Schedule II - Valuation and Qualifying Accounts (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2019
Current allowance for credit losses
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at beginning of period	$ 3	$ 3	$ 4
Charged to expenses	1	1	0
Charged to other accounts	1	(1)	0
Deductions	0	0	(1)
Balance at end of period	5	3	3
Inventory excess and obsolete reserves
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at beginning of period	4	3	3
Charged to expenses	0	1	0
Charged to other accounts	0	0	0
Deductions	0	0	0
Balance at end of period	4	4	3
Deferred tax asset valuation allowance
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at beginning of period	30	2	7
Charged to expenses	1	29	0
Charged to other accounts	1	0	0
Deductions	0	(1)	(5)
Balance at end of period	32	30	2
SEC Schedule, 12-09, Allowance, Notes Receivable
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at beginning of period	4	2	0
Charged to expenses	1	1	0
Charged to other accounts	(2)	1	2
Deductions	0	0	0
Balance at end of period	$ 3	$ 4	$ 2