Special (Income) Charges (Details) (Unusual or Infrequent Item [Member], USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013
Roving Networks Acquisition [Member]
Unusual or Infrequent Item [Line Items]
Other Nonrecurring Expense	$ 0.8		$ 0.8
Change in the Fair Value of Contingent Consideration			1.4
SMSC Acquisition [Member]
Unusual or Infrequent Item [Line Items]
Other Nonrecurring Income	1.1		1.1
Severance-Related, Office Closing Costs and Other Restructuring Costs	$ 0.4	$ 10.9	$ 0.7