Partners' Capital, Mezzanine Capital and Distributions (Distributions Paid) (Details) - Common Unitholders - USD ($) $ / shares in Units, $ in Thousands	Aug. 14, 2019	May 15, 2019	Feb. 14, 2019	Nov. 14, 2018	Aug. 14, 2018	May 15, 2018
Partners Capital And Distributions [Line Items]
Date Paid		May 15, 2019	Feb. 14, 2019	Nov. 14, 2018	Aug. 14, 2018	May 15, 2018
Per Unit Amount (in dollars per unit)		$ 0.5500	$ 0.5500	$ 0.5400	$ 0.5300	$ 0.5200
Total Amount		$ 67,419	$ 67,419	$ 66,193	$ 64,967	$ 63,741
Forecast | Subsequent Event
Partners Capital And Distributions [Line Items]
Date Paid	Aug. 14, 2019
Per Unit Amount (in dollars per unit)	$ 0.5500
Total Amount	$ 67,419