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Data Type:	xbrli:durationItemType
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Incentive Distribution, PercentageIncentive Distribution, Percentage Of Available Cash Distributed From Operating Surplus

No definition available.

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Namespace Prefix:	gpp_
Data Type:	dtr-types:percentItemType
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Period Type:	duration

Amount of cash distribution paid to unit-holder of limited partnership (LP).

Name:	us-gaap_DistributionMadeToLimitedPartnerCashDistributionsPaid
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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

Date of record for distribution of cash or unit to limited partner of limited partnership (LP), in YYYY-MM-DD format.

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

Date of declaration for distribution of cash or unit to limited partner of limited partnership (LP), in YYYY-MM-DD format.

Name:	us-gaap_DistributionMadeToLimitedPartnerDeclarationDate
Namespace Prefix:	us-gaap_
Data Type:	xbrli:dateItemType
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Period Type:	duration

Date of distribution for distribution of cash or unit to limited partner of limited partnership (LP), in YYYY-MM-DD format.

Name:	us-gaap_DistributionMadeToLimitedPartnerDistributionDate
Namespace Prefix:	us-gaap_
Data Type:	xbrli:dateItemType
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Period Type:	duration

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

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Data Type:	dtr-types:perShareItemType
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Period Type:	duration

Per-share or per-unit amount of incentive dividend declared and paid to managing member or general partner.

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

Reference 2: 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 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

Reference 4: 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

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Data Type:	dtr-types:perShareItemType
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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.