FEDERAL FUNDS, SECURITIES BORROWED, LOANED AND SUBJECT TO REPURCHASE AGREEMENTS - Repurchase Agreements (Details) - USD ($) $ in Millions	Mar. 31, 2018	Dec. 31, 2017
Assets Sold under Agreements to Repurchase
Securities sold under agreements to repurchase	$ 244,093	$ 216,122
Deposits received for securities loaned	13,884	13,305
Total	257,977	229,427
U.S. Treasury and federal agency securities
Assets Sold under Agreements to Repurchase
Securities sold under agreements to repurchase	72,336	58,774
Deposits received for securities loaned	0	0
Total	72,336	58,774
State and municipal securities
Assets Sold under Agreements to Repurchase
Securities sold under agreements to repurchase	1,794	1,605
Deposits received for securities loaned	0	0
Total	1,794	1,605
Foreign government
Assets Sold under Agreements to Repurchase
Securities sold under agreements to repurchase	99,870	89,576
Deposits received for securities loaned	226	105
Total	100,096	89,681
Corporate bonds
Assets Sold under Agreements to Repurchase
Securities sold under agreements to repurchase	23,168	20,194
Deposits received for securities loaned	691	657
Total	23,859	20,851
Equity securities
Assets Sold under Agreements to Repurchase
Securities sold under agreements to repurchase	21,659	20,724
Deposits received for securities loaned	12,310	11,907
Total	33,969	32,631
Mortgage-backed securities
Assets Sold under Agreements to Repurchase
Securities sold under agreements to repurchase	15,930	17,791
Deposits received for securities loaned	0	0
Total	15,930	17,791
Asset-backed securities
Assets Sold under Agreements to Repurchase
Securities sold under agreements to repurchase	6,593	5,479
Deposits received for securities loaned	0	0
Total	6,593	5,479
Other
Assets Sold under Agreements to Repurchase
Securities sold under agreements to repurchase	2,743	1,979
Deposits received for securities loaned	657	636
Total	3,400	2,615
Open and overnight
Assets Sold under Agreements to Repurchase
Securities sold under agreements to repurchase	96,155	82,073
Deposits received for securities loaned	9,369	9,946
Total	105,524	92,019
Up to 30 days
Assets Sold under Agreements to Repurchase
Securities sold under agreements to repurchase	77,118	68,372
Deposits received for securities loaned	397	266
Total	77,515	68,638
31–90 days
Assets Sold under Agreements to Repurchase
Securities sold under agreements to repurchase	26,587	33,846
Deposits received for securities loaned	2,197	1,912
Total	28,784	35,758
Greater than 90 days
Assets Sold under Agreements to Repurchase
Securities sold under agreements to repurchase	44,233	31,831
Deposits received for securities loaned	1,921	1,181
Total	$ 46,154	$ 33,012