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Finance Receivables and Loans, Net (Financing Receivable Credit Quality Indicators Consumer) (Details) $ in Millions	6 Months Ended
	Jun. 30, 2020 USD ($)	Dec. 31, 2019 USD ($)	Jun. 30, 2019 USD ($)
Financing Receivable, Credit Quality Indicator [Line Items]
Finance receivables and loans, net	$ 118,234	$ 128,231	$ 129,210
Consumer portfolio segment
Financing Receivable, Credit Quality Indicator [Line Items]
Finance receivables and loans, net	90,365	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	16,208
Financing Receivable, Originated in Fiscal Year before Latest Fiscal Year	27,289
Financing Receivable, Originated Two Years before Latest Fiscal Year	18,457
Financing Receivable, Originated Three Years before Latest Fiscal Year	13,042
Financing Receivable, Originated Four Years before Latest Fiscal Year	6,858
Financing Receivable, Originated Five or More Years before Latest Fiscal Year	8,028
Financing Receivable, Revolving	351
Converted to term loans	124
Finance receivables and loans, net	90,357	89,913
Consumer portfolio segment \| Automotive loan
Financing Receivable, Credit Quality Indicator [Line Items]
Financing Receivable, Originated in Current Fiscal Year	14,041
Financing Receivable, Originated in Fiscal Year before Latest Fiscal Year	24,187
Financing Receivable, Originated Two Years before Latest Fiscal Year	16,035
Financing Receivable, Originated Three Years before Latest Fiscal Year	9,868
Financing Receivable, Originated Four Years before Latest Fiscal Year	5,466
Financing Receivable, Originated Five or More Years before Latest Fiscal Year	3,115
Financing Receivable, Revolving	0
Converted to term loans	0
Finance receivables and loans, net	72,712	72,390	72,898
Consumer portfolio segment \| Real estate-backed loan
Financing Receivable, Credit Quality Indicator [Line Items]
Financing Receivable, Originated in Current Fiscal Year	2,056
Financing Receivable, Originated in Fiscal Year before Latest Fiscal Year	3,014
Financing Receivable, Originated Two Years before Latest Fiscal Year	2,397
Financing Receivable, Originated Three Years before Latest Fiscal Year	3,167
Financing Receivable, Originated Four Years before Latest Fiscal Year	1,391
Financing Receivable, Originated Five or More Years before Latest Fiscal Year	4,913
Financing Receivable, Revolving	351
Converted to term loans	124
Finance receivables and loans, net	17,413	17,322	$ 17,800
Consumer portfolio segment \| Other loan
Financing Receivable, Credit Quality Indicator [Line Items]
Finance receivables and loans, net	240	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	111
Financing Receivable, Originated in Fiscal Year before Latest Fiscal Year	88
Financing Receivable, Originated Two Years before Latest Fiscal Year	25
Financing Receivable, Originated Three Years before Latest Fiscal Year	7
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	232	$ 201
Current period \| Consumer portfolio segment \| Automotive loan
Financing Receivable, Credit Quality Indicator [Line Items]
Financing Receivable, Originated in Current Fiscal Year	13,963
Financing Receivable, Originated in Fiscal Year before Latest Fiscal Year	23,534
Financing Receivable, Originated Two Years before Latest Fiscal Year	15,405
Financing Receivable, Originated Three Years before Latest Fiscal Year	9,404
Financing Receivable, Originated Four Years before Latest Fiscal Year	5,152
Financing Receivable, Originated Five or More Years before Latest Fiscal Year	2,905
Financing Receivable, Revolving	0
Converted to term loans	0
Finance receivables and loans, net	70,363
Current period \| Consumer portfolio segment \| Other loan
Financing Receivable, Credit Quality Indicator [Line Items]
Financing Receivable, Originated in Current Fiscal Year	109
Financing Receivable, Originated in Fiscal Year before Latest Fiscal Year	86
Financing Receivable, Originated Two Years before Latest Fiscal Year	25
Financing Receivable, Originated Three Years before Latest Fiscal Year	7
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	228
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	52
Financing Receivable, Originated in Fiscal Year before Latest Fiscal Year	410
Financing Receivable, Originated Two Years before Latest Fiscal Year	374
Financing Receivable, Originated Three Years before Latest Fiscal Year	270
Financing Receivable, Originated Four Years before Latest Fiscal Year	176
Financing Receivable, Originated Five or More Years before Latest Fiscal Year	114
Financing Receivable, Revolving	0
Converted to term loans	0
Finance receivables and loans, net	1,396
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	1
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	0
Financing Receivable, Revolving	0
Converted to term loans	0
Finance receivables and loans, net	1
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	17
Financing Receivable, Originated in Fiscal Year before Latest Fiscal Year	122
Financing Receivable, Originated Two Years before Latest Fiscal Year	120
Financing Receivable, Originated Three Years before Latest Fiscal Year	87
Financing Receivable, Originated Four Years before Latest Fiscal Year	59
Financing Receivable, Originated Five or More Years before Latest Fiscal Year	39
Financing Receivable, Revolving	0
Converted to term loans	0
Finance receivables and loans, net	444
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	1
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	2
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	9
Financing Receivable, Originated in Fiscal Year before Latest Fiscal Year	121
Financing Receivable, Originated Two Years before Latest Fiscal Year	136
Financing Receivable, Originated Three Years before Latest Fiscal Year	107
Financing Receivable, Originated Four Years before Latest Fiscal Year	79
Financing Receivable, Originated Five or More Years before Latest Fiscal Year	57
Financing Receivable, Revolving	0
Converted to term loans	0
Finance receivables and loans, net	509
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	0
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	$ 1
Operating Segments \| Automotive Finance operations \| Consumer portfolio segment
Financing Receivable, Credit Quality Indicator [Line Items]
Retail automotive and lease customers enrolled in program	1,300,000
Retail automotive customers enrolled in program	1,200,000
Percent of customers electing 120 day deferral	64.00%
Customers enrolled in loan program	840,000
Percent of customers enrolling in program	21.00%
Percent of customers electing deferral considered current at time of enrollment	97.00%
Customers who made at least one payment while enrolled in deferral program	16.00%
Operating Segments \| Mortgage Finance operations \| Consumer portfolio segment
Financing Receivable, Credit Quality Indicator [Line Items]
Customers enrolled in loan program	1,900
Percent of customers enrolling in program	5.00%
Percent of customers electing deferral considered current at time of enrollment	92.00%
Customers who made at least one payment while enrolled in deferral program	44.00%
Corporate and Other \| Consumer portfolio segment
Financing Receivable, Credit Quality Indicator [Line Items]
Customers enrolled in loan program	6,300
Percent of customers enrolling in program	7.00%
Percent of customers electing deferral considered current at time of enrollment	84.00%
Customers who made at least one payment while enrolled in deferral program	20.00%