Partners' Capital and Distributions - Preferred Unit Distributions (Details) - USD ($) $ / shares in Units, $ in Millions	Aug. 14, 2020	May 15, 2020	Feb. 14, 2020	Jun. 30, 2020
Cash Distribution | Series A Preferred Units
Partners Capital and Distribution [Line Items]
Preferred unit distribution amount		$ 37.0	$ 37.0
Preferred distributions per unit (in dollars per unit)		$ 0.525	$ 0.525
Cash Distribution | Series A Preferred Units | Forecast
Partners Capital and Distribution [Line Items]
Preferred unit distribution amount	$ 37.0
Preferred distributions per unit (in dollars per unit)	$ 0.525
Cash Distribution | Series B Preferred Units
Partners Capital and Distribution [Line Items]
Preferred unit distribution amount		$ 24.5
Preferred distributions per unit (in dollars per unit)		$ 30.625
Other current liabilities | Series B Preferred Units
Partners Capital and Distribution [Line Items]
Amount accrued to distributions payable				$ 6.0