Investments (Details 3) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Apr. 02, 2011	Mar. 31, 2012	Dec. 31, 2011
Carrying value of non-marketable investments
Cost method		$ 6,157	$ 6,157
Equity method		4,343	4,303
Total non-marketable investments		10,500	10,460
Net realized gains on the sale of non-marketable investments
Gains on sale of non-marketable investments	$ 2,621