Acquisitions, Divestitures and Other Transactions - Pro Forma (Details) - Plains Oryx Permian Basin LLC (Permian JV) - Oryx Midstream Holdings LLC - Joint Venture Formation - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Business Acquisition [Line Items]
Total revenues	$ 42,359	$ 23,536
Net income/(loss) attributable to PAGP	$ 37	$ (629)
Class A Shares
Business Acquisition [Line Items]
Basic net income/(loss) per Class A Share (in shares)	$ 0.19	$ (3.38)
Diluted net income/(loss) per Class A Share (in shares)	$ 0.19	$ (3.41)