Segment and Geographical Information - Reconciliation of Segment Revenue to Condensed Consolidated GAAP Revenue (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jul. 04, 2021	Jun. 28, 2020	Jul. 04, 2021	Jun. 28, 2020
Segment Reporting Information [Line Items]
Revenue	$ 308,927	$ 217,667	$ 615,325	$ 508,213
Operating Segments
Segment Reporting Information [Line Items]
Total segment revenue as reviewed by CODM	308,923	223,310	614,689	538,920
Intersegment elimination
Segment Reporting Information [Line Items]
Revenue	0	(5,643)	11	(25,522)
Segment Reconciling Items
Segment Reporting Information [Line Items]
Revenue	0	0	0	(5,392)
Legacy utility and power plant projects	0	0	0	207
Results of operations of legacy business to be exited	$ 4	$ 0	$ 625	$ 0