PREMISES, EQUIPMENT, AND SOFTWARE - Schedule of Amortization (Details) $ in Millions	Dec. 31, 2016 USD ($)
Capitalized Software, Expected Future Amortization Expense [Abstract]
2017	$ 160
2018	139
2019	108
2020	78
2021	41
Thereafter	114
Total	640	[1]
In-process software	$ 138

[1] Excluded from this balance is $138 million of in-process software at December 31, 2016.