Segment and Geographical Information - Reconciliation of Segments EBITDA to Loss before income taxes and equity in earnings (losses) of unconsolidated investees (Details) - USD ($) $ in Thousands	3 Months Ended			9 Months Ended		12 Months Ended
	Sep. 27, 2020	Dec. 29, 2019	Sep. 29, 2019	Sep. 27, 2020	Sep. 29, 2019	Dec. 29, 2019
Segment Reporting Information [Line Items]
Adjusted EBITDA	$ 146,405		$ 17,354	$ 223,084	$ 136,775
Construction revenue on solar services contracts	274,806		286,042	783,019	690,608
Stock-based compensation				18,788	18,927
Restructuring charges	(97)		4,252	2,738	6,626
Loss (gain) on sale and impairment of residential lease assets				(815)	(36,709)
Mark-to-market gain on equity investments				275,645	129,038
Equity in losses of unconsolidated investees	0		(960)	0	(716)
Net loss attributable to noncontrolling interests	(488)		4,191	1,199	30,417
Operating Segments
Segment Reporting Information [Line Items]
Adjusted EBITDA	13,557	$ 37,119		10,823		$ 16,504
Construction revenue on solar services contracts	282,100		$ 317,379	821,020	$ 841,495
Income (Loss) From Continuing Operations Before Income Taxes Minority Interest And Income (Loss) From Equity Method Investments | Segment Reconciling Items
Segment Reporting Information [Line Items]
Legacy utility and power plant projects	0	7		34		(993)
Legacy sale-leaseback transactions	0	181		(20)		(5,755)
Construction revenue on solar services contracts	0	(1,160)		(4,735)		8,978
Stock-based compensation	(4,454)	(4,975)		(13,387)		(13,682)
Amortization of intangible assets	(1,189)	(1,783)		(4,759)		(5,352)
Depreciation and amortization	(5,156)	(5,373)		(12,589)		(19,472)
Transaction-related costs	0	(976)		(1,863)		(3,571)
Litigation	(395)	0		(880)		0
Restructuring charges	97	(4,283)		(2,738)		(6,071)
Loss (gain) on sale and impairment of residential lease assets	83	(5,135)		1,122		(29,002)
Gain on business divestiture	0	0		10,529		143,400
Cash interest expense, net of interest income	(6,918)	(7,635)		(24,102)		(25,691)
Mark-to-market gain on equity investments	155,431	27,595		274,362		128,095
Gain on convertible notes repurchased	104	0		3,060		0
Equity in losses of unconsolidated investees	0	960		0		716
Net loss attributable to noncontrolling interests	230	(5,178)		(2,512)		(33,474)
Income (Loss) From Continuing Operations Before Income Taxes Minority Interest And Income (Loss) From Equity Method Investments | Corporate
Segment Reporting Information [Line Items]
Adjusted EBITDA	$ (4,985)	$ (12,010)		$ (9,261)		$ (17,855)