Restructuring Costs - Narrative (Details) (USD $)	12 Months Ended			3 Months Ended
	Jan. 25, 2015	Jan. 26, 2014	Jan. 27, 2013	Jan. 26, 2014
Restructuring Cost and Reserve [Line Items]
Inventory write-downs	$ 0	$ 15,047,000	$ 0
Cost of sales
Restructuring Cost and Reserve [Line Items]
Inventory write-downs				15,047,000
Contract termination
Restructuring Cost and Reserve [Line Items]
Additional contract commitment cancellation charges		4,900,000
Contract termination | Product development and engineering
Restructuring Cost and Reserve [Line Items]
Additional contract commitment cancellation charges		3,200,000
Contract termination | Cost of sales
Restructuring Cost and Reserve [Line Items]
Additional contract commitment cancellation charges	$ 3,000,000	$ 1,700,000