COMPUTATION OF EARNINGS PER COMMON SHARE (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Earnings Per Share [Abstract]
Net income	$ 20,474	$ 17,896	$ 40,861	$ 39,124
Earnings Per Share, Basic and Diluted [Abstract]
Weighted average common shares-basic	32,281	33,590	32,269	35,796
Dilutive effect of employee equity incentive plans	445	655	596	880
Weighted average common shares-diluted	32,726	34,245	32,865	36,676
Basic earnings per common share (in dollars per share)	$ 0.63	$ 0.53	$ 1.27	$ 1.09
Diluted earnings per common share (in dollars per share)	$ 0.63	$ 0.52	$ 1.24	$ 1.07
Potentially dilutive securities excluded from diluted earnings per common share because their effect is anti-dilutive	543	283	634	257