CONDENSED CONSOLIDATED STATEMENTS OF PARTNERS' CAPITAL - USD ($) $ in Thousands	Total	Accumulated Other Comprehensive Income (Loss)	Noncontrolling Interests	Limited Partners	Class C Units Limited Partners
Beginning balance at Dec. 31, 2016	$ 4,698,423	$ (25,593)	$ 286,700	$ 4,437,316	$ 0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	126,309		2,733	123,576
Distributions paid to unitholders	(174,149)		737	(174,886)
Net proceeds from issuance of units	3,212			3,212
Amortization of unit-based compensation awards	8,715			8,715
Payment of tax withholding on vesting of LTIP awards	(8,175)			(8,175)
Net proceeds from exercise of Unit options	481			481
Distributions paid to noncontrolling interests	(6,825)		(6,825)
Contributions from noncontrolling interests	3,600		3,600
Other comprehensive income	9,091	9,091		0
Accrual of distribution equivalent rights	(1,193)	0		(1,193)
Other			17	(17)
Ending balance at Mar. 31, 2017	4,659,489	(16,502)	286,962	4,389,029	0
Beginning balance at Dec. 31, 2017	4,868,322	28,631	277,385	4,562,306
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	117,092		4,719	110,808	1,565
Distributions paid to unitholders	(186,069)		695	(186,764)
Net proceeds from issuance of units	262,066				262,066
Amortization of unit-based compensation awards	8,764			8,764
Payment of tax withholding on vesting of LTIP awards	(6,596)			(6,596)
Distributions paid to noncontrolling interests	(7,759)		(7,759)
Contributions from noncontrolling interests	4,400		4,400
Other comprehensive income	30,456	30,456
Accrual of distribution equivalent rights	(1,488)			(1,488)
Ending balance at Mar. 31, 2018	$ 5,089,188	$ 59,087	$ 279,440	$ 4,487,030	$ 263,631