Segment and Geographical Information - Reconciliation of Segment Revenue to Condensed Consolidated GAAP Revenue (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 28, 2020	Jun. 30, 2019	Jun. 28, 2020	Jun. 30, 2019
Segment Reporting Information [Line Items]
Revenue	$ 352,914	$ 436,281	$ 802,104	$ 784,506
Operating Segments
Segment Reporting Information [Line Items]
Total segment revenue as reviewed by CODM	388,320	572,288	931,570	1,044,647
Intersegment Eliminations
Segment Reporting Information [Line Items]
Revenue	(35,406)	(90,416)	(124,281)	(151,216)
Segment Reconciling Items
Segment Reporting Information [Line Items]
Legacy utility and power plant projects	0	23	207	194
Service
Segment Reporting Information [Line Items]
Revenue	0	6,398	(4,735)	10,138
Service | Segment Reconciling Items
Segment Reporting Information [Line Items]
Revenue	$ 0	$ (45,614)	$ (5,392)	$ (109,119)