Property, Plant and Equipment (Depreciation Expense, Software Amortization and Capitalized Interest) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Property, Plant and Equipment [Abstract]
Depreciation expense	$ 977	$ 960	$ 1,005
Interest capitalized during development and construction	238	199	$ 139
Property plant and equipment, net of accumulated depreciation mortgaged, pledged or subject to liens	$ 10,000	$ 11,000