Partners' Capital and Distributions - Distributions (Details) - USD ($) $ / shares in Units, $ in Millions			3 Months Ended
	May 15, 2020	Feb. 14, 2020	Mar. 31, 2020	Mar. 31, 2019
Partners Capital and Distribution [Line Items]
Total distributions paid			$ 311	$ 267
Common Units | Cash Distribution
Partners Capital and Distribution [Line Items]
Total distributions paid		$ 262
Distributions per common unit, paid (usd per unit)		$ 0.36
Common Units | Forecast | Cash Distribution
Partners Capital and Distribution [Line Items]
Total distributions paid	$ 131
Distributions per common unit, paid (usd per unit)	$ 0.18
Public | Common Units | Cash Distribution
Partners Capital and Distribution [Line Items]
Distributions to common unitholders		$ 172
Public | Common Units | Forecast | Cash Distribution
Partners Capital and Distribution [Line Items]
Distributions to common unitholders	$ 86
AAP | Common Units | Cash Distribution
Partners Capital and Distribution [Line Items]
Distributions to common unitholders		$ 90
AAP | Common Units | Forecast | Cash Distribution
Partners Capital and Distribution [Line Items]
Distributions to common unitholders	$ 45