Debt, Interest Incurred (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Interest and Debt Expense, Net of Capitalized Interest
Interest and debt expense	$ 162	$ 133	$ 468	$ 405
Less: Capitalized interest	19	22	58	70
Interest and debt expense, net of capitalized interest	$ 143	$ 111	$ 410	$ 335