CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME/(LOSS) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Statement of Comprehensive Income [Abstract]
Net income/(loss)	$ 137	$ 426	$ (2,556)	$ 1,340
Other comprehensive income/(loss)	116	51	(212)	109
Comprehensive income/(loss)	253	477	(2,768)	1,449
Comprehensive (income)/loss attributable to noncontrolling interests	(207)	(399)	2,150	(1,211)
Comprehensive income/(loss) attributable to PAGP	$ 46	$ 78	$ (618)	$ 238