Business Acquisitions (Narrative) (Details) - USD ($) $ in Thousands		12 Months Ended
	Aug. 03, 2015	Mar. 31, 2016	Mar. 31, 2015	Jul. 17, 2014
Business Acquisition [Line Items]
Non cash consideration transferred in the form of share-based payment awards (amount)		$ 4,052
Micrel Incorporated [Member]
Business Acquisition [Line Items]
Cash paid for shares	$ 430,000
Shares issued in Micrel acquisition	8,626,795
Non cash consideration transferred in the form of share-based payment awards (amount)	$ 4,100
Cash paid in a business combination for employee vested stock awards	13,100
Total consideration transferred	816,200
Net deferred tax liability for future amortization expense of acquired intangible assets	99,700
Long-term deferred tax assets	$ 11,400
Revenue of acquiree included in statement of income since the acquisition date		$ 116,400
ISSC Technologies Corporation [Member]
Business Acquisition [Line Items]
Percentage of interest acquired in acquisition				83.50%
Supertex Inc. [Member]
Business Acquisition [Line Items]
Non cash consideration transferred in the form of share-based payment awards (amount)			$ 1,622