Convertible Notes (Details) (USD $) Share data in Millions, unless otherwise specified	6 Months Ended
	Jun. 30, 2013	Jul. 01, 2012
Convertible Notes [Line Items]
Convertible notes, amount converted	$ 89,000,000
Debt Conversion, Converted Instrument, NonCash Transaction, Amount	88,937,000	0
Shares issued during period for debt conversion	3.0
Convertible Subordinated Debt [Member]
Convertible Notes [Line Items]
Convertible notes, issuance date	May 19, 2006
Convertible notes, face amount at issuance	115,000,000
Convertible notes, stated interest rate	2.875%
Convertible notes, issuance costs at time of issuance	3,100,000
Convertible notes, redeemed	26,000,000
Convertible notes, maturity date	Jun. 01, 2013
Converted Into Cash [Member]
Convertible Notes [Line Items]
Convertible notes, amount converted	$ 100,000