Name:	shlx_CashReceivedFromGeneralPartnerForAdditionalSharesIssued
Namespace Prefix:	shlx_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

Gross proceeds from issuance of private placement, prior to any placement fees.

No definition available.

Name:	shlx_GrossProceedsFromIssuanceOfPrivatePlacement
Namespace Prefix:	shlx_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

Partners' Capital, Sale of Units, Maximum Gross Proceeds

No definition available.

Name:	shlx_PartnersCapitalSaleofUnitsMaximumGrossProceeds
Namespace Prefix:	shlx_
Data Type:	xbrli:monetaryItemType
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Period Type:	duration

Placement agent fees in connection with the private placement.

No definition available.

Name:	shlx_PlacementFees
Namespace Prefix:	shlx_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

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.

No definition available.

Name:	us-gaap_ClassOfStockLineItems
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Period Type:	duration

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.

No definition available.

Name:	us-gaap_DebtInstrumentTerm
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Data Type:	xbrli:durationItemType
Balance Type:	na
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Percentage investment held by the managing member or general partner of the limited liability company (LLC) or limited partnership (LP).

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 272
-SubTopic 10
-Section 50
-Paragraph 3
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=6373374&loc=d3e70478-108055

Name:	us-gaap_LimitedLiabilityCompanyLLCOrLimitedPartnershipLPManagingMemberOrGeneralPartnerOwnershipInterest
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

Monetary value of the issuance of new units of limited partnership interest in a private placement.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section S99
-Paragraph 5
-Subparagraph (SAB TOPIC 4.F)
-URI http://asc.fasb.org/extlink&oid=27012166&loc=d3e187171-122770

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 04
-Article 3

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

The number of units sold in a private placement of each class of partners' capital account. Units represent shares of ownership of the general, limited, and preferred partners.

Name:	us-gaap_PartnersCapitalAccountUnitsSoldInPrivatePlacement
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

Per share or per unit amount of equity securities issued.

No definition available.

Name:	us-gaap_SharesIssuedPricePerShare
Namespace Prefix:	us-gaap_
Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	instant

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Name:	us-gaap_PartnerTypeOfPartnersCapitalAccountAxis=us-gaap_GeneralPartnerMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	dei_LegalEntityAxis=shlx_GeneralPublicMember
Namespace Prefix:
Data Type:	na
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Name:	us-gaap_RelatedPartyTransactionsByRelatedPartyAxis=shlx_ShellTreasuryCenterWestIncMember
Namespace Prefix:
Data Type:	na
Balance Type:
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Name:	us-gaap_DebtInstrumentAxis=shlx_FiveYearRevolverMember
Namespace Prefix:
Data Type:	na
Balance Type:
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