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Amount of currency on hand as well as demand deposits with banks or financial institutions. Includes other kinds of accounts that have the general characteristics of demand deposits. Also includes short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates. Excludes cash and cash equivalents within disposal group and discontinued operation.

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Summary of Significant Accounting Policies - Additional Information (Detail) - USD ($)	1 Months Ended		3 Months Ended		6 Months Ended		12 Months Ended
	Apr. 30, 2020	Apr. 30, 2019	Mar. 31, 2020	Mar. 31, 2019	Mar. 31, 2020	Mar. 31, 2019	Sep. 30, 2021	Sep. 30, 2020	Oct. 01, 2019	Sep. 30, 2019	Sep. 30, 2018
Schedule Of Significant Accounting Policies [Line Items]
Cash, cash equivalents, and restricted cash			$ 10,551,000	$ 16,622,000	$ 10,551,000	$ 16,622,000				$ 5,149,000	$ 14,781,000
Cash and cash equivalents			10,301,000		10,301,000					4,899,000
Restricted cash			250,000		250,000					250,000
Captive insurance collateral, debt securities			65,776,000		65,776,000					58,490,000
Additional payment obligated to pay if degree days exceed ten year average			5,000,000.0		5,000,000.0
Payments and receivables of derivative hedging contract					(10,053,000)	$ 2,110,000
Accrued expenses and other current liabilities			158,989,000		158,989,000					120,839,000
Other long-term liabilities			22,444,000		22,444,000					25,746,000
Operating lease right-of-use assets			103,672,000		103,672,000
Current portion of operating lease liabilities			19,567,000		19,567,000
Long-term operating lease liabilities			89,373,000		89,373,000
Interest rate swap
Schedule Of Significant Accounting Policies [Line Items]
Notional Value			66,500,000		66,500,000					45,000,000.0
ASC Topic 842
Schedule Of Significant Accounting Policies [Line Items]
Operating lease right-of-use assets									$ 104,700,000
Current portion of operating lease liabilities									20,100,000
Long-term operating lease liabilities									$ 89,900,000
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			16,800,000		16,800,000
Subsidiaries of Swiss Re
Schedule Of Significant Accounting Policies [Line Items]
Payments and receivables of derivative hedging contract		$ 2,100,000
Subsidiaries of Swiss Re \| Subsequent Event
Schedule Of Significant Accounting Policies [Line Items]
Payments and receivables of derivative hedging contract	$ (10,100,000)
Delivery and branch expenses \| Financial Products Corporation
Schedule Of Significant Accounting Policies [Line Items]
Change on weather hedge contract			(10,100,000)	$ 2,100,000
Scenario Forecast
Schedule Of Significant Accounting Policies [Line Items]
Derivative maximum payout							$ 5,000,000.0	$ 5,000,000.0
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			29,400,000		29,400,000					21,100,000
Captive Insurance Collateral \| Level 1
Schedule Of Significant Accounting Policies [Line Items]
Captive insurance collateral, debt securities			60,200,000		60,200,000					58,000,000.0
Captive Insurance Collateral \| Mutual Funds
Schedule Of Significant Accounting Policies [Line Items]
Captive insurance collateral, net asset value			$ 5,600,000		$ 5,600,000					$ 500,000
Maximum
Schedule Of Significant Accounting Policies [Line Items]
Cash equivalents, highly liquid investments maturity			3 months
Maximum \| Scenario Forecast
Schedule Of Significant Accounting Policies [Line Items]
Derivative maximum receivable							$ 12,500,000	$ 12,500,000