Unaudited Condensed Consolidated Statements of Partners' Capital - USD ($) $ in Thousands	Total	Scenario, Previously Reported	Restatement Adjustment	Partners’ Capital	Partners’ Capital Scenario, Previously Reported	Partners’ Capital Restatement Adjustment	Partners’ Capital Common Units	Partners’ Capital Common Units Scenario, Previously Reported	Noncontrolling Interest	Noncontrolling Interest Scenario, Previously Reported	Noncontrolling Interest Restatement Adjustment	Accumulated Other Comprehensive Loss	Accumulated Other Comprehensive Loss Scenario, Previously Reported	Accumulated Other Comprehensive Loss Restatement Adjustment
Partners' capital, beginning balance (units) at Dec. 31, 2016							117,979,000
Partners' capital, beginning balance at Dec. 31, 2016	$ 2,120,050			$ 2,130,331					$ (10,281)			$ 0
Increase (Decrease) in Partners' Capital [Roll Forward]
Net income (loss)	66,678			67,135			$ 0		(457)			0
Cash distributions to partners	(260,586)			(260,586)			0		0			0
Cash contributions from noncontrolling interests	1,850			0			$ 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			0
Partners' capital, ending balance (units) at Sep. 30, 2017							122,579,000
Partners' capital, ending balance at Sep. 30, 2017	2,068,505			2,077,393					(8,888)			0
Increase (Decrease) in Partners' Capital [Roll Forward]
Impact of adoption of ASC 606 | ASC 606			$ (3,550)			$ (3,550)					$ 0			$ 0
Partners' capital, adjusted beginning balance	$ 2,013,914			2,022,597					(8,079)			(604)
Partners' capital, beginning balance (units) at Dec. 31, 2017	122,579,218						122,579,000	122,579,000
Partners' capital, beginning balance at Dec. 31, 2017	$ 2,017,464	$ 2,017,464			$ 2,026,147					$ (8,079)			$ (604)
Increase (Decrease) in Partners' Capital [Roll Forward]
Net income (loss)	17,135			18,708			$ 0		(1,573)			0
Cash distributions to partners	(191,224)			(191,224)			0		0			0
Cash contributions from noncontrolling interests	1,980			0			0		1,980			0
Distributions to Class A Convertible Preferred unitholders	$ (50,672)			(50,672)			$ 0		0			0
Partners' capital, ending balance (units) at Sep. 30, 2018	122,579,218						122,579,000
Partners' capital, ending balance at Sep. 30, 2018	$ 1,791,133			$ 1,799,409					$ (7,672)			$ (604)