Segment and Geographical Information - Reconciliation of Segment Gross Profit to Condensed Consolidated GAAP Gross Profit) (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]
Gross profit	$ 21,598	$ 19,800	$ 59,046	$ (17,485)
Construction revenue on solar services contracts	352,914	436,281	802,104	784,506
Gain on sale and impairment of residential lease assets			429	25,954
Stock-based compensation			12,746	11,936
Business reorganization costs	1,259	2,453	2,835	1,788
Operating Segments
Segment Reporting Information [Line Items]
Gross profit	33,825	48,583	82,026	65,598
Intersegment Eliminations
Segment Reporting Information [Line Items]
Gross profit	628	2,157	9,391	9,793
Construction revenue on solar services contracts	(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
Gross Profit \| Segment Reconciling Items
Segment Reporting Information [Line Items]
Legacy utility and power plant projects	0	(884)	34	(1,000)
Business process improvements	(793)	0	(3,257)	0
Legacy sale-leaseback transactions	0	3,684	(20)	4,507
Gain on sale and impairment of residential lease assets	458	632	906	757
Cost of above-market polysilicon	(9,569)	(25,950)	(19,612)	(75,378)
Litigation	0	0	163	0
Stock-based compensation	(1,175)	(1,133)	(2,284)	(1,301)
Amortization of intangible assets	(1,783)	(1,783)	(3,568)	(3,569)
Business reorganization costs	7	0	2	0
Service
Segment Reporting Information [Line Items]
Construction revenue on solar services contracts	0	6,398	(4,735)	10,138
Service \| Segment Reconciling Items
Segment Reporting Information [Line Items]
Construction revenue on solar services contracts	0	(45,614)	(5,392)	(109,119)
Service \| Gross Profit \| Segment Reconciling Items
Segment Reporting Information [Line Items]
Construction revenue on solar services contracts	$ 0	$ (5,506)	$ (4,735)	$ (16,892)

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