Supplemental Balance Sheet Information - Property, Plant and Equipment (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Property, Plant and Equipment [Abstract]
Land and mineral deposits	$ 120	$ 116
Buildings and improvements	1,100	1,078
Machinery and equipment	2,595	2,473
Property, plant and equipment, gross	3,815	3,667
Reserves for depreciation and depletion	(2,053)	(1,960)
Total	1,762	1,707
Annual depreciation and depletion expense	$ 129	$ 129