Finance Receivables - Credit Risk Profile by FICO Score (Details) - Retail Finance Receivables [Member] - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Financing Receivable, Credit Quality Indicator [Line Items]
2020	$ 26,183
2019	12,050
2018	7,463
2017	3,693
2016	1,390
Prior	509
Total	$ 51,288	$ 42,268
Percent of portfolio	100.00%
Prime - FICO Score 680 and greater [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2020	$ 18,685
2019	7,033
2018	4,491
2017	1,917
2016	555
Prior	119
Total	$ 32,800
Percent of portfolio	64.00%
Near-prime - FICO Score 620 to 679 [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2020	$ 3,695
2019	2,097
2018	1,232
2017	603
2016	225
Prior	83
Total	$ 7,935
Percent of portfolio	15.40%
Sub-prime - FICO Score less than 620 [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2020	$ 3,803
2019	2,920
2018	1,740
2017	1,173
2016	610
Prior	307
Total	$ 10,553
Percent of portfolio	20.60%