Net Income/(Loss) Per Common Unit (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Basic and Diluted Net Income/(Loss) per Common Unit
Net income/(loss) attributable to PAA	$ 203	$ (220)	$ 390	$ 202
Distributions to participating securities	(1)	0	(1)
Net income/(loss) allocated to common unitholders - Basic	153	(269)	290	103
Net income/(loss) allocated to common unitholders - Diluted	$ 153	$ (269)	$ 290	$ 103
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)		0.7
Dilutive equity-indexed compensation plan awards (units)	0.8		0.7	0.4
Series A Preferred Units
Basic and Diluted Net Income/(Loss) per Common Unit
Distributions to preferred unitholders	$ (37)	$ (37)	$ (74)	$ (74)
Series A Preferred Units | Weighted average
Net Income/(Loss) Per Common Unit
Antidilutive securities excluded from computation of net income per common unit (units)	71.0	71.0	71.0	71.0
Series B Preferred Units
Basic and Diluted Net Income/(Loss) per Common Unit
Distributions to preferred unitholders	$ (12)	$ (12)	$ (25)	$ (25)
Common Units
Basic and Diluted Net Income/(Loss) per Common Unit
Basic weighted average common units outstanding (units)	702.0	720.0	703.0	721.0
Diluted weighted average common units outstanding (units)	702.0	720.0	703.0	721.0
Basic net income/(loss) per common unit (usd per unit)	$ 0.22	$ (0.37)	$ 0.41	$ 0.14
Diluted net income/(loss) per common unit (usd per unit)	$ 0.22	$ (0.37)	$ 0.41	$ 0.14