Segment Information - Revenue and Other Financial Information by Reportable Segment (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 25, 2016	Jun. 27, 2015	Jun. 25, 2016	Jun. 27, 2015
Segment Reporting Information [Line Items]
Revenue	$ 434,055	$ 339,573	$ 788,923	$ 659,987
Operating income	58,061	55,735	109,533	98,740
Depreciation and amortization	32,353	23,148	57,008	45,516
Capital expenditures	11,791	13,908	20,041	24,556
Operating segments
Segment Reporting Information [Line Items]
Operating income	94,947	82,041	181,778	151,200
Depreciation and amortization	30,243	21,369	53,426	41,839
Capital expenditures	11,281	12,227	19,170	21,904
RMS | Operating segments
Segment Reporting Information [Line Items]
Revenue	125,058	119,287	248,397	238,676
Operating income	35,445	33,304	71,831	62,154
Depreciation and amortization	5,118	5,308	10,368	11,311
Capital expenditures	2,381	6,356	3,434	9,089
DSA | Operating segments
Segment Reporting Information [Line Items]
Revenue	221,059	153,375	379,042	293,387
Operating income	32,381	28,149	63,211	51,665
Depreciation and amortization	18,600	12,412	30,557	23,551
Capital expenditures	4,644	4,101	9,351	9,479
Manufacturing | Operating segments
Segment Reporting Information [Line Items]
Revenue	87,938	66,911	161,484	127,924
Operating income	27,121	20,588	46,736	37,381
Depreciation and amortization	6,525	3,649	12,501	6,977
Capital expenditures	$ 4,256	$ 1,770	$ 6,385	$ 3,336