Business Acquisitions (Schedule of Proforma Results) (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	12 Months Ended
Mar. 31, 2015	Mar. 31, 2014
ISSC Technologies Corporation [Member]
Business Acquisition [Line Items]
Net sales	$ 2,169,390	$ 1,998,647
Net income	367,428	364,169
Basic earnings per share	$ 1.83	$ 1.84
Diluted earnings per share	$ 1.64	$ 1.67
Supertex Inc. [Member]
Business Acquisition [Line Items]
Net sales	2,149,505	1,996,819
Net income	$ 391,573	$ 353,381
Basic earnings per share	$ 1.95	$ 1.78
Diluted earnings per share	$ 1.75	$ 1.62

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The pro forma basic net income per share for a period as if the business combination or combinations had been completed at the beginning of a period.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 805

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (h)(2)-(3)

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The pro forma diluted net income per share for a period as if the business combination or combinations had been completed at the beginning of a period.

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The pro forma net Income or Loss for the period as if the business combination or combinations had been completed at the beginning of a period.

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The pro forma revenue for a period as if the business combination or combinations had been completed at the beginning of the period.

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