Consolidated Statements of Partners' Capital - USD ($) $ in Thousands	Total	Partners' Capital		Partners' Capital Number of Common Units	Noncontrolling Interest	Accumulated Other Comprehensive Loss
Partners' capital, units (in shares) at Dec. 31, 2014				95,029,000
Partners' capital, value at Dec. 31, 2014	$ 1,229,203	$ 1,229,203			$ 0	$ 0
Net income (loss)	421,585	422,528		$ 0	(943)	0
Noncontrolling interest from acquisition	(6,447)	0		0	(6,447)	0
Cash distributions to partners, net	(256,389)	(256,389)		0	0	0
Cash distributions to noncontrolling interests	(960)	0		$ 0	(960)	0
Issuance of units for cash, net, units				14,950,000
Issuance of units for cash, net	633,759	633,759			0	0
Other comprehensive loss	0
Partners' capital, units (in shares) at Dec. 31, 2015				109,979,000
Partners' capital, value at Dec. 31, 2015	2,020,751	2,029,101			(8,350)	0
Net income (loss)	111,082	113,249		$ 0	(2,167)	0
Cash distributions to partners, net	(310,039)	(310,039)		$ 0	0	0
Issuance of units for cash, net, units				8,000,000
Issuance of units for cash, net	298,020	298,020			0	0
Cash contributions from noncontrolling interests	236	0		$ 0	236	0
Other comprehensive loss	$ 0
Partners' capital, units (in shares) at Dec. 31, 2016	117,979,218			117,979,000
Partners' capital, value at Dec. 31, 2016	$ 2,120,050	2,130,331			(10,281)	0
Net income (loss)	82,079	82,647	[1]	$ 0	(568)	0
Cash distributions to partners, net	(321,875)	(321,875)		$ 0	0	0
Issuance of units for cash, net, units				4,600,000
Issuance of units for cash, net	140,513	140,513			0	0
Cash contributions from noncontrolling interests	2,770	0		$ 0	2,770	0
Other comprehensive loss	(604)	0		0	0	(604)
Distributions to preferred unitholders	$ (5,469)	(5,469)		$ 0	0	0
Partners' capital, units (in shares) at Dec. 31, 2017	122,579,218			122,579,000
Partners' capital, value at Dec. 31, 2017	$ 2,017,464	$ 2,026,147			$ (8,079)	$ (604)
Accumulated distributions to preferred unitholders	$ (22,000)

[1] Net income (loss) includes $22 million attributable to preferred unitholders accumulated as of December 31, 2017.