Net Income Per Common Unit (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Basic and Diluted Net Income per Common Unit
Net income attributable to PAA	$ 187	$ 422
Distributions to participating securities	(1)	(1)
Other	0	(1)
Net income allocated to common unitholders - Basic	137	371
Net income allocated to common unitholders - Diluted	$ 137	$ 371
Equity-indexed Compensation Plan Award
Net Income/(Loss) Per Common Unit
Dilutive equity-indexed compensation plan awards (units)		0
Equity-indexed Compensation Plan Award | Weighted average
Net Income/(Loss) Per Common Unit
Antidilutive securities excluded from computation of net income per common unit (units)	700,000
Series A Preferred Units
Basic and Diluted Net Income per Common Unit
Distributions to preferred unitholders	$ (37)	$ (37)
Series A Preferred Units | Weighted average
Net Income/(Loss) Per Common Unit
Antidilutive securities excluded from computation of net income per common unit (units)	71,000,000	71,000,000
Series B Preferred Units
Basic and Diluted Net Income per Common Unit
Distributions to preferred unitholders	$ (12)	$ (12)
Common Units
Basic and Diluted Net Income per Common Unit
Basic weighted average common units outstanding (units)	705,000,000	722,000,000
Diluted weighted average common units outstanding (units)	705,000,000	722,000,000
Basic net income per common unit (usd per unit)	$ 0.19	$ 0.51
Diluted net income per common unit (usd per unit)	$ 0.19	$ 0.51