Goodwill and Intangible Assets (Narrative) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jul. 29, 2012	Jul. 31, 2011	Jul. 29, 2012	Jul. 31, 2011
Finite and Indefinite Lived Intangible Assets [Line Items]
Goodwill increase due to acquisitions			$ 260.4
Amortization expense related to finite-lived intangible assets	8.0	2.1	12.9	4.2
Gennum [Member]
Finite and Indefinite Lived Intangible Assets [Line Items]
Intangible assets from acquisition	129.9		129.9
Indefinite-lived intangible assets from acquisition	35.1		35.1
Cycleo [Member]
Finite and Indefinite Lived Intangible Assets [Line Items]
Intangible assets from acquisition	6.1		6.1
Core Technologies [Member] | Gennum [Member]
Finite and Indefinite Lived Intangible Assets [Line Items]
Intangible assets from acquisition	95.1		95.1
Core Technologies [Member] | Cycleo [Member]
Finite and Indefinite Lived Intangible Assets [Line Items]
Intangible assets from acquisition	$ 6.1		$ 6.1