Supplemental Financial Information - Summary of Accounts Receivable (Details) - USD ($) $ in Millions	Dec. 31, 2023	Sep. 30, 2023
Current
Trade	$ 65.9	$ 64.0
Other	18.1	17.9
Receivables, gross	84.0	81.9
Allowance for credit losses	(0.5)	(0.6)
Receivables, net	83.5	81.3
Non-current
Notes receivable	2.4	2.3
Other	7.6	7.5
Noncurrent notes receivable, gross	10.0	9.8
Allowance for losses	(2.4)	(2.4)
Noncurrent notes receivable, net	$ 7.6	$ 7.4