Net Income Per Limited Partner Unit - Reconciliation of Net Income (Loss) and Weighted-Average Units Used in Computing Basic and Diluted Net Income (Loss) Per Limited Partner Unit (Details) - USD ($) $ / shares in Units, $ in Thousands		3 Months Ended		9 Months Ended
		Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Numerator:
Distributions paid		$ 18,115	$ 18,084	$ 54,313	$ 57,501
Allocation of distributions in excess of net income (loss)		(11,083)	(12,909)	(40,894)	(61,379)
Limited partners’ interest in net income (loss) - basic and diluted		$ 7,032	$ 5,175	$ 13,419	$ (3,878)
Denominator:
Weighted-average limited partnership units outstanding - basic		34,453,162	34,439,416	34,447,185	34,311,998
Adjustment for phantom and phantom performance units	[1]	10,865		538
Weighted-average limited partnership units outstanding - diluted		34,464,027	34,439,416	34,447,723	34,311,998
Net income (loss) per limited partnership unit - basic and diluted		$ 0.20	$ 0.15	$ 0.39	$ (0.11)
Distributions paid per common unit		0.5250	0.5250	1.5750	1.6775
Distributions declared (with respect to each respective period) per common unit		$ 0.5250	$ 0.5250	$ 1.5750	$ 1.5750

[1] Excludes 21,393 and 15,521 potentially dilutive securities from the calculation of diluted earnings per common unit because to do so would be antidilutive for the three and nine months ended September 30, 2018.