Distributions and Net Income Per Limited Partner Unit (Income In Excess Of Distribution) (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Distribution declared									$ 64,718	$ 54,249	$ 45,708
Net income subsequent to the IPO in excess of distribution									(3,737)	(4,902)	2,962
Limited partners' interest in net income subsequent to IPO	$ 17,371	$ 14,922	$ 13,733	$ 14,955	$ 11,883	$ 12,412	$ 12,757	$ 12,295	60,981	49,347	48,670
Common units [Member]
Distribution declared									64,718	53,516	34,909
Net income subsequent to the IPO in excess of distribution									(3,737)	(4,902)	3,101
Limited partners' interest in net income subsequent to IPO									60,981	48,614	38,010
Subordinated units [Member]
Distribution declared									0	0	9,133
Net income subsequent to the IPO in excess of distribution											(139)
Limited partners' interest in net income subsequent to IPO											8,994
IDR Holders [Member]
Distributions declared with respect to the incentive distribution rights									0	733	1,666
Net income subsequent to the IPO in excess of distribution									0	0	0
Limited partners' interest in net income subsequent to IPO									$ 0	$ 733	$ 1,666