CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS (Unaudited) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2014	Dec. 31, 2013
Income Statement [Abstract]
Net revenues	$ 231,781	$ 212,739	$ 664,248	$ 609,537
Cost of revenues	111,865	102,412	311,795	293,964
Gross profit	119,916	110,327	352,453	315,573
Operating expenses:
Research, development, and engineering	22,991	21,018	69,280	62,328
Selling, general, and administrative	57,977	51,467	174,756	148,071
Gain from litigation settlements	(1,666)	0	(7,816)	0
Restructuring and other related charges	0	0	0	547
Total operating expenses	79,302	72,485	236,220	210,946
Operating income	40,614	37,842	116,233	104,627
Interest and other income (expense), net	(2,018)	186	(1,683)	59
Income before income taxes	38,596	38,028	114,550	104,686
Income tax expense	8,212	3,645	28,073	20,212
Net income	$ 30,384	$ 34,383	$ 86,477	$ 84,474
Earnings per common share:
Basic	$ 0.73	$ 0.81	$ 2.07	$ 1.98
Diluted	$ 0.71	$ 0.80	$ 2.03	$ 1.94
Shares used in computing basic earnings per common share	41,901	42,441	41,780	42,647
Shares used in computing diluted earnings per common share	42,700	43,228	42,674	43,554
Cash dividends declared per common share	$ 0.15	$ 0.10	$ 0.45	$ 0.30