Revenues - Remaining Performance Obligations (Details) - USD ($)	12 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2021
Remaining Performance Obligations
Revenue recognized	$ 80,000,000
Accounts receivable	198,557,000	$ 164,645,000	$ 146,300,000
Contract assets	138,600,000	125,200,000	93,800,000
Contract liabilities	123,100,000	$ 137,600,000	$ 108,800,000
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2023-10-01
Remaining Performance Obligations
Remaining performance obligations amount	$ 360,000,000
Percentage of remaining performance obligation expected to be recognized	80.00%
Revenue remaining performance obligation expected timing of satisfaction, Period	24 months
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2025-10-01
Remaining Performance Obligations
Remaining performance obligations amount	$ 20
Revenue remaining performance obligation expected timing of satisfaction, Period