Premises and Equipment and Other Assets - Premises and Equipment Carried at Cost (Details) - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015
Premises and Equipment
Cost	$ 1,635	$ 1,784
Accumulated Depreciation and Amortization	(1,044)	(1,140)
Net Book Value	591	644
Land
Premises and Equipment
Cost	120	140
Accumulated Depreciation and Amortization	0	0
Net Book Value	120	140
Premises
Premises and Equipment
Cost	473	599
Accumulated Depreciation and Amortization	(275)	(341)
Net Book Value	198	258
Leasehold improvements
Premises and Equipment
Cost	405	357
Accumulated Depreciation and Amortization	(255)	(239)
Net Book Value	150	118
Furniture, fixtures and equipment
Premises and Equipment
Cost	637	688
Accumulated Depreciation and Amortization	(514)	(560)
Net Book Value	$ 123	$ 128