Goodwill by Reporting Segment (Details) (USD $)	12 Months Ended
	Mar. 31, 2012	Mar. 31, 2011
Goodwill [Roll Forward]
Goodwill, ending balance	$ 93,513,000	$ 76,018,000
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
Semiconductor products [Member]
Goodwill [Roll Forward]
Goodwill, beginning balance	56,818,000	40,338,000
Additions due to contingent consideration payments to previousowners of R and E International	120,000	9,747,000
Goodwill, ending balance	74,313,000	56,818,000
Semiconductor products [Member] | SST acquisition [Member]
Goodwill [Roll Forward]
Additions due to business combination		5,761,000
Semiconductor products [Member] | Other acquisitions
Goodwill [Roll Forward]
Additions due to business combination	17,375,000	972,000
Technology licensing [Member]
Goodwill [Roll Forward]
Goodwill, beginning balance	19,200,000	0
Additions due to contingent consideration payments to previousowners of R and E International	0	0
Goodwill, ending balance	19,200,000	19,200,000
Technology licensing [Member] | SST acquisition [Member]
Goodwill [Roll Forward]
Additions due to business combination		19,200,000
Technology licensing [Member] | Other acquisitions
Goodwill [Roll Forward]
Additions due to business combination	$ 0	$ 0