Segment Information - Goodwill and Total Assets (Details) (USD $) In Thousands, unless otherwise specified	Mar. 30, 2014	Dec. 31, 2013	Mar. 31, 2013	Dec. 31, 2012
Segment Reporting Information [Line Items]
Goodwill	$ 184,260	$ 136,152	$ 128,172	$ 131,320
Total Assets	1,477,600	1,426,084
Industry [Member]
Segment Reporting Information [Line Items]
Goodwill	99,688	51,532
Total Assets	401,073	297,987
Science [Member]
Segment Reporting Information [Line Items]
Goodwill	84,572	84,620
Total Assets	361,215	365,571
Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Total Assets	$ 715,312	$ 762,526