v3.26.1
Organization - Additional Information (Detail)
shares in Thousands
9 Months Ended
Sep. 27, 2024
USD ($)
Jun. 30, 2026
Contract
Customer
Segment
shares
Mar. 31, 2026
shares
Sep. 30, 2025
shares
Jun. 30, 2025
shares
Mar. 31, 2025
shares
Sep. 30, 2024
shares
Limited Partners' Capital Account [Line Items]              
Number of reportable segments | Segment   1          
Seventh Amendment              
Limited Partners' Capital Account [Line Items]              
Non Seasonal maximum borrowing capacity under revolving credit facility | $ $ 400,000,000            
Maximum borrowing capacity (heating season December to April) under revolving credit facility | $ $ 475,000,000            
Due date of debt Sep. 27, 2029            
Seventh Amendment | Term Loan              
Limited Partners' Capital Account [Line Items]              
Outstanding term loan | $ $ 210,000,000            
Senior secured term loan maturity period 5 years            
Petro Holdings, Inc              
Limited Partners' Capital Account [Line Items]              
Ownership interest of Star Acquisitions Inc.   100.00%          
Number of residential and commercial home heating oil and propane customers served | Customer   396,900          
Number of customers to whom only home heating oil, gasoline and diesel were sells on a delivery only basis | Customer   66,000          
Number of service contracts for natural gas and other heating systems | Contract   19,800          
Number of customers to whom sell gasoline and diesel fuel | Customer   27,500          
Star Group L.P.              
Limited Partners' Capital Account [Line Items]              
Percentage of limited partner interest   99.00%          
Percentage of general partner interest   1.00%          
Star Acquisitions, Inc              
Limited Partners' Capital Account [Line Items]              
Ownership interest of partnership   100.00%          
Common Stock              
Limited Partners' Capital Account [Line Items]              
Number of outstanding units | shares   32,816 32,839 33,278 33,751 34,568 34,587
General Partner              
Limited Partners' Capital Account [Line Items]              
Number of outstanding units | shares   326 326 326 326 326 326