Debt - Schedule of Reconciliation of Interest Expense (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Debt Disclosure [Abstract]
Corporate-level interest and commitment fees incurred	$ 11	$ 10	$ 33	$ 28
Project-level interest and commitment fees incurred	13	16	40	47
Capitalized interest, commitment fees, and letter of credit fees	(1)	(2)	(4)	(3)
Amortization of debt discount/premium, net	2	2	5	4
Amortization of financing costs	2	2	4	5
Interest expense	$ 27	$ 28	$ 78	$ 81