Distributions (Schedule Of Distributions) (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	0 Months Ended						6 Months Ended		12 Months Ended	0 Months Ended		12 Months Ended
	May 15, 2012	Feb. 14, 2012	Nov. 14, 2011	Aug. 12, 2011	May 13, 2011	Feb. 14, 2011	Jun. 30, 2012	Jun. 30, 2011	Dec. 31, 2011	Aug. 14, 2012 Scenario, Forecast [Member]		Dec. 31, 2012 Scenario, Forecast [Member]
Per Unit Cash Distribution Amount	$ 0.8400	$ 0.8150	$ 0.8000	$ 0.7850	$ 0.7700	$ 0.7575	$ 1.6550	$ 1.5275	$ 3.1125	$ 0.9425	[1]	$ 2.5975
Total Cash Distribution to Limited Partners	$ 95,004	$ 92,177	$ 90,189	$ 88,498	$ 86,807	$ 85,398	$ 187,181	$ 172,205	$ 350,892	$ 106,597	[1]	$ 293,778
Distributions declared							Jul. 26, 2012
Distribution date							Aug. 14, 2012
Distribution date of record							Aug. 07, 2012

[1] Our general partner's board of directors declared this cash distribution on July 26, 2012 to be paid on August 14, 2012 to unitholders of record at the close of business on August 7, 2012.