Related Party Transactions - Schedule of Condensed Combined Statement of Operations (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Sep. 30, 2017
Related Party Transactions [Abstract]
Allocated operating expenses	$ 14	$ 4
Maintenance service costs	1	0
Insurance expense	5	5
Other	7	5
Operations and maintenance – related parties	27	14	$ 14
Allocated general corporate expenses	5	7
Management Agreement fee	2	2
Omnibus Agreement fee	3	3
General and administrative – related parties	$ 10	$ 12