Restructuring Costs (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended		12 Months Ended	49 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018	Sep. 30, 2019
Restructuring and Related Cost [Abstract]
Restructuring costs	$ 24	$ 110	$ 182	$ 293
Employee Separation Charges [Roll Forward]
Liability balance at beginning of period			85	249	$ 249
Increase in liability (separation charges)			33		112
Reduction in liability (payments)			(73)		(276)
Liability balance at end of period	45		45		$ 85	$ 45
September 2015 announcement [Member]
Restructuring and Related Cost [Abstract]
Restructuring costs			30			1,818
Estimated restructuring costs	20		20			$ 20
Employee separations | Other Operating Income (Expense)
Restructuring and Related Cost [Abstract]
Restructuring costs	8	44	33	121
Long-lived asset impairments | Other Operating Income (Expense)
Restructuring and Related Cost [Abstract]
Restructuring costs	3	18	39	49
Other | Cost of Sales
Restructuring and Related Cost [Abstract]
Restructuring costs	$ 13	$ 48	$ 110	$ 123