Debt, Interest Incurred (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Interest and Debt Expense, Net of Capitalized Interest
Interest and debt expense	$ 164	$ 145
Less: Capitalized interest	15	20
Interest and debt expense, net of capitalized interest	$ 149	$ 125