Related Party Transactions - Schedule of Condensed Combined Statement of Operations (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2017
Related Party Transactions [Abstract]
Allocated operating expenses	$ 13	$ 5	$ 33	$ 13
Maintenance service costs	0	0	3	0
Insurance expense	6	4	16	13
Other	11	5	24	18
Operations and maintenance – related parties	30	14	76	44	$ 44
Allocated general corporate expenses	8	8	25	22
Management Agreement fee	2	3	7	7
Omnibus Agreement fee	3	3	8	8
Other	(2)	0	0	0
General and administrative – related parties	$ 11	$ 14	$ 40	$ 37