PREMISES, EQUIPMENT, AND SOFTWARE - Schedule of Premises and Equipment (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Property, Plant and Equipment [Line Items]
Total premises and equipment, gross	$ 1,853	$ 2,275
Less: accumulated depreciation	(1,092)	(1,484)
Total premises and equipment, net	761	791
Land and land improvements
Property, Plant and Equipment [Line Items]
Total premises and equipment, gross	$ 102	112
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	$ 848	852
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	$ 535	1,019
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	$ 368	$ 292