Net Income Per Share (Schedule of Net Income Per Share) (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jul. 01, 2018	Jul. 02, 2017	Jul. 01, 2018	Jul. 02, 2017
Numerator:
Net income	$ (5,230)	$ 14,582	$ 360	$ 30,576
Denominator:
Weighted average common shares - basic (in shares)	31,674	32,352	31,550	32,650
Potentially dilutive common share equivalent (in shares)	0	764	1,172	1,006
Weighted average common shares - dilutive (in shares)	31,674	33,116	32,722	33,656
Basic net income per share (in dollars per share)	$ (0.17)	$ 0.45	$ 0.01	$ 0.94
Diluted net income per share (in dollars per share)	$ (0.17)	$ 0.44	$ 0.01	$ 0.91
Anti-dilutive employee stock-based awards, excluded (in shares)	1,014	782	892	271