SECURITIZATIONS AND VARIABLE INTEREST ENTITIES - Carrying Amounts and Classifications of Consolidated Assets (Details) - USD ($) $ in Millions	Mar. 31, 2018	Dec. 31, 2017	Mar. 31, 2017
Variable Interest Entity
Cash	$ 21,850	$ 23,775	$ 22,272
Trading account assets	268,808	252,790
Investments	351,971	352,290
Total loans, net of allowance	660,584	654,679
Other	105,882	103,926
Total assets	1,922,104	1,842,465
Significant unconsolidated VIE assets
Variable Interest Entity
Cash	0	0
Trading account assets	7,700	8,500
Investments	4,400	4,400
Total loans, net of allowance	21,900	22,200
Other	500	500
Total assets	$ 34,500	$ 35,600