Premises, Equipment & Lease Commitments Premises, Equipment & Lease Commitments - Components of Premises and Equipment (Details) - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015
Property, Plant and Equipment [Line Items]
Total premises and equipment, gross	$ 7,487	$ 6,999
Less: Accumulated depreciation and amortization	(3,812)	(3,415)
Total premises and equipment, net	3,675	3,584
Land
Property, Plant and Equipment [Line Items]
Total premises and equipment, gross	423	458
Buildings and improvements
Property, Plant and Equipment [Line Items]
Total premises and equipment, gross	2,958	2,674
Furniture and equipment
Property, Plant and Equipment [Line Items]
Total premises and equipment, gross	1,834	1,735
Computer software
Property, Plant and Equipment [Line Items]
Total premises and equipment, gross	1,681	1,618
In progress
Property, Plant and Equipment [Line Items]
Total premises and equipment, gross	$ 591	$ 514