Property, Plant and Equipment Property, Plant and Equipment - (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Property, Plant and Equipment [Line Items]
Land	$ 427	$ 433
Buildings	2,593	2,619
Machinery and equipment	13,483	13,502
Construction in progress	655	721
Property, plant and equipment, gross	17,158	17,275
Accumulated depreciation	(10,161)	(10,078)
Property plant and equipment, net before spare parts	6,997	7,197
Spare parts	262	254
Property, plant and equipment, net	7,259	7,451
Owned
Property, Plant and Equipment [Line Items]
Land	427	433
Buildings	2,564	2,589
Machinery and equipment	13,440	13,456
Construction in progress	654	721
Property, plant and equipment, gross	17,085	17,199
Accumulated depreciation	(10,128)	(10,047)
Property plant and equipment, net before spare parts	6,957	7,152
Spare parts	262	254
Property, plant and equipment, net	7,219	7,406
Capital Leases
Property, Plant and Equipment [Line Items]
Land	0	0
Buildings	29	30
Machinery and equipment	43	46
Construction in progress	1	0
Property, plant and equipment, gross	73	76
Accumulated depreciation	(33)	(31)
Property plant and equipment, net before spare parts	40	45
Spare parts	0	0
Property, plant and equipment, net	$ 40	$ 45
Building and Building Improvements | Minimum
Property, Plant and Equipment [Line Items]
Property, plant and equipment, useful life	3 years
Building and Building Improvements | Maximum
Property, Plant and Equipment [Line Items]
Property, plant and equipment, useful life	45 years
Machinery and Equipment | Minimum
Property, Plant and Equipment [Line Items]
Property, plant and equipment, useful life	3 years
Machinery and Equipment | Maximum
Property, Plant and Equipment [Line Items]
Property, plant and equipment, useful life	40 years