Goodwill and Intangible Assets - Goodwill Balances (Details) $ in Thousands	12 Months Ended
	Jan. 31, 2016 USD ($)
Goodwill [Roll Forward]
Beginning balance	$ 280,319
Additions	49,384
Ending balance	329,703
Signal Integrity and Timing
Goodwill [Roll Forward]
Beginning balance	261,891
Additions	0
Ending balance	261,891
Power and High Reliability
Goodwill [Roll Forward]
Beginning balance	0
Additions	49,384
Ending balance	49,384
Wireless and Sensing
Goodwill [Roll Forward]
Beginning balance	18,428
Additions	0
Ending balance	$ 18,428