GOODWILL AND INTANGIBLE ASSETS - Changes in Goodwill (Details) - USD ($) $ in Millions	3 Months Ended
	Jun. 30, 2021	Mar. 31, 2021
Goodwill
Balance of goodwill at beginning of period	$ 21,905	$ 22,162
Foreign currency translation	155	(257)
Balance of goodwill at end of period	22,060	21,905
Global Consumer Banking
Goodwill
Balance of goodwill at beginning of period	12,074	12,142
Foreign currency translation	34	(68)
Balance of goodwill at end of period	12,108	12,074
Institutional Clients Group
Goodwill
Balance of goodwill at beginning of period	9,831	10,020
Foreign currency translation	121	(189)
Balance of goodwill at end of period	$ 9,952	$ 9,831