Segment Information Revenue and Long-lived assets by region (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended								12 Months Ended
	Jan. 25, 2015	Oct. 26, 2014	Jul. 27, 2014	Apr. 27, 2014	Jan. 26, 2014	Oct. 27, 2013	Jul. 28, 2013	Apr. 28, 2013	Jan. 25, 2015	Jan. 26, 2014	Jan. 27, 2013
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue	$ 1,250,514	$ 1,225,382	$ 1,102,824	$ 1,102,787	$ 1,144,218	$ 1,053,967	$ 977,238	$ 954,739	$ 4,681,507	$ 4,130,162	$ 4,280,159
Long-Lived Assets	648,178				686,992				648,178	686,992
CHINA
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue									922,121	793,790	780,493
Long-Lived Assets	28,073				29,313				28,073	29,313
TAIWAN
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue									1,594,435	1,321,503	1,356,838
Long-Lived Assets	52,176				51,993				52,176	51,993
Other Asia Pacific
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue									637,029	675,339	783,573
Long-Lived Assets	587				1,092				587	1,092
Europe
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue									368,921	295,160	263,488
Long-Lived Assets	51,521				50,677				51,521	50,677
UNITED STATES
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue									790,614	726,830	799,430
Long-Lived Assets	467,277				522,461				467,277	522,461
Other Americas
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue									368,387	317,540	296,337
INDIA
Revenues from External Customers and Long-Lived Assets [Line Items]
Long-Lived Assets	$ 48,544				$ 31,456				$ 48,544	$ 31,456