Finance Receivables - Delinquency (Details) - Retail Finance Receivables [Member] - USD ($) $ in Millions	Jun. 30, 2020	Dec. 31, 2019
Financing Receivable, Past Due [Line Items]
2020	$ 14,007
2019	14,730
2018	9,619
2017	5,042
2016	2,113
2015	787
Prior	191
Total	$ 46,489	$ 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	$ 13,875
2019	14,244
2018	9,231
2017	4,752
2016	1,930
2015	689
Prior	148
Current, Total	$ 44,869
Percent of portfolio	96.50%
Nonperforming Financial Instruments [Member]
Financing Receivable, Past Due [Line Items]
2020	$ 132
2019	486
2018	388
2017	290
2016	183
2015	98
Prior	43
Financing receivable past due	$ 1,620
Financing receivable past due (percent)	3.50%
Nonperforming Financial Instruments [Member] | 31 to 60 Days [Member]
Financing Receivable, Past Due [Line Items]
2020	$ 86
2019	295
2018	236
2017	181
2016	114
2015	61
Prior	25
Financing receivable past due	$ 998
Financing receivable past due (percent)	2.20%
Nonperforming Financial Instruments [Member] | Greater Than 60 Days [Member]
Financing Receivable, Past Due [Line Items]
2020	$ 44
2019	183
2018	147
2017	106
2016	67
2015	36
Prior	18
Financing receivable past due	$ 601
Financing receivable past due (percent)	1.30%
Nonperforming Financial Instruments [Member] | Financing Receivables, Greater than 30 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
2020	$ 130
2019	478
2018	383
2017	287
2016	181
2015	97
Prior	43
Financing receivable past due	$ 1,599
Financing receivable past due (percent)	3.50%
Nonperforming Financial Instruments [Member] | Financing Receivables, In Repossession [Member]
Financing Receivable, Past Due [Line Items]
2020	$ 2
2019	8
2018	5
2017	3
2016	2
2015	1
Prior	0
Financing receivable past due	$ 21
Financing receivable past due (percent)	0.00%