GOODWILL AND INTANGIBLE ASSETS - Changes in Goodwill (Details) - USD ($) $ in Millions	3 Months Ended
	Jun. 30, 2018	Mar. 31, 2018
Goodwill
Balance of goodwill at beginning of period	$ 22,659	$ 22,256
Foreign exchange translation and other	(601)	419
Divestiture	0	(16)
Balance of goodwill at end of period	22,058	22,659
Global Consumer Banking
Goodwill
Balance of goodwill at beginning of period	12,968	12,784
Foreign exchange translation and other	(226)	184
Divestiture	0	0
Balance of goodwill at end of period	12,742	12,968
Institutional Clients Group
Goodwill
Balance of goodwill at beginning of period	9,691	9,456
Foreign exchange translation and other	(375)	235
Divestiture	0	0
Balance of goodwill at end of period	9,316	9,691
Corporate/Other
Goodwill
Balance of goodwill at beginning of period	0	16
Foreign exchange translation and other	0	0
Divestiture	0	(16)
Balance of goodwill at end of period	$ 0	$ 0