Subsequent Events - Additional Information (Detail) - USD ($)		1 Months Ended	12 Months Ended
	Dec. 04, 2019	Oct. 31, 2019	Sep. 30, 2019	Sep. 30, 2018
Subsequent Event [Line Items]
Repayment of borrowings			$ 79,331,000	$ 160,104,000
Subsequent Event | Fifth Amendment
Subsequent Event [Line Items]
Non Seasonal maximum borrowing capacity under revolving credit facility	$ 300,000,000
Maximum borrowing capacity (heating season December to April) under revolving credit facility	450,000,000
Issuance of line of credit for working capital purposes	$ 25,000,000
Senior secured term loan maturity date	Dec. 04, 2024
Availability required to repurchase common units	$ 45,000,000
Percentage of the maximum facility size on a historical proforma and forward-looking basis	15.00%
Minimum fixed charge coverage ratio for distributions to unit holders or to repurchase common units	115.00%
Subsequent Event | Fifth Amendment | Term Loan
Subsequent Event [Line Items]
Outstanding term loan	$ 130,000,000
Senior secured term loan maturity period	5 years
Repayment of borrowings	$ 90,000,000
Subsequent Event | Fifth Amendment | Revolving Credit Facility
Subsequent Event [Line Items]
Repayment of borrowings	$ 40,000,000
Subsequent Event | Dividend Declared
Subsequent Event [Line Items]
Distribution declared		$ 0.1250
Partners capital projected distribution amount on annualized basis		0.50
Minimum dividend distribution per unit		$ 0.0675
Amount to paid to common unit holders		$ 5,900,000
Amount to paid to the General Partner		200,000
Incentive distribution to the General Partner		200,000
Incentive distributions to management		$ 200,000
Dividend paid date		Nov. 05, 2019
Dividend record date		Oct. 28, 2019
Subsequent Event | Motor Fuel Dealer
Subsequent Event [Line Items]
Aggregate purchase price		$ 500,000