COMPUTATION OF EARNINGS PER COMMON SHARE (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2013	Dec. 31, 2012
Earnings Per Share [Abstract]
Net income	$ 34,383	$ 28,206	$ 84,474	$ 77,693
Earnings Per Share, Basic and Diluted [Abstract]
Weighted average common shares-basic	42,441	41,745	42,647	41,629
Dilutive effect of employee equity incentive plans	787	873	907	950
Weighted average common shares-diluted	43,228	42,618	43,554	42,579
Basic earnings per common share	$ 0.81	$ 0.68	$ 1.98	$ 1.87
Diluted earnings per common share	$ 0.80	$ 0.66	$ 1.94	$ 1.82
Potentially dilutive securities excluded from diluted earnings per common share because their effect is anti-dilutive	268	1,210	173	1,125