Finance Receivables - Credit Risk Profile by FICO Score (Details) - Retail Finance Receivables [Member] - USD ($) $ in Millions	Mar. 31, 2020	Dec. 31, 2019
Financing Receivable, Credit Quality Indicator [Line Items]
2020	$ 6,098
2019	16,138
2018	10,730
2017	5,747
2016	2,502
2015	1,007
Prior	282
Total	$ 42,504	$ 42,268
Percent of portfolio	100.00%
Prime - FICO Score 680 and greater [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2020	$ 4,027
2019	9,990
2018	6,821
2017	3,200
2016	1,143
2015	343
Prior	15
Total	$ 25,539
Percent of portfolio	60.10%
Near-prime - FICO Score 620 to 679 [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2020	$ 902
2019	2,746
2018	1,744
2017	942
2016	402
2015	178
Prior	38
Total	$ 6,952
Percent of portfolio	16.30%
Sub-prime - FICO Score less than 620 [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2020	$ 1,169
2019	3,402
2018	2,165
2017	1,605
2016	957
2015	486
Prior	229
Total	$ 10,013
Percent of portfolio	23.60%