Long-Term Debt and Note Payable - Affiliate - Interest Expense (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Amount of gross interest expense, net of capitalized interest and interest expense - affiliates
Gross interest expense	$ 308	$ 407	$ 472
Capitalized interest	(29)	(27)	(24)
Total interest expense	279	380	448
Interest expense-affiliates, net	$ 74	$ 62	$ 57