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v3.25.2

Derivatives and Hedging-Disclosures and Fair Value Measurements - Additional Information (Detail) gal in Millions | 9 Months Ended |
--- | --- | ---
Jun. 30, 2025 USD ($) gal | Jun. 30, 2024 gal | Sep. 30, 2024 USD ($)
Derivative Instruments and Hedging Activities Disclosures [Line Items] |  |  |
Hedging positions or payable amounts secured under credit facility | $ | $ 2,200,000 |  | $ 14,200,000
Prepaid expense and other current assets |  |  |
Derivative Instruments and Hedging Activities Disclosures [Line Items] |  |  |
Aggregated cash posted as collateral in normal course of business | $ | 1,500,000 |  |
Interest rate swap |  |  |
Derivative Instruments and Hedging Activities Disclosures [Line Items] |  |  |
Notional Value | $ | $ 75,400,000 |  | 52,000,000.0
Percentage of market risk exposure of long term debt | 39.00% |  |
Fair Value | $ | $ (600,000) |  | $ (300,000)
Call Option |  |  |
Derivative Instruments and Hedging Activities Disclosures [Line Items] |  |  |
Derivative activity volume | 3.3 | 3.8 |
Call Option | Synthetic calls |  |  |
Derivative Instruments and Hedging Activities Disclosures [Line Items] |  |  |
Derivative activity volume | 36.0 | 37.0 |
Put Option |  |  |
Derivative Instruments and Hedging Activities Disclosures [Line Items] |  |  |
Derivative activity volume | 3.7 | 3.5 |
Swap Contracts Bought |  |  |
Derivative Instruments and Hedging Activities Disclosures [Line Items] |  |  |
Derivative activity volume | 8.6 | 7.2 |
Swap Contracts Bought | Short |  |  |
Derivative Instruments and Hedging Activities Disclosures [Line Items] |  |  |
Derivative activity volume | 0.7 | 0.1 |
Future Contracts | Long |  |  |
Derivative Instruments and Hedging Activities Disclosures [Line Items] |  |  |
Derivative activity volume |  | 0.2 |
Future Contracts | Short |  |  |
Derivative Instruments and Hedging Activities Disclosures [Line Items] |  |  |
Derivative activity volume | 6.5 | 6.9 |
Hedge its Internal Fuel Usage and Other Related Activities Swap Contracts Bought |  |  |
Derivative Instruments and Hedging Activities Disclosures [Line Items] |  |  |
Derivative activity volume | 7.7 | 7.9 |

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