CONSOLIDATED STATEMENTS OF OPERATIONS (USD $) In Thousands, except Per Share data, unless otherwise specified	12 Months Ended
	Mar. 31, 2014	Mar. 31, 2013	Mar. 31, 2012
Income Statement [Abstract]
Net revenues	$ 818,607	$ 762,226	$ 713,368
Cost of revenues	391,979	359,045	329,017
Gross profit	426,628	403,181	384,351
Operating expenses:
Research, development, and engineering	84,781	80,373	69,664
Selling, general, and administrative	201,176	182,445	173,334
Restructuring and other related charges	547	2,266	0
Total operating expenses	286,504	265,084	242,998
Operating income	140,124	138,097	141,353
Interest and other income, net	1,015	328	1,249
Income before income taxes	141,139	138,425	142,602
Income tax expense	28,722	32,023	33,566
Net income	$ 112,417	$ 106,402	$ 109,036
Earnings Per Share, Basic [Abstract]
Basic (in dollars per share)	$ 2.65	$ 2.55	$ 2.48
Earnings Per Share, Diluted [Abstract]
Diluted (in dollars per share)	$ 2.59	$ 2.49	$ 2.41
Shares used in basic per share calculations	42,452	41,748	44,023
Shares used in diluted per share calculations	43,364	42,738	45,265
Cash dividends declared per common share (in dollars per share)	$ 0.40	$ 0.40	$ 0.20