Business Acquisitions Business Acquisitions Identifiable Intangible Assets Acquired (Details) (USD $) In Thousands, unless otherwise specified	6 Months Ended		6 Months Ended		6 Months Ended		6 Months Ended		6 Months Ended		6 Months Ended		6 Months Ended		6 Months Ended
	Sep. 30, 2012	Aug. 02, 2012 SMSC Acquisition [Member]	Sep. 30, 2012 SMSC Acquisition [Member] Developed Technology [Member]	Aug. 02, 2012 SMSC Acquisition [Member] Developed Technology [Member]	Sep. 30, 2012 SMSC Acquisition [Member] In Process Research And Development Member	Aug. 02, 2012 SMSC Acquisition [Member] In Process Research And Development Member	Sep. 30, 2012 SMSC Acquisition [Member] Trade Names [Member]	Aug. 02, 2012 SMSC Acquisition [Member] Trade Names [Member]	Sep. 30, 2012 SMSC Acquisition [Member] Trademarks [Member]	Aug. 02, 2012 SMSC Acquisition [Member] Trademarks [Member]	Sep. 30, 2012 SMSC Acquisition [Member] Customer Relationships [Member]	Aug. 02, 2012 SMSC Acquisition [Member] Customer Relationships [Member]	Sep. 30, 2012 SMSC Acquisition [Member] Order or Production Backlog [Member]	Aug. 02, 2012 SMSC Acquisition [Member] Order or Production Backlog [Member]	Sep. 30, 2012 Roving Networks Acquisition [Member]	Apr. 18, 2012 Roving Networks Acquisition [Member]	Apr. 18, 2012 Roving Networks Acquisition [Member] Developed Technology [Member]	Apr. 18, 2012 Roving Networks Acquisition [Member] In Process Research And Development Member	Apr. 18, 2012 Roving Networks Acquisition [Member] Customer Relationships [Member]	Apr. 18, 2012 Roving Networks Acquisition [Member] Order or Production Backlog [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Intangible Assets, Useful Life, Minimum (in years)	1		7		7										4
Intangible Assets, Useful Life, Maximum (in years)	15		15		15										10
Intangible Asset, Weighted Average Useful Life (in years)							1		6		5		1
Acquired Finite-lived Intangible Asset, Amount		$ 517,800		$ 238,100		$ 80,300		$ 2,300		$ 11,700		$ 163,500		$ 21,900		$ 22,800	$ 10,600	$ 1,300	$ 10,600	$ 300