CONDENSED CONSOLIDATED STATEMENTS OF PARTNERS' CAPITAL - USD ($) $ in Thousands	Total	Accumulated Other Comprehensive Income (Loss)	Noncontrolling Interests	Limited Partners
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	439,746		11,803	427,943
Distributions paid to unitholders	(469,764)		2,292	(472,056)
Net proceeds from issuance of LP Units	108,422			108,422
Amortization of unit-based compensation awards	22,977			22,977
Net proceeds from exercise of Unit options	300			300
Payment of tax withholding on issuance of LTIP awards	(5,123)			(5,123)
Distributions paid to noncontrolling interests	(11,531)		(11,531)
Contributions from noncontrolling interests	3,760		3,760
Other comprehensive income	9,654	9,654
Accrual of distribution equivalent rights	(2,248)			(2,248)
Other			44	(44)
Ending balance at Sep. 30, 2016	4,112,934	(88,187)	287,720	3,913,401
Beginning balance at Dec. 31, 2016	4,698,423	(25,593)	286,700	4,437,316
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	362,912		10,427	352,485
Distributions paid to unitholders	(529,169)		2,182	(531,351)
Net proceeds from issuance of LP Units	345,955			345,955
Amortization of unit-based compensation awards	25,935			25,935
Net proceeds from exercise of Unit options	481			481
Payment of tax withholding on issuance of LTIP awards	(8,487)			(8,487)
Distributions paid to noncontrolling interests	(24,657)		(24,657)
Contributions from noncontrolling interests	7,700		7,700
Other comprehensive income	36,863	36,863
Accrual of distribution equivalent rights	(2,931)			(2,931)
Other			141	(141)
Ending balance at Sep. 30, 2017	$ 4,913,025	$ 11,270	$ 282,493	$ 4,619,262