Other Assets (Schedule of Other Assets) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Dec. 31, 2018
Other Assets [Abstract]
Property and equipment at cost	$ 1,286	$ 1,250
Accumulated depreciation, property and equipment	(708)	(686)
Property and equipment, net	578	564
Nonmarketable equity securities	1,240	1,410
Restricted cash collections for securitization trusts	838	965
Investments in qualified affordable housing projects	687	649
Accrued interest, late fees, and rent receivables	624	599
Equity method investments	289	262
Other accounts receivable	269	203
Goodwill	240	240
Deferred tax assets, net	137	317
Restricted cash and cash equivalents	109	124
Derivative contracts in a receivable position, fair value	22	41
Cash collateral placed with counterparties	20	26
Other assets, other	940	753
Total other assets	5,993	6,153
Federal Home Loan Bank stock	732	903
Federal Reserve Bank stock	448	448
Equity securities without a readily determinable fair value	60	59
Impairment related to equity securities without a readily determinable fair value	3
Investments in qualified affordable housing projects, unfunded commitment	336	319
Goodwill [Line Items]
Goodwill	240	240
Corporate and Other
Other Assets [Abstract]
Goodwill	193	193
Goodwill [Line Items]
Goodwill	193	193
Insurance operations
Other Assets [Abstract]
Goodwill	27	27
Goodwill [Line Items]
Goodwill	27	27
Automotive Finance operations
Other Assets [Abstract]
Goodwill	20	20
Goodwill [Line Items]
Goodwill	$ 20	$ 20