Net Income Per Share (Schedule Of Net Income Per Share) (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended									12 Months Ended
	Dec. 31, 2014		Sep. 28, 2014	Jun. 29, 2014	Mar. 30, 2014	Dec. 31, 2013	Sep. 29, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Earnings Per Share [Abstract]
Net Income	$ (40,353)	[1]	$ 20,025	$ 14,705	$ 14,411	$ 11,432	$ 14,457	$ 13,985	$ 15,343	$ 8,788	$ 55,217	$ 86,539
Weighted average shares outstanding: Basic (in shares)										35,771	38,379	38,057
Weighted average shares outstanding: Dilutive potential common shares (in shares)										674	569	690
Weighted average shares outstanding: Total diluted shares (in shares)										36,445	38,948	38,747
Basic net income per share (in dollars per share)	$ (1.16)		$ 0.56	$ 0.41	$ 0.39	$ 0.30	$ 0.37	$ 0.36	$ 0.40	$ 0.25	$ 1.44	$ 2.27
Diluted net income per share (in dollars per share)	$ (1.16)		$ 0.55	$ 0.40	$ 0.39	$ 0.30	$ 0.37	$ 0.36	$ 0.39	$ 0.24	$ 1.42	$ 2.23
Anti-dilutive common stock options (in shares)										2,617	2,846	2,611

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