Segment Information - Goodwill and Total Assets (Details) - USD ($) $ in Thousands	Apr. 03, 2016	Dec. 31, 2015	Mar. 29, 2015	Dec. 31, 2014
Segment Reporting Information [Line Items]
Goodwill	$ 258,240	$ 145,607	$ 166,923	$ 170,773
Total Assets	1,435,869	1,349,849
Industry [Member]
Segment Reporting Information [Line Items]
Goodwill	170,146	60,360
Science [Member]
Segment Reporting Information [Line Items]
Goodwill	88,094	85,247
Operating Segments [Member] | Industry [Member]
Segment Reporting Information [Line Items]
Total Assets	653,157	516,397
Operating Segments [Member] | Science [Member]
Segment Reporting Information [Line Items]
Total Assets	394,507	488,096
Corporate And Eliminations [Member] | Corporate Eliminations [Member]
Segment Reporting Information [Line Items]
Total Assets	$ 388,205	$ 345,356