Supplemental Quarterly Information (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended									9 Months Ended	12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 19, 2016	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Total Revenues	$ 136,653	$ 139,163	$ 121,971	$ 97,733	$ 68,073	$ 63,111	$ 57,783	$ 50,314			$ 495,520	$ 239,281	$ 160,724
Operating Income	55,461	48,249	42,215	37,375	44,887	42,750	37,566	33,722			183,300	158,925	112,637
Income Before Income Taxes	56,653	48,609	44,625	39,210	46,240	43,789	39,107	34,520			189,097	163,656	113,790
Net Income	56,595	48,703	44,442	39,136	46,253	43,756	39,107	34,520	$ 39,512	$ 45,990	188,876	163,636	85,502
Net Income Attributable to Limited Partners	$ 39,751	$ 43,155	$ 35,450	$ 38,542	$ 42,448	$ 41,447	$ 31,500	$ 24,342			156,898	139,737	28,458
Basic
Net Income Attributable to Limited Partners											$ 93,875	$ 75,076	$ 14,229
Net Income Attributable to Limited Partners Per Limited Partner Unit — Basic and Diluted (in dollars per share)	$ 1.00	$ 1.09	$ 0.9	$ 0.97	$ 1.16	$ 1.15	$ 0.98	$ 0.77			$ 3.96	$ 4.10	$ 0.89
Subordinated Units
Net Income Attributable to Limited Partners											$ 63,023	$ 64,661	$ 14,229
Net Income Attributable to Limited Partners Per Limited Partner Unit — Basic and Diluted (in dollars per share)	$ 1.00	$ 1.09	$ 0.9	$ 0.97	$ 1.16	$ 1.15	$ 0.98	$ 0.77			$ 3.96	$ 4.10	$ 0.89