Partners' Capital (Preferred Units) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Mezzanine equity, beginning balance	$ 349,857
Distributions	17,675	$ 33,338
Mezzanine equity, ending balance		349,857
Deemed contribution from exchange	103,773
Class C preferred units, ending balance	281,688
Class B preferred units
Mezzanine equity, beginning balance	349,857	343,912
Amortization of discount	1,708	2,358
Distributions	23,247	36,925
Distributions paid	(17,675)	(33,338)
Class B Preferred Unit exchange	(357,137)
Mezzanine equity, ending balance		$ 349,857
Class C preferred units
Deemed contribution from exchange	103,800
Private placement of Class C Preferred Units	353,500
Discount	(104,250)
Amortization of discount	13,129
Distributions	19,309
Class C preferred units, ending balance	$ 281,688
Warrant exercise period	30 days
Class C preferred units | Distribution period commencing with the quarter ended on September 30, 2019
Distributions (as a percent)	12.50%
Class C preferred units | Distribution period commencing with the quarter ending March 31, 2022
Distributions (as a percent)	14.00%