SUMMARY OF QUARTERLY DATA (UNAUDITED) (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended								12 Months Ended
	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2013	Mar. 31, 2012	Mar. 31, 2011
SUMMARY OF QUARTERLY DATA (UNAUDITED) [Abstract]
Revenues	$ 49,951	$ 49,802	$ 44,258	$ 42,014	$ 42,718	$ 37,850	$ 40,025	$ 36,003	$ 186,025	$ 156,596	$ 143,676
Gross profit	26,183	26,076	23,123	22,849	23,381	20,478	22,021	19,223	98,231	85,103	79,792
Income tax provision	2,223	2,996	8,012	1,699	2,184	1,696	1,918	1,278	14,930	7,076	9,034
Net income	$ 6,698	$ 4,988	$ 12,909	$ 2,864	$ 4,706	$ 2,850	$ 3,321	$ 2,214	$ 27,459	$ 13,091	$ 14,537
Net income per share - basic (in dollars per share)	$ 0.30	$ 0.23	$ 0.59	$ 0.13	$ 0.22	$ 0.13	$ 0.15	$ 0.10	$ 1.25	$ 0.59	$ 0.65
Net income per share - diluted (in dollars per share)	$ 0.30	$ 0.22	$ 0.58	$ 0.13	$ 0.21	$ 0.13	$ 0.15	$ 0.10	$ 1.23	$ 0.58	$ 0.64