GOODWILL AND INTANGIBLE ASSETS - Goodwill Rollforward (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2018	Dec. 31, 2017
Goodwill [Roll Forward]
Beginning balance		$ 6,887	$ 6,876
Business acquisition		59	11
Adjustments	[1]	(23)
Ending balance		6,923	6,887
Consumer Banking
Goodwill [Roll Forward]
Beginning balance		2,136	2,136
Business acquisition		59	0
Adjustments	[1]	(23)
Ending balance		2,172	2,136
Commercial Banking
Goodwill [Roll Forward]
Beginning balance		4,751	4,740
Business acquisition		0	11
Adjustments	[1]	0
Ending balance		$ 4,751	$ 4,751

[1] Adjustments to goodwill are the result of an update to the purchase price allocation for the FAMC acquisition, given higher value attributed to purchased net assets.