Special Charges (Details) (USD $)	12 Months Ended
	Mar. 31, 2014	Mar. 31, 2013	Mar. 31, 2012
Unusual or Infrequent Item [Member]
Unusual or Infrequent Item [Line Items]
Other Nonrecurring Expense	$ 3,000,000	$ 32,200,000
Business Combination, Contingent Consideration Arrangements, Change in Amount of Contingent Consideration, Liability			(1,000,000)
Other Nonrecurring Income			700,000
Severance Costs			300,000
Total Payment for Patent License Settlement			2,800,000
Patent License Expense Charged to Operations			1,500,000
Patent License Settlement Recorded as Prepaid Royalty			1,300,000
SMSC Acquisition [Member] | Unusual or Infrequent Item [Member]
Unusual or Infrequent Item [Line Items]
Severance related, office closing and other costs		16,300,000
SST acquisition [Member] | Unusual or Infrequent Item [Member]
Unusual or Infrequent Item [Line Items]
Legal settlement costs		11,500,000
Roving Networks Acquisition [Member]
Unusual or Infrequent Item [Line Items]
Business Combination, Contingent Consideration Arrangements, Change in Amount of Contingent Consideration, Liability	1,400,000	4,400,000
Roving Networks Acquisition [Member] | Unusual or Infrequent Item [Member]
Unusual or Infrequent Item [Line Items]
Business Combination, Contingent Consideration Arrangements, Change in Amount of Contingent Consideration, Liability		$ 4,400,000