Note 14 Segment Information (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Segment Reporting Information [Line Items]
Net Revenues	$ 68,461	$ 99,004	$ 149,318	$ 200,782
Power Semiconductors [Member]
Segment Reporting Information [Line Items]
Net Revenues	48,203	74,731	107,785	151,195
Integrated Circuits [Member]
Segment Reporting Information [Line Items]
Net Revenues	15,100	16,949	30,699	35,060
System and RF Semiconductors [Member]
Segment Reporting Information [Line Items]
Net Revenues	5,158	7,324	10,834	14,527
United States [Member]
Segment Reporting Information [Line Items]
Net Revenues	20,241	27,562	45,163	55,267
France [Member] | Europe and Middle East [Member]
Segment Reporting Information [Line Items]
Net Revenues	1,125	1,915	2,698	3,946
Germany [Member] | Europe and Middle East [Member]
Segment Reporting Information [Line Items]
Net Revenues	7,446	12,888	16,603	26,304
United Kingdom [Member] | Europe and Middle East [Member]
Segment Reporting Information [Line Items]
Net Revenues	6,429	8,430	13,553	16,432
China [Member] | Asia Pacific [Member]
Segment Reporting Information [Line Items]
Net Revenues	10,586	16,971	23,970	35,536
Japan [Member] | Asia Pacific [Member]
Segment Reporting Information [Line Items]
Net Revenues	1,717	2,607	3,545	4,695
Korea [Member] | Asia Pacific [Member]
Segment Reporting Information [Line Items]
Net Revenues	2,082	3,004	4,325	6,949
Malaysia [Member] | Asia Pacific [Member]
Segment Reporting Information [Line Items]
Net Revenues	1,146	1,036	2,449	2,156
Singapore [Member] | Asia Pacific [Member]
Segment Reporting Information [Line Items]
Net Revenues	2,509	3,101	5,154	5,585
Taiwan [Member] | Asia Pacific [Member]
Segment Reporting Information [Line Items]
Net Revenues	1,253	1,765	2,477	3,997
India [Member] | Rest of the World [Member]
Segment Reporting Information [Line Items]
Net Revenues	1,470	2,425	3,272	5,254
Other Geographic Regions [Member] | Europe and Middle East [Member]
Segment Reporting Information [Line Items]
Net Revenues	9,227	13,643	19,477	27,783
Other Geographic Regions [Member] | Asia Pacific [Member]
Segment Reporting Information [Line Items]
Net Revenues	1,319	1,717	2,674	3,086
Other Geographic Regions [Member] | Rest of the World [Member]
Segment Reporting Information [Line Items]
Net Revenues	$ 1,911	$ 1,940	$ 3,958	$ 3,792