Finance Receivables - Credit Risk Profile by Dealer (Details) - Commercial Finance Receivables - USD ($) $ in Millions	Jun. 30, 2021	Dec. 31, 2020
Accounts, Notes, Loans and Financing Receivable [Line Items]
Revolving	$ 4,550	$ 7,921
2021	240	581
2020	525	205
2019	168	117
2018	84	127
2017	85	72
Prior	53	57
Total	$ 5,705	$ 9,080
Percent of portfolio	100.00%	100.00%
Floorplan Advances
Accounts, Notes, Loans and Financing Receivable [Line Items]
Percent of revolving balance	94.00%	97.00%
Group I - Performing accounts with strong to acceptable financial metrics
Accounts, Notes, Loans and Financing Receivable [Line Items]
Revolving	$ 4,149	$ 7,210
2021	227	579
2020	507	179
2019	147	77
2018	56	110
2017	72	43
Prior	43	19
Total	$ 5,201	$ 8,217
Percent of portfolio	91.20%	90.50%
Group II - Performing accounts experiencing potential weakness in financial metrics
Accounts, Notes, Loans and Financing Receivable [Line Items]
Revolving	$ 298	$ 508
2021	5	2
2020	18	18
2019	18	11
2018	0	15
2017	11	18
Prior	5	34
Total	$ 355	$ 606
Percent of portfolio	6.20%	6.70%
Group III - Non-Performing accounts with inadequate paying capacity for current obligations
Accounts, Notes, Loans and Financing Receivable [Line Items]
Revolving	$ 103	$ 203
2021	8	0
2020	0	8
2019	3	29
2018	28	2
2017	2	11
Prior	5	0
Total	$ 149	$ 253
Percent of portfolio	2.60%	2.80%
Group IV - Non-Performing accounts with inadequate paying capacity for current obligations and inherent weaknesses
Accounts, Notes, Loans and Financing Receivable [Line Items]
Revolving	$ 0	$ 0
2021	0	0
2020	0	0
2019	0	0
2018	0	0
2017	0	0
Prior	0	4
Total	$ 0	$ 4
Percent of portfolio	0.00%	0.00%