EXIT COSTS AND RESTRUCTURING RESERVES - Reserve Rollforward (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Restructuring Reserve [Roll Forward]
Beginning balance	$ 20	$ 52	$ 33	$ 44
Additions	0	1	0	29
Reversals	0	(1)	0	(3)
Utilization	(7)	(14)	(20)	(32)
Ending balance	13	38	13	38
Salaries & Employee Benefits | Salaries & Employee Benefits
Restructuring Reserve [Roll Forward]
Beginning balance	8	21	12	23
Additions	0	0	0	5
Reversals	0	0	0	(2)
Utilization	(6)	(5)	(10)	(10)
Ending balance	2	16	2	16
Occupancy & Equipment | Occupancy & Equipment
Restructuring Reserve [Roll Forward]
Beginning balance	12	27	16	18
Additions	0	1	0	18
Reversals	0	(1)	0	(1)
Utilization	(1)	(8)	(5)	(16)
Ending balance	11	19	11	19
Other | Other
Restructuring Reserve [Roll Forward]
Beginning balance	0	4	5	3
Additions	0	0	0	6
Reversals	0	0	0	0
Utilization	0	(1)	(5)	(6)
Ending balance	$ 0	$ 3	$ 0	$ 3