Finance Receivables and Loans, Net (Past Due Financing Receivables and Loans) (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Financing Receivable, Past Due [Line Items]
Financing receivable, recorded investment, past due		$ 3,151
Financing receivable, recorded investment, current		126,775
Total finance receivables and loans	$ 128,231	129,926
Excludes fair value option elected other loans
Financing Receivable, Past Due [Line Items]
Financing receivable, recorded investment, past due	3,369
Financing receivable, recorded investment, current	124,851
Total finance receivables and loans	128,220
Consumer portfolio segment
Financing Receivable, Past Due [Line Items]
Financing receivable, recorded investment, past due		3,098
Financing receivable, recorded investment, current		84,142
Total finance receivables and loans	89,924	87,240
Consumer portfolio segment | Fair value | Finance receivables and Loans, net
Financing Receivable, Past Due [Line Items]
Loans Receivable, Fair Value Disclosure	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	89,913
Consumer portfolio segment | Automotive loan
Financing Receivable, Past Due [Line Items]
Financing receivable, recorded investment, past due	3,142	2,940
Financing receivable, recorded investment, current	69,248	67,599
Total finance receivables and loans	72,390	70,539
Consumer portfolio segment | Real estate-backed loan
Financing Receivable, Past Due [Line Items]
Financing receivable, recorded investment, past due	137	158
Financing receivable, recorded investment, current	17,185	16,543
Total finance receivables and loans	17,322	16,701
Consumer portfolio segment | Mortgage Finance operations
Financing Receivable, Past Due [Line Items]
Financing receivable, recorded investment, past due	76	76
Financing receivable, recorded investment, current	16,105	15,079
Total finance receivables and loans	16,181	15,155
Consumer portfolio segment | Mortgage - Legacy
Financing Receivable, Past Due [Line Items]
Financing receivable, recorded investment, past due	61	82
Financing receivable, recorded investment, current	1,080	1,464
Total finance receivables and loans	1,141	1,546
Consumer portfolio segment | Other loan
Financing Receivable, Past Due [Line Items]
Total finance receivables and loans	212	0
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	201
Commercial portfolio segment
Financing Receivable, Past Due [Line Items]
Financing receivable, recorded investment, past due	83	53
Financing receivable, recorded investment, current	38,224	42,633
Total finance receivables and loans	38,307	42,686
Commercial portfolio segment | Automotive loan
Financing Receivable, Past Due [Line Items]
Financing receivable, recorded investment, past due	62	32
Financing receivable, recorded investment, current	28,270	33,640
Total finance receivables and loans	28,332	33,672
Commercial portfolio segment | Real estate-backed loan
Financing Receivable, Past Due [Line Items]
Financing receivable, recorded investment, past due	4	1
Financing receivable, recorded investment, current	4,957	4,808
Total finance receivables and loans	4,961	4,809
Commercial portfolio segment | Other loan
Financing Receivable, Past Due [Line Items]
Financing receivable, recorded investment, past due	17	20
Financing receivable, recorded investment, current	4,997	4,185
Total finance receivables and loans	5,014	4,205
Financing receivables, 30 to 59 days past due
Financing Receivable, Past Due [Line Items]
Financing receivable, recorded investment, past due		2,204
Financing receivables, 30 to 59 days past due | Excludes fair value option elected other loans
Financing Receivable, Past Due [Line Items]
Financing receivable, recorded investment, past due	2,303
Financing receivables, 30 to 59 days past due | Consumer portfolio segment
Financing Receivable, Past Due [Line Items]
Financing receivable, recorded investment, past due		2,204
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	2,107
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	97
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	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	30
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, 30 to 59 days past due | Commercial portfolio segment
Financing Receivable, Past Due [Line Items]
Financing receivable, recorded investment, past due	34	0
Financing receivables, 30 to 59 days past due | Commercial portfolio segment | Automotive loan
Financing Receivable, Past Due [Line Items]
Financing receivable, recorded investment, past due	34	0
Financing receivables, 30 to 59 days past due | Commercial portfolio segment | Real estate-backed loan
Financing Receivable, Past Due [Line Items]
Financing receivable, recorded investment, past due	0	0
Financing receivables, 30 to 59 days past due | Commercial portfolio segment | Other loan
Financing Receivable, Past Due [Line Items]
Financing receivable, recorded investment, past due	0	0
Financing receivables, 60 to 89 days past due
Financing Receivable, Past Due [Line Items]
Financing receivable, recorded investment, past due		557
Financing receivables, 60 to 89 days past due | 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
Financing Receivable, Past Due [Line Items]
Financing receivable, recorded investment, past due		552
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	537
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	15
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	5
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	10
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, 60 to 89 days past due | Commercial portfolio segment
Financing Receivable, Past Due [Line Items]
Financing receivable, recorded investment, past due	0	5
Financing receivables, 60 to 89 days past due | Commercial portfolio segment | Automotive loan
Financing Receivable, Past Due [Line Items]
Financing receivable, recorded investment, past due	0	1
Financing receivables, 60 to 89 days past due | Commercial portfolio segment | Real estate-backed loan
Financing Receivable, Past Due [Line Items]
Financing receivable, recorded investment, past due	0	0
Financing receivables, 60 to 89 days past due | Commercial portfolio segment | Other loan
Financing Receivable, Past Due [Line Items]
Financing receivable, recorded investment, past due	0	4
Financing receivables, equal to greater than 90 days past due
Financing Receivable, Past Due [Line Items]
Financing receivable, recorded investment, past due		390
Financing receivables, equal to greater than 90 days past due | Excludes fair value option elected other loans
Financing Receivable, Past Due [Line Items]
Financing receivable, recorded investment, past due	455
Financing receivables, equal to greater than 90 days past due | Consumer portfolio segment
Financing Receivable, Past Due [Line Items]
Financing receivable, recorded investment, past due		342
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	296
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	46
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	4
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	42
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
Financing receivables, equal to greater than 90 days past due | Commercial portfolio segment
Financing Receivable, Past Due [Line Items]
Financing receivable, recorded investment, past due	49	48
Financing receivables, equal to greater than 90 days past due | Commercial portfolio segment | Automotive loan
Financing Receivable, Past Due [Line Items]
Financing receivable, recorded investment, past due	28	31
Financing receivables, equal to greater than 90 days past due | Commercial portfolio segment | Real estate-backed loan
Financing Receivable, Past Due [Line Items]
Financing receivable, recorded investment, past due	4	1
Financing receivables, equal to greater than 90 days past due | Commercial portfolio segment | Other loan
Financing Receivable, Past Due [Line Items]
Financing receivable, recorded investment, past due	$ 17	$ 16