XML 91 R68.htm IDEA: XBRL DOCUMENT
v3.20.4

Investments in Unconsolidated Entities - Equity Method Investments (Details) - USD ($) $ in Millions | 1 Months Ended | 3 Months Ended | 9 Months Ended | 12 Months Ended
--- | --- | --- | --- | ---
Feb. 29, 2020 | Sep. 30, 2020 | Jun. 30, 2020 | Mar. 31, 2020 | Mar. 31, 2019 | Jun. 30, 2018 | Sep. 30, 2018 | Dec. 31, 2020 | Dec. 31, 2019 | Dec. 31, 2018
Investments in Unconsolidated Entities |  |  |  |  |  |  |  |  |  |
Investments in unconsolidated entities |  |  |  |  |  |  |  | $ 3,764 | $ 3,683 | $ 2,702
Carrying value of undivided joint interest |  |  |  |  |  |  |  | 14,620 | 15,367 |
Advance cash payment, pipeline capacity agreements |  |  |  |  |  |  |  | 501 | 354 | 338
Capital contributions to equity method investees excluding capitalized interest |  |  |  |  |  |  |  | 445 | 504 | 459
Capitalized interest related to contributions to unconsolidated entities |  |  |  |  |  |  |  | 24 | 34 | 30
Amount by which investments in unconsolidated entities exceeded our share of the underlying equity in the net assets |  |  |  |  |  |  |  | $ 170 | 349 |
Level 3 | Measurement Input, Discount Rate | Valuation Technique, Discounted Cash Flow |  |  |  |  |  |  |  |  |  |
Investments in Unconsolidated Entities |  |  |  |  |  |  |  |  |  |
Discount rate, asset impairment analysis, cost of capital, theoretical market participant |  |  |  |  |  |  |  | 14.00% |  |
Gain on/(impairment of) investments in unconsolidated entities, net |  |  |  |  |  |  |  |  |  |
Investments in Unconsolidated Entities |  |  |  |  |  |  |  |  |  |
Write down of investments |  | $ 91 | $ 69 | $ 43 |  |  |  |  |  |
BridgeTex Pipeline Company, LLC (“BridgeTex”) |  |  |  |  |  |  |  |  |  |
Investments in Unconsolidated Entities |  |  |  |  |  |  |  |  |  |
Ownership interest in unconsolidated entity |  |  |  |  |  |  | 20.00% | 20.00% |  |
Investments in unconsolidated entities |  |  |  |  |  |  |  | $ 421 | 431 |
Proceeds from sale of equity method investment |  |  |  |  |  |  | $ 868 |  |  | $ 868
Ownership percentage sold |  |  |  |  |  |  | 30.00% |  |  | 30.00%
Gain on sale of investment in unconsolidated entities |  |  |  |  |  |  | $ 200 |  |  | $ 200
Cactus II Pipeline LLC (“Cactus II”) |  |  |  |  |  |  |  |  |  |
Investments in Unconsolidated Entities |  |  |  |  |  |  |  |  |  |
Ownership interest in unconsolidated entity |  |  |  |  |  |  |  | 65.00% |  |
Investments in unconsolidated entities |  |  |  |  |  |  |  | $ 752 | 738 |
Reduction of property and equipment from deconsolidation |  |  |  |  |  | $ 74 |  |  |  |
Proceeds from sale of equity method investment |  |  |  |  |  | $ 26 |  |  |  |
Capline Pipeline Company LLC |  |  |  |  |  |  |  |  |  |
Investments in Unconsolidated Entities |  |  |  |  |  |  |  |  |  |
Ownership interest in unconsolidated entity |  |  |  |  |  |  |  | 54.00% |  |
Investments in unconsolidated entities |  |  |  |  |  |  |  | $ 514 | 484 |
Fair value of investment in unconsolidated entity |  |  |  |  | $ 444 |  |  |  |  |
Capline Pipeline Company LLC | Gain on/(impairment of) investments in unconsolidated entities, net |  |  |  |  |  |  |  |  |  |
Investments in Unconsolidated Entities |  |  |  |  |  |  |  |  |  |
Gain from remeasurement to fair value of retained investment |  | 2 |  | 267 |  |  |  |  | 269 |
Diamond Pipeline LLC (“Diamond”) |  |  |  |  |  |  |  |  |  |
Investments in Unconsolidated Entities |  |  |  |  |  |  |  |  |  |
Ownership interest in unconsolidated entity |  |  |  |  |  |  |  | 50.00% |  |
Investments in unconsolidated entities |  |  |  |  |  |  |  | $ 480 | 476 |
Eagle Ford Pipeline LLC (“Eagle Ford Pipeline”) |  |  |  |  |  |  |  |  |  |
Investments in Unconsolidated Entities |  |  |  |  |  |  |  |  |  |
Ownership interest in unconsolidated entity |  |  |  |  |  |  |  | 50.00% |  |
Investments in unconsolidated entities |  |  |  |  |  |  |  | $ 372 | 382 |
Eagle Ford Terminals Corpus Christi LLC (“Eagle Ford Terminals”) |  |  |  |  |  |  |  |  |  |
Investments in Unconsolidated Entities |  |  |  |  |  |  |  |  |  |
Ownership interest in unconsolidated entity |  |  |  |  |  |  |  | 50.00% |  |
Investments in unconsolidated entities |  |  |  |  |  |  |  | $ 122 | 126 |
Red Oak Pipeline LLC (“Red Oak”) |  |  |  |  |  |  |  |  |  |
Investments in Unconsolidated Entities |  |  |  |  |  |  |  |  |  |
Ownership interest in unconsolidated entity |  |  | 50.00% |  |  |  |  | 50.00% |  |
Investments in unconsolidated entities |  |  |  |  |  |  |  | $ 35 | 20 |
Write down of investments |  |  | $ 69 |  |  |  |  |  |  |
Saddlehorn |  |  |  |  |  |  |  |  |  |
Investments in Unconsolidated Entities |  |  |  |  |  |  |  |  |  |
Ownership interest in unconsolidated entity | 30.00% |  |  |  |  |  |  | 30.00% |  |
Investments in unconsolidated entities |  |  |  |  |  |  |  | $ 208 | 234 |
Proceeds from sale of equity method investment | $ 78 |  |  |  |  |  |  | $ 78 |  |
Ownership percentage sold | 10.00% |  |  |  |  |  |  | 10.00% |  |
Saddlehorn | Gain on/(impairment of) investments in unconsolidated entities, net |  |  |  |  |  |  |  |  |  |
Investments in Unconsolidated Entities |  |  |  |  |  |  |  |  |  |
Gain on sale of investment in unconsolidated entities | $ 21 |  |  |  |  |  |  |  |  |
STACK Pipeline LLC (“STACK”) |  |  |  |  |  |  |  |  |  |
Investments in Unconsolidated Entities |  |  |  |  |  |  |  |  |  |
Ownership interest in unconsolidated entity |  |  |  |  |  |  |  | 50.00% |  |
Investments in unconsolidated entities |  |  |  |  |  |  |  | $ 22 | 117 |
Write down of investments |  | $ 91 |  |  |  |  |  |  |  |
STACK Pipeline LLC (“STACK”) | Level 3 | Measurement Input, Discount Rate | Valuation Technique, Discounted Cash Flow |  |  |  |  |  |  |  |  |  |
Investments in Unconsolidated Entities |  |  |  |  |  |  |  |  |  |
Discount rate, asset impairment analysis, cost of capital, theoretical market participant |  |  |  |  |  |  |  | 14.00% |  |
White Cliffs Pipeline, LLC |  |  |  |  |  |  |  |  |  |
Investments in Unconsolidated Entities |  |  |  |  |  |  |  |  |  |
Ownership interest in unconsolidated entity |  |  |  |  |  |  |  | 36.00% |  |
Investments in unconsolidated entities |  |  |  |  |  |  |  | $ 192 | $ 196 |
Wink to Webster Pipeline LLC (“W2W Pipeline”) |  |  |  |  |  |  |  |  |  |
Investments in Unconsolidated Entities |  |  |  |  |  |  |  |  |  |
Ownership interest in unconsolidated entity |  |  |  |  |  |  |  | 16.00% | 16.00% |
Investments in unconsolidated entities |  |  |  |  |  |  |  | $ 330 | $ 136 |
Other investments |  |  |  |  |  |  |  |  |  |
Investments in Unconsolidated Entities |  |  |  |  |  |  |  |  |  |
Investments in unconsolidated entities |  |  |  |  |  |  |  | 316 | $ 343 |
Write down of investments |  |  |  | $ 43 |  |  |  |  |  |
Cushing Connect Pipeline & Terminal LLC |  |  |  |  |  |  |  |  |  |
Investments in Unconsolidated Entities |  |  |  |  |  |  |  |  |  |
Ownership interest in unconsolidated entity |  |  |  |  |  |  |  |  | 50.00% |
Equity Method Investees |  |  |  |  |  |  |  |  |  |
Investments in Unconsolidated Entities |  |  |  |  |  |  |  |  |  |
Capitalized interest related to contributions to unconsolidated entities |  |  |  |  |  |  |  | $ 16 | $ 20 | $ 9
Capline Pipeline Company LLC | Capline pipeline system |  |  |  |  |  |  |  |  |  |
Investments in Unconsolidated Entities |  |  |  |  |  |  |  |  |  |
Percentage of Capline pipeline system owned |  |  |  |  | 100.00% |  |  |  |  |
Oxy | Cactus II Pipeline LLC (“Cactus II”) |  |  |  |  |  |  |  |  |  |
Investments in Unconsolidated Entities |  |  |  |  |  |  |  |  |  |
Interest acquired |  |  |  |  |  | 20.00% |  |  |  |
Third Party | Cactus II Pipeline LLC (“Cactus II”) |  |  |  |  |  |  |  |  |  |
Investments in Unconsolidated Entities |  |  |  |  |  |  |  |  |  |
Interest acquired |  |  |  |  |  | 15.00% |  |  |  |
Other long-term liabilities and deferred credits | Cactus II Pipeline LLC (“Cactus II”) |  |  |  |  |  |  |  |  |  |
Investments in Unconsolidated Entities |  |  |  |  |  |  |  |  |  |
Advance cash payment, pipeline capacity agreements |  |  |  |  |  | $ 100 |  |  |  |
Undivided joint interest in Capline pipeline system |  |  |  |  |  |  |  |  |  |
Investments in Unconsolidated Entities |  |  |  |  |  |  |  |  |  |
Undivided joint interest ownership percentage |  |  |  |  | 54.00% |  |  |  |  |
Carrying value of undivided joint interest |  |  |  |  | $ 175 |  |  |  |  |
Undivided joint interest in pipeline segment | Wink to Webster Pipeline LLC (“W2W Pipeline”) | Midland, Texas to Webster, Texas pipeline segment |  |  |  |  |  |  |  |  |  |
Investments in Unconsolidated Entities |  |  |  |  |  |  |  |  |  |
Undivided joint interest ownership percentage |  |  |  |  |  |  |  |  | 71.00% |
Undivided joint interest in pipeline segment | Enterprise Products Partners, L.P. | Midland, Texas to Webster, Texas pipeline segment |  |  |  |  |  |  |  |  |  |
Investments in Unconsolidated Entities |  |  |  |  |  |  |  |  |  |
Undivided joint interest ownership percentage |  |  |  |  |  |  |  |  | 29.00% |

X
- Definition Cash outflow for capital contributions (excluding capitalized interest) subsequent to the initial purchase of interest in equity method investments, to fund the entity's portion of development, construction or capital expansion projects of the equity method investees, net of cash received as a return of investment. + References No definition available. + Details
Name: | pagp_CapitalContributionsToEquityMethodInvesteesExcludingCapitalizedInterest
Namespace Prefix: | pagp_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition The percentage of ownership of common stock or equity participation in the investee accounted for under the equity method of accounting that was acquired during the period. + References No definition available. + Details
Name: | pagp_EquityMethodInvestmentOwnershipPercentageAcquired
Namespace Prefix: | pagp_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition Equity Method Investment Ownership Percentage Sold + References No definition available. + Details
Name: | pagp_EquityMethodInvestmentOwnershipPercentageSold
Namespace Prefix: | pagp_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition Impairment Analysis, Cost of Capital, Theoretical Market Participant + References No definition available. + Details
Name: | pagp_ImpairmentAnalysisCostOfCapitalTheoreticalMarketParticipant
Namespace Prefix: | pagp_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Undivided Joint Interest Ownership Percentage + References No definition available. + Details
Name: | pagp_UndividedJointInterestOwnershipPercentage
Namespace Prefix: | pagp_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition Amount of obligation to transfer good or service to customer for which consideration has been received or is receivable. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 606 -SubTopic 10 -Section 45 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=121556615&loc=SL49130531-203044 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 606 -SubTopic 10 -Section 50 -Paragraph 8 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=121604090&loc=SL49130549-203045 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 606 -SubTopic 10 -Section 45 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=121556615&loc=SL49130532-203044 + Details
Name: | us-gaap_ContractWithCustomerLiability
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Amount of gain (loss) from remeasurement to fair value of retained investment in former subsidiary and group of assets constituting business or nonprofit activity deconsolidated and derecognized, excluding conveyance of oil and gas mineral rights and transfer of product or service in contract with customer. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 810 -SubTopic 10 -Section 50 -Paragraph 1B -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=109239629&loc=SL4582445-111684 + Details
Name: | us-gaap_DeconsolidationRevaluationOfRetainedInvestmentGainOrLossAmount
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Difference between amount at which an investment accounted for under the equity method of accounting is carried (reported) on the balance sheet and amount of underlying equity in net assets the reporting Entity has in the investee. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 323 -SubTopic 10 -Section 50 -Paragraph 3 -Subparagraph (a)(3) -URI http://asc.fasb.org/extlink&oid=114001798&loc=d3e33918-111571 + Details
Name: | us-gaap_EquityMethodInvestmentDifferenceBetweenCarryingAmountAndUnderlyingEquity
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition The percentage of ownership of common stock or equity participation in the investee accounted for under the equity method of accounting. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 323 -SubTopic 10 -Section 50 -Paragraph 3 -Subparagraph (a)(1) -URI http://asc.fasb.org/extlink&oid=114001798&loc=d3e33918-111571 + Details
Name: | us-gaap_EquityMethodInvestmentOwnershipPercentage
Namespace Prefix: | us-gaap_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition Amount of gain (loss) on sale or disposal of an equity method investment. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 28 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=121586364&loc=d3e3602-108585 Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section S99 -Paragraph 2 -Subparagraph (SX 210.5-03(b)(7)(c)) -URI http://asc.fasb.org/extlink&oid=120395209&loc=SL114868664-224227 Reference 3: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section S99 -Paragraph 2 -Subparagraph (SX 210.5-03(b)(9)(a)) -URI http://asc.fasb.org/extlink&oid=120395209&loc=SL114868664-224227 + Details
Name: | us-gaap_EquityMethodInvestmentRealizedGainLossOnDisposal
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition This item represents the carrying amount on the entity's balance sheet of its investment in common stock of an equity method investee. This is not an indicator of the fair value of the investment, rather it is the initial cost adjusted for the entity's share of earnings and losses of the investee, adjusted for any distributions (dividends) and other than temporary impairment (OTTI) losses recognized. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 323 -SubTopic 10 -Section 45 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=109237563&loc=d3e33749-111570 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 280 -SubTopic 10 -Section 50 -Paragraph 25 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e8813-108599 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.12) -URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682 + Details
Name: | us-gaap_EquityMethodInvestments
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Fair value portion of investments accounted under the equity method. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 323 -SubTopic 10 -Section 25 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=117311354&loc=d3e32014-111567 + Details
Name: | us-gaap_EquityMethodInvestmentsFairValueDisclosure
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition The amount by which the fair value of an investment is less than the amortized cost basis or carrying amount of that investment at the balance sheet date and the decline in fair value is deemed to be other than temporary, before considering whether or not such amount is recognized in earnings or other comprehensive income. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 45 -Paragraph 8A -URI http://asc.fasb.org/extlink&oid=121553693&loc=SL6284422-111562 + Details
Name: | us-gaap_ImpairmentOfInvestments
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Amount of interest capitalized during the period. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 835 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=6450988&loc=d3e26243-108391 + Details
Name: | us-gaap_InterestCostsCapitalized
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition The level of ownership or equity interest acquired in a noncash (or part noncash) transaction. "Part noncash" refers to that portion of the transaction not resulting in cash receipts or cash payments in the period. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 50 -Paragraph 5 -URI http://asc.fasb.org/extlink&oid=121583591&loc=d3e4332-108586 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 50 -Paragraph 3 -URI http://asc.fasb.org/extlink&oid=121583591&loc=d3e4304-108586 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 50 -Paragraph 4 -URI http://asc.fasb.org/extlink&oid=121583591&loc=d3e4313-108586 + Details
Name: | us-gaap_NoncashOrPartNoncashAcquisitionInterestAcquired1
Namespace Prefix: | us-gaap_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition The cash inflow associated with the sale of equity method investments, which are investments in joint ventures and entities in which the entity has an equity ownership interest normally of 20 to 50 percent and exercises significant influence. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 12 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=121586364&loc=d3e3179-108585 + Details
Name: | us-gaap_ProceedsFromSaleOfEquityMethodInvestments
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Amount of divestiture of long-lived, physical assets used in the normal conduct of business and not intended for resale. Examples include, but are not limited to, land, buildings, machinery and equipment, office equipment, furniture and fixtures, and computer equipment. + References No definition available. + Details
Name: | us-gaap_PropertyPlantAndEquipmentDisposals
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Amount after accumulated depreciation, depletion and amortization of physical assets used in the normal conduct of business to produce goods and services and not intended for resale. Examples include, but are not limited to, land, buildings, machinery and equipment, office equipment, and furniture and fixtures. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02(14)) -URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 360 -SubTopic 10 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=6391035&loc=d3e2868-110229 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-03(a)(8)) -URI http://asc.fasb.org/extlink&oid=120400017&loc=d3e572229-122910 Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02(13)) -URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682 + Details
Name: | us-gaap_PropertyPlantAndEquipmentNet
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- 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_ScheduleOfEquityMethodInvestmentsLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | us-gaap_FairValueByFairValueHierarchyLevelAxis=us-gaap_FairValueInputsLevel3Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_MeasurementInputTypeAxis=us-gaap_MeasurementInputDiscountRateMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_ValuationTechniqueAxis=us-gaap_ValuationTechniqueDiscountedCashFlowMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_IncomeStatementLocationAxis=pagp_GainOnImpairmentOfInvestmentsInUnconsolidatedEntitiesNetMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis=pagp_BridgeTexPipelineCompanyLLCMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis=pagp_CactusIIPipelineLLCMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis=pagp_CaplinePipelineCompanyLLCMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis=pagp_DiamondPipelineLlcMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis=pagp_EagleFordPipelineLLCMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis=pagp_EagleFordTerminalsCorpusChristiLlcMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis=pagp_RedOakPiplelineLLCMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis=pagp_SaddlehornPipelineCompanyLlcMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis=pagp_STACKPipelineLLCMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis=pagp_WhiteCliffsPipelineLlcMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis=pagp_WinktoWebsterPipelineLLCMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis=pagp_OtherEquityMethodInvestmentMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis=pagp_CushingConnectPipelineTerminalLLCMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RelatedPartyTransactionsByRelatedPartyAxis=us-gaap_EquityMethodInvesteeMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | dei_LegalEntityAxis=pagp_CaplinePipelineCompanyLLCMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_PropertyPlantAndEquipmentByTypeAxis=us-gaap_PropertyPlantAndEquipmentMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | dei_LegalEntityAxis=pagp_OxyMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | dei_LegalEntityAxis=pagp_ThirdPartyMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_BalanceSheetLocationAxis=pagp_OtherLongTermLiabilitiesAndDeferredCreditsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_OwnershipAxis=pagp_UndividedJointInterestInCaplinePipelineSystemMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_OwnershipAxis=pagp_UndividedJointInterestInPipelineSegmentMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | dei_LegalEntityAxis=pagp_WinktoWebsterPipelineLLCMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_PropertyPlantAndEquipmentByTypeAxis=pagp_MidlandTexasToWebsterTexasPipelineSegmentMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | dei_LegalEntityAxis=pagp_EnterpriseProductsPartnersLPMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |