CONDENSED CONSOLIDATED STATEMENTS OF PARTNERS' CAPITAL - USD ($) $ in Thousands	Total	Accumulated Other Comprehensive Income (Loss)	Noncontrolling Interests	Limited Partners
Beginning balance at Dec. 31, 2014	$ 3,940,596	$ (115,288)	$ 237,968	$ 3,817,916
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	111,164		(447)	111,611
Adjusted value of noncontrolling interest in acquisition	(1,220)		(1,220)
Distributions paid to unitholders	(144,294)		1,088	(145,382)
Net proceeds from issuance of LP Units	3,682			3,682
Amortization of unit-based compensation awards	5,213			5,213
Net proceeds from exercise of Unit options	136			136
Payment of tax withholding on issuance of LTIP awards	(6,465)			(6,465)
Distributions paid to noncontrolling interests	(1,908)		(1,908)
Contributions from noncontrolling interests	12,600		12,600
Other comprehensive income	3,298	3,298
Noncash accrual for distribution equivalent rights	(794)			(794)
Other	(2)		(402)	400
Ending balance at Mar. 31, 2015	3,922,006	(111,990)	247,679	3,786,317
Beginning balance at Dec. 31, 2015	4,016,741	(97,841)	281,352	3,833,230
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	134,977		3,864	131,113
Distributions paid to unitholders	(154,147)		781	(154,928)
Net proceeds from issuance of LP Units	37,590			37,590
Amortization of unit-based compensation awards	6,342			6,342
Net proceeds from exercise of Unit options	161			161
Payment of tax withholding on issuance of LTIP awards	(4,909)			(4,909)
Distributions paid to noncontrolling interests	(1,258)		(1,258)
Contributions from noncontrolling interests	2,200		2,200
Other comprehensive income	1,967	1,967
Noncash accrual for distribution equivalent rights	(697)			(697)
Other	0		48	(48)
Ending balance at Mar. 31, 2016	$ 4,038,967	$ (95,874)	$ 286,987	$ 3,847,854