EXIT COSTS AND RESTRUCTURING RESERVES - Reserve Rollforward (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Restructuring Reserve [Roll Forward]
Beginning balance	$ 33	$ 44	$ 26
Additions	2	31	124
Reversals	(2)	(5)	(10)
Utilization	(23)	(37)	(96)
Ending balance	10	33	44
Salaries & Employee Benefits | Salaries & Employee Benefits
Restructuring Reserve [Roll Forward]
Beginning balance	12	23	2
Additions	2	5	43
Reversals	(2)	(4)	(1)
Utilization	(11)	(12)	(21)
Ending balance	1	12	23
Occupancy & Equipment | Occupancy & Equipment
Restructuring Reserve [Roll Forward]
Beginning balance	16	18	24
Additions	0	18	24
Reversals	0	(1)	(5)
Utilization	(7)	(19)	(25)
Ending balance	9	16	18
Other | Other
Restructuring Reserve [Roll Forward]
Beginning balance	5	3	0
Additions	0	8	57
Reversals	0	0	(4)
Utilization	(5)	(6)	(50)
Ending balance	$ 0	$ 5	$ 3