FEDERAL FUNDS, SECURITIES BORROWED, LOANED AND SUBJECT TO REPURCHASE AGREEMENTS - Offsetting (Details) - USD ($) $ in Millions	Mar. 31, 2019	Dec. 31, 2018
Securities purchased under agreements to resell
Gross amounts of recognized assets	$ 268,095	$ 246,788
Gross amounts offset on the Consolidated Balance Sheet	104,713	87,424
Net amounts of assets included on the Consolidated Balance Sheet	163,382	159,364
Amounts not offset on the Consolidated Balance Sheet but eligible for offsetting upon counterparty default	129,911	124,557
Net amounts	33,471	34,807
Deposits paid for securities borrowed
Gross amounts of recognized assets	101,113	111,320
Net amounts of assets included on the Consolidated Balance Sheet	101,113	111,320
Amounts not offset on the Consolidated Balance Sheet but eligible for offsetting upon counterparty default	28,040	35,766
Net amounts	73,073	75,554
Total
Gross amounts of recognized assets	369,208	358,108
Gross amounts offset on the Consolidated Balance Sheet	104,713	87,424
Net amounts of assets included on the Consolidated Balance Sheet	264,495	270,684
Amounts not offset on the Consolidated Balance Sheet but eligible for offsetting upon counterparty default	157,951	160,323
Net amounts	106,544	110,361
Securities sold under agreements to repurchase
Gross amounts of recognized liabilities	276,944	253,514
Gross amounts offset on the Consolidated Balance Sheet	104,713	87,424
Net amounts of liabilities included on the Consolidated Balance Sheet	172,231	166,090
Amounts not offset on the Consolidated Balance Sheet but eligible for offsetting upon counterparty default	91,923	82,823
Net amounts	80,308	83,267
Deposits received for securities loaned
Gross amounts of recognized liabilities	18,141	11,678
Net amounts of liabilities included on the Consolidated Balance Sheet	18,141	11,678
Amounts not offset on the Consolidated Balance Sheet but eligible for offsetting upon counterparty default	5,351	3,415
Net amounts	12,790	8,263
Total
Gross amounts of recognized liabilities	295,085	265,192
Gross amounts offset on the Consolidated Balance Sheet	104,713	87,424
Net amounts of liabilities included on the Consolidated Balance Sheet	190,372	177,768
Amounts not offset on the Consolidated Balance Sheet but eligible for offsetting upon counterparty default	97,274	86,238
Net amounts	$ 93,098	$ 91,530