Unaudited Condensed Consolidated Statements of Partners' Capital - USD ($) $ in Thousands	Total	Partners’ Capital	Noncontrolling Interest	Common Units Partners’ Capital
Partners' capital, beginning balance (units) at Dec. 31, 2015				109,979,000
Partners' capital, beginning balance at Dec. 31, 2015	$ 2,020,751	$ 2,029,101	$ (8,350)
Increase (Decrease) in Partners' Capital [Roll Forward]
Net income	90,761	91,131	(370)	$ 0
Cash distributions to partners	(227,454)	(227,454)	0	$ 0
Issuance of common units for cash, net (units)				8,000,000
Issuance of common units for cash, net	298,051	298,051	0
Partners' capital, ending balance (units) at Sep. 30, 2016				117,979,000
Partners' capital, ending balance at Sep. 30, 2016	$ 2,182,109	2,190,829	(8,720)
Partners' capital, beginning balance (units) at Dec. 31, 2016	117,979,218			117,979,000
Partners' capital, beginning balance at Dec. 31, 2016	$ 2,120,050	2,130,331	(10,281)
Increase (Decrease) in Partners' Capital [Roll Forward]
Net income	66,678	67,135	(457)	$ 0
Cash distributions to partners	(260,586)	(260,586)	0	0
Cash contributions from noncontrolling interests	1,850	0	1,850	$ 0
Issuance of common units for cash, net (units)				4,600,000
Issuance of common units for cash, net	$ 140,513	140,513	0
Partners' capital, ending balance (units) at Sep. 30, 2017	122,579,218			122,579,000
Partners' capital, ending balance at Sep. 30, 2017	$ 2,068,505	$ 2,077,393	$ (8,888)