Cost method investment ownership percentage.

No definition available.

Name:	shlx_CostMethodInvestmentOwnershipPercentage
Namespace Prefix:	shlx_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Description of business and basis of presentation.

+ References

No definition available.

+ Details

Name:	shlx_DescriptionOfBusinessAndBasisOfPresentationLineItems
Namespace Prefix:	shlx_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Number of Cities in which Entity Operates

+ References

No definition available.

+ Details

Name:	shlx_NumberofCitiesinwhichEntityOperates
Namespace Prefix:	shlx_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- Definition

Number of Pipeline Systems

+ References

No definition available.

+ Details

Name:	shlx_NumberofPipelineSystems
Namespace Prefix:	shlx_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

Number of Refined Products Systems

+ References

No definition available.

+ Details

Name:	shlx_NumberofRefinedProductsSystems
Namespace Prefix:	shlx_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

Percentage of voting equity interests acquired at the acquisition date in the business combination.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=56956515&loc=d3e1392-128463

+ Details

Name:	us-gaap_BusinessAcquisitionPercentageOfVotingInterestsAcquired
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

The percentage of ownership of common stock or equity participation in the investee accounted for under the equity method of accounting.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 323
-SubTopic 10
-Section 50
-Paragraph 3
-Subparagraph (a)(1)
-URI http://asc.fasb.org/extlink&oid=6382943&loc=d3e33918-111571

+ Details

Name:	us-gaap_EquityMethodInvestmentOwnershipPercentage
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

The equity interest of noncontrolling shareholders, partners or other equity holders in consolidated entity.

+ References

No definition available.

+ Details

Name:	us-gaap_MinorityInterestOwnershipPercentageByNoncontrollingOwners
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

The parent entity's interest in net assets of the subsidiary, expressed as a percentage.

+ References

No definition available.

+ Details

Name:	us-gaap_MinorityInterestOwnershipPercentageByParent
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

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.

+ References

No definition available.

+ Details

Name:	us-gaap_NumberOfReportableSegments
Namespace Prefix:	us-gaap_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

The number of states the entity operates in as of the balance sheet date.

+ References

No definition available.

+ Details

Name:	us-gaap_NumberOfStatesInWhichEntityOperates
Namespace Prefix:	us-gaap_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- Details

Name:	us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis=shlx_PectenMidstreamLLCMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis=shlx_ZydecoMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis=shlx_ExplorerPipelineCompanyMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis=shlx_MarsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis=shlx_PoseidonMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis=shlx_BengalMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis=shlx_ColonialMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Description of Business and Basis of Presentation (Details)	9 Months Ended
	Sep. 30, 2016 state city segment system	Aug. 09, 2016	Dec. 31, 2015
Description Of Business And Basis Of Presentation [Line Items]
Number of pipeline systems	4
Number of refined products systems	3
Number of cities the entity serves \| city	70
Number of states the entity serves \| state	16
Number of reportable segments \| segment	1
Pecten
Description Of Business And Basis Of Presentation [Line Items]
Equity method investment percentage	100.00%
Zydeco
Description Of Business And Basis Of Presentation [Line Items]
Minority interest ownership percentage by parent	92.50%
Noncontrolling Interest	7.50%
Explorer
Description Of Business And Basis Of Presentation [Line Items]
Minority interest ownership percentage by parent		35.97%
Interest acquired	2.62%
Mars
Description Of Business And Basis Of Presentation [Line Items]
Equity method investment percentage	28.60%		28.60%
Poseidon
Description Of Business And Basis Of Presentation [Line Items]
Equity method investment percentage	36.00%		36.00%
Bengal
Description Of Business And Basis Of Presentation [Line Items]
Equity method investment percentage	50.00%		49.00%
Colonial
Description Of Business And Basis Of Presentation [Line Items]
Cost method investment percentage	6.00%