v3.26.1
Business Combinations and Divestitures - Additional Information (Detail)
$ in Thousands
9 Months Ended
Jun. 30, 2026
USD ($)
PartnershipUnit
Jun. 30, 2025
USD ($)
PartnershipUnit
Sep. 30, 2025
USD ($)
Business Acquisition [Line Items]      
Goodwill $ 293,955   $ 293,350
Heating Oil Businesses      
Business Acquisition [Line Items]      
Number of businesses acquired | PartnershipUnit 1 1  
Aggregate purchase price partnership acquired $ 1,000 $ 80,500  
Aggregate purchase price allocation, intangible assets 1,200 38,700  
Goodwill 600 17,700  
Aggregate purchase price allocation, fixed assets 300 25,200  
Gross purchase price increased (reduced) by net working capital credits $ (1,100) (1,100)  
Acquisition of intangible and fixed assets   7,700  
Cash proceeds from sale of assets   $ 300  
Propane Dealers      
Business Acquisition [Line Items]      
Number of businesses acquired | PartnershipUnit   3