EXIT COSTS AND RESTRUCTURING RESERVES - Reserve Rollforward (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Restructuring Reserve [Roll Forward]
Beginning balance	$ 24	$ 35	$ 33	$ 44
Additions	0	25	0	28
Reversals	0	0	0	(2)
Utilization	(4)	(8)	(13)	(18)
Ending balance	20	52	20	52
Salaries & Employee Benefits | Salaries & Employee Benefits
Restructuring Reserve [Roll Forward]
Beginning balance	10	18	12	23
Additions	0	5	0	5
Reversals	0	0	0	(2)
Utilization	(2)	(2)	(4)	(5)
Ending balance	8	21	8	21
Occupancy & Equipment | Occupancy & Equipment
Restructuring Reserve [Roll Forward]
Beginning balance	14	17	16	18
Additions	0	15	0	17
Reversals	0	0	0	0
Utilization	(2)	(5)	(4)	(8)
Ending balance	12	27	12	27
Other | Other
Restructuring Reserve [Roll Forward]
Beginning balance	0	0	5	3
Additions	0	5	0	6
Reversals	0	0	0	0
Utilization	0	(1)	(5)	(5)
Ending balance	$ 0	$ 4	$ 0	$ 4