Premises, Equipment & Lease Commitments Premises, Equipment & Lease Commitments - Components of Premises and Equipment (Details) - USD ($) $ in Millions	Dec. 31, 2015	Dec. 31, 2014
Property, Plant and Equipment [Line Items]
Total premises and equipment, gross	$ 6,999	$ 6,882
Less: Accumulated depreciation and amortization	(3,415)	(3,197)
Total premises and equipment, net	3,584	3,685
Land
Property, Plant and Equipment [Line Items]
Total premises and equipment, gross	458	552
Buildings and improvements
Property, Plant and Equipment [Line Items]
Total premises and equipment, gross	2,674	2,577
Furniture and equipment
Property, Plant and Equipment [Line Items]
Total premises and equipment, gross	1,735	1,730
Computer software
Property, Plant and Equipment [Line Items]
Total premises and equipment, gross	1,618	1,556
In progress
Property, Plant and Equipment [Line Items]
Total premises and equipment, gross	$ 514	$ 467