Business Combinations (Summary Of Purchase Price Components And Equity Interests Acquired) (Details) (USD $) In Millions, unless otherwise specified			0 Months Ended
	Jul. 29, 2011	Jul. 30, 2010	Jan. 31, 2011 Fiscal 2011 Acquisitions [Member] Akorri [Member]	May 13, 2010 Fiscal 2011 Acquisitions [Member] Bycast [Member]
Acquisition date			January 31,2011	May 13,2010
Percentage of equity interest acquired			100.00%	100.00%
Total purchase price			$ 62.3	$ 83.8
Cash component of purchase price			62.3	80.5
Fair value of vested options assumed	0	3.3	0	3.3
Purchase price held in escrow to secure obligations of acquired entity			$ 7.9	$ 13.1
Release of escrow (number of years subsequent to acquisition date)			1.5	1.5