Name:	pagp_NumberOfDaysRequiredForDistributionToShareholdersAfterEndOfQuarter
Namespace Prefix:	pagp_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- References

No definition available.

Name:	pagp_PartnersCapitalAndDistributionLineItems
Namespace Prefix:	pagp_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

This element represents the percentage of cash distributed out of available cash.

No definition available.

Name:	pagp_PercentageDistributionOfAvailableCash
Namespace Prefix:	pagp_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

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

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 https://asc.fasb.org/extlink&oid=120397183&loc=d3e187085-122770

Name:	us-gaap_DistributionMadeToLimitedPartnerDistributionsDeclaredPerUnit
Namespace Prefix:	us-gaap_
Data Type:	dtr-types:perShareItemType
Balance Type:	na
Period Type:	duration

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

Name:	us-gaap_DistributionMadeToLimitedPartnerDistributionsPaidPerUnit
Namespace Prefix:	us-gaap_
Data Type:	dtr-types:perShareItemType
Balance Type:	na
Period Type:	duration

The total amount of distributions to limited partners.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section S99
-Paragraph 5
-Subparagraph (SAB TOPIC 4.F)
-URI https://asc.fasb.org/extlink&oid=120397183&loc=d3e187171-122770

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

Name:	us-gaap_LimitedPartnersCapitalAccountByClassAxis=pagp_SharesClassAMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_DistributionsMadeToMemberOrLimitedPartnerByDistributionTypeAxis=us-gaap_CashDistributionMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_DividendsAxis=pagp_FourthQuarterDistributionMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: