Finance Receivables - Credit Risk Profile by Dealer (Details) - Commercial Finance Receivables [Member] - USD ($) $ in Millions	Jun. 30, 2020	Dec. 31, 2019
Accounts, Notes, Loans and Financing Receivable [Line Items]
Revolving	$ 6,888
2020	171
2019	268
2018	141
2017	152
2016	141
2015	93
Prior	30
Total	$ 7,884	$ 12,149
Percent of portfolio	100.00%
Floorplan Advances [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Percent of revolving balance	97.00%
Group I - Performing accounts with strong to acceptable financial metrics [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Revolving	$ 6,232
2020	170
2019	253
2018	100
2017	117
2016	127
2015	75
Prior	8
Total	$ 7,082
Percent of portfolio	89.80%
Group II - Performing accounts experiencing potential weakness in financial metrics [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Revolving	$ 408
2020	1
2019	7
2018	12
2017	33
2016	4
2015	13
Prior	22
Total	$ 500
Percent of portfolio	6.30%
Group III - Non-Performing accounts with inadequate paying capacity for current obligations [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Revolving	$ 247
2020	0
2019	8
2018	29
2017	2
2016	10
2015	1
Prior	0
Total	$ 297
Percent of portfolio	3.80%
Group IV - Non-Performing accounts with inadequate paying capacity for current obligations and inherent weaknesses [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Revolving	$ 1
2020	0
2019	0
2018	0
2017	0
2016	0
2015	4
Prior	0
Total	$ 5
Percent of portfolio	0.10%