1,938
Deposits received for securities loaned	1	5
Total	897	1,943
Foreign government securities
Assets Sold under Agreements to Repurchase
Securities sold under agreements to repurchase	115,031	95,880
Deposits received for securities loaned	309	272
Total	115,340	96,152
Corporate bonds
Assets Sold under Agreements to Repurchase
Securities sold under agreements to repurchase	19,891	18,761
Deposits received for securities loaned	370	249
Total	20,261	19,010
Equity securities
Assets Sold under Agreements to Repurchase
Securities sold under agreements to repurchase	15,124	12,010
Deposits received for securities loaned	15,249	19,069
Total	30,373	31,079
Mortgage-backed securities
Assets Sold under Agreements to Repurchase
Securities sold under agreements to repurchase	39,652	28,458
Deposits received for securities loaned	0	0
Total	39,652	28,458
Asset-backed securities
Assets Sold under Agreements to Repurchase
Securities sold under agreements to repurchase	3,792	4,873
Deposits received for securities loaned	0	0
Total	3,792	4,873
Other
Assets Sold under Agreements to Repurchase
Securities sold under agreements to repurchase	5,689	3,863
Deposits received for securities loaned	2,405	152
Total	8,094	4,015
Open and overnight
Assets Sold under Agreements to Repurchase
Securities sold under agreements to repurchase	152,290	108,534
Deposits received for securities loaned	11,412	15,758
Total	163,702	124,292
Up to 30 days
Assets Sold under Agreements to Repurchase
Securities sold under agreements to repurchase	76,162	82,749
Deposits received for securities loaned	651	208
Total	76,813	82,957
31–90 days
Assets Sold under Agreements to Repurchase
Securities sold under agreements to repurchase	39,462	35,108
Deposits received for securities loaned	2,421	1,789
Total	41,883	36,897
Greater than 90 days
Assets Sold under Agreements to Repurchase
Securities sold under agreements to repurchase	41,835	40,173
Deposits received for securities loaned	3,852	2,019
Total	$ 45,687	$ 42,192