Distribution To Partner, Unit Distribution

No definition available.

Name:	shlx_DistributionToPartnerUnitDistribution
Namespace Prefix:	shlx_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

- Definition

Per unit of ownership amount of cash distributions paid to unit-holder of a limited partnership (LP).

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.3-04)
-URI http://asc.fasb.org/extlink&oid=120397183&loc=d3e187085-122770

+ Details

Name:	us-gaap_DistributionMadeToLimitedPartnerDistributionsPaidPerUnit
Namespace Prefix:	us-gaap_
Data Type:	num:perShareItemType
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_DistributionMadeToLimitedPartnerLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

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

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-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

+ Details

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

- Definition

Amount of cash or stock or unit payment to a limited liability corporation managing member or limited partnership general partner after the end of the accounting period.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 260
-SubTopic 10
-Section 45
-Paragraph 73
-URI http://asc.fasb.org/extlink&oid=6926462&loc=SL5163674-159010

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 260
-SubTopic 10
-Section 55
-Paragraph 103
-URI http://asc.fasb.org/extlink&oid=109243028&loc=SL5199526-159011

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 260
-SubTopic 10
-Section 45
-Paragraph 72
-URI http://asc.fasb.org/extlink&oid=6926462&loc=SL5163672-159010

+ Details

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

- Definition

Amount of cash outflow in the form of ordinary dividends provided by the non-wholly owned subsidiary to noncontrolling interests.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 15
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=121586364&loc=d3e3291-108585

+ Details

Name:	us-gaap_PaymentsOfDividendsMinorityInterest
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Details

Name:	srt_OwnershipAxis=shlx_ShellMidstreamPartnersLPMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	dei_LegalEntityAxis=shlx_ZydecoMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	dei_LegalEntityAxis=shlx_OdysseyPipelineL.L.C.Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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

- Details

Name:	dei_LegalEntityAxis=shlx_GeneralPublicMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	dei_LegalEntityAxis=shlx_ShellPipelineCompanyLPMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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

- Details

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

- Details

Name:	dei_LegalEntityAxis=shlx_GeneralPartnerIncentiveMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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

- Details

Name:	shlx_AgreementAxis=shlx_PartnershipInterestsRestructuringAgreementMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_StatementClassOfStockAxis=shlx_CommonUnitsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

(Deficit) Equity - Schedule of Distributions Declared and/or Paid (Details) - USD ($) $ / shares in Units, $ in Millions		3 Months Ended							6 Months Ended		9 Months Ended
	Apr. 01, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Jun. 30, 2020	Jun. 30, 2019	Sep. 30, 2018
Distribution Made To Limited Partner [Line Items]
Distributions declared and/or paid		$ 173	$ 162	$ 162	$ 140	$ 131	$ 119	$ 129
Distributions paid per limited partner unit (in dollars per share)		$ 0.4600	$ 0.4600	$ 0.4600	$ 0.4450	$ 0.4300	$ 0.4150	$ 0.4000	$ 0.9200	$ 0.8450
Shell Midstream Partners L.P.
Distribution Made To Limited Partner [Line Items]
Aggregate percentage of general partner interest			2.00%								2.00%
Zydeco Pipeline Company LLC (“Zydeco”)
Distribution Made To Limited Partner [Line Items]
Distributions to noncontrolling interest		$ 2				$ 2			$ 3	$ 3
Odyssey Pipeline L.L.C. (“Odyssey”)
Distribution Made To Limited Partner [Line Items]
Distributions to noncontrolling interest		2				4			$ 6	$ 6
Common Units \| General Public
Distribution Made To Limited Partner [Line Items]
Distributions declared and/or paid		57	$ 57	$ 57	$ 56	53	$ 51	$ 49
Unit distribution (in units)									0
Common Units \| Shell Pipeline Company L P
Distribution Made To Limited Partner [Line Items]
Distributions declared and/or paid		104	50	50	48	47	42	40
Unit distribution (in units)									160,000,000
Preferred Units \| Shell Pipeline Company L P
Distribution Made To Limited Partner [Line Items]
Distributions declared and/or paid		12	0	0	0	0	0	0
General Partner
Distribution Made To Limited Partner [Line Items]
Distributions declared and/or paid		0	3	3	3	3	3	3
Unit distribution (in units)									(4,761,012)
General Partner \| IDR's
Distribution Made To Limited Partner [Line Items]
Distributions declared and/or paid		$ 0	$ 52	$ 52	$ 33	$ 28	$ 23	$ 37
Limited Partner \| Partnership Interests Restructuring Agreement \| Common Units
Distribution Made To Limited Partner [Line Items]
Unit distribution (in units)	160,000,000