Finance Receivables - Delinquency (Details) - Retail Finance Receivables [Member] - USD ($) $ in Millions	Sep. 30, 2020	Dec. 31, 2019
Financing Receivable, Past Due [Line Items]
2020	$ 20,172
2019	13,279
2018	8,473
2017	4,325
2016	1,731
2015	591
Prior	124
Total	$ 48,695	$ 42,268
Percent of portfolio	100.00%
Total	100.00%
Performing Financial Instruments [Member] | Not Past Due [Member]
Financing Receivable, Past Due [Line Items]
2020	$ 19,962
2019	12,848
2018	8,143
2017	4,083
2016	1,580
2015	513
Prior	93
Current, Total	$ 47,222
Percent of portfolio	97.00%
Nonperforming Financial Instruments [Member]
Financing Receivable, Past Due [Line Items]
2020	$ 210
2019	431
2018	330
2017	242
2016	151
2015	78
Prior	31
Financing receivable past due	$ 1,473
Financing receivable past due (percent)	3.00%
Nonperforming Financial Instruments [Member] | 31 to 60 Days [Member]
Financing Receivable, Past Due [Line Items]
2020	$ 147
2019	294
2018	227
2017	167
2016	102
2015	53
Prior	19
Financing receivable past due	$ 1,009
Financing receivable past due (percent)	2.10%
Nonperforming Financial Instruments [Member] | Greater Than 60 Days [Member]
Financing Receivable, Past Due [Line Items]
2020	$ 57
2019	122
2018	92
2017	69
2016	45
2015	23
Prior	11
Financing receivable past due	$ 419
Financing receivable past due (percent)	0.80%
Nonperforming Financial Instruments [Member] | Financing Receivables, Greater than 30 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
2020	$ 204
2019	416
2018	319
2017	236
2016	147
2015	76
Prior	30
Financing receivable past due	$ 1,428
Financing receivable past due (percent)	2.90%
Nonperforming Financial Instruments [Member] | Financing Receivables, In Repossession [Member]
Financing Receivable, Past Due [Line Items]
2020	$ 6
2019	15
2018	11
2017	6
2016	4
2015	2
Prior	1
Financing receivable past due	$ 45
Financing receivable past due (percent)	0.10%