PREMISES, EQUIPMENT, AND SOFTWARE - Schedule of Premises and Equipment (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Property, Plant and Equipment [Line Items]
Total premises and equipment, gross	$ 2,275	$ 2,590
Less: accumulated depreciation	(1,484)	(1,905)
Total premises and equipment, net	791	685
Land and land improvements
Property, Plant and Equipment [Line Items]
Total premises and equipment, gross	$ 112	47
Land and land improvements | Minimum
Property, Plant and Equipment [Line Items]
Useful life	10 years
Land and land improvements | Maximum
Property, Plant and Equipment [Line Items]
Useful life	75 years
Buildings and leasehold improvements
Property, Plant and Equipment [Line Items]
Total premises and equipment, gross	$ 852	719
Buildings and leasehold improvements | Minimum
Property, Plant and Equipment [Line Items]
Useful life	5 years
Buildings and leasehold improvements | Maximum
Property, Plant and Equipment [Line Items]
Useful life	60 years
Furniture, fixtures and equipment
Property, Plant and Equipment [Line Items]
Total premises and equipment, gross	$ 1,019	1,465
Furniture, fixtures and equipment | Minimum
Property, Plant and Equipment [Line Items]
Useful life	5 years
Furniture, fixtures and equipment | Maximum
Property, Plant and Equipment [Line Items]
Useful life	20 years
Construction in progress
Property, Plant and Equipment [Line Items]
Total premises and equipment, gross	$ 292	$ 359