Partners' Capital, Mezzanine Equity and Distributions (Preferred Cash Distributions Paid) (Details) - USD ($) $ / shares in Units, $ in Thousands		Feb. 14, 2020	Nov. 14, 2019	Aug. 14, 2019	May 15, 2019	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018
Temporary Equity [Line Items]
Per Unit Amount (in dollars per unit)	[1]					$ 0.5500	$ 0.5500	$ 0.5500	$ 0.5500	$ 0.5500	$ 0.5400	$ 0.5300	$ 0.5200
Class A Convertible Preferred Units | Preferred Unitholders
Temporary Equity [Line Items]
Date Paid			Nov. 14, 2019	Aug. 14, 2019	May 15, 2019
Per Unit Amount (in dollars per unit)			$ 0.7374	$ 0.7374	$ 0.2458
Total Amount			$ 18,684	$ 18,684	$ 6,138
Scenario, Forecast | Subsequent Event | Class A Convertible Preferred Units | Preferred Unitholders
Temporary Equity [Line Items]
Date Paid		Feb. 14, 2020
Per Unit Amount (in dollars per unit)		$ 0.7374
Total Amount		$ 18,684

[1] (1) Represents cash distributions declared and paid in the applicable period.