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Summary of Significant Accounting Policies - Additional Information (Detail) - USD ($)
6 Months Ended 12 Months Ended
Mar. 31, 2021
Mar. 31, 2020
Sep. 30, 2022
Sep. 30, 2021
Sep. 30, 2020
Sep. 30, 2019
Schedule Of Significant Accounting Policies [Line Items]            
Cash, cash equivalents, and restricted cash $ 9,133,000 $ 10,551,000     $ 57,161,000 $ 5,149,000
Cash and cash equivalents 8,883,000       56,911,000  
Restricted cash 250,000       250,000  
Derivative maximum payout         5,000,000.0  
Accrued expenses and other current liabilities 159,880,000       127,286,000  
Other long-term liabilities 26,065,000       25,001,000  
New England Teamsters & Trucking Industry Pension Fund            
Schedule Of Significant Accounting Policies [Line Items]            
Accrued expenses and other current liabilities 200,000       200,000  
Other long-term liabilities 16,600,000       16,700,000  
New England Teamsters & Trucking Industry Pension Fund | Significant Other Observable Inputs Level 2            
Schedule Of Significant Accounting Policies [Line Items]            
Multiemployer plan discounted withdrawal liability 25,600,000       29,000,000.0  
Financial Products Corporation | Delivery and branch expenses            
Schedule Of Significant Accounting Policies [Line Items]            
Charge on weather hedge contract $ (3,400,000) $ (10,100,000)        
Scenario Forecast            
Schedule Of Significant Accounting Policies [Line Items]            
Derivative maximum payout     $ 0 $ 5,000,000.0    
Maximum            
Schedule Of Significant Accounting Policies [Line Items]            
Cash equivalents, highly liquid investments maturity 3 months          
Derivative maximum receivable         $ 12,500,000  
Maximum | Scenario Forecast            
Schedule Of Significant Accounting Policies [Line Items]            
Derivative maximum receivable     $ 7,500,000 $ 12,500,000