Acquisitions, Divestitures and Other Transactions - Pro Forma (Details) - Plains Oryx Permian Basin LLC (Permian JV) - Oryx Midstream Holdings LLC - Joint Venture Transaction - 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 PAA	524	(2,898)
Net income/(loss) allocated to common unitholders	$ 324	$ (3,098)
Basic net income/(loss) per common unit (in shares)	$ 0.45	$ (4.26)
Diluted net income/(loss) per common unit (in shares)	$ 0.45	$ (4.26)