Debt and Finance Lease Obligations, Interest Incurred (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Interest and Debt Expense, Net of Capitalized Interest
Interest and debt expense	$ 544	$ 557	$ 539
Less: Capitalized interest	90	87	71
Interest and debt expense, net of capitalized interest	$ 454	$ 470	$ 468