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Derivatives and Hedging-Disclosures and Fair Value Measurements - Additional Information (Detail) gal in Millions	3 Months Ended
	Dec. 31, 2022 USD ($) gal	Dec. 31, 2021 gal	Sep. 30, 2022 USD ($)
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Hedging positions or payable amounts secured under credit facility \| $	$ 3,300,000		$ 0
Prepaid expense and other current assets
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Aggregated cash posted as collateral in normal course of business \| $	2,200,000
Interest rate swap
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Notional Value \| $	$ 86,900,000		54,000,000.0
Percentage of market risk exposure of long term debt	53.00%
Fair Value \| $	$ 1,700,000		$ 2,000,000.0
Call Option
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Derivative activity volume	23.2	34.6
Call Option \| Synthetic calls
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Derivative activity volume	61.3	52.6
Put Option
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Derivative activity volume	4.3	4.5
Swap Contracts Bought
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Derivative activity volume	9.4	14.8
Swap Contracts Bought \| Short
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Derivative activity volume	25.3
Future Contracts \| Long
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Derivative activity volume		1.1
Future Contracts \| Short
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Derivative activity volume	7.3	26.7
Hedge its Internal Fuel Usage and Other Related Activities Swap Contracts Bought
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Derivative activity volume	3.7
Hedge its Internal Fuel Usage and Other Related Activities Call Options and Swap Contracts Bought
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Derivative activity volume		5.0