Debt, Interest Incurred (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Interest and Debt Expense, Net of Capitalized Interest
Interest and debt expense	$ 161	$ 136	$ 306	$ 272
Less: Capitalized interest	19	24	39	48
Interest and debt expense, net of capitalized interest	$ 142	$ 112	$ 267	$ 224