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Distributions and Net Income Per Limited Partner Unit (Distributions Declared) (Details) - USD ($) $ / shares in Units, $ in Thousands		3 Months Ended		6 Months Ended
	Jul. 31, 2020	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Distribution Made to Limited Partner [Line Items]
Distribution in excess of net income		$ (1,730)	$ (2,380)	$ (574)	$ (3,091)
Net income attributable to the Partnership		$ 14,860	$ 13,733	$ 32,607	$ 28,688
Weighted Average Number of Limited Partnership and General Partnership Unit Outstanding, Basic and Diluted		35,194,545	35,188,189	35,194,545	33,774,647
Distributions declared		$ 16,590	$ 16,113	$ 33,181	$ 31,779
IDR Holders [Member]
Distribution Made to Limited Partner [Line Items]
Distribution in excess of net income		0	0	0	0
Net income attributable to the Partnership		0	0	0	0
Distributions declared with respect to the incentive distribution rights		0	0	0	0
Common units [Member]
Distribution Made to Limited Partner [Line Items]
Distribution in excess of net income		(1,730)	(2,380)	(574)	(3,091)
Net income attributable to the Partnership		$ 14,860	$ 13,733	$ 32,607	$ 28,688
Weighted Average Number of Limited Partnership and General Partnership Unit Outstanding, Basic and Diluted		35,194,545	35,188,189	35,194,545	33,774,647
Distributions declared		$ 16,590	$ 16,113	$ 33,181	$ 31,779
Net Income (Loss), Per Outstanding Limited Partnership Unit, Basic, Net of Tax		$ 0.43	$ 0.39	$ 0.93	$ 0.85
Cash Distribution [Member] \| Common units [Member]
Distribution Made to Limited Partner [Line Items]
Distributions declared		$ 16,590	$ 16,113	$ 33,181	$ 31,779
Cash Distribution [Member] \| Common And Subordinated Units [Member]
Distribution Made to Limited Partner [Line Items]
Incentive Distribution Rights, Target Distribution Per Unit Requiring Marginal Percentage Distribution to IDR Holders				$ 1.2938
Cash Distribution [Member] \| Common And Subordinated Units [Member] \| Subsequent Event [Member]
Distribution Made to Limited Partner [Line Items]
Distribution declared per unit (in usd per unit)	$ 0.4714
Above $1.2938 up to $1.4063 \| Minimum [Member]
Distribution Made to Limited Partner [Line Items]
Incentive Distribution Rights, Target Distribution Per Unit Requiring Marginal Percentage Distribution to IDR Holders				1.2938
Above $1.2938 up to $1.4063 \| Maximum [Member]
Distribution Made to Limited Partner [Line Items]
Incentive Distribution Rights, Target Distribution Per Unit Requiring Marginal Percentage Distribution to IDR Holders				$ 1.4063
Above $1.2938 up to $1.4063 \| Unit Holders [Member]
Distribution Made to Limited Partner [Line Items]
Incentive Distribution, Marginal Percentage Interest in Distributions				85.00%
Above $1.2938 up to $1.4063 \| IDR Holders [Member]
Distribution Made to Limited Partner [Line Items]
Incentive Distribution, Marginal Percentage Interest in Distributions				15.00%
Above $1.4063 up to $1.6875 \| Minimum [Member]
Distribution Made to Limited Partner [Line Items]
Incentive Distribution Rights, Target Distribution Per Unit Requiring Marginal Percentage Distribution to IDR Holders				$ 1.4063
Above $1.4063 up to $1.6875 \| Maximum [Member]
Distribution Made to Limited Partner [Line Items]
Incentive Distribution Rights, Target Distribution Per Unit Requiring Marginal Percentage Distribution to IDR Holders				$ 1.6875
Above $1.4063 up to $1.6875 \| Unit Holders [Member]
Distribution Made to Limited Partner [Line Items]
Incentive Distribution, Marginal Percentage Interest in Distributions				75.00%
Above $1.4063 up to $1.6875 \| IDR Holders [Member]
Distribution Made to Limited Partner [Line Items]
Incentive Distribution, Marginal Percentage Interest in Distributions				25.00%
Above $1.6875 \| Minimum [Member]
Distribution Made to Limited Partner [Line Items]
Incentive Distribution Rights, Target Distribution Per Unit Requiring Marginal Percentage Distribution to IDR Holders				$ 1.6875
Above $1.6875 \| Unit Holders [Member]
Distribution Made to Limited Partner [Line Items]
Incentive Distribution, Marginal Percentage Interest in Distributions				50.00%
Above $1.6875 \| IDR Holders [Member]
Distribution Made to Limited Partner [Line Items]
Incentive Distribution, Marginal Percentage Interest in Distributions				50.00%