Quarterly Results of Operations (Unaudited) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Quarterly Financial Information Disclosure [Abstract]
REVENUE	$ 52,351	$ 41,299	$ 47,334	$ 57,053	$ 59,569	$ 44,410	$ 47,544	$ 51,351	$ 198,037	$ 202,874	$ 240,458
Operating income	8,944	15,780	10,543	11,644	20,620	6,225	13,398	14,587	46,911	54,830	71,152
Net income	$ 725	$ 4,486	$ 2,575	$ 1,892	$ 105,338	$ 237	$ 6,368	$ 1,738	$ 9,678	$ 113,681	$ 37,050