Debt, Interest Incurred (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Interest and Debt Expense, Net of Capitalized Interest
Interest and debt expense	$ 162	$ 161	$ 326	$ 306
Less: Capitalized interest	12	19	27	39
Interest and debt expense, net of capitalized interest	$ 150	$ 142	$ 299	$ 267