Segment Information Income (Loss) by Segment and Reconciliation to Income Before Taxes (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended				9 Months Ended
	Oct. 26, 2014	Apr. 27, 2014	Jan. 26, 2014	Oct. 27, 2013	Oct. 26, 2014	Oct. 27, 2013
Segment Reporting Information [Line Items]
Operating income	$ 22,810			$ 13,265	$ 56,016	$ 57,800
Items to reconcile segment operating income to consolidated income before taxes
Stock-based compensation expense	7,935			6,829	21,056	21,610
Inventory write-down			15,000		1,100
Restructuring charge	0	1,000		0	1,001	0
Amortization of fair value adjustments related to acquired PP&E					0	2,529
Interest expense, net	1,462			1,818	4,437	16,462
Non-operating (income) expense, net	(216)			259	407	1,264
Income before taxes	21,564			11,188	51,172	40,074
Corporate, Non-Segment [Member]
Items to reconcile segment operating income to consolidated income before taxes
Intangible amortization and impairments	6,423			7,349	19,292	25,016
Stock-based compensation expense	7,935			6,829	21,056	21,610
Inventory write-down	0			0	1,052	0
Restructuring charge	0			0	1,001	0
Other non-segment related expenses	(762)			606	(261)	2,042
Amortization of fair value adjustments related to acquired PP&E	314			338	993	3,424
Interest expense, net	1,462			1,818	4,437	16,462
Non-operating (income) expense, net	(216)			259	407	1,264
Operating Segments [Member]
Segment Reporting Information [Line Items]
Operating income	36,720			28,387	99,149	109,892
Semiconductor Products Group [Member]
Segment Reporting Information [Line Items]
Operating income	39,905			29,272	106,383	110,431
All others [Member]
Segment Reporting Information [Line Items]
Operating income	$ (3,185)			$ (885)	$ (7,234)	$ (539)