Premises and Equipment - 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	$ 2,478	$ 2,508
Less: Accumulated depreciation and amortization	(1,596)	(1,578)
Premises and equipment, net	882	930
Land
Property, Plant and Equipment [Line Items]
Total premises and equipment	135	138
Buildings and improvements
Property, Plant and Equipment [Line Items]
Total premises and equipment	$ 747	741
Buildings and improvements | Minimum [Member]
Property, Plant and Equipment [Line Items]
Useful life (in years)	15 years
Buildings and improvements | Maximum [Member]
Property, Plant and Equipment [Line Items]
Useful life (in years)	40 years
Leasehold improvements
Property, Plant and Equipment [Line Items]
Total premises and equipment	$ 626	633
Leasehold improvements | Minimum [Member]
Property, Plant and Equipment [Line Items]
Useful life (in years)	1 year
Leasehold improvements | Maximum [Member]
Property, Plant and Equipment [Line Items]
Useful life (in years)	15 years
Furniture and equipment
Property, Plant and Equipment [Line Items]
Total premises and equipment	$ 907	931
Furniture and equipment | Minimum [Member]
Property, Plant and Equipment [Line Items]
Useful life (in years)	2 years
Furniture and equipment | Maximum [Member]
Property, Plant and Equipment [Line Items]
Useful life (in years)	15 years
Capitalized building leases
Property, Plant and Equipment [Line Items]
Total premises and equipment	$ 28	27
Capitalized building leases | Minimum [Member]
Property, Plant and Equipment [Line Items]
Useful life (in years)	1 year
Capitalized building leases | Maximum [Member]
Property, Plant and Equipment [Line Items]
Useful life (in years)	15 years
Construction in process
Property, Plant and Equipment [Line Items]
Total premises and equipment	$ 35	$ 38