MEMBERS' EQUITY Table 5 (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended					9 Months Ended
	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Distribution Made to Limited Liability Company (LLC) Member [Line Items]
Cash distributions per unit applicable to members (distribution earned)	$ 0.545	$ 0.545	$ 0.545	$ 0.545	$ 0.545	$ 1.635	$ 1.565
Total cash distributions (distribution earned)	$ 23,231	$ 23,236	$ 23,222	$ 23,223	$ 23,204	$ 69,689	$ 66,637
Distribution date of record (distribution earned)	Nov. 11, 2013	Aug. 05, 2013	May 06, 2013	Feb. 11, 2013
Distribution payment date (distribution earned)	Nov. 19, 2013	Aug. 14, 2013	May 15, 2013	Feb. 19, 2013
Distribution announcement date (distribution earned)	Oct. 31, 2013