Restructuring Costs (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015	Dec. 31, 2015
Restructuring and Related Cost [Abstract]
Restructuring costs	$ 324	$ 98	$ 624	$ 219	$ 898
Employee Separation Charges [Roll Forward]
Liability balance at beginning of period			483	182	182
Increase in liability (separation charges)			175		641
Reduction in liability (payments)			(507)		(340)
Liability balance at end of period	151		151		483
Discontinue production on-highway vocational trucks
Restructuring and Related Cost [Abstract]
Restructuring costs	10		92
Estimated restructuring costs	120		120
Q3 2016 announcement [Member]
Restructuring and Related Cost [Abstract]
Restructuring costs			221
Impairment of Intangible Assets, Finite-lived			132
Estimated restructuring costs	260		260
Employee separations | September 2015 announcement
Restructuring and Related Cost [Abstract]
Restructuring costs	2		78		379
Employee separations | Q3 2016 announcement [Member]
Restructuring and Related Cost [Abstract]
Restructuring costs			72
Employee separations | Other Operating Income (Expense)
Restructuring and Related Cost [Abstract]
Restructuring costs	99	60	175	180	641
Contract terminations | Other Operating Income (Expense)
Restructuring and Related Cost [Abstract]
Restructuring costs	9	0	55	0
Long-lived asset impairments | Other Operating Income (Expense)
Restructuring and Related Cost [Abstract]
Restructuring costs	158	26	254	27	127
Other
Restructuring and Related Cost [Abstract]
Restructuring costs	$ 58	$ 12	140	$ 12	48
Other | Q3 2016 announcement [Member]
Restructuring and Related Cost [Abstract]
Restructuring costs			$ 17
Defined benefit retirement plan curtailment losses | September 2015 announcement
Restructuring and Related Cost [Abstract]
Restructuring costs					82
Defined benefit retirement plan curtailment losses | Other Operating Income (Expense)
Restructuring and Related Cost [Abstract]
Restructuring costs					$ 82