Net Income Per Share (Schedule Of Net Income Per Share) (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended									12 Months Ended
	Dec. 31, 2015	Sep. 27, 2015	Jun. 28, 2015	Mar. 29, 2015	Dec. 31, 2014		Sep. 28, 2014	Jun. 29, 2014	Mar. 30, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Earnings Per Share [Abstract]
Net Income	$ 21,807	$ 15,099	$ 3,667	$ 8,011	$ (40,353)	[1]	$ 20,025	$ 14,705	$ 14,411	$ 48,584	$ 8,788	$ 55,217
Weighted average shares outstanding: Basic (in shares)										33,161	35,771	38,379
Dilutive potential common shares (in shares)										627	674	569
Weighted average shares outstanding: Total (in shares)										33,788	36,445	38,948
Basic net income per share (in dollars per share)	$ 0.68	$ 0.47	$ 0.11	$ 0.23	$ (1.16)		$ 0.56	$ 0.41	$ 0.39	$ 1.47	$ 0.25	$ 1.44
Diluted net income per share (in dollars per share)	$ 0.66	$ 0.47	$ 0.11	$ 0.23	$ (1.16)		$ 0.55	$ 0.40	$ 0.39	$ 1.44	$ 0.24	$ 1.42
Anti-dilutive common stock options (in shares)										1,807	2,617	2,846

[1] Net loss includes a non-cash goodwill impairment charge of $74.2 million relating to the service provider business unit.