Intangible Assets, by Major Class (Details) (USD $)	12 Months Ended
	Mar. 31, 2012	Mar. 31, 2011	Mar. 31, 2010
Finite-Lived Intangible Assets, Net [Abstract]
Gross Amount	$ 138,943,000	$ 113,427,000
Accumulated Amortization	(48,507,000)	(35,498,000)
Net Amount	90,436,000	77,929,000
Minimum expected useful life of finite lived intangible assets	1
Maximum expected useful life of finite lived intangible assets	10
Amortization of Intangible Assets	13,000,000	13,900,000	3,700,000
Projected Amortization Expense
2013	13,218,000
2014	13,042,000
2015	12,901,000
2016	10,784,000
2017	9,134,000
Cost of sales [Member]
Finite-Lived Intangible Assets, Net [Abstract]
Amortization of Intangible Assets	8,200,000	7,800,000	1,900,000
Operating Expense [Member]
Finite-Lived Intangible Assets, Net [Abstract]
Amortization of Intangible Assets	4,800,000	6,100,000	1,800,000
Developed technology [Member]
Finite-Lived Intangible Assets, Net [Abstract]
Gross Amount	94,681,000	83,751,000
Accumulated Amortization	(35,920,000)	(27,705,000)
Net Amount	58,761,000	56,046,000
Acquired Finite-lived Intangible Asset, Amount	10,900,000
Acquired Finite-lived Intangible Asset, Weighted Average Useful Life	10
Customer-related [Member]
Finite-Lived Intangible Assets, Net [Abstract]
Gross Amount	20,400,000	15,600,000
Accumulated Amortization	(4,633,000)	(1,621,000)
Net Amount	15,767,000	13,979,000
Acquired Finite-lived Intangible Asset, Amount	4,800,000
Acquired Finite-lived Intangible Asset, Weighted Average Useful Life	10
Trademarks and trade names [Member]
Finite-Lived Intangible Assets, Net [Abstract]
Gross Amount	1,730,000	1,730,000
Accumulated Amortization	(684,000)	(250,000)
Net Amount	1,046,000	1,480,000
Backlog [Member]
Finite-Lived Intangible Assets, Net [Abstract]
Gross Amount	2,410,000	2,410,000
Accumulated Amortization	(2,410,000)	(1,709,000)
Net Amount	0	701,000
In-process technology [Member]
Finite-Lived Intangible Assets, Net [Abstract]
Gross Amount	14,086,000	4,300,000
Accumulated Amortization	0	0
Net Amount	14,086,000	4,300,000
Acquired Finite-lived Intangible Asset, Amount	9,800,000
Distribution rights [Member]
Finite-Lived Intangible Assets, Net [Abstract]
Gross Amount	5,236,000	5,236,000
Accumulated Amortization	(4,660,000)	(4,147,000)
Net Amount	576,000	1,089,000
Covenants not to compete [Member]
Finite-Lived Intangible Assets, Net [Abstract]
Gross Amount	400,000	400,000
Accumulated Amortization	(200,000)	(66,000)
Net Amount	$ 200,000	$ 334,000