v3.26.1
Derivatives and Hedging-Disclosures and Fair Value Measurements - Effect of Derivative Instruments on Statement of Operations (Detail) - USD ($)
$ in Thousands
 3 Months Ended 9 Months Ended
Jun. 30, 2026
Jun. 30, 2025
Jun. 30, 2026
Jun. 30, 2025
Derivative Instruments, Gain (Loss) [Line Items]        
Amount of (Gain) or Loss Unrealized, commodity contracts [1] $ 8,019 $ (603) $ (13,398) $ (11,962)
Fair Value, Measurements, Recurring | Derivatives Not Designated as Hedging Instruments under FASB ASC 815-10 | Commodity Contract | Cost of product        
Derivative Instruments, Gain (Loss) [Line Items]        
Amount of (Gain) or Loss Recognized, commodity contracts [2] $ (4,425) $ 2,248 $ (1,388) $ 16,002
Derivative, Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration] Cost and expenses Cost and expenses Cost and expenses Cost and expenses
Fair Value, Measurements, Recurring | Derivatives Not Designated as Hedging Instruments under FASB ASC 815-10 | Commodity Contract | Cost of installations and service        
Derivative Instruments, Gain (Loss) [Line Items]        
Amount of (Gain) or Loss Recognized, commodity contracts [2] $ (474) $ 40 $ (581) $ 171
Derivative, Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration] Cost and expenses Cost and expenses Cost and expenses Cost and expenses
Fair Value, Measurements, Recurring | Derivatives Not Designated as Hedging Instruments under FASB ASC 815-10 | Commodity Contract | Delivery and branch expenses        
Derivative Instruments, Gain (Loss) [Line Items]        
Amount of (Gain) or Loss Recognized, commodity contracts [2] $ (478) $ 234 $ (2,558) $ 890
Derivative, Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration] Delivery and branch expenses Delivery and branch expenses Delivery and branch expenses Delivery and branch expenses
[1] Represents the change in value of unrealized open positions and expired options.
[2] Represents realized closed positions and includes the cost of options as they expire.