MEMBERS' EQUITY Table 1 (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Changes in Members' Equity [Roll Forward]
Balance as of December 31, 2013			$ 349,986
Net income	17,639	12,035	47,053	35,669
Distributions to unitholders			(69,747)	(69,681)
Other comprehensive income (loss)			(1,900)
Unit-based compensation			4,270
Other			(26)
Balance as of September 30, 2014	$ 329,636		$ 329,636