XML 49 R37.htm IDEA: XBRL DOCUMENT v3.19.1
Summary of Significant Accounting Policies - Additional Information (Detail) - USD ($)
 1 Months Ended 6 Months Ended 12 Months Ended
Apr. 30, 2019
Apr. 30, 2018
Mar. 31, 2019
Mar. 31, 2018
Sep. 30, 2021
Sep. 30, 2020
Sep. 30, 2019
Sep. 30, 2018
Sep. 30, 2017
Schedule Of Significant Accounting Policies [Line Items]                  
Cash, cash equivalents, and restricted cash     $ 16,622,000 $ 35,679,000       $ 14,781,000 $ 52,708,000
Cash and cash equivalents     16,372,000         14,531,000  
Restricted cash     250,000         250,000  
Captive insurance collateral, debt securities [1]     54,148,000         45,419,000  
Accrued expenses and other current liabilities     157,524,000         116,436,000  
Other long-term liabilities     $ 24,692,000         24,012,000  
Operating lease expiration year     2033            
Undiscounted future minimum lease payments through 2033     $ 126,500,000            
ASU 2014-09                  
Schedule Of Significant Accounting Policies [Line Items]                  
Revenue, practical expedient, financing component [true false]     true            
New England Teamsters & Trucking Industry Pension Fund                  
Schedule Of Significant Accounting Policies [Line Items]                  
Accrued expenses and other current liabilities     $ 200,000            
Other long-term liabilities     17,000,000            
Subsidiaries of Swiss Re                  
Schedule Of Significant Accounting Policies [Line Items]                  
Additional payment obligated to pay if degree days exceed ten year average     5,000,000            
Charge on weather hedge contract       $ 1,900,000          
Payments of derivative hedging contract   $ 1,900,000              
Subsidiaries of Swiss Re | Subsequent Event                  
Schedule Of Significant Accounting Policies [Line Items]                  
Payments of derivative hedging contract $ 2,100,000                
Subsidiaries of Swiss Re | Delivery and branch expenses                  
Schedule Of Significant Accounting Policies [Line Items]                  
Charge on weather hedge contract     2,100,000            
Subsidiaries of Swiss Re | Scenario Forecast                  
Schedule Of Significant Accounting Policies [Line Items]                  
Derivative maximum payout         $ 5,000,000 $ 5,000,000 $ 5,000,000    
Significant Other Observable Inputs Level 2 | New England Teamsters & Trucking Industry Pension Fund                  
Schedule Of Significant Accounting Policies [Line Items]                  
Multiemployer plan discounted withdrawal liability     21,300,000            
Captive Insurance Collateral | Level 1                  
Schedule Of Significant Accounting Policies [Line Items]                  
Captive insurance collateral, debt securities     52,700,000         44,800,000  
Captive Insurance Collateral | Mutual Funds                  
Schedule Of Significant Accounting Policies [Line Items]                  
Captive insurance collateral, net asset value     $ 1,500,000         $ 600,000  
Maximum                  
Schedule Of Significant Accounting Policies [Line Items]                  
Cash equivalents, highly liquid investments maturity     3 months            
Maximum | Subsidiaries of Swiss Re | Scenario Forecast                  
Schedule Of Significant Accounting Policies [Line Items]                  
Derivative maximum receivable         $ 12,500,000 $ 12,500,000 $ 12,500,000    
[1] See Note 2 – Significant Accounting Policies – Captive Insurance Collateral.