Income Taxes - Schedule of Significant Components of Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015
Deferred tax assets:
Allowance for loan and lease losses	$ 2,350	$ 1,853
Rewards programs	1,348	1,192
Security and loan valuations	869	912
Goodwill and intangibles	294	245
Compensation and employee benefits	276	303
Representation and warranty reserve	234	226
Net operating loss and tax credit carryforwards	188	176
Unearned income	186	143
Net unrealized losses on derivatives	35	0
Other assets	270	329
Subtotal	6,050	5,379
Valuation allowance	(179)	(166)
Total deferred tax assets	5,871	5,213
Deferred tax liabilities:
Original issue discount	1,012	940
Fixed assets and leases	221	242
Deferred Tax Liabilities, Derivatives	0	46
Other liabilities	328	323
Total deferred tax liabilities	1,561	1,551
Net deferred tax assets	$ 4,310	$ 3,662