Stock-Based Compensation (Details 2) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jul. 02, 2011	Jun. 30, 2012	Jul. 02, 2011
Stock-based compensation expense for all share-based payment awards
Total stock-based compensation expense	$ 1,593	$ 955	$ 3,054	$ 1,777
Cost of Products [Member]
Stock-based compensation expense for all share-based payment awards
Total stock-based compensation expense	20	28	77	66
Cost of Service [Member]
Stock-based compensation expense for all share-based payment awards
Total stock-based compensation expense	75	43	133	95
Research and development [Member]
Stock-based compensation expense for all share-based payment awards
Total stock-based compensation expense	347	221	666	368
Selling [Member]
Stock-based compensation expense for all share-based payment awards
Total stock-based compensation expense	481	311	922	526
General and administrative [Member]
Stock-based compensation expense for all share-based payment awards
Total stock-based compensation expense	$ 670	$ 352	$ 1,256	$ 722