Finance Receivables - Credit Risk Profile by FICO Score (Details) - Retail Finance Receivables [Member] - USD ($) $ in Millions	Sep. 30, 2020	Dec. 31, 2019
Financing Receivable, Credit Quality Indicator [Line Items]
2020	$ 20,172
2019	13,279
2018	8,473
2017	4,325
2016	1,731
2015	591
Prior	124
Total	$ 48,695	$ 42,268
Percent of portfolio	100.00%
Prime - FICO Score 680 and greater [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2020	$ 14,746
2019	8,064
2018	5,296
2017	2,348
2016	744
2015	177
Prior	5
Total	$ 31,380
Percent of portfolio	64.40%
Near-prime - FICO Score 620 to 679 [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2020	$ 2,725
2019	2,293
2018	1,392
2017	712
2016	280
2015	103
Prior	15
Total	$ 7,520
Percent of portfolio	15.50%
Sub-prime - FICO Score less than 620 [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2020	$ 2,701
2019	2,922
2018	1,785
2017	1,265
2016	707
2015	311
Prior	104
Total	$ 9,795
Percent of portfolio	20.10%