3dfx (Details) (USD $)	12 Months Ended
	Jan. 25, 2015		Jan. 26, 2014		Jan. 27, 2013
Notes to financial statements [Abstract]
Aggregate purchase price of acquisition paid initially	$ 74,200,000
Accrued legal settlement	0	[1]	30,600,000	[1]
Litigation Reserve Administrative Expenses And Trustee Fee paid	5,600,000
Goodwill adjustment related to previously acquired business-3dfx	$ 25,000,000		$ 0		$ 0

[1] Please refer to Note 10 of these Notes to the Consolidated Financial Statements for discussion regarding the warranty accrual.