Equity and Stock Based Compensation Plans (Details 3) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 29, 2013	Jun. 30, 2012	Jun. 29, 2013	Jun. 30, 2012
Stock-based compensation expense for all share-based payment awards
Total stock-based compensation expense	$ 1,751	$ 1,593	$ 3,208	$ 3,054
Cost of products [Member]
Stock-based compensation expense for all share-based payment awards
Total stock-based compensation expense	53	20	98	77
Cost of service [Member]
Stock-based compensation expense for all share-based payment awards
Total stock-based compensation expense	71	75	130	133
Research and development [Member]
Stock-based compensation expense for all share-based payment awards
Total stock-based compensation expense	362	347	679	666
Selling [Member]
Stock-based compensation expense for all share-based payment awards
Total stock-based compensation expense	501	481	941	922
General and administrative [Member]
Stock-based compensation expense for all share-based payment awards
Total stock-based compensation expense	$ 764	$ 670	$ 1,360	$ 1,256