UNAUDITED CONDENSED CONSOLIDATED STATEMENTS OF PARTNERS’ CAPITAL - USD ($) $ in Thousands	Total	Partners’ Capital	Partners’ Capital Common Units	Noncontrolling Interest	Accumulated Other Comprehensive Income
Partners' capital, beginning balance (units) at Dec. 31, 2017			122,579,000
Partners' capital, beginning balance at Dec. 31, 2017	$ 2,013,914	$ 2,022,597		$ (8,079)	$ (604)
Increase (Decrease) in Partners' Capital [Roll Forward]
Net income	17,135	18,708		(1,573)
Cash distributions to partners	(191,224)	(191,224)
Cash contributions from noncontrolling interests	1,980			1,980
Distributions to Class A Convertible Preferred unitholders	(50,672)	(50,672)
Partners' capital, ending balance (units) at Sep. 30, 2018			122,579,000
Partners' capital, ending balance at Sep. 30, 2018	1,791,133	1,799,409		(7,672)	(604)
Partners' capital, beginning balance (units) at Jun. 30, 2018			122,579,000
Partners' capital, beginning balance at Jun. 30, 2018	1,874,332	1,881,957		(7,021)	(604)
Increase (Decrease) in Partners' Capital [Roll Forward]
Net income	(1,634)	(323)		(1,311)
Cash distributions to partners	(64,967)	(64,967)
Cash contributions from noncontrolling interests	660			660
Distributions to Class A Convertible Preferred unitholders	(17,258)	(17,258)
Partners' capital, ending balance (units) at Sep. 30, 2018			122,579,000
Partners' capital, ending balance at Sep. 30, 2018	$ 1,791,133	1,799,409		(7,672)	(604)
Partners' capital, beginning balance (units) at Dec. 31, 2018	122,579,218		122,579,000
Partners' capital, beginning balance at Dec. 31, 2018	$ 1,680,534	1,690,799		(11,204)	939
Increase (Decrease) in Partners' Capital [Roll Forward]
Net income	75,134	73,631		1,503
Cash distributions to partners	(202,256)	(202,256)
Cash contributions from noncontrolling interests	3,605			3,605
Distributions to Class A Convertible Preferred unitholders	$ (55,120)	(55,120)
Partners' capital, ending balance (units) at Sep. 30, 2019	122,579,218		122,579,000
Partners' capital, ending balance at Sep. 30, 2019	$ 1,501,897	1,507,054		(6,096)	939
Partners' capital, beginning balance (units) at Jun. 30, 2019			122,579,000
Partners' capital, beginning balance at Jun. 30, 2019	1,568,089	1,575,599		(8,449)	939
Increase (Decrease) in Partners' Capital [Roll Forward]
Net income	17,535	17,557		(22)
Cash distributions to partners	(67,418)	(67,418)
Cash contributions from noncontrolling interests	2,375			2,375
Distributions to Class A Convertible Preferred unitholders	$ (18,684)	(18,684)
Partners' capital, ending balance (units) at Sep. 30, 2019	122,579,218		122,579,000
Partners' capital, ending balance at Sep. 30, 2019	$ 1,501,897	$ 1,507,054		$ (6,096)	$ 939