Income Taxes - Schedule of Significant Components of Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Deferred tax assets:
Allowance for loan and lease losses	$ 1,768	$ 2,350
Rewards programs	936	1,348
Security and loan valuations	424	869
Net operating loss and tax credit carryforwards	244	188
Compensation and employee benefits	208	276
Goodwill and intangibles	201	294
Unearned income	130	186
Net unrealized losses on derivatives	104	35
Representation and warranty reserve	8	234
Other assets	278	270
Subtotal	4,301	6,050
Valuation allowance	(226)	(179)
Total deferred tax assets	4,075	5,871
Deferred tax liabilities:
Original issue discount	703	1,012
Fixed assets and leases	168	221
Deferred tax liabilities, loan fees and expenses	68	84
Deferred Tax Liabilities, Mortgage Servicing Rights	57	67
Other liabilities	215	177
Total deferred tax liabilities	1,211	1,561
Net deferred tax assets	$ 2,864	$ 4,310