Segment Information - Reconciliation of Segment Adjusted EBITDA (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
Mar. 31, 2020	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Segment Adjusted EBITDA		$ 2,194	$ 2,543	$ 3,220
Adjustments:
Depreciation and amortization of unconsolidated entities		(123)	(73)	(62)
Gains/(losses) from derivative activities and inventory valuation adjustments		271	(480)	(160)
Long-term inventory costing adjustments		94	(44)	20
Deficiencies under minimum volume commitments, net		7	(74)	18
Equity-indexed compensation expense		(19)	(19)	(17)
Net gain/(loss) on foreign currency revaluation		4	3	(14)
Significant transaction-related expenses		(16)	(3)
Adjusted EBITDA attributable to noncontrolling interests in consolidated joint ventures		94	14	10
Unallocated general and administrative expenses		(298)	(276)	(302)
Depreciation and amortization		(777)	(656)	(604)
Gains/(losses) on asset sales and asset impairments, net		(592)	(719)	(28)
Goodwill impairment losses	$ (2,515)	0	(2,515)	0
Gain on/(impairment of) investments in unconsolidated entities, net		2	(182)	271
Interest expense, net		(425)	(436)	(425)
Other income, net		19	39	24
INCOME/(LOSS) BEFORE TAX		712	(2,607)	2,238
Income tax (expense)/benefit		(112)	167	(176)
NET INCOME/(LOSS)		600	(2,440)	2,062
Net (income)/loss attributable to noncontrolling interests		(540)	1,872	(1,731)
NET INCOME/(LOSS) ATTRIBUTABLE TO PAGP		60	(568)	331
Unallocated
Adjustments:
Unallocated general and administrative expenses		(6)	$ (5)	(5)
Line 901 Incident
Adjustments:
Line 901 incident		$ (15)		$ (10)

Adjusted EBITDA Attributable To Noncontrolling Interests In Consolidated Joint Ventures

No definition available.

Name:	pagp_AdjustedEBITDAAttributableToNoncontrollingInterestsInConsolidatedJointVentures
Namespace Prefix:	pagp_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Includes the impact of amounts billed to counterparties for their deficiency obligation, net of applicable amounts subsequently recognized into revenue. Certain agreements require counterparties to deliver, transport or throughput a minimum volume over an agreed upon period. Substantially all of such agreements were entered into with counterparties to economically support the return on the reporting entity's capital expenditure necessary to construct the related asset. Some of these agreements include make-up rights if the minimum volume is not met. A receivable from the counterparty is recorded in the period that services are provided or when the transaction occurs, including amounts for deficiency obligations from counterparties associated with minimum volume commitments. If a counterparty has a make-up right associated with a deficiency, the revenue attributable to the counterparty’s make-up right is deferred and is subsequently recognized at the earlier of when the deficiency volume is delivered or shipped, when the make-up right expires or when it is determined that the counterparty’s ability to utilize the make-up right is remote.

+ References

No definition available.