Segment Reporting Revenues and long-lived assets by geographic region (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Revenues from External Customers and Long-Lived Assets [Line Items]
Net sales and revenue									$ 145,922	$ 151,092	$ 152,092
GM Financial revenue									6,434	4,837	3,335
Total net sales and revenue	$ 39,621	$ 38,843	$ 38,180	$ 35,712	$ 39,617	$ 39,255	$ 39,649	$ 37,408	152,356	155,929	155,427
Long-Lived Assets	$ 54,224				$ 38,400				54,224	38,400	31,648
U.S.
Revenues from External Customers and Long-Lived Assets [Line Items]
Net sales and revenue									100,008	93,559	88,784
GM Financial revenue									4,357	2,549	2,233
Non-U.S.
Revenues from External Customers and Long-Lived Assets [Line Items]
Net sales and revenue									45,914	57,533	63,308
GM Financial revenue									$ 2,077	$ 2,288	$ 1,102
Maximum percent of total net sales and revenue in an individual country									10.00%	10.00%	10.00%
Maximum percent of total long-lived assets in an individual country	10.00%				10.00%				10.00%	10.00%	10.00%
Automotive [Member] | U.S.
Revenues from External Customers and Long-Lived Assets [Line Items]
Long-Lived Assets	$ 21,091				$ 18,813				$ 21,091	$ 18,813	$ 15,844
Automotive [Member] | Non-U.S.
Revenues from External Customers and Long-Lived Assets [Line Items]
Long-Lived Assets	12,742				12,355				12,742	12,355	12,289
GM Financial [Member] | U.S.
Revenues from External Customers and Long-Lived Assets [Line Items]
Long-Lived Assets	18,501				5,477				18,501	5,477	2,472
GM Financial [Member] | Non-U.S.
Revenues from External Customers and Long-Lived Assets [Line Items]
Long-Lived Assets	$ 1,890				$ 1,755				$ 1,890	$ 1,755	$ 1,043