CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS (Unaudited) (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
Net revenues	$ 193,980	$ 179,280	$ 396,798	$ 360,645
Cost of revenues	94,366	82,052	191,552	165,721
Gross profit	99,614	97,228	205,246	194,924
Operating expenses:
Research, development, and engineering	20,447	19,581	41,310	39,277
Selling, general, and administrative	48,507	43,130	96,604	89,034
Restructuring and other related charges	(176)	0	547	0
Total operating expenses	68,778	62,711	138,461	128,311
Operating income	30,836	34,517	66,785	66,613
Interest and other income (expense), net	359	275	(127)	287
Income before income taxes	31,195	34,792	66,658	66,900
Income tax expense	8,057	8,868	16,567	17,413
Net income	$ 23,138	$ 25,924	$ 50,091	$ 49,487
Earnings per common share:
Basic	$ 0.54	$ 0.62	$ 1.17	$ 1.19
Diluted	$ 0.53	$ 0.61	$ 1.15	$ 1.16
Shares used in computing basic earnings per common share	42,810	41,482	42,751	41,571
Shares used in computing diluted earnings per common share	43,597	42,403	43,667	42,521
Cash dividends declared per common share	$ 0.10	$ 0.10	$ 0.20	$ 0.20