NET INCOME PER SHARE - Calculations of Basic and Diluted Net Income Per Share and Potential Common Shares (Detail) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Numerator:
Net income	$ 9,883	$ 9,910	$ 15,136	$ 14,918
Denominator:
Denominator for basic net income per share - weighted average shares outstanding	41,392	41,695	41,398	41,718
Dilutive common equivalent shares:
Weighted average stock options	76	134	81	135
Weighted average restricted stock units	482	515	525	547
Denominator for diluted net income per share - weighted average shares outstanding	41,950	42,344	42,004	42,400
Net income per share:
Basic net income per share (in dollars per share)	$ 0.24	$ 0.24	$ 0.37	$ 0.36
Diluted net income per share (in dollars per share)	$ 0.24	$ 0.23	$ 0.36	$ 0.35