Net Income Per Limited Partner Unit (Reconciliation Of Net Income) (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended				6 Months Ended
	Jun. 30, 2011		Jun. 30, 2010		Jun. 30, 2011		Jun. 30, 2010
Net Income Per Limited Partner Unit
Net income	$ 98,178		$ 85,461		$ 193,558		$ 160,449
General partner's priority distributions	(20,658)		(16,579)		(40,146)		(32,439)
General partners' 2% equity ownership	(1,551)		(1,378)		(3,068)		(2,560)
Limited partners' interest in Net Income	75,969		67,504		150,344		125,450
Distributions to participating securities	(491)		(308)		(961)		(608)
Undistributed earnings attributable to participating securities	(591)		(384)		(1,191)		(674)
Net income available to limited partners	$ 74,887		$ 66,812		$ 148,192		$ 124,168
Weighted average limited partner units outstanding - Basic and Diluted	36,776		36,717		36,762		36,704
Basic and Diluted Net income per limited partner unit	$ 2.04	[1]	$ 1.82	[1]	$ 4.03	[1]	$ 3.38	[1]
Percentage of equity ownership					2.00%
Anti-dilutive under the treasury stock method	392,719		210,328		400,626		206,988

[1] Diluted EPU gives effect to all dilutive potential common units outstanding during the period using the treasury stock method. Diluted EPU excludes all dilutive potential units calculated under the treasury stock method if their effect is anti-dilutive. For the three and six months ended June 30, 2011, LTIP, SERP and Deferred Compensation Plan units of 392,719 and 400,626, respectively, were considered anti-dilutive. For the three and six months ended June 30, 2010, LTIP units of 210,328 and 206,988, respectively, were considered anti-dilutive.