Distributions and Net Income Per Limited Partner Unit (Basic and Diluted Income Per Limited Partner Unit) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Limited Partners' Capital Account [Line Items]
Distributions declared	$ 13,179	$ 10,200	$ 26,726	$ 20,034
Distribution in excess of net income	(422)	(225)	(1,674)	(295)
Net income	$ 12,757	$ 9,975	$ 25,052	$ 19,739
Weighted average units outsanding:
Basic and diluted (shares)	32,237,266	27,059,730	32,236,860	27,059,730
Common units [Member]
Limited Partners' Capital Account [Line Items]
Distributions declared	$ 13,179	$ 5,246	$ 25,993	$ 10,347
Distribution in excess of net income	(422)	(119)	(1,674)	(156)
Net income	$ 12,757	$ 5,127	$ 24,319	$ 10,191
Weighted average units outsanding:
Basic and diluted (shares)	32,237,266	14,373,615	32,236,860	14,373,615
Net income per limited partner unit:
Income per limited partner unit (usd per share)	$ 0.40	$ 0.36	$ 0.75	$ 0.71
Subordinated units [Member]
Limited Partners' Capital Account [Line Items]
Distributions declared		$ 4,631		$ 9,133
Distribution in excess of net income		(106)		(139)
Net income		$ 4,525		$ 8,994
Weighted average units outsanding:
Basic and diluted (shares)		12,686,115		12,686,115
Net income per limited partner unit:
Income per limited partner unit (usd per share)	$ 0.00	$ 0.36	$ 0.00	$ 0.71
IDR Holders [Member]
Limited Partners' Capital Account [Line Items]
Subsequent distribution to IDR holders	$ 0	$ 323	$ 733	$ 554
Distribution in excess of net income	0	0	0	0
Net income	$ 0	$ 323	$ 733	$ 554