Net Income Per Share (Schedule Of Net Income Per Share) (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jul. 01, 2012	Jun. 30, 2013	Jul. 01, 2012
Earnings Per Share [Abstract]
Net income	$ 13,985	$ 21,522	$ 29,328	$ 46,669
Weighted average shares outstanding: Basic (in shares)	38,539,000	37,978,000	38,493,000	37,886,000
Weighted average shares outstanding: Dilutive potential common shares (in shares)	535,000	617,000	584,000	726,000
Weighted average shares outstanding: Total diluted shares (in shares)	39,074,000	38,595,000	39,077,000	38,612,000
Basic net income per share (in dollars per share)	$ 0.36	$ 0.57	$ 0.76	$ 1.23
Diluted net income per share (in dollars per share)	$ 0.36	$ 0.56	$ 0.75	$ 1.21
Anti-dilutive common stock options (in shares)	2,900,000	2,700,000	2,800,000	2,500,000