Debt, Interest Incurred (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Interest and Debt Expense, Net of Capitalized Interest
Interest and debt expense	$ 162	$ 162	$ 488	$ 468
Less: Capitalized interest	10	19	37	58
Interest and debt expense, net of capitalized interest	$ 152	$ 143	$ 451	$ 410