Net Income Per Unit (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Net Income Per Unit [Line Items]
Net income attributable to partners	$ 27,796	$ 19,696
Less: Partners' distribution	21,739	20,014
Distributions in excess of earnings	$ (3,082)	$ (7,742)
Common units - (basic) (in shares)	24,480,570	24,407,168
Common units - (diluted) (in shares)	24,485,336	24,416,058
Common units - (basic) (in dollars per share)	$ 0.76	$ 0.51
Common units - (diluted) (in dollars per share)	$ 0.76	$ 0.51
General Partner
Net Income Per Unit [Line Items]
Net income attributable to partners	$ 9,077	$ 7,270
Less: General partner's distribution (including IDRs)	9,139	7,424
Distributions in excess of earnings	(62)	(154)
Total partner's earnings	9,077	7,270
Common unitholders
Net Income Per Unit [Line Items]
Less: Partners' distribution	21,739	20,014
Distributions in excess of earnings	$ (3,020)	$ (7,588)
Common units - (basic) (in shares)	24,480,570	24,407,168
Common units - (diluted) (in shares)	24,485,336	24,416,058
Common units - (basic) (in dollars per share)	$ 0.76	$ 0.51
Common units - (diluted) (in dollars per share)	$ 0.76	$ 0.51
Common unitholders | Common Units
Net Income Per Unit [Line Items]
Total partner's earnings	$ 18,719	$ 12,426
Maximum
Footnote [Abstract]
Distribution Payment Targets	$ 0.43125
General Partnership [Member]
Footnote [Abstract]
General partner's ownership interest (as percent)	2.00%	2.00%