CONDENSED CONSOLIDATED STATEMENTS OF PARTNERS' CAPITAL - USD ($) $ in Thousands	Total	Accumulated Other Comprehensive (Loss) Income	Noncontrolling Interests	Limited Partners
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	210,409		6,132	204,277
Acquisition of noncontrolling interest	(210,000)		(267,006)	57,006
Distributions paid to unitholders	(372,157)		1,372	(373,529)
Net proceeds from issuance of Units	262,086			262,086
Amortization of unit-based compensation awards	16,772			16,772
Payment of tax withholding on vesting of LTIP awards	(6,728)			(6,728)
Distributions paid to noncontrolling interest	(14,034)		(14,034)
Contributions from noncontrolling interests	7,400		7,400
Accrual for distribution equivalent rights	(2,386)			(2,386)
Other	(44)			(44)
Other comprehensive income	19,949	19,949
Ending balance at Jun. 30, 2018	4,779,589	48,580	11,249	4,719,760
Beginning balance at Mar. 31, 2018	5,089,188	59,087	279,440	4,750,661
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	93,317		1,413	91,904
Acquisition of noncontrolling interest	(210,000)		(267,006)	57,006
Distributions paid to unitholders	(186,088)		677	(186,765)
Net proceeds from issuance of Units	20			20
Amortization of unit-based compensation awards	8,008			8,008
Payment of tax withholding on vesting of LTIP awards	(132)			(132)
Distributions paid to noncontrolling interest	(6,275)		(6,275)
Contributions from noncontrolling interests	3,000		3,000
Accrual for distribution equivalent rights	(898)			(898)
Other	(44)			(44)
Other comprehensive income	(10,507)	(10,507)
Ending balance at Jun. 30, 2018	4,779,589	48,580	11,249	4,719,760
Beginning balance at Dec. 31, 2018	4,131,170	(40,061)	11,088	4,160,143
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	171,775		994	170,781
Distributions paid to unitholders	(231,778)		727	(232,505)
Amortization of unit-based compensation awards	15,681			15,681
Payment of tax withholding on vesting of LTIP awards	(2,310)			2,310
Distributions paid to noncontrolling interest	(1,905)		(1,905)
Accrual for distribution equivalent rights	(1,058)			(1,058)
Other	(3)			(3)
Other comprehensive income	3,049	3,049
Ending balance at Jun. 30, 2019	4,084,621	(37,012)	10,904	4,110,729
Beginning balance at Mar. 31, 2019	4,104,396	(38,419)	11,017	4,131,798
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	90,515		496	90,019
Distributions paid to unitholders	(115,926)		349	(116,275)
Amortization of unit-based compensation awards	5,769			5,769
Payment of tax withholding on vesting of LTIP awards	(65)			(65)
Distributions paid to noncontrolling interest	(958)		(958)
Accrual for distribution equivalent rights	(517)		0	(517)
Other comprehensive income	1,407	1,407
Ending balance at Jun. 30, 2019	$ 4,084,621	$ (37,012)	$ 10,904	$ 4,110,729