Other Assets (Schedule of Other Assets) (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
	Jun. 30, 2019	Jun. 30, 2019	Dec. 31, 2018
Other Assets [Abstract]
Property and equipment at cost	$ 1,245	$ 1,245	$ 1,250
Accumulated depreciation, property and equipment	(640)	(640)	(686)
Property and equipment, net	605	605	564
Nonmarketable equity securities	1,303	1,303	1,410
Investments in qualified affordable housing projects	724	724	649
Accrued interest, late fees, and rent receivables	631	631	599
Restricted cash collections for securitization trusts	608	608	965
Other accounts receivable	396	396	203
Equity method investments	317	317	262
Goodwill	240	240	240
Deferred tax assets, net	173	173	317
Restricted cash and cash equivalents	99	99	124
Fair value of derivative contracts in receivable position	59	59	41
Cash collateral placed with counterparties	9	9	26
Other assets, other	911	911	753
Total other assets	6,075	6,075	6,153
Federal Home Loan Bank stock	778	778	903
Federal Reserve Bank stock	448	448	448
Equity securities without a readily determinable fair value	77	77	59
Equity Securities without Readily Determinable Fair Value, Upward Price Adjustment, Annual Amount	7	7
Equity Securities without Readily Determinable Fair Value, Upward Price Adjustment, Cumulative Amount	7	7
Impairment related to equity securities without a readily determinable fair value	3	3
Investments in qualified affordable housing projects, unfunded commitment	322	322	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