Segment Information - Sales to External Customers and Gross Profit (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Apr. 01, 2012	Apr. 03, 2011
Segment Reporting Information [Line Items]
Sales to external customers	$ 217,555	$ 196,960
Gross profit	98,111	85,904
Electronics [Member]
Segment Reporting Information [Line Items]
Sales to external customers	77,890	61,348
Gross profit	41,729	31,762
Materials Science [Member]
Segment Reporting Information [Line Items]
Sales to external customers	73,220	70,659
Gross profit	33,328	30,773
Life Sciences [Member]
Segment Reporting Information [Line Items]
Sales to external customers	18,234	24,025
Gross profit	6,949	9,902
Service and Components [Member]
Segment Reporting Information [Line Items]
Sales to external customers	48,211	40,928
Gross profit	$ 16,105	$ 13,467