Intangible Assets and Goodwill (Details) (USD $)	12 Months Ended
	Mar. 31, 2011	Mar. 31, 2010	Mar. 31, 2009
Finite-Lived Intangible Assets, Net [Abstract]
Gross Amount	$ 113,427,000	$ 57,145,000
Accumulated Amortization	(35,498,000)	(21,618,000)
Net Amount	77,929,000	35,527,000
Minimum expected useful life of finite lived intangible assets	1
Maximum expected useful life of finite lived intangible assets	10
Finite Lived Intangible Assets Amortization Expense Cost Of Sales	7,800,000	1,900,000	800,000
Finite Lived Intangible Assets Amortization Expense Operating Expenses	6,100,000	1,800,000	1,900,000
Projected Amortization Expense
2012	12,811,000
2013	13,304,000
2014	12,281,000
2015	12,201,000
2016	10,284,000
Amortization expense	13,900,000	3,700,000	2,700,000
Goodwill [Roll Forward]
Goodwill, beginning balance	40,338,000
Goodwill, ending balance	76,018,000	40,338,000
Amount of contingent consideration payments made to the previous owners of R and E international	12,100,000
Amount of derecognition of negative goodwill recorded on the acquisition	2,400,000
Developed technology [Member]
Finite-Lived Intangible Assets, Net [Abstract]
Gross Amount	83,451,000	48,609,000
Accumulated Amortization	(27,694,000)	(17,967,000)
Net Amount	55,757,000	30,642,000
Acquired Finite-lived Intangible Asset, Amount	34,800,000
Acquired Finite-lived Intangible Asset, Weighted Average Useful Life	10
Customer-related [Member]
Finite-Lived Intangible Assets, Net [Abstract]
Gross Amount	15,600,000	400,000
Accumulated Amortization	(1,621,000)	(12,000)
Net Amount	13,979,000	388,000
Acquired Finite-lived Intangible Asset, Amount	15,200,000
Acquired Finite-lived Intangible Asset, Weighted Average Useful Life	9
Trademarks and trade names [Member]
Finite-Lived Intangible Assets, Net [Abstract]
Gross Amount	1,730,000
Accumulated Amortization	(250,000)
Net Amount	1,480,000
Acquired Finite-lived Intangible Asset, Amount	1,700,000
Acquired Finite-lived Intangible Asset, Weighted Average Useful Life	5
Backlog [Member]
Finite-Lived Intangible Assets, Net [Abstract]
Gross Amount	2,410,000
Accumulated Amortization	(1,709,000)
Net Amount	701,000
Acquired Finite-lived Intangible Asset, Amount	2,400,000
Acquired Finite-lived Intangible Asset, Weighted Average Useful Life	1
In-process technology [Member]
Finite-Lived Intangible Assets, Net [Abstract]
Gross Amount	4,600,000	2,900,000
Accumulated Amortization	(11,000)	0
Net Amount	4,589,000	2,900,000
Acquired Finite-lived Intangible Asset, Amount	1,700,000
Distribution rights [Member]
Finite-Lived Intangible Assets, Net [Abstract]
Gross Amount	5,236,000	5,236,000
Accumulated Amortization	(4,147,000)	(3,639,000)
Net Amount	1,089,000	1,597,000
Covenants not to compete [Member]
Finite-Lived Intangible Assets, Net [Abstract]
Gross Amount	400,000
Accumulated Amortization	(66,000)
Net Amount	334,000
Acquired Finite-lived Intangible Asset, Amount	400,000
Acquired Finite-lived Intangible Asset, Weighted Average Useful Life	3
Semiconductor products [Member]
Goodwill [Roll Forward]
Goodwill, beginning balance	40,338,000	36,165,000
Additions due to the acquisition of SST	5,761,000
Additions due to contingent consideration payments to previousowners of R and E International	9,747,000
Additions due to other acquisitions	972,000	4,173,000
Goodwill, ending balance	56,818,000	40,338,000
Technology licensing [Member]
Goodwill [Roll Forward]
Additions due to the acquisition of SST	19,200,000
Goodwill, ending balance	$ 19,200,000