Other Assets (Schedule of Other Assets) (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2019	Dec. 31, 2018
Other Assets [Abstract]
Property and equipment at cost	$ 1,294	$ 1,294	$ 1,250
Accumulated depreciation, property and equipment	(662)	(662)	(686)
Property and equipment, net	632	632	564
Nonmarketable equity securities	1,243	1,243	1,410
Investments in qualified affordable housing projects	784	784	649
Restricted cash collections for securitization trusts	666	666	965
Accrued interest, late fees, and rent receivables	594	594	599
Equity method investments	322	322	262
Goodwill	240	240	240
Other accounts receivable	118	118	203
Fair value of derivative contracts in receivable position	94	94	41
Restricted cash and cash equivalents	88	88	124
Deferred tax assets, net	75	75	317
Cash collateral placed with counterparties	6	6	26
Other assets, other	928	928	753
Total other assets	5,790	5,790	6,153
Federal Home Loan Bank stock	711	711	903
Federal Reserve Bank stock	449	449	448
Equity securities without a readily determinable fair value	83	83	59
Equity Securities without Readily Determinable Fair Value, Upward Price Adjustment, Annual Amount	2	9
Equity Securities without Readily Determinable Fair Value, Upward Price Adjustment, Cumulative Amount	9	9
Impairment related to equity securities without a readily determinable fair value	3	3
Investments in qualified affordable housing projects, unfunded commitment	350	350	319
Goodwill [Line Items]
Goodwill	240	240	240
Corporate and Other
Other Assets [Abstract]
Goodwill	193	193	193
Goodwill [Line Items]
Goodwill	193	193	193
Insurance operations | Operating Segments
Other Assets [Abstract]
Goodwill	27	27	27
Goodwill [Line Items]
Goodwill	27	27	27
Automotive Finance operations | Operating Segments
Other Assets [Abstract]
Goodwill	20	20	20
Goodwill [Line Items]
Goodwill	$ 20	$ 20	$ 20