Equity method investment acquired, ownership percentage.

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- Definition

Line of credit facility maximum borrowing capacity during the heating season.

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- Definition

Number of customers to whom only home heating oil gasoline and diesel were sells on delivery only basis.

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No definition available.

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- Definition

Number of residential and commercial home heating oil and propane customers served.

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- Definition

Number of service contracts heating oil and propane for natural gas and other heating systems.

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- Definition

Date the original debt was scheduled to mature, in CCYY-MM-DD format.

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Face (par) amount of debt instrument at time of issuance.

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Period of time between issuance and maturity of debt instrument, in PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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- Definition

Percentage investment held by the managing member or general partner of the limited liability company (LLC) or limited partnership (LP).

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Percentage investment held by members or limited partners of limited liability company (LLC) or limited partnership (LP).

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility.

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Number of segments reported by the entity. A reportable segment is a component of an entity for which there is an accounting requirement to report separate financial information on that component in the entity's financial statements.

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The number of each class of partnership units outstanding at the balance sheet date. Units represent shares of ownership of the general, limited, and preferred partners.

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The number of units or percentage investment held in the subsidiary by the limited liability company or limited partnership.

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Organization - Additional Information (Detail) shares in Thousands			6 Months Ended
	Jul. 02, 2018 USD ($)	Jul. 30, 2015 USD ($)	Mar. 31, 2019 Segment Customer Contract shares	Dec. 31, 2018 shares	Sep. 30, 2018 shares	Mar. 31, 2018 shares	Dec. 31, 2017 shares	Sep. 30, 2017 shares
Limited Partners' Capital Account [Line Items]
Number of reportable segments \| Segment			1
Percentage of general partner interest			0.60%
Non Seasonal maximum borrowing capacity under revolving credit facility	$ 300,000,000
Fourth Amendment
Limited Partners' Capital Account [Line Items]
Non Seasonal maximum borrowing capacity under revolving credit facility	300,000,000	$ 300,000,000
Maximum borrowing capacity (heating season December to April) under revolving credit facility	450,000,000	$ 450,000,000
Due date of debt		Jul. 02, 2023
Fourth Amendment \| Term Loan
Limited Partners' Capital Account [Line Items]
Outstanding senior notes	$ 100,000,000	$ 100,000,000
Senior secured term loan maturity period	5 years	5 years
Petro Holdings, Inc
Limited Partners' Capital Account [Line Items]
Ownership interest of Star Acquisitions Inc.			100.00%
Number of residential and commercial home heating oil and propane customers served \| Customer			448,000
Number of customers to whom only home heating oil, gasoline and diesel were sells on a delivery only basis \| Customer			81,000
Number of service contracts heating oil and propane for natural gas and other heating systems \| Contract			17,000
Star Group L.P.
Limited Partners' Capital Account [Line Items]
Percentage of limited partner interest			99.40%
Star Acquisitions, Inc
Limited Partners' Capital Account [Line Items]
Ownership interest of partnership			100.00%
Petroleum Heat and Power Co., Inc.
Limited Partners' Capital Account [Line Items]
Ownership interest of partnership			100.00%
Common Stock
Limited Partners' Capital Account [Line Items]
Number of outstanding units \| shares			50,302	52,489	53,088	54,607	55,888	55,888
General Partner
Limited Partners' Capital Account [Line Items]
Number of outstanding units \| shares			326	326	326	326	326	326