CONDENSED CONSOLIDATED STATEMENTS OF PARTNERS' CAPITAL (USD $) In Thousands	Total	Accumulated Other Comprehensive Income (Loss)	Noncontrolling Interests	Limited Partners	Class B Units
Beginning balance at Dec. 31, 2012	$ 2,388,840	$ (158,779)	$ 16,527	$ 2,117,788	$ 413,304
Net income	90,499		1,158	82,383	6,958
Distributions paid to unitholders	(100,272)		1,203	(101,475)
Net proceeds from issuance of LP units	349,564			349,564
Amortization of unit-based compensation awards	3,343			3,343
Payment of tax withholding on issuance of LTIP awards	(3,498)			(3,498)
Distributions paid to noncontrolling interests	(2,295)		(2,295)
Other comprehensive income (loss)	8,823	8,823
Noncash accrual for distribution equivalent rights	(334)			(334)
Other	5		(11)	16
Ending balance at Mar. 31, 2013	2,734,675	(149,956)	16,582	2,447,787	420,262
Beginning balance at Dec. 31, 2013	3,080,836	(103,552)	15,171	3,169,217
Net income	91,497		1,029	90,468
Distributions paid to unitholders	(124,954)		852	(125,806)
Net proceeds from issuance of LP units	52,217			52,217
Amortization of unit-based compensation awards	3,252			3,252
Proceeds from exercise of unit options	269			269
Payment of tax withholding on issuance of LTIP awards	(4,744)			(4,744)
Distributions paid to noncontrolling interests	(1,953)		(1,953)
Other comprehensive income (loss)	(7,432)	(7,432)
Noncash accrual for distribution equivalent rights	(300)			(300)
Other	(61)		(74)	13
Ending balance at Mar. 31, 2014	$ 3,088,627	$ (110,984)	$ 15,025	$ 3,184,586