PREMISES, EQUIPMENT, AND SOFTWARE - Schedule of Amortization (Details) $ in Millions	Dec. 31, 2015 USD ($)
Capitalized Software, Expected Future Amortization Expense [Abstract]
2016	$ 142
2017	125
2018	104
2019	72
2020	43
Thereafter	129
Total	615	[1]
In-process software	$ 171

[1] Excluded from this balance is $171 million of in-process software at December 31, 2015.