Employer identification number or pension plan number.

No definition available.

Name:	sgu_EmployerIdentificationNumberOrPensionPlanNumber
Namespace Prefix:	sgu_
Data Type:	dei:nineDigitItemType
Balance Type:	na
Period Type:	duration

- Definition

Indicates certified zone status of multiemployer pension plan determined to be individually significant. Acceptable values are "Green", "Yellow", "Orange", "Red", "Other", and "NA".

+ References

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 80
-Section 55
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=35742348&loc=SL14450788-114948

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 80
-Section 50
-Paragraph 5
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=65877416&loc=SL14450657-114947

+ Details

Name:	us-gaap_MultiemployerPlanPensionSignificantCertifiedZoneStatusFixedList
Namespace Prefix:	us-gaap_
Data Type:	us-types:zoneStatusItemType
Balance Type:	na
Period Type:	duration

- Definition

Expiration date of collective-bargaining arrangement (CBA) requiring contribution to multiemployer pension plan determined to be individually significant, in CCYY-MM-DD format.

+ References

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 80
-Section 55
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=35742348&loc=SL14450788-114948

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 80
-Section 50
-Paragraph 5
-Subparagraph (d)
-URI http://asc.fasb.org/extlink&oid=65877416&loc=SL14450657-114947

+ Details

Name:	us-gaap_MultiemployerPlanPensionSignificantCollectiveBargainingArrangementExpirationDate
Namespace Prefix:	us-gaap_
Data Type:	xbrli:dateItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of cost for employer contribution to multiemployer pension plan determined to be individually significant.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 80
-Section 50
-Paragraph 5
-Subparagraph (e)(1)
-URI http://asc.fasb.org/extlink&oid=65877416&loc=SL14450657-114947

Reference 2: http://www.xbrl.org/2003/role/exampleRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 80
-Section 55
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=35742348&loc=SL14450788-114948

+ Details

Name:	us-gaap_MultiemployerPlanPensionSignificantEmployerContributionCost
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Indicates whether funding improvement plan or rehabilitation plan was implemented or pending for multiemployer pension plan, determined to be individually significant. Acceptable values are "No", "Pending", "Implemented", "Other", and "NA".

+ References

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 80
-Section 55
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=35742348&loc=SL14450788-114948

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 80
-Section 50
-Paragraph 5
-Subparagraph (f)(1)
-URI http://asc.fasb.org/extlink&oid=65877416&loc=SL14450657-114947

+ Details

Name:	us-gaap_MultiemployerPlanPensionSignificantFundingImprovementOrRehabilitationPlanImplementationStatusFixedList
Namespace Prefix:	us-gaap_
Data Type:	us-types:fundingImprovementAndRehabilitationPlanItemType
Balance Type:	na
Period Type:	duration

- Definition

Plan number for multiemployer pension plan determined to be individually significant, in three-digit numeric format.

+ References

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 80
-Section 55
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=35742348&loc=SL14450788-114948

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 80
-Section 50
-Paragraph 5
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=65877416&loc=SL14450657-114947

+ Details

Name:	us-gaap_MultiemployerPlanPensionSignificantPlanNumber
Namespace Prefix:	us-gaap_
Data Type:	us-types:threeDigitItemType
Balance Type:	na
Period Type:	duration

- Definition

Indicates whether employer paid surcharge to multiemployer pension plan determined to be individually significant. Acceptable values are "No", "Yes" and "NA".

+ References

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 80
-Section 55
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=35742348&loc=SL14450788-114948

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 80
-Section 50
-Paragraph 5
-Subparagraph (f)(2)
-URI http://asc.fasb.org/extlink&oid=65877416&loc=SL14450657-114947

+ Details

Name:	us-gaap_MultiemployerPlanPensionSignificantSurchargeFixedList
Namespace Prefix:	us-gaap_
Data Type:	us-types:surchargeItemType
Balance Type:	na
Period Type:	duration

- Definition

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.

+ References

No definition available.

+ Details

Name:	us-gaap_MultiemployerPlansLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	us-gaap_RetirementPlanTypeAxis=us-gaap_PensionPlansDefinedBenefitMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_RangeAxis=srt_MinimumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_RangeAxis=srt_MaximumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RetirementPlanNameAxis=sgu_WestchesterTeamstersPensionFundMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RetirementPlanNameAxis=sgu_LocalFiveHundredAndFiftyThreePensionFundMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RetirementPlanNameAxis=sgu_LocalFourHundredAndSixtyThreePensionFundMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RetirementPlanNameAxis=sgu_IAMNationalPensionFundMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RetirementPlanNameAxis=sgu_AllOtherMultiemployerPensionPlansMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RetirementPlanNameAxis=sgu_TeamstersLocalFourHundredAndSixtyNinePensionPlanMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RetirementPlanNameAxis=sgu_LocalFourHundredAndFortyFivePensionFundMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Participation and Contributions to Multi Employer Pension Plans (Detail) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2018
Multiemployer Plans [Line Items]
Company Contributions	$ 9,657	$ 9,598	$ 9,141
New England Teamsters & Trucking Industry Pension Fund
Multiemployer Plans [Line Items]
EIN	046372430
Pension Plan Number	001
Pension Protection Act Zone Status	Red	Red
FIP / RP Status Pending / Implemented	Implemented
Company Contributions	$ 2,659	$ 2,468	2,455
Surcharge Imposed	No
New England Teamsters & Trucking Industry Pension Fund \| Minimum
Multiemployer Plans [Line Items]
Expiration Date of Collective-Bargaining Agreements, Date	Apr. 30, 2021
New England Teamsters & Trucking Industry Pension Fund \| Maximum
Multiemployer Plans [Line Items]
Expiration Date of Collective-Bargaining Agreements, Date	Apr. 30, 2023
Westchester Teamsters Pension Fund
Multiemployer Plans [Line Items]
EIN	136123973
Pension Plan Number	001
Pension Protection Act Zone Status	Green	Green
FIP / RP Status Pending / Implemented	NA
Company Contributions	$ 887	$ 1,039	846
Surcharge Imposed	No
Westchester Teamsters Pension Fund \| Minimum
Multiemployer Plans [Line Items]
Expiration Date of Collective-Bargaining Agreements, Date	Jan. 31, 2024
Westchester Teamsters Pension Fund \| Maximum
Multiemployer Plans [Line Items]
Expiration Date of Collective-Bargaining Agreements, Date	Dec. 31, 2024
Local 553 Pension Fund
Multiemployer Plans [Line Items]
EIN	136637826
Pension Plan Number	001
Pension Protection Act Zone Status	Green	Green
FIP / RP Status Pending / Implemented	NA
Company Contributions	$ 2,678	$ 3,114	2,888
Surcharge Imposed	No
Local 553 Pension Fund \| Minimum
Multiemployer Plans [Line Items]
Expiration Date of Collective-Bargaining Agreements, Date	Dec. 15, 2022
Local 553 Pension Fund \| Maximum
Multiemployer Plans [Line Items]
Expiration Date of Collective-Bargaining Agreements, Date	Jan. 15, 2023
Local 463 Pension Fund
Multiemployer Plans [Line Items]
EIN	111800729
Pension Plan Number	001
Pension Protection Act Zone Status	Green	Green
FIP / RP Status Pending / Implemented	NA
Company Contributions	$ 138	$ 144	145
Surcharge Imposed	No
Local 463 Pension Fund \| Minimum
Multiemployer Plans [Line Items]
Expiration Date of Collective-Bargaining Agreements, Date	Jun. 30, 2022
Local 463 Pension Fund \| Maximum
Multiemployer Plans [Line Items]
Expiration Date of Collective-Bargaining Agreements, Date	Feb. 28, 2023
IAM National Pension Fund
Multiemployer Plans [Line Items]
EIN	516031295
Pension Protection Act Zone Status	Red	Red
FIP / RP Status Pending / Implemented	Implemented
Company Contributions	$ 2,822	$ 2,296	2,320
Surcharge Imposed	Yes
IAM National Pension Fund \| Minimum
Multiemployer Plans [Line Items]
Expiration Date of Collective-Bargaining Agreements, Date	Dec. 31, 2020
IAM National Pension Fund \| Maximum
Multiemployer Plans [Line Items]
Expiration Date of Collective-Bargaining Agreements, Date	Jul. 01, 2023
All Other Multiemployer Pension Plans
Multiemployer Plans [Line Items]
Company Contributions	$ 448	$ 507	437
Teamsters Local 469 Pension Plan
Multiemployer Plans [Line Items]
EIN	226172237
Pension Protection Act Zone Status	Red	Red
FIP / RP Status Pending / Implemented	Implemented
Company Contributions	$ 20	$ 26	46
Surcharge Imposed	Yes
Expiration Date of Collective-Bargaining Agreements, Date	Aug. 31, 2021
Local 445 Pension Fund
Multiemployer Plans [Line Items]
EIN	131864489
Pension Protection Act Zone Status	Red	Red
FIP / RP Status Pending / Implemented	Implemented
Company Contributions	$ 5	$ 4	$ 4
Surcharge Imposed	Yes
Expiration Date of Collective-Bargaining Agreements, Date	Oct. 31, 2021