Members' Capital and Distributions (Details 1) (USD $)	3 Months Ended	6 Months Ended
Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2010	Jun. 30, 2011	Jun. 30, 2010
Quarterly cash distributions
Distribution Per Unit	$ 0.575	$ 0.575	$ 0.575
Date Declared	Jul. 13, 2011	Apr. 13, 2011	Jan. 12, 2011
Record Date	Aug. 01, 2011	Apr. 29, 2011	Feb. 01, 2011
Payment Date	Aug. 11, 2011	May 12, 2011	Feb. 11, 2011
Amount	$ 38,687,000	$ 38,538,000	$ 38,456,000	$ 76,970,000	$ 70,037,000

Date of record for distribution of cash, stock, or units to a member or limited partner of LLC or LP.

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Date of declaration for distribution of cash, stock, or units to a member or limited partner of LLC or LP.

+ Details

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- Definition

Date of distribution for distribution of cash, stock, or units to a member or limited partner of LLC or LP.

+ Details

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- Definition

Per-share or per-unit cash dividends declared or paid to a common shareholder or unit-holder by LLC or LP.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 04
-Article 3

+ Details

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- Definition

Total distributions to each class of partners (i.e., general, limited and preferred partners).

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 04
-Article 3

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Emerging Issues Task Force (EITF)
-Number 87-21

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher AICPA
-Name Practice Bulletin (PB)
-Number 14
-Paragraph 15

+ Details

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