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	18,769	19,031		(262)
Cash distributions to partners	(126,257)	(126,257)
Cash contributions from noncontrolling interests	1,320			1,320
Distributions to Class A Convertible Preferred unitholders	(33,414)	(33,414)
Partners' capital, ending balance (units) at Jun. 30, 2018			122,579,000
Partners' capital, ending balance at Jun. 30, 2018	1,874,332	1,881,957		(7,021)	(604)
Partners' capital, beginning balance (units) at Mar. 31, 2018			122,579,000
Partners' capital, beginning balance at Mar. 31, 2018	1,943,171	1,951,590		(7,815)	(604)
Increase (Decrease) in Partners' Capital [Roll Forward]
Net income	10,871	10,997		(126)
Cash distributions to partners	(63,742)	(63,742)
Cash contributions from noncontrolling interests	920			920
Distributions to Class A Convertible Preferred unitholders	(16,888)	(16,888)
Partners' capital, ending balance (units) at Jun. 30, 2018			122,579,000
Partners' capital, ending balance at Jun. 30, 2018	$ 1,874,332	1,881,957		(7,021)	(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	57,599	56,074		1,525
Cash distributions to partners	(134,838)	(134,838)
Cash contributions from noncontrolling interests	1,230			1,230
Distributions to Class A Convertible Preferred unitholders	$ (36,436)	(36,436)
Partners' capital, ending balance (units) at Jun. 30, 2019	122,579,218		122,579,000
Partners' capital, ending balance at Jun. 30, 2019	$ 1,568,089	1,575,599		(8,449)	939
Partners' capital, beginning balance (units) at Mar. 31, 2019			122,579,000
Partners' capital, beginning balance at Mar. 31, 2019	1,611,652	1,621,314		(10,601)	939
Increase (Decrease) in Partners' Capital [Roll Forward]
Net income	41,652	40,120		1,532
Cash distributions to partners	(67,419)	(67,419)
Cash contributions from noncontrolling interests	620			620
Distributions to Class A Convertible Preferred unitholders	$ (18,416)	(18,416)
Partners' capital, ending balance (units) at Jun. 30, 2019	122,579,218		122,579,000
Partners' capital, ending balance at Jun. 30, 2019	$ 1,568,089	$ 1,575,599		$ (8,449)	$ 939