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Segment Reporting - Revenues and long-lived assets by geographic region (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Revenues from External Customers and Long-Lived Assets [Line Items]
Automotive net sales and revenue									$ 122,697	$ 133,045
GM Financial net sales and revenue									14,540	14,004
Total net sales and revenue	$ 30,826	$ 35,473	$ 36,060	$ 34,878	$ 38,399	$ 35,791	$ 36,760	$ 36,099	137,237	147,049	$ 145,588
Long-Lived Assets	80,872				82,698				80,872	82,698	80,329
Automotive
Revenues from External Customers and Long-Lived Assets [Line Items]
Automotive net sales and revenue									122,697	133,045	133,449
Automotive \| U.S.
Revenues from External Customers and Long-Lived Assets [Line Items]
Automotive net sales and revenue									97,887	104,413	100,674
Long-Lived Assets	25,401				25,625				25,401	25,625	24,473
Automotive \| Non-U.S.
Revenues from External Customers and Long-Lived Assets [Line Items]
Automotive net sales and revenue									24,810	28,632	32,775
Long-Lived Assets	13,190				13,263				13,190	13,263	12,715
GM Financial
Revenues from External Customers and Long-Lived Assets [Line Items]
Total net sales and revenue									14,540	14,004	12,139
GM Financial \| U.S.
Revenues from External Customers and Long-Lived Assets [Line Items]
GM Financial net sales and revenue									12,727	12,169	10,489
Long-Lived Assets	39,509				41,334				39,509	41,334	40,674
GM Financial \| Non-U.S.
Revenues from External Customers and Long-Lived Assets [Line Items]
GM Financial net sales and revenue									1,813	1,835	1,650
Long-Lived Assets	$ 2,772				$ 2,476				$ 2,772	$ 2,476	$ 2,467