GOODWILL AND INTANGIBLE ASSETS - Changes in Goodwill (Details) - USD ($) $ in Millions	3 Months Ended
	Jun. 30, 2019	Mar. 31, 2019
Goodwill
Balance of goodwill at beginning of period	$ 22,037	$ 22,046
Foreign exchange translation	28	(9)
Balance of goodwill at end of period	22,065	22,037
Global Consumer Banking
Goodwill
Balance of goodwill at beginning of period	12,743	12,743
Foreign exchange translation	(15)	0
Balance of goodwill at end of period	12,728	12,743
Institutional Clients Group
Goodwill
Balance of goodwill at beginning of period	9,294	9,303
Foreign exchange translation	43	(9)
Balance of goodwill at end of period	$ 9,337	$ 9,294