Finance Receivables and Loans, Net (Past Due Financing Receivables and Loans Consumer) (Details) - USD ($) $ in Millions	Mar. 31, 2020	Dec. 31, 2019	Mar. 31, 2019
Financing Receivable, Past Due [Line Items]
Total finance receivables and loans	$ 128,139	$ 128,231	$ 130,055
Consumer portfolio segment
Financing Receivable, Past Due [Line Items]
Total finance receivables and loans	90,066	89,924
Consumer portfolio segment | Fair value | Finance receivables and loans, net
Financing Receivable, Past Due [Line Items]
Loans receivable, fair value	10	11
Consumer portfolio segment | Excludes fair value option elected other loans
Financing Receivable, Past Due [Line Items]
Financing receivable, recorded investment, past due		3,286
Financing receivable, recorded investment, current		86,627
Total finance receivables and loans	90,056	89,913
Consumer portfolio segment | Automotive loan
Financing Receivable, Past Due [Line Items]
Financing receivable, recorded investment, past due		3,142
Financing receivable, recorded investment, current		69,248
Total finance receivables and loans	72,832	72,390	71,553
Consumer portfolio segment | Real estate-backed loan
Financing Receivable, Past Due [Line Items]
Financing receivable, recorded investment, past due		137
Financing receivable, recorded investment, current		17,185
Total finance receivables and loans	17,010	17,322	$ 17,658
Consumer portfolio segment | Mortgage Finance operations
Financing Receivable, Past Due [Line Items]
Financing receivable, recorded investment, past due		76
Financing receivable, recorded investment, current		16,105
Total finance receivables and loans	15,949	16,181
Consumer portfolio segment | Mortgage - Legacy
Financing Receivable, Past Due [Line Items]
Financing receivable, recorded investment, past due		61
Financing receivable, recorded investment, current		1,080
Total finance receivables and loans	1,061	1,141
Consumer portfolio segment | Other loan
Financing Receivable, Past Due [Line Items]
Total finance receivables and loans	224	212
Consumer portfolio segment | Other loan | Excludes fair value option elected other loans
Financing Receivable, Past Due [Line Items]
Financing receivable, recorded investment, past due		7
Financing receivable, recorded investment, current		194
Total finance receivables and loans	214	201
Financing receivables, 30 to 59 days past due | Consumer portfolio segment | Excludes fair value option elected other loans
Financing Receivable, Past Due [Line Items]
Financing receivable, recorded investment, past due		2,269
Financing receivables, 30 to 59 days past due | Consumer portfolio segment | Automotive loan
Financing Receivable, Past Due [Line Items]
Financing receivable, recorded investment, past due		2,185
Total finance receivables and loans	2,118
Financing receivables, 30 to 59 days past due | Consumer portfolio segment | Real estate-backed loan
Financing Receivable, Past Due [Line Items]
Financing receivable, recorded investment, past due		81
Financing receivables, 30 to 59 days past due | Consumer portfolio segment | Mortgage Finance operations
Financing Receivable, Past Due [Line Items]
Financing receivable, recorded investment, past due		56
Total finance receivables and loans	67
Financing receivables, 30 to 59 days past due | Consumer portfolio segment | Mortgage - Legacy
Financing Receivable, Past Due [Line Items]
Financing receivable, recorded investment, past due		25
Total finance receivables and loans	21
Financing receivables, 30 to 59 days past due | Consumer portfolio segment | Other loan
Financing Receivable, Past Due [Line Items]
Total finance receivables and loans	3
Financing receivables, 30 to 59 days past due | Consumer portfolio segment | Other loan | Excludes fair value option elected other loans
Financing Receivable, Past Due [Line Items]
Financing receivable, recorded investment, past due		3
Financing receivables, 60 to 89 days past due | Consumer portfolio segment | Excludes fair value option elected other loans
Financing Receivable, Past Due [Line Items]
Financing receivable, recorded investment, past due		611
Financing receivables, 60 to 89 days past due | Consumer portfolio segment | Automotive loan
Financing Receivable, Past Due [Line Items]
Financing receivable, recorded investment, past due		590
Total finance receivables and loans	573
Financing receivables, 60 to 89 days past due | Consumer portfolio segment | Real estate-backed loan
Financing Receivable, Past Due [Line Items]
Financing receivable, recorded investment, past due		19
Financing receivables, 60 to 89 days past due | Consumer portfolio segment | Mortgage Finance operations
Financing Receivable, Past Due [Line Items]
Financing receivable, recorded investment, past due		11
Total finance receivables and loans	10
Financing receivables, 60 to 89 days past due | Consumer portfolio segment | Mortgage - Legacy
Financing Receivable, Past Due [Line Items]
Financing receivable, recorded investment, past due		8
Total finance receivables and loans	6
Financing receivables, 60 to 89 days past due | Consumer portfolio segment | Other loan
Financing Receivable, Past Due [Line Items]
Total finance receivables and loans	2
Financing receivables, 60 to 89 days past due | Consumer portfolio segment | Other loan | Excludes fair value option elected other loans
Financing Receivable, Past Due [Line Items]
Financing receivable, recorded investment, past due		2
Financing receivables, equal to greater than 90 days past due | Consumer portfolio segment | Excludes fair value option elected other loans
Financing Receivable, Past Due [Line Items]
Financing receivable, recorded investment, past due		406
Financing receivables, equal to greater than 90 days past due | Consumer portfolio segment | Automotive loan
Financing Receivable, Past Due [Line Items]
Financing receivable, recorded investment, past due		367
Total finance receivables and loans	428
Financing receivables, equal to greater than 90 days past due | Consumer portfolio segment | Real estate-backed loan
Financing Receivable, Past Due [Line Items]
Financing receivable, recorded investment, past due		37
Financing receivables, equal to greater than 90 days past due | Consumer portfolio segment | Mortgage Finance operations
Financing Receivable, Past Due [Line Items]
Financing receivable, recorded investment, past due		9
Total finance receivables and loans	11
Financing receivables, equal to greater than 90 days past due | Consumer portfolio segment | Mortgage - Legacy
Financing Receivable, Past Due [Line Items]
Financing receivable, recorded investment, past due		28
Total finance receivables and loans	26
Financing receivables, equal to greater than 90 days past due | Consumer portfolio segment | Other loan
Financing Receivable, Past Due [Line Items]
Total finance receivables and loans	$ 1
Financing receivables, equal to greater than 90 days past due | Consumer portfolio segment | Other loan | Excludes fair value option elected other loans
Financing Receivable, Past Due [Line Items]
Financing receivable, recorded investment, past due		$ 2