SELECTED QUARTERLY FINANCIAL DATA (UNAUDITED) (Details) (USD $) In Thousands, except Per Share data, 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
SELECTED QUARTERLY FINANCIAL DATA (UNAUDITED)
Revenues	$ 61,898	$ 65,280	$ 62,069	$ 60,435	$ 50,131	$ 24,876	$ 25,352	$ 25,143	$ 249,682	$ 125,502
Gross margin	18,154	19,612	18,568	17,092	14,226	7,238	7,535	7,523	73,426	36,522
Net income	$ 4,904	$ 4,115	$ 2,693	$ 2,148	$ 1,341	$ 833	$ 819	$ 960	$ 13,860	$ 3,953
Basic earnings per share (in dollars per share)	$ 0.54	$ 0.45	$ 0.29	$ 0.24	$ 0.15	$ 0.09	$ 0.09	$ 0.11	$ 1.52	$ 0.45
Diluted earnings per share (in dollars per share)	$ 0.53	$ 0.45	$ 0.29	$ 0.24	$ 0.15	$ 0.09	$ 0.09	$ 0.11	$ 1.51	$ 0.45