Condensed Consolidated Statement of Comprehensive Income (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 29, 2012	Oct. 01, 2011	Sep. 29, 2012	Oct. 01, 2011
Net income	$ 12,442	$ 10,464	$ 33,813	$ 28,059
Other comprehensive income, net of tax:
Unrealized gain (loss) on available-for-sale investments	75	(30)	35	38
Change in minimum postretirement medical obligation	2	1	8	5
Total comprehensive income	77	(29)	43	43
Total comprehensive income	$ 12,519	$ 10,435	$ 33,856	$ 28,102