Property, Plant and Equipment Property, Plant and Equipment - (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Property, Plant and Equipment [Line Items]
Land	$ 437	$ 426
Buildings	2,699	2,658
Machinery and equipment	13,922	13,654
Construction in progress	737	682
Property, plant, and equipment and finance lease right-of-use asset, gross	17,795	17,420
Accumulated depreciation	(10,991)	(10,488)
Property plant and equipment, net before spare parts	6,804	6,932
Spare parts	269	276
Property, plant and equipment, net	7,073	7,208
Owned
Property, Plant and Equipment [Line Items]
Land	436	425
Buildings	2,467	2,431
Machinery and equipment	13,893	13,624
Construction in progress	737	681
Property, plant, and equipment and finance lease right-of-use asset, gross	17,533	17,161
Accumulated depreciation	(10,931)	(10,438)
Property plant and equipment, net before spare parts	6,602	6,723
Spare parts	269	276
Property, plant and equipment, net	6,871	6,999
Finance Leases
Property, Plant and Equipment [Line Items]
Land	1	1
Buildings	232	227
Machinery and equipment	29	30
Construction in progress		1
Property, plant, and equipment and finance lease right-of-use asset, gross	262	259
Accumulated depreciation	(60)	(50)
Property plant and equipment, net before spare parts	202	209
Property, plant and equipment, net	$ 202	$ 209
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