Business Acquisitions (Details) (USD $)		3 Months Ended		6 Months Ended			6 Months Ended
	Sep. 30, 2012	Sep. 30, 2012 SMSC Acquisition [Member]	Sep. 30, 2011 SMSC Acquisition [Member]	Sep. 30, 2012 SMSC Acquisition [Member]	Sep. 30, 2011 SMSC Acquisition [Member]	Aug. 02, 2012 SMSC Acquisition [Member]	Sep. 30, 2012 Roving Networks Acquisition [Member]	Apr. 18, 2012 Roving Networks Acquisition [Member]
Business Acquisition [Line Items]
Business Acquisition, Effective Date of Acquisition				8/2/2012			April 18, 2012
Price Per Share Paid to Acquire Oustanding Shares in Business Acquisition						$ 37.00
Business Acquisition, Cost of Acquired Entity, Purchase Price						$ 919,600,000		$ 20,600,000
Business Acquisition, Cost of Acquired Entity, Equity Interests Issued and Issuable						6,900,000
Business Acquisition, Cost of Acquired Entity, Cash Paid						731,800,000
Business Combination, Reason for Business Combination				The Company's primary reason for this acquisition was to expand the Company's range of solutions, products and capabilities in the automotive, industrial, computing, consumer and wireless audio markets by extending its served available market
Business Acquisition, Period Results Included in Combined Entity				the operating results of SMSC have been included in the Company's consolidated financial statements as of the closing date of the acquisition
Business Acquisition, Purchase Price Allocation [Abstract]
Cash and cash equivalents						180,925,000
Accounts recevable, net						58,441,000
Inventories						89,662,000
Prepaid expenses						5,675,000
Deferred tax assets						13,717,000
Other current assets						18,290,000
Property, plant and equipment						36,669,000
Long-term investments						24,275,000
Goodwill						157,840,000		8,700,000
Intangible assets, net						7,390,000
Purchased intangible assets						517,800,000		22,800,000
Other assets						3,835,000
Total assets acquired						1,114,519,000
Accounts payable						(28,035,000)
Accrued liabilities						(52,453,000)
Deferred income on shipments to distributors						(11,376,000)
Long-term income tax payable						(72,781,000)
Deferred tax liability						(20,194,000)
Other liabilities						(10,079,000)
Contingent consideration	16,632,000							14,700,000
Total liabilities assumed						194,918,000
Purchase price allocated						919,601,000
Net deferred tax liability for future amortization expense of acquired intangible assets						10,100,000
Revenue of acquiree included in statement of income since the acquisition date				48,200,000
Net income (loss) of acquiree included in statement of income since the acquisition date				(89,200,000)
Business Acquisition, Pro Forma Information [Abstract]
Pro forma net sales		441,192,000	453,183,000	896,404,000	907,185,000
Pro form net income		$ 59,593,000	$ 23,685,000	$ 118,619,000	$ 16,217,000
Pro forma basic earnings per share		$ 0.31	$ 0.12	$ 0.61	$ 0.08
Pro forma diluted earnings per share		$ 0.29	$ 0.12	$ 0.58	$ 0.08