Finance Receivables and Loans, Net (Financing Receivable Credit Quality Indicators Consumer) (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Financing Receivable, Credit Quality Indicator [Line Items]
Finance receivables and loans, net	$ 118,534	$ 128,231
Excludes fair value option elected other loans
Financing Receivable, Credit Quality Indicator [Line Items]
Finance receivables and loans, net		128,220
Consumer portfolio segment
Financing Receivable, Credit Quality Indicator [Line Items]
Finance receivables and loans, net	89,202	89,924
Consumer portfolio segment | Excludes fair value option elected other loans
Financing Receivable, Credit Quality Indicator [Line Items]
Financing Receivable, Originated in Current Fiscal Year	31,399
Financing Receivable, Originated in Fiscal Year before Latest Fiscal Year	22,426
Financing Receivable, Originated Two Years before Latest Fiscal Year	14,509
Financing Receivable, Originated Three Years before Latest Fiscal Year	9,765
Financing Receivable, Originated Four Years before Latest Fiscal Year	5,143
Financing Receivable, Originated Five or More Years before Latest Fiscal Year	5,604
Financing Receivable, Revolving	310
Converted to term loans	38
Finance receivables and loans, net	89,194	89,913
Consumer portfolio segment | Automotive loan
Financing Receivable, Credit Quality Indicator [Line Items]
Financing Receivable, Originated in Current Fiscal Year	27,634
Financing Receivable, Originated in Fiscal Year before Latest Fiscal Year	19,943
Financing Receivable, Originated Two Years before Latest Fiscal Year	12,730
Financing Receivable, Originated Three Years before Latest Fiscal Year	7,483
Financing Receivable, Originated Four Years before Latest Fiscal Year	3,953
Financing Receivable, Originated Five or More Years before Latest Fiscal Year	1,925
Financing Receivable, Revolving	0
Converted to term loans	0
Finance receivables and loans, net	73,668	72,390
Consumer portfolio segment | Real estate-backed loan
Financing Receivable, Credit Quality Indicator [Line Items]
Financing Receivable, Originated in Current Fiscal Year	3,444
Financing Receivable, Originated in Fiscal Year before Latest Fiscal Year	2,425
Financing Receivable, Originated Two Years before Latest Fiscal Year	1,765
Financing Receivable, Originated Three Years before Latest Fiscal Year	2,277
Financing Receivable, Originated Four Years before Latest Fiscal Year	1,189
Financing Receivable, Originated Five or More Years before Latest Fiscal Year	3,679
Financing Receivable, Revolving	310
Converted to term loans	38
Finance receivables and loans, net	15,127	17,322
Consumer portfolio segment | Mortgage Finance operations
Financing Receivable, Credit Quality Indicator [Line Items]
Financing Receivable, Originated in Current Fiscal Year	3,444
Financing Receivable, Originated in Fiscal Year before Latest Fiscal Year	2,425
Financing Receivable, Originated Two Years before Latest Fiscal Year	1,765
Financing Receivable, Originated Three Years before Latest Fiscal Year	2,277
Financing Receivable, Originated Four Years before Latest Fiscal Year	1,189
Financing Receivable, Originated Five or More Years before Latest Fiscal Year	3,532
Financing Receivable, Revolving	0
Converted to term loans	0
Finance receivables and loans, net	14,632	16,181
Consumer portfolio segment | Mortgage - Legacy
Financing Receivable, Credit Quality Indicator [Line Items]
Financing Receivable, Originated in Current Fiscal Year	0
Financing Receivable, Originated in Fiscal Year before Latest Fiscal Year	0
Financing Receivable, Originated Two Years before Latest Fiscal Year	0
Financing Receivable, Originated Three Years before Latest Fiscal Year	0
Financing Receivable, Originated Four Years before Latest Fiscal Year	0
Financing Receivable, Originated Five or More Years before Latest Fiscal Year	147
Financing Receivable, Revolving	310
Converted to term loans	38
Finance receivables and loans, net	495	1,141
Consumer portfolio segment | Other loan
Financing Receivable, Credit Quality Indicator [Line Items]
Finance receivables and loans, net	407	212
Loans receivable, fair value	8	11
Consumer portfolio segment | Other loan | Excludes fair value option elected other loans
Financing Receivable, Credit Quality Indicator [Line Items]
Financing Receivable, Originated in Current Fiscal Year	321
Financing Receivable, Originated in Fiscal Year before Latest Fiscal Year	58
Financing Receivable, Originated Two Years before Latest Fiscal Year	14
Financing Receivable, Originated Three Years before Latest Fiscal Year	5
Financing Receivable, Originated Four Years before Latest Fiscal Year	1
Financing Receivable, Originated Five or More Years before Latest Fiscal Year	0
Financing Receivable, Revolving	0
Converted to term loans	0
Finance receivables and loans, net	399	$ 201
Current period | Consumer portfolio segment | Automotive loan
Financing Receivable, Credit Quality Indicator [Line Items]
Financing Receivable, Originated in Current Fiscal Year	27,255
Financing Receivable, Originated in Fiscal Year before Latest Fiscal Year	19,204
Financing Receivable, Originated Two Years before Latest Fiscal Year	12,129
Financing Receivable, Originated Three Years before Latest Fiscal Year	7,060
Financing Receivable, Originated Four Years before Latest Fiscal Year	3,678
Financing Receivable, Originated Five or More Years before Latest Fiscal Year	1,766
Financing Receivable, Revolving	0
Converted to term loans	0
Finance receivables and loans, net	71,092
Current period | Consumer portfolio segment | Mortgage Finance operations
Financing Receivable, Credit Quality Indicator [Line Items]
Financing Receivable, Originated in Current Fiscal Year	3,432
Financing Receivable, Originated in Fiscal Year before Latest Fiscal Year	2,410
Financing Receivable, Originated Two Years before Latest Fiscal Year	1,744
Financing Receivable, Originated Three Years before Latest Fiscal Year	2,254
Financing Receivable, Originated Four Years before Latest Fiscal Year	1,177
Financing Receivable, Originated Five or More Years before Latest Fiscal Year	3,492
Financing Receivable, Revolving	0
Converted to term loans	0
Finance receivables and loans, net	14,509
Current period | Consumer portfolio segment | Mortgage - Legacy
Financing Receivable, Credit Quality Indicator [Line Items]
Financing Receivable, Originated in Current Fiscal Year	0
Financing Receivable, Originated in Fiscal Year before Latest Fiscal Year	0
Financing Receivable, Originated Two Years before Latest Fiscal Year	0
Financing Receivable, Originated Three Years before Latest Fiscal Year	0
Financing Receivable, Originated Four Years before Latest Fiscal Year	0
Financing Receivable, Originated Five or More Years before Latest Fiscal Year	121
Financing Receivable, Revolving	303
Converted to term loans	36
Finance receivables and loans, net	460
Current period | Consumer portfolio segment | Other loan
Financing Receivable, Credit Quality Indicator [Line Items]
Financing Receivable, Originated in Current Fiscal Year	306
Financing Receivable, Originated in Fiscal Year before Latest Fiscal Year	53
Financing Receivable, Originated Two Years before Latest Fiscal Year	13
Financing Receivable, Originated Three Years before Latest Fiscal Year	4
Financing Receivable, Originated Four Years before Latest Fiscal Year	1
Financing Receivable, Originated Five or More Years before Latest Fiscal Year	0
Financing Receivable, Revolving	0
Converted to term loans	0
Finance receivables and loans, net	377
Financing receivables, 30 to 59 days past due | Consumer portfolio segment | Automotive loan
Financing Receivable, Credit Quality Indicator [Line Items]
Financing Receivable, Originated in Current Fiscal Year	281
Financing Receivable, Originated in Fiscal Year before Latest Fiscal Year	466
Financing Receivable, Originated Two Years before Latest Fiscal Year	376
Financing Receivable, Originated Three Years before Latest Fiscal Year	264
Financing Receivable, Originated Four Years before Latest Fiscal Year	174
Financing Receivable, Originated Five or More Years before Latest Fiscal Year	97
Financing Receivable, Revolving	0
Converted to term loans	0
Finance receivables and loans, net	1,658
Financing receivables, 30 to 59 days past due | Consumer portfolio segment | Mortgage Finance operations
Financing Receivable, Credit Quality Indicator [Line Items]
Financing Receivable, Originated in Current Fiscal Year	10
Financing Receivable, Originated in Fiscal Year before Latest Fiscal Year	9
Financing Receivable, Originated Two Years before Latest Fiscal Year	10
Financing Receivable, Originated Three Years before Latest Fiscal Year	11
Financing Receivable, Originated Four Years before Latest Fiscal Year	7
Financing Receivable, Originated Five or More Years before Latest Fiscal Year	16
Financing Receivable, Revolving	0
Converted to term loans	0
Finance receivables and loans, net	63
Financing receivables, 30 to 59 days past due | Consumer portfolio segment | Mortgage - Legacy
Financing Receivable, Credit Quality Indicator [Line Items]
Financing Receivable, Originated in Current Fiscal Year	0
Financing Receivable, Originated in Fiscal Year before Latest Fiscal Year	0
Financing Receivable, Originated Two Years before Latest Fiscal Year	0
Financing Receivable, Originated Three Years before Latest Fiscal Year	0
Financing Receivable, Originated Four Years before Latest Fiscal Year	0
Financing Receivable, Originated Five or More Years before Latest Fiscal Year	4
Financing Receivable, Revolving	2
Converted to term loans	0
Finance receivables and loans, net	6
Financing receivables, 30 to 59 days past due | Consumer portfolio segment | Other loan
Financing Receivable, Credit Quality Indicator [Line Items]
Financing Receivable, Originated in Current Fiscal Year	9
Financing Receivable, Originated in Fiscal Year before Latest Fiscal Year	3
Financing Receivable, Originated Two Years before Latest Fiscal Year	1
Financing Receivable, Originated Three Years before Latest Fiscal Year	0
Financing Receivable, Originated Four Years before Latest Fiscal Year	0
Financing Receivable, Originated Five or More Years before Latest Fiscal Year	0
Financing Receivable, Revolving	0
Converted to term loans	0
Finance receivables and loans, net	13
Financing receivables, 60 to 89 days past due | Consumer portfolio segment | Automotive loan
Financing Receivable, Credit Quality Indicator [Line Items]
Financing Receivable, Originated in Current Fiscal Year	66
Financing Receivable, Originated in Fiscal Year before Latest Fiscal Year	165
Financing Receivable, Originated Two Years before Latest Fiscal Year	129
Financing Receivable, Originated Three Years before Latest Fiscal Year	88
Financing Receivable, Originated Four Years before Latest Fiscal Year	55
Financing Receivable, Originated Five or More Years before Latest Fiscal Year	32
Financing Receivable, Revolving	0
Converted to term loans	0
Finance receivables and loans, net	535
Financing receivables, 60 to 89 days past due | Consumer portfolio segment | Mortgage Finance operations
Financing Receivable, Credit Quality Indicator [Line Items]
Financing Receivable, Originated in Current Fiscal Year	1
Financing Receivable, Originated in Fiscal Year before Latest Fiscal Year	1
Financing Receivable, Originated Two Years before Latest Fiscal Year	3
Financing Receivable, Originated Three Years before Latest Fiscal Year	2
Financing Receivable, Originated Four Years before Latest Fiscal Year	1
Financing Receivable, Originated Five or More Years before Latest Fiscal Year	3
Financing Receivable, Revolving	0
Converted to term loans	0
Finance receivables and loans, net	11
Financing receivables, 60 to 89 days past due | Consumer portfolio segment | Mortgage - Legacy
Financing Receivable, Credit Quality Indicator [Line Items]
Financing Receivable, Originated in Current Fiscal Year	0
Financing Receivable, Originated in Fiscal Year before Latest Fiscal Year	0
Financing Receivable, Originated Two Years before Latest Fiscal Year	0
Financing Receivable, Originated Three Years before Latest Fiscal Year	0
Financing Receivable, Originated Four Years before Latest Fiscal Year	0
Financing Receivable, Originated Five or More Years before Latest Fiscal Year	2
Financing Receivable, Revolving	0
Converted to term loans	0
Finance receivables and loans, net	2
Financing receivables, 60 to 89 days past due | Consumer portfolio segment | Other loan
Financing Receivable, Credit Quality Indicator [Line Items]
Financing Receivable, Originated in Current Fiscal Year	4
Financing Receivable, Originated in Fiscal Year before Latest Fiscal Year	1
Financing Receivable, Originated Two Years before Latest Fiscal Year	0
Financing Receivable, Originated Three Years before Latest Fiscal Year	1
Financing Receivable, Originated Four Years before Latest Fiscal Year	0
Financing Receivable, Originated Five or More Years before Latest Fiscal Year	0
Financing Receivable, Revolving	0
Converted to term loans	0
Finance receivables and loans, net	6
Financing receivables, equal to greater than 90 days past due | Consumer portfolio segment | Automotive loan
Financing Receivable, Credit Quality Indicator [Line Items]
Financing Receivable, Originated in Current Fiscal Year	32
Financing Receivable, Originated in Fiscal Year before Latest Fiscal Year	108
Financing Receivable, Originated Two Years before Latest Fiscal Year	96
Financing Receivable, Originated Three Years before Latest Fiscal Year	71
Financing Receivable, Originated Four Years before Latest Fiscal Year	46
Financing Receivable, Originated Five or More Years before Latest Fiscal Year	30
Financing Receivable, Revolving	0
Converted to term loans	0
Finance receivables and loans, net	383
Financing receivables, equal to greater than 90 days past due | Consumer portfolio segment | Mortgage Finance operations
Financing Receivable, Credit Quality Indicator [Line Items]
Financing Receivable, Originated in Current Fiscal Year	1
Financing Receivable, Originated in Fiscal Year before Latest Fiscal Year	5
Financing Receivable, Originated Two Years before Latest Fiscal Year	8
Financing Receivable, Originated Three Years before Latest Fiscal Year	10
Financing Receivable, Originated Four Years before Latest Fiscal Year	4
Financing Receivable, Originated Five or More Years before Latest Fiscal Year	21
Financing Receivable, Revolving	0
Converted to term loans	0
Finance receivables and loans, net	49
Financing receivables, equal to greater than 90 days past due | Consumer portfolio segment | Mortgage - Legacy
Financing Receivable, Credit Quality Indicator [Line Items]
Financing Receivable, Originated in Current Fiscal Year	0
Financing Receivable, Originated in Fiscal Year before Latest Fiscal Year	0
Financing Receivable, Originated Two Years before Latest Fiscal Year	0
Financing Receivable, Originated Three Years before Latest Fiscal Year	0
Financing Receivable, Originated Four Years before Latest Fiscal Year	0
Financing Receivable, Originated Five or More Years before Latest Fiscal Year	20
Financing Receivable, Revolving	5
Converted to term loans	2
Finance receivables and loans, net	27
Financing receivables, equal to greater than 90 days past due | Consumer portfolio segment | Other loan
Financing Receivable, Credit Quality Indicator [Line Items]
Financing Receivable, Originated in Current Fiscal Year	2
Financing Receivable, Originated in Fiscal Year before Latest Fiscal Year	1
Financing Receivable, Originated Two Years before Latest Fiscal Year	0
Financing Receivable, Originated Three Years before Latest Fiscal Year	0
Financing Receivable, Originated Four Years before Latest Fiscal Year	0
Financing Receivable, Originated Five or More Years before Latest Fiscal Year	0
Financing Receivable, Revolving	0
Converted to term loans	0
Finance receivables and loans, net	$ 3