Segment Reporting - Information by Reportable Segment (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 27, 2021	Jun. 28, 2020	Jun. 27, 2021	Jun. 28, 2020
Segment Reporting Information [Line Items]
Revenues	$ 747,198	$ 643,303	$ 1,495,765	$ 1,260,556
Operating income (loss)	30,761	34,295	56,957	41,753
Amortization of intangible assets	12,631	8,047	24,846	16,094
Corporate
Segment Reporting Information [Line Items]
Revenues	0	0	0	0
Operating income (loss)	(7,187)	(4,967)	(16,895)	(14,479)
Amortization of intangible assets	0	0	0	0
GMS | Operating Segments
Segment Reporting Information [Line Items]
Revenues	511,343	507,854	1,032,904	965,298
Operating income (loss)	28,700	31,537	53,214	44,140
Amortization of intangible assets	4,161	4,115	8,322	8,231
NSS | Operating Segments
Segment Reporting Information [Line Items]
Revenues	235,855	135,449	462,861	295,258
Operating income (loss)	9,248	7,725	20,638	12,092
Amortization of intangible assets	$ 8,470	$ 3,932	$ 16,524	$ 7,863