Fair Value of Financial Instruments (in thousands) Unobservable Inputs (Details) (USD $)	6 Months Ended				6 Months Ended
	Jun. 30, 2012	Jul. 02, 2011	Jun. 30, 2012 Short Term Maximum	Jul. 02, 2011 Short Term Maximum	Jun. 30, 2012 Long Term	Jul. 02, 2011 Long Term	Jun. 30, 2012 Level 3	Dec. 31, 2011 Level 3	Jul. 02, 2011 Level 3	Jan. 01, 2011 Level 3
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning fair value of Long-term marketable securities							$ 4,661,000	$ 6,946,000	$ 7,389,000	$ 10,232,000
Fair value of securities sold or redeemed	(2,285,000)	(2,843,000)
Ending fair value of Long-term marketable securities							4,661,000	6,946,000	7,389,000	10,232,000
Unrealilzed loss on certain short-term marketable securities			100,000	100,000
Realized gain on sale of securities					$ 400,000	$ 600,000