Sum of the carrying values as of the balance sheet date of all debt, including all short-term borrowings, long-term debt, and capital lease obligations.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03.13,16)
-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03.16)
-URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910

+ Details

Name:	us-gaap_DebtAndCapitalLeaseObligations
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of short-term debt and current maturity of long-term debt and capital lease obligations due within one year or the normal operating cycle, if longer.

+ References

+ Details

Name:	us-gaap_DebtCurrent
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount, before unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but is not limited to, notes payable, bonds payable, commercial loans, mortgage loans, convertible debt, subordinated debt and other types of debt.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(22))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03(16))
-URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03(16))
-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

+ Details

Name:	us-gaap_DebtInstrumentCarryingAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Face (par) amount of debt instrument at time of issuance.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 55
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=64930739&loc=d3e28878-108400

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=64930785&loc=d3e28551-108399

+ Details

Name:	us-gaap_DebtInstrumentFaceAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Fair value portion of debt instrument payable, including, but not limited to, notes payable and loans payable.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 50
-Paragraph 10
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=73719730&loc=d3e13433-108611

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 50
-Paragraph 12
-URI http://asc.fasb.org/extlink&oid=73719730&loc=d3e13476-108611

+ Details

Name:	us-gaap_DebtInstrumentFairValue
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Contractual interest rate for funds borrowed, under the debt agreement.

+ References

+ Details

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

- Definition

Amount of unamortized debt discount (premium) and debt issuance costs.

+ References

+ Details

Name:	us-gaap_DebtInstrumentUnamortizedDiscountPremiumAndDebtIssuanceCostsNet
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount, after accumulated amortization, of debt issuance costs. Includes, but is not limited to, legal, accounting, underwriting, printing, and registration costs.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=64930785&loc=d3e28555-108399

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.17)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

Name:	us-gaap_DeferredFinanceCostsNet
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- References

No definition available.

+ Details

Name:	us-gaap_LongTermDebtAbstract
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of long-term debt and capital lease obligation due after one year or beyond the normal operating cycle, if longer.

+ References

+ Details

Name:	us-gaap_LongTermDebtAndCapitalLeaseObligations
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Weighted average interest rate of long-term debt outstanding.

+ References

No definition available.

+ Details

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

- Definition

Amount of long-term debt classified as other, payable within one year or the operating cycle, if longer.

+ References

+ Details

Name:	us-gaap_OtherLongTermDebtCurrent
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of long-term debt classified as other, payable after one year or the operating cycle, if longer.

+ References

+ Details

Name:	us-gaap_OtherLongTermDebtNoncurrent
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The cash outflow for a long-term debt where the holder has highest claim on the entity's asset in case of bankruptcy or liquidation during the period.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Financing Activities
-URI http://asc.fasb.org/extlink&oid=6513228

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 15
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=66902209&loc=d3e3291-108585

+ Details

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

- Definition

Carrying value as of the balance sheet date of Notes with the highest claim on the assets of the issuer in case of bankruptcy or liquidation (with maturities initially due after one year or beyond the operating cycle if longer), excluding current portion. Senior note holders are paid off in full before any payments are made to junior note holders.

+ References

+ Details

Name:	us-gaap_SeniorLongTermNotes
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Carrying value as of the balance sheet date of the portion of long-term notes having the highest claim on the assets of the issuer in case of bankruptcy or liquidation, due within one year or the normal operating cycle, if longer. Senior note holders are paid off in full before any payments are made to debt holders having a lesser priority of repayment.

+ References

+ Details

Name:	us-gaap_SeniorNotesCurrent
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Reflects the total carrying amount as of the balance sheet date of debt having initial terms less than one year or the normal operating cycle, if longer.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(19)(a))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03(13))
-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03(a)(16)(a)(1))
-URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910

+ Details

Name:	us-gaap_ShortTermBorrowings
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- References

No definition available.

+ Details

Name:	us-gaap_ShortTermBorrowingsAbstract
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Weighted average interest rate of short-term debt outstanding.

+ References

+ Details

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

- Details

Name:	us-gaap_CreditFacilityAxis=us-gaap_CommercialPaperMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_CreditFacilityAxis=pagp_AAPSeniorSecuredCreditAgreementMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_CreditFacilityAxis=pagp_AAPTermLoanMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_CreditFacilityAxis=pagp_AAPRevolvingCreditFacilityMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_ShortTermDebtTypeAxis=us-gaap_CommercialPaperMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_ShortTermDebtTypeAxis=pagp_OtherLongTermDebtMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=pagp_SeniorSecuredHedgedInventoryFacilityMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_ShortTermDebtTypeAxis=us-gaap_LineOfCreditMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LongtermDebtTypeAxis=us-gaap_SeniorNotesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=pagp_SeniorNotesDueInJanuary2017At6.13PercentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=pagp_SeniorNotesDueInAugust2016At5.88PercentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=pagp_SeniorNotesDueInMay2018At6.50PercentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=pagp_SeniorNotesDueInMay2019At8.75PercentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=pagp_SeniorNotesDueInDecember2019At2.60PercentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=pagp_SeniorNotesDueInJanuary2020At5.75PercentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=pagp_SeniorNotesDueInFebruary2021At5.00PercentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=pagp_SeniorNotesDueInJune2022At3.65PercentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=pagp_SeniorNotesDueInJanuary2023At2.85PercentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=pagp_SeniorNotesDueInOctober2023At3.85PercentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=pagp_SeniorNotesDueInNovember2024At3.60PercentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=pagp_SeniorNotesDueInOctober2025At4.65PercentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=pagp_SeniorNotesDueinDecember2026At4.50PercentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=pagp_SeniorNotesDueInMay2036At6.70PercentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=pagp_SeniorNotesDueInJanuary2037At6.65PercentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=pagp_SeniorNotesDueInJune2042At5.15PercentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=pagp_SeniorNotesDueInJanuary2043At4.30PercentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=pagp_SeniorNotesDueInJune2044At4.70PercentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=pagp_SeniorNotesDueInFebruary2045At4.90PercentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FairValueByFairValueHierarchyLevelAxis=us-gaap_FairValueInputsLevel2Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LongtermDebtTypeAxis=pagp_OtherLongTermDebtMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_TransactionTypeAxis=us-gaap_ExchangeTradedMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Debt - Components (Details) - USD ($)	1 Months Ended	12 Months Ended
Debt - Components (Details) - USD ($)	Aug. 31, 2016	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Short-term debt:
Total short-term debt		$ 1,715,000,000	$ 999,000,000
Long-term debt:
PAA senior notes, net of unamortized discounts and debt issuance costs		9,874,000,000	9,698,000,000
Noncurrent portion of other long-term debt		250,000,000	1,234,000,000
Total long-term debt		10,124,000,000	10,932,000,000
Total debt		11,839,000,000	11,931,000,000
Repayments of senior notes		175,000,000	549,000,000	$ 0
PAA commercial paper notes
Long-term debt:
Noncurrent portion of other long-term debt		$ 247,000,000	$ 672,000,000
Weighted average interest rate, long-term		1.60%	1.10%
AAP senior secured credit agreement
Long-term debt:
Unamortized debt issuance costs			$ (2,000,000)
AAP term loan
Long-term debt:
Long-term debt, before deducting unamortized discounts and debt issuance costs			$ 550,000,000
Weighted average interest rate, long-term			2.00%
AAP senior secured revolving credit facility
Long-term debt:
Long-term debt, before deducting unamortized discounts and debt issuance costs			$ 9,000,000
Weighted average interest rate, long-term			2.00%
PAA commercial paper notes
Short-term debt:
Short-term notes and borrowings		$ 563,000,000	$ 696,000,000
Weighted average interest rate, short-term		1.60%	1.10%
Other
Short-term debt:
Current portion of other long-term debt		$ 2,000,000	$ 3,000,000
PAA senior secured hedged inventory facility \| Line of Credit
Short-term debt:
Short-term notes and borrowings		$ 750,000,000	$ 300,000,000
Weighted average interest rate, short-term		1.80%	1.40%
PAA senior notes
Long-term debt:
Unamortized discounts and debt issuance costs		$ (76,000,000)	$ (77,000,000)
PAA senior notes, net of unamortized discounts and debt issuance costs		9,874,000,000	9,698,000,000
Debt instrument face value		10,300,000,000	9,800,000,000
PAA senior notes \| 6.13% senior notes due January 2017
Short-term debt:
Senior notes, current		$ 400,000,000
Long-term debt:
Long-term debt, before deducting unamortized discounts and debt issuance costs			$ 400,000,000
Debt instrument, interest rate		6.13%	6.13%
PAA senior notes \| 5.88% senior notes due August 2016
Long-term debt:
Long-term debt, before deducting unamortized discounts and debt issuance costs			$ 175,000,000
Debt instrument, interest rate	5.88%		5.88%
Repayments of senior notes	$ 175,000,000		$ 175,000,000
PAA senior notes \| 6.50% senior notes due May 2018
Long-term debt:
Long-term debt, before deducting unamortized discounts and debt issuance costs		$ 600,000,000	$ 600,000,000
Debt instrument, interest rate		6.50%	6.50%
PAA senior notes \| 8.75% senior notes due May 2019
Long-term debt:
Long-term debt, before deducting unamortized discounts and debt issuance costs		$ 350,000,000	$ 350,000,000
Debt instrument, interest rate		8.75%	8.75%
PAA senior notes \| 2.60% senior notes due December 2019
Long-term debt:
Long-term debt, before deducting unamortized discounts and debt issuance costs		$ 500,000,000	$ 500,000,000
Debt instrument, interest rate		2.60%	2.60%
Debt instrument face value				500,000,000
PAA senior notes \| 5.75% senior notes due January 2020
Long-term debt:
Long-term debt, before deducting unamortized discounts and debt issuance costs		$ 500,000,000	$ 500,000,000
Debt instrument, interest rate		5.75%	5.75%
PAA senior notes \| 5.00% senior notes due February 2021
Long-term debt:
Long-term debt, before deducting unamortized discounts and debt issuance costs		$ 600,000,000	$ 600,000,000
Debt instrument, interest rate		5.00%	5.00%
PAA senior notes \| 3.65% senior notes due June 2022
Long-term debt:
Long-term debt, before deducting unamortized discounts and debt issuance costs		$ 750,000,000	$ 750,000,000
Debt instrument, interest rate		3.65%	3.65%
PAA senior notes \| 2.85% senior notes due January 2023
Long-term debt:
Long-term debt, before deducting unamortized discounts and debt issuance costs		$ 400,000,000	$ 400,000,000
Debt instrument, interest rate		2.85%	2.85%
PAA senior notes \| 3.85% senior notes due October 2023
Long-term debt:
Long-term debt, before deducting unamortized discounts and debt issuance costs		$ 700,000,000	$ 700,000,000
Debt instrument, interest rate		3.85%	3.85%
PAA senior notes \| 3.60% senior notes due November 2024
Long-term debt:
Long-term debt, before deducting unamortized discounts and debt issuance costs		$ 750,000,000	$ 750,000,000
Debt instrument, interest rate		3.60%	3.60%
Debt instrument face value				750,000,000
PAA senior notes \| 4.65% senior notes due October 2025
Long-term debt:
Long-term debt, before deducting unamortized discounts and debt issuance costs		$ 1,000,000,000	$ 1,000,000,000
Debt instrument, interest rate		4.65%	4.65%
Debt instrument face value			$ 1,000,000,000
PAA senior notes \| 4.50% senior notes due December 2026
Long-term debt:
Long-term debt, before deducting unamortized discounts and debt issuance costs		$ 750,000,000
Debt instrument, interest rate		4.50%
Debt instrument face value		$ 750,000,000
PAA senior notes \| 6.70% senior notes due May 2036
Long-term debt:
Long-term debt, before deducting unamortized discounts and debt issuance costs		$ 250,000,000	$ 250,000,000
Debt instrument, interest rate		6.70%	6.70%
PAA senior notes \| 6.65% senior notes due January 2037
Long-term debt:
Long-term debt, before deducting unamortized discounts and debt issuance costs		$ 600,000,000	$ 600,000,000
Debt instrument, interest rate		6.65%	6.65%
PAA senior notes \| 5.15% senior notes due June 2042
Long-term debt:
Long-term debt, before deducting unamortized discounts and debt issuance costs		$ 500,000,000	$ 500,000,000
Debt instrument, interest rate		5.15%	5.15%
PAA senior notes \| 4.30% senior notes due January 2043
Long-term debt:
Long-term debt, before deducting unamortized discounts and debt issuance costs		$ 350,000,000	$ 350,000,000
Debt instrument, interest rate		4.30%	4.30%
PAA senior notes \| 4.70% senior notes due June 2044
Long-term debt:
Long-term debt, before deducting unamortized discounts and debt issuance costs		$ 700,000,000	$ 700,000,000
Debt instrument, interest rate		4.70%	4.70%
Debt instrument face value				700,000,000
PAA senior notes \| 4.90% senior notes due February 2045
Long-term debt:
Long-term debt, before deducting unamortized discounts and debt issuance costs		$ 650,000,000	$ 650,000,000
Debt instrument, interest rate		4.90%	4.90%
Debt instrument face value				$ 650,000,000
PAA senior notes \| Level 2
Long-term debt:
Debt instrument fair value		$ 10,400,000,000	$ 8,600,000,000
Other
Long-term debt:
Noncurrent portion of other long-term debt		3,000,000	$ 5,000,000
Exchange Traded
Short-term debt:
Total short-term debt		$ 410,000,000