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		9 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Interest Rate Swaps
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 Expense	Interest Expense
Income recognized in Other comprehensive income	$ 21.9	$ 1.8	$ 23.4	$ 5.4
Net gain (loss) reclassified from Accumulated other comprehensive (loss) income into Interest expense	$ 2.6	$ (0.1)	6.9	(1.7)
Fuel Swap 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
Income recognized in Other comprehensive income	$ 0.0	$ 0.0	0.0	0.2
Net gain (loss) reclassified from Accumulated other comprehensive (loss) income into Interest expense	$ 0.0	$ 0.0	$ 0.0	$ 1.5