FEDERAL FUNDS, SECURITIES BORROWED, LOANED AND SUBJECT TO REPURCHASE AGREEMENTS - Offsetting (Details) - USD ($) $ in Millions	Sep. 30, 2017	Dec. 31, 2016
Securities purchased under agreements to resell
Gross amounts of recognized assets	$ 207,485	$ 176,284
Gross amounts offset on the Consolidated Balance Sheet	68,282	44,811
Net amounts of assets included on the Consolidated Balance Sheet	139,203	131,473
Amounts not offset on the Consolidated Balance Sheet but eligible for offsetting upon counterparty default	105,439	102,874
Net amounts	33,764	28,599
Deposits paid for securities borrowed
Gross amounts of recognized assets	113,385	105,340
Net amounts of assets included on the Consolidated Balance Sheet	113,385	105,340
Amounts not offset on the Consolidated Balance Sheet but eligible for offsetting upon counterparty default	23,136	16,200
Net amounts	90,249	89,140
Total
Total	320,870	281,624
Gross amounts offset on the Consolidated Balance Sheet	68,282	44,811
Net amounts of assets included on the Consolidated Balance Sheet	252,588	236,813
Amounts not offset on the Consolidated Balance Sheet but eligible for offsetting upon counterparty default	128,575	119,074
Net amounts	124,013	117,739
Securities sold under agreements to repurchase
Gross amounts of recognized liabilities	213,562	170,496
Gross amounts offset on the Consolidated Balance Sheet	68,282	44,811
Net amounts of liabilities included on the Consolidated Balance Sheet	145,280	125,685
Amounts not offset on the Consolidated Balance Sheet but eligible for offsetting upon counterparty default	67,974	63,517
Net amounts	77,306	62,168
Deposits received for securities loaned
Gross amounts of recognized liabilities	15,614	15,958
Net amounts of liabilities included on the Consolidated Balance Sheet	15,614	15,958
Amounts not offset on the Consolidated Balance Sheet but eligible for offsetting upon counterparty default	4,359	3,529
Net amounts	11,255	12,429
Total
Gross amounts of recognized liabilities	229,176	186,454
Gross amounts offset on the Consolidated Balance Sheet	68,282	44,811
Net amounts of liabilities included on the Consolidated Balance Sheet	160,894	141,643
Amounts not offset on the Consolidated Balance Sheet but eligible for offsetting upon counterparty default	72,333	67,046
Net amounts	$ 88,561	$ 74,597