Partners' Capital and Distributions - Distributions, Class A (Details) - USD ($) $ / shares in Units, $ in Millions	Nov. 14, 2017	Aug. 14, 2017	May 15, 2017	Feb. 14, 2017
Class A Shares
Distributions
Distributions to Class A Shareholders		$ 84	$ 84	$ 57
Distribution per Class A share, paid (usd per share)		$ 0.55	$ 0.55	$ 0.55
Forecast | Class A Shares
Distributions
Distributions to Class A Shareholders	$ 46
Distribution per Class A share, paid (usd per share)	$ 0.30
PAA | Cash Distributions | Common Units
Distributions
Distribution per Class A share, paid (usd per share)		$ 0.55	$ 0.55	$ 0.55
PAA | Cash Distributions | Forecast | Common Units
Partners Capital and Distributions
Annualized distributions per common unit (usd per unit)	1.20
Distributions
Distribution per Class A share, paid (usd per share)	$ 0.30