Segment and Geographical Information - Reconciliation of Segment Revenue to Condensed Consolidated GAAP Revenue (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 27, 2020	Sep. 29, 2019	Sep. 27, 2020	Sep. 29, 2019
Segment Reporting Information [Line Items]
Revenue	$ 274,806	$ 286,042	$ 783,019	$ 690,608
Operating Segments
Segment Reporting Information [Line Items]
Revenue	282,100	317,379	821,020	841,495
Intersegment Eliminations
Segment Reporting Information [Line Items]
Revenue	(7,294)	(15,612)	(32,816)	(26,237)
Legacy utility and power plant projects
Segment Reporting Information [Line Items]
Revenue	0	65	207	259
Construction revenue on solar services contracts
Segment Reporting Information [Line Items]
Revenue	$ 0	$ (15,790)	$ (5,392)	$ (124,909)