Partners' Capital and Distributions - Noncontrolling Interests in Subsidiaries (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Partners' Capital and Distributions
Contribution from noncontrolling interests	$ 1		$ 11	$ 0
Distributions	182	$ 315	679	894
Noncontrolling Interests
Partners' Capital and Distributions
Contribution from noncontrolling interests	1		11
Distributions	$ 149	$ 255	$ 547	$ 729
AAP
Partners' Capital and Distributions
Noncontrolling interests in subsidiaries (percent)	23.00%		23.00%
Red River LLC
Partners' Capital and Distributions
Noncontrolling interests in subsidiaries (percent)	33.00%		33.00%
Common Units and Series A Preferred Units | PAA
Partners' Capital and Distributions
Noncontrolling interests in subsidiaries (percent)	69.00%		69.00%
Series B Preferred Units | PAA
Partners' Capital and Distributions
Noncontrolling interests in subsidiaries (percent)	100.00%		100.00%
Red River LLC | Noncontrolling Interests
Partners' Capital and Distributions
Contribution from noncontrolling interests			$ 11
Distributions			$ 6