Summary of Significant Accounting Policies - Additional Information (Detail) - USD ($)	1 Months Ended	6 Months Ended		9 Months Ended		12 Months Ended
	Jul. 31, 2025	Mar. 31, 2025	Mar. 31, 2024	Jun. 30, 2025	Jun. 30, 2024	Sep. 30, 2026	Sep. 30, 2024	Sep. 30, 2023
Schedule Of Significant Accounting Policies [Line Items]
Cash, cash equivalents, and restricted cash				$ 28,332,000	$ 45,951,000		$ 117,585,000	$ 45,441,000
Cash and cash equivalents				28,082,000			117,335,000
Restricted cash				250,000			250,000
Assets held-for-sale				1,000,000
Derivative maximum payout				5,000,000	0
Accrued expenses and other current liabilities				133,163,000			116,317,000
Other long-term liabilities				16,244,000			16,273,000
Subsequent Event
Schedule Of Significant Accounting Policies [Line Items]
Assets held-for-sale	$ 1,000,000
Cash proceeds from sale of assets	$ 4,900,000
New England Teamsters & Trucking Industry Pension Fund
Schedule Of Significant Accounting Policies [Line Items]
Accrued expenses and other current liabilities				300,000			300,000
Other long-term liabilities				15,400,000			15,700,000
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				$ 18,300,000			$ 19,300,000
Financial Products Corporation
Schedule Of Significant Accounting Policies [Line Items]
Delivery and branch expense reduced under weather hedge contract		$ 3,100,000	$ 7,500,000
Scenario Forecast
Schedule Of Significant Accounting Policies [Line Items]
Derivative maximum receivable						$ 15,000,000
Derivative maximum payout						$ 5,000,000
Maximum
Schedule Of Significant Accounting Policies [Line Items]
Cash equivalents, highly liquid investments maturity				3 months
Derivative maximum receivable				$ 15,000,000	$ 12,500,000