Partners' Capital and Distributions (Quarterly Distributions Of Available Cash) (Details) (USD $)	3 Months Ended
Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2010	Sep. 30, 2010	Jun. 30, 2010	Mar. 31, 2010	Dec. 31, 2009
Partners’ Capital and Distributions [Abstract]
Distribution date	Feb. 13, 2012	Nov. 14, 2011	Aug. 12, 2011	May 13, 2011	Feb. 14, 2011	Nov. 12, 2010	Aug. 13, 2010	May 14, 2010	Feb. 14, 2010
Cash distribution per unit	$ 0.46	$ 0.455	$ 0.450	$ 0.445	$ 0.445	$ 0.445	$ 0.445	$ 0.445	$ 0.445

Cash dividends declared or paid to each outstanding limited partnership unit during the reporting period.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Staff Accounting Bulletin (SAB)

-Number Topic 4

-Section F

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 505

-SubTopic 10

-Section S99

-Paragraph 5

-URI http://asc.fasb.org/extlink&oid=6959260&loc=d3e187171-122770

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