Income Taxes - Schedule of Significant Components of Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Millions	Dec. 31, 2015	Dec. 31, 2014
Deferred tax assets:
Allowance for loan and lease losses	$ 1,853	$ 1,574
Rewards programs	1,192	993
Security and loan valuations	912	928
Compensation and employee benefits	303	305
Goodwill and intangibles	245	140
Representation and warranty reserve	226	271
Net operating loss and tax credit carryforwards	176	163
Unearned income	143	100
Net unrealized losses on derivatives	0	41
Other assets	329	323
Subtotal	5,379	4,838
Valuation allowance	(166)	(148)
Total deferred tax assets	5,213	4,690
Deferred tax liabilities:
Original issue discount	940	875
Fixed assets and leases	242	208
Deferred Tax Liabilities, Derivatives	46	0
Other liabilities	323	275
Total deferred tax liabilities	1,551	1,358
Net deferred tax assets	$ 3,662	$ 3,332