CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Statement of Comprehensive Income [Abstract]
Net income	$ 431	$ 676	$ 1,771	$ 1,046
Other comprehensive income/(loss)	(99)	76	10	(46)
Comprehensive income	332	752	1,781	1,000
Comprehensive income attributable to noncontrolling interests	(285)	(624)	(1,496)	(856)
Comprehensive income attributable to PAGP	$ 47	$ 128	$ 285	$ 144