Supporting Financial Information - Amortization and Weighted Average Amortization period of Intangible Assets (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2023	Sep. 30, 2022
Finite-Lived Intangible Assets [Line Items]
Amortization expense of intangibles	$ 14.8	$ 6.6
Finite-Lived Intangible Assets, Remaining Amortization Period	8 years 3 months 18 days
Customer contracts and related customer relationships
Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Assets, Remaining Amortization Period	8 years 2 months 12 days
Backlog
Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Assets, Remaining Amortization Period	8 years 3 months 18 days
Trade names
Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Assets, Remaining Amortization Period	8 years 8 months 12 days
Covenants-not-to-compete
Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Assets, Remaining Amortization Period	6 years