Goodwill by Reporting Segment (Details) $ in Thousands	6 Months Ended
Sep. 30, 2015 USD ($)
Goodwill [Roll Forward]
Goodwill, beginning balance	$ 571,271
Goodwill, ending balance	1,008,720
ISSC Technologies Corporation [Member]
Goodwill [Roll Forward]
Goodwill, beginning balance	154,399
Semiconductor products [Member]
Goodwill [Roll Forward]
Goodwill, beginning balance	552,071
Goodwill, ending balance	989,520
Semiconductor products [Member] \| ISSC Technologies Corporation [Member]
Goodwill [Roll Forward]
Additions due to business combination	389
Semiconductor products [Member] \| Micrel Incorporated [Member]
Goodwill [Roll Forward]
Additions due to business combination	437,060
Technology licensing [Member]
Goodwill [Roll Forward]
Goodwill, beginning balance	19,200
Goodwill, ending balance	19,200
Technology licensing [Member] \| ISSC Technologies Corporation [Member]
Goodwill [Roll Forward]
Additions due to business combination	0
Technology licensing [Member] \| Micrel Incorporated [Member]
Goodwill [Roll Forward]
Additions due to business combination	$ 0

Amount after accumulated impairment loss of an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 350

-SubTopic 20

-Section 50

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=35741047&loc=d3e13816-109267

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 350

-SubTopic 20

-Section 45

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=6388280&loc=d3e13770-109266

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- Definition

Amount of increase in asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized resulting from a business combination.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 350

-SubTopic 20

-Section 50

-Paragraph 1

-Subparagraph (a)

-URI http://asc.fasb.org/extlink&oid=35741047&loc=d3e13816-109267

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- Definition

A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

+ References

No definition available.

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