Segment Information (Details) (USD $) In Thousands	3 Months Ended	6 Months Ended
Sep. 30, 2011	Sep. 30, 2010	Sep. 30, 2011	Sep. 30, 2010
Segment reporting information [Line Items]
Net sales	$ 340,602	$ 382,271	$ 715,109	$ 739,396
Gross Profit	194,994	225,005	414,742	432,448
Semiconductor products [Member]
Segment reporting information [Line Items]
Net sales	318,618	364,999	672,478	706,767
Gross Profit	174,469	208,729	374,534	401,833
Technology licensing [Member]
Segment reporting information [Line Items]
Net sales	21,984	17,272	42,631	32,629
Gross Profit	$ 20,525	$ 16,276	$ 40,208	$ 30,615

Amount of total revenue for the reportable segments, including revenue from external customers, transactions with other operating segments of the same entity, and (gross) interest revenue. All considered to be "operating revenue" for purposes of the taxonomy.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 131

-Paragraph 27

-Subparagraph a, b, c

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 280

-SubTopic 10

-Section 50

-Paragraph 22

-Subparagraph (a),(b),(c)

-URI http://asc.fasb.org/extlink&oid=6534315&loc=d3e8736-108599

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Namespace Prefix:	us-gaap
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration