GOODWILL AND INTANGIBLE ASSETS - Changes in Goodwill (Details) $ in Millions	3 Months Ended
	Mar. 31, 2019 USD ($)
Goodwill
Balance of goodwill at beginning of period	$ 22,046
Foreign exchange translation and other	(9)
Balance of goodwill at end of period	22,037
Global Consumer Banking
Goodwill
Balance of goodwill at beginning of period	12,743
Foreign exchange translation and other	0
Balance of goodwill at end of period	12,743
Institutional Clients Group
Goodwill
Balance of goodwill at beginning of period	9,303
Foreign exchange translation and other	(9)
Balance of goodwill at end of period	9,294
Corporate/Other
Goodwill
Balance of goodwill at beginning of period	0
Foreign exchange translation and other	0
Balance of goodwill at end of period	$ 0