Restructuring Costs - Contract Commitment Cancellation Charges (Details) - USD ($) $ in Thousands	12 Months Ended
	Jan. 31, 2016	Jan. 25, 2015	Jan. 26, 2014
Restructuring Cost and Reserve [Line Items]
Contract commitment cancellation charges	$ 0	$ 2,983	$ 4,926
Cost of sales
Restructuring Cost and Reserve [Line Items]
Contract commitment cancellation charges	0	2,983	1,729
Product development and engineering
Restructuring Cost and Reserve [Line Items]
Contract commitment cancellation charges	$ 0	$ 0	$ 3,197