MEMBERS' EQUITY Table 1 (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Changes in Members' Equity [Roll Forward]
Balance as of December 31, 2013	$ 349,986
Net income (loss)	13,646	11,075
Distributions to unitholders	(23,249)	(23,223)
Other comprehensive income (loss)	(948)
Unit-based compensation	86
Balance as of March 31, 2014	$ 339,521