CONSOLIDATED STATEMENTS OF PARTNERS' CAPITAL - USD ($) $ in Thousands	Total	Accumulated other comprehensive income (loss)	Class A units	Limited Partner Common units	Limited Partner Class A units	Limited Partner Subordinated units	General Partner
Partners' capital account beginning balance (in shares) at Dec. 31, 2015			185,000	11,947,127	185,000	10,463,545	461,136
Partners' capital account beginning balance at Dec. 31, 2015		$ (1,004)		$ 146,645	$ 1,858	$ (88,151)	$ 438
Increase (Decrease) in Partners' Capital [Roll Forward]
Units issued (in shares)				0
Units issued				$ 0
Conversion of units (in shares)				(2,138,959)	(46,250)	(2,092,709)
Conversion of units				$ (18,300)	$ (871)	$ 19,171
Common units issued for vested phantom units (in units)				99,513
Common units issued for vested Phantom Units				$ (77)
Capital contributions	$ 0
Net income	25,557			15,474	157	9,417	509
Unit based compensation expense	0			2,670	$ 977
Forfeited units (in shares)			0		0
Forfeited units					$ 0
Distributions				$ (17,509)	$ (192)	$ (11,373)	$ (591)
Cumulative translation adjustment	(722)	(722)
Partners' capital account ending balance (in shares) at Dec. 31, 2016			138,750	14,185,599	138,750	8,370,836	461,136
Partners' capital account ending balance at Dec. 31, 2016	$ 58,526	(1,726)		$ 128,903	$ 1,929	$ (70,936)	$ 356
Increase (Decrease) in Partners' Capital [Roll Forward]
Units issued (in shares)	3,000,000
Units issued	$ 33,700
Conversion of units (in shares)				(2,162,084)	(46,250)	(2,092,709)
Conversion of units				$ (19,047)	$ (606)	$ 19,653
Common units issued for vested phantom units (in units)				190,288
Common units issued for vested Phantom Units				$ (1,073)
Capital contributions							0
Net income	21,331			15,093	80	5,577	581
Unit based compensation expense				3,694	$ 450	23	1
Forfeited units (in shares)			(10,000)		(10,000)
Forfeited units					$ (247)
Distributions				$ (24,625)	$ (138)	$ (9,554)	$ (758)
Cumulative translation adjustment	3,560	3,560
Partners' capital account ending balance (in shares) at Dec. 31, 2017			82,500	19,537,971	82,500	6,278,127	461,136
Partners' capital account ending balance at Dec. 31, 2017	84,890	1,834		$ 136,645	$ 1,468	$ (55,237)	$ 180
Increase (Decrease) in Partners' Capital [Roll Forward]
Units issued (in shares)				0
Units issued				$ 0
Conversion of units (in shares)				(2,131,459)	(38,750)	(2,092,709)
Conversion of units				$ (18,245)	$ (674)	$ 18,919
Common units issued for vested phantom units (in units)				246,594
Common units issued for vested Phantom Units				$ (1,352)
Capital contributions							3,366
Net income	21,132			16,796	36	3,524	776
Unit based compensation expense				5,617	$ 186	26	1
Forfeited units (in shares)			(5,000)		(5,000)
Forfeited units					$ 73
Distributions				$ (31,558)	$ (71)	$ (6,955)	$ (1,048)
Cumulative translation adjustment	(4,843)	(4,843)
Partners' capital account ending balance (in shares) at Dec. 31, 2018			38,750	21,916,024	38,750	4,185,418	461,136
Partners' capital account ending balance at Dec. 31, 2018	$ 69,464	$ (3,009)		$ 107,903	$ 1,018	$ (39,723)	$ 3,275