Borrowing Arrangements (Narrative) (Details) (USD $) Share data in Millions, unless otherwise specified	3 Months Ended						3 Months Ended
	Mar. 30, 2012	Dec. 30, 2011	Dec. 31, 2010	Sep. 30, 2011	Mar. 02, 2007 tranches	Mar. 02, 2007 Convertible Subordinated Notes 1.25% due March 2010 [Member]	Dec. 30, 2011 Convertible Subordinated Notes 1.50% Due March 2012 [Member]	Oct. 02, 2009 Convertible Subordinated Notes 1.50% Due March 2012 [Member]	Mar. 02, 2007 Convertible Subordinated Notes 1.50% Due March 2012 [Member]
Principal amount of convertible subordinated notes issued		$ 17,277,000		$ 26,677,000	$ 200,000,000	$ 100,000,000			$ 100,000,000
Debt Offering Number of Tranches					2
Non convertible borrowing rate for estimating fair value		6.86%	6.86%				6.86%
Percentage of convertible subordinated notes						1.25%			1.50%
Repayment of convertible debt and premium	32,800,000
Convertible debt Premium Paid Upon Retirement		5,600,000
Extinguishment of Debt, Amount		9,400,000
Principal amount of the convertible notes								77,300,000
Fair value of equity component		$ 3,926,000		$ 6,061,000				$ 22,700,000
Number of shares underlying the remaining 1.50% Notes							1.8