Restructuring Costs (Details) $ in Millions	1 Months Ended	12 Months Ended			28 Months Ended
	Mar. 31, 2017	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)	Dec. 31, 2017 USD ($)
Restructuring Cost [Abstract]
Restructuring costs		$ 1,256	$ 1,019	$ 898
Employee separation costs		525	297
Employee Separation Activity
Liability balance at beginning of period		147	483
Employee separation costs		525	297
Reduction in liability (payments and other adjustments)		423	633
Liability balance at end of period		249	147	483	$ 249
Other restructuring costs
Restructuring Cost [Abstract]
Restructuring costs		173	262	48
Voluntary retirement enhancement program
Restructuring Cost [Abstract]
Curtailment expense			(82)
Other operating income (expense) | Employee separation
Restructuring Cost [Abstract]
Restructuring costs		525	297	641
Other operating income (expense) | Contract termination
Restructuring Cost [Abstract]
Restructuring costs		183	62	0
Other operating income (expense) | Long-lived asset impairments
Restructuring Cost [Abstract]
Restructuring costs		346	391	127
Other operating income (expense) | Defined benefit retirement plan curtailment losses
Restructuring Cost [Abstract]
Restructuring costs		29	7	82
Gosselies closure announcement [Domain]
Restructuring Cost [Abstract]
Restructuring and Related Cost, Number of Positions Eliminated	2,000
Restructuring costs		653
Estimated restructuring costs		675			675
Gosselies closure announcement [Domain] | Other restructuring costs
Restructuring Cost [Abstract]
Restructuring costs		77
Gosselies closure announcement [Domain] | Employee separation
Restructuring Cost [Abstract]
Restructuring costs		436
Gosselies closure announcement [Domain] | Long-lived asset impairments
Restructuring Cost [Abstract]
Restructuring costs		205
Gosselies closure announcement [Domain] | LIFO inventory decrement benefit(expense) [Member]
Restructuring Cost [Abstract]
Restructuring costs		65
Discontinue production on-highway vocational trucks
Restructuring Cost [Abstract]
Restructuring costs			104
Second half of 2016 announcement
Restructuring Cost [Abstract]
Restructuring costs			369
September 2015 announcement [Member]
Restructuring Cost [Abstract]
Restructuring costs		817	$ 281	$ 569	1,667
Estimated restructuring costs		$ 200			$ 200