GM Financial Receivables and Transactions - Credit Risk Profile by FICO Score (Details) - GM Financial [Member] - USD ($) $ in Millions	Sep. 30, 2020	Dec. 31, 2019
Financing Receivable, Credit Quality Indicator [Line Items]
GM Financial receivables, net of fees	$ 56,756	$ 53,900
Retail Finance Receivables [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2020	20,172
2019	13,279
2018	8,472
2017	4,325
2016	1,731
2015	591
Prior	124
GM Financial receivables, net of fees	$ 48,694	$ 42,229
Percent	100.00%	100.00%
Retail Finance Receivables [Member] | Prime - FICO score 680 and greater [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2020	$ 14,746
2019	8,064
2018	5,295
2017	2,348
2016	744
2015	177
Prior	5
GM Financial receivables, net of fees	$ 31,379	$ 25,400
Percent	64.40%	60.10%
Retail Finance Receivables [Member] | 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
GM Financial receivables, net of fees	$ 7,520	$ 6,862
Percent	15.50%	16.30%
Retail Finance Receivables [Member] | 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
GM Financial receivables, net of fees	$ 9,795	$ 9,967
Percent	20.10%	23.60%