Fair Value Measurements and Derivative Instruments - Summary of Effects on Consolidated Financial Statements of Designated As Cash Flow Hedges (Details) - Cash Flow Hedges - Designated - USD ($) $ in Millions	3 Months Ended
	Dec. 31, 2025	Dec. 31, 2024
Interest Rate Contracts
Derivative Instruments Gain Loss [Line Items]
Income (loss) recognized in Other comprehensive (loss) income	$ 0.3	$ 13.1
Net income (loss) reclassified from Accumulated other comprehensive (loss) into Interest expense	0.8	2.0
Fuel Contracts [Member]
Derivative Instruments Gain Loss [Line Items]
Income (loss) recognized in Other comprehensive (loss) income	(0.5)	0.0
Net income (loss) reclassified from Accumulated other comprehensive (loss) into Interest expense	$ (0.1)	$ (0.4)