Long-Term Debt and Bank Facility Borrowings - Additional Information (Detail) - USD ($)			6 Months Ended		12 Months Ended
		Jul. 06, 2022	Mar. 31, 2023	Mar. 31, 2022	Sep. 30, 2022
Debt Instrument [Line Items]
Term loan periodic payment			$ 8,500,000
Additional term loan repayments			$ 8,250,000	$ 11,365,000
Debt instrument, effective interest rate			6.10%
Hedging positions and payable amounts secured under credit facility			$ 13,500,000		$ 0
Letters of credit issued and outstanding			5,100,000		5,100,000
Long-term debt, fair value	[1]		226,686,000		185,276,000
Revolving credit facility outstanding			69,936,000		20,276,000
Availability under credit agreement			223,600,000		$ 189,400,000
Term Loan
Debt Instrument [Line Items]
Debt instrument, effective interest rate					4.70%
Long-term debt, fair value	[1],[2]		$ 156,750,000		$ 165,000,000
Revolving Credit Facility
Debt Instrument [Line Items]
Debt instrument, effective interest rate			6.30%		2.60%
Revolving credit facility outstanding			$ 69,900,000		$ 20,300,000
Credit Agreement
Debt Instrument [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		550,000,000
Issuance of line of credit for working capital purposes		$ 25,000,000
Senior secured term loan maturity date		Jul. 06, 2027
Facility size that can be increased additional without consulting bank group			200,000,000
Facility size that can be increased without consulting bank group			$ 200,000,000
Term loan annual payment percentage		25.00%
Additional term loan repayments					$ 4,900,000
Commitment fee on the unused portion of the facility from December through April		0.30%
Commitment fee on the unused portion of the facility from May through November		0.20%
Minimum fixed charge coverage ratio		110.00%
Availability percentage to maximum facility size		12.50%
Credit Agreement | Maximum
Debt Instrument [Line Items]
Senior secured leverage ratio during quarters ending June or September		300.00%
Senior secured leverage ratio during quarters ending December or March		550.00%
Credit Agreement | Quarterly
Debt Instrument [Line Items]
Term loan periodic payment		$ 4,100,000
Credit Agreement | Term Loan
Debt Instrument [Line Items]
Outstanding term loan		$ 165,000,000
Senior secured term loan maturity period		5 years

[1] The face amount of the Company’s variable rate long-term debt approximates fair value.

[2] Carrying amounts are net of unamortized debt issuance costs of $0.8 million as of March 31, 2023 and $0.9 million as of September 30, 2022