MEMBERS' EQUITY Table 4 (Details) - USD ($) $ / shares in Units, $ in Thousands		3 Months Ended
	Apr. 27, 2016	Mar. 31, 2016	Dec. 31, 2015	Mar. 31, 2015
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
Total cash distributions (distribution earned)		$ 23,397	$ 23,397	$ 23,388
Distribution date of record (distribution earned)		May 09, 2016	Feb. 08, 2016
Distribution payment date (distribution earned)		May 17, 2016	Feb. 16, 2016
Subsequent Event [Member]
Distribution Made to Limited Liability Company (LLC) Member [Line Items]
Distribution announcement date (distribution earned)	Apr. 27, 2016