Business Acquisitions (Details) (USD $)	12 Months Ended			0 Months Ended	12 Months Ended			12 Months Ended		0 Months Ended	12 Months Ended		0 Months Ended	12 Months Ended		0 Months Ended	12 Months Ended	0 Months Ended		12 Months Ended	0 Months Ended		12 Months Ended
	Mar. 31, 2014	Mar. 31, 2013	Mar. 31, 2012	Nov. 23, 2013 Eqcologic Acquisition [Member]	Mar. 31, 2014 Eqcologic Acquisition [Member]	Nov. 21, 2013 Eqcologic Acquisition [Member]	Nov. 20, 2013 Eqcologic Acquisition [Member]	Mar. 31, 2014 SMSC Acquisition [Member]	Mar. 31, 2013 SMSC Acquisition [Member]	Apr. 18, 2012 Roving Networks Acquisition [Member]	Mar. 31, 2014 Roving Networks Acquisition [Member]	Mar. 31, 2013 Roving Networks Acquisition [Member]	Feb. 09, 2012 Ident Technology AG acquisition [Member]	Mar. 31, 2014 Ident Technology AG acquisition [Member]	Mar. 31, 2014 Developed Technology [Member]	Apr. 18, 2012 Developed Technology [Member] Roving Networks Acquisition [Member]	Mar. 31, 2014 Customer Relationships [Member]	Apr. 18, 2012 Customer Relationships [Member] Roving Networks Acquisition [Member]	Apr. 18, 2012 Order or Production Backlog [Member] Roving Networks Acquisition [Member]	Mar. 31, 2014 In Process Research and Development [Member]	Apr. 18, 2012 In Process Research and Development [Member] Roving Networks Acquisition [Member]	Feb. 09, 2012 In Process Research and Development [Member] Ident Technology AG acquisition [Member]	Mar. 31, 2014 Minimum [Member]	Mar. 31, 2014 Minimum [Member] Roving Networks Acquisition [Member]	Mar. 31, 2014 Maximum [Member]	Mar. 31, 2014 Maximum [Member] Roving Networks Acquisition [Member]
Business Acquisition [Line Items]
Business Combination, Step Acquisition, Equity Interest in Acquiree, Percentage							18.30%
Business Combination, Step Acquisition, Equity Interest in Acquiree, Remeasurement Gain	$ 2,438,000	$ 0	$ 0	$ 2,400,000
Business Acquisition, Percentage of Voting Interests Acquired						81.70%
Business Acquisition, Consideration Paid, Net of Cash Acquired	11,187,000	20,556,000	38,580,000	9,000,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Finite-Lived Intangibles						4,100,000
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life					8 years										11 years		5 years
Business Acquisition, Effective Date of Acquisition											Apr. 18, 2012
Business Combination, Consideration Transferred										20,600,000			39,500,000
Business Acquisition, Purchase Price Allocation [Abstract]
Cash and cash equivalents								180,925,000	180,925,000
Accounts receivable, net								58,441,000	58,441,000
Inventories								86,244,000	86,244,000
Prepaid expenses								5,617,000	5,617,000
Deferred tax assets								15,843,000	15,843,000
Other current assets								17,578,000	17,578,000
Property, plant and equipment, net								35,608,000	35,608,000
Long-term investments								24,275,000	24,275,000
Goodwill	276,097,000	271,348,000				6,400,000		165,592,000	169,065,000	8,700,000			17,400,000
Intangible assets, net								10,214,000	10,214,000
Purchased intangible assets								517,800,000	517,800,000
Other assets								3,835,000	3,835,000
Total assets acquired								1,121,972,000	1,125,445,000
Accounts payable								(28,035,000)	(28,035,000)
Accrued liabilities								(62,247,000)	(62,038,000)
Deferred income on shipments to distributors								(11,376,000)	(11,376,000)
Long-term income tax payable								(72,781,000)	(72,781,000)
Deferred tax liability								(16,682,000)	(21,079,000)
Other liabilities								(11,250,000)	(10,535,000)
Total liabilities assumed								(202,371,000)	(205,844,000)
Purchase price allocated								919,601,000	919,601,000
Contingent consideration	0	19,100,000								14,700,000	20,500,000	19,100,000
Increase in fair value of contingent consideration											1,400,000	4,400,000
Business Combination, Provisional Information, Initial Accounting Incomplete, Adjustments [Abstract]
Goodwill								(3,473,000)
Total assets acquired								(3,473,000)
Accrued liabilities								(209,000)
Deferred tax liabilities								4,397,000
Other liabilities								(715,000)
Total liabilities assumed								(3,473,000)
Finite-lived Intangible Assets Acquired										$ 22,800,000			$ 18,100,000		$ 12,700,000	$ 10,600,000	$ 1,300,000	$ 10,600,000	$ 300,000	$ 800,000	$ 1,300,000	$ 8,200,000
Finite-Lived Intangible Asset, Useful Life														10 years									1 year	4 years	15 years	10 years