Goodwill and Intangible Assets - Goodwill Balances (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Jan. 25, 2015	Jan. 26, 2014		Jan. 27, 2013
Goodwill [Roll Forward]
Beginning balance	$ 276,898	$ 393,584
Impairments	0	(116,686)		0
Transfers		0
Acquisitions	3,421
Ending balance	280,319	276,898		393,584
Signal Integrity and Timing
Goodwill [Roll Forward]
Beginning balance	261,891	0
Impairments		0
Transfers		261,891
Acquisitions	0
Ending balance	261,891	261,891
Gennum
Goodwill [Roll Forward]
Beginning balance	0	261,891	[1]
Impairments		0
Transfers		(261,891)	[1]
Acquisitions	0
Ending balance	0	0
Advanced Communications
Goodwill [Roll Forward]
Beginning balance	0	116,686	[1]
Impairments		(116,686)	[1]
Transfers		0
Acquisitions	0
Ending balance	0	0
Wireless, Sensing and Timing
Goodwill [Roll Forward]
Beginning balance		15,007
Impairments		0
Transfers		0
Ending balance	$ 18,428	$ 15,007

[1] In the fourth quarter of fiscal year 2014, the Gennum and former Advanced Communications reporting units were integrated to form the new reporting unit Signal Integrity and Timing, which in the first quarter of fiscal 2015 became the new reporting unit Signal Integrity with Timing becoming a part of Wireless, Sensing and Timing. There were no transfers of goodwill associated with the fiscal 2015 realignment.