Segment Information - Revenue Per Significant Product or Service (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jul. 01, 2017	Jun. 25, 2016	Jul. 01, 2017	Jun. 25, 2016
Segment Reporting Information [Line Items]
Revenue	$ 469,129	$ 434,055	$ 914,892	$ 788,923
Operating segments | RMS
Segment Reporting Information [Line Items]
Revenue	124,002	125,058	251,163	248,397
Operating segments | DSA
Segment Reporting Information [Line Items]
Revenue	252,092	221,059	479,850	379,042
Operating segments | Manufacturing
Segment Reporting Information [Line Items]
Revenue	$ 93,035	$ 87,938	$ 183,879	$ 161,484