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		6 Months Ended
	Mar. 31, 2025	Mar. 31, 2024	Mar. 31, 2025	Mar. 31, 2024
Interest Rate Contracts
Derivative Instruments Gain Loss [Line Items]
Derivative Instrument, Gain (Loss) Reclassified from AOCI into Income, Effective Portion, Statement of Income or Comprehensive Income [Extensible Enumeration]	Interest Income (Expense), Operating	Interest Income (Expense), Operating	Interest Income (Expense), Operating	Interest Income (Expense), Operating
(Loss) Income recognized in Other comprehensive (loss) income	$ (5.1)	$ 10.9	$ 8.0	$ (3.6)
Net income (loss) reclassified from Accumulated other comprehensive income (loss) into Interest expense	$ 1.3	$ 2.8	$ 3.3	$ 5.6
Fuel Contracts
Derivative Instruments Gain Loss [Line Items]
Derivative Instrument, Gain (Loss) Reclassified from AOCI into Income, Effective Portion, Statement of Income or Comprehensive Income [Extensible Enumeration]	Cost of Goods and Services Sold	Cost of Goods and Services Sold	Cost of Goods and Services Sold	Cost of Goods and Services Sold
(Loss) Income recognized in Other comprehensive (loss) income	$ 0.0	$ 0.1	$ 0.0	$ 0.1
Net income (loss) reclassified from Accumulated other comprehensive income (loss) into Interest expense	$ (0.2)	$ 0.0	$ (0.5)	$ 0.0