Net Income Per Class A Share (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Basic Net Income per Class A Share
Net income attributable to PAGP	$ 24	$ 32	$ 102	$ 93
Diluted Net Income per Class A Share
Net income attributable to PAGP	24	32	102	93
Incremental net income attributable to PAGP resulting from assumed exchange of AAP units and AAP Management Units			138
Net income attributable to PAGP including incremental net income from assumed exchange of AAP units and AAP Management Units	$ 24	$ 32	$ 240	$ 93
Class A Shares
Basic Net Income per Class A Share
Basic weighted average Class A shares outstanding (shares)	268	225	263	220
Basic net income per Class A share (usd per share)	$ 0.09	$ 0.14	$ 0.39	$ 0.42
Diluted Net Income per Class A Share
Basic weighted average Class A shares outstanding (shares)	268	225	263	220
Dilutive shares resulting from assumed exchange of AAP units and AAP Management Units (shares)			366
Diluted weighted average Class A shares outstanding (shares)	268	225	629	220
Diluted net income per Class A share (usd per share)	$ 0.09	$ 0.14	$ 0.38	$ 0.42