Goodwill and Intangible Assets - Changes in Carrying Amounts of Goodwill (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Apr. 26, 2015
Goodwill [Roll Forward]
Balance as of January 25, 2015	$ 280,319
Additions	49,384
Balance at April 26, 2015	329,703
Signal Integrity [Member]
Goodwill [Roll Forward]
Balance as of January 25, 2015	261,891
Additions	0
Balance at April 26, 2015	261,891
Power and High Reliability [Member]
Goodwill [Roll Forward]
Balance as of January 25, 2015	0
Additions	49,384
Balance at April 26, 2015	49,384
Wireless, Sensing and Timing [Member]
Goodwill [Roll Forward]
Balance as of January 25, 2015	18,428
Additions	0
Balance at April 26, 2015	$ 18,428