Quarterly Financial Data (Unaudited) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Quarterly Financial Data [Abstract]
Revenue	$ 77,014	$ 87,942	$ 87,030	$ 82,373	$ 124,503	$ 116,761	$ 105,318	$ 102,575	$ 334,359	$ 449,157	$ 371,065
Gross margin	28,104	31,227	29,252	26,527	50,890	46,078	42,310	43,681	115,110	182,959	147,527
Net income (loss)	$ (1,375)	$ 1,975	$ (12,547)	$ (1,515)	$ 16,272	$ 14,272	$ 11,041	$ 12,018	$ (13,462)	$ 53,603	$ 36,178
Earnings (loss) per common share:
Basic (in dollars per share)	$ (0.03)	$ 0.04	$ (0.23)	$ (0.03)	$ 0.30	$ 0.26	$ 0.20	$ 0.22	$ (0.25)	$ 0.98	$ 0.70
Diluted (in dollars per share)	$ (0.03)	$ 0.04	$ (0.23)	$ (0.03)	$ 0.29	$ 0.26	$ 0.20	$ 0.22	$ (0.25)	$ 0.97	$ 0.67