Quarterly Results of Operations (Unaudited) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Quarterly Financial Information Disclosure [Abstract]
REVENUE	$ 59,569	$ 44,410	$ 47,544	$ 51,351	$ 70,327	$ 51,556	$ 46,028	$ 72,547	$ 202,874	$ 240,458	$ 218,008
Operating income	20,620	6,225	13,398	14,587	28,939	8,904	8,335	24,974	54,830	71,152	43,296
Net income	$ 105,338	$ 237	$ 6,368	$ 1,738	$ 19,945	$ 1,129	$ 1,270	$ 14,706	$ 113,681	$ 37,050	$ 2,216