Summary of Significant Accounting Policies - Schedule of Revenues from External Customers (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Revenue, Major Customer [Line Items]
Total revenue	$ 240,120	$ 204,960	$ 170,538	$ 144,363	$ 152,265	$ 144,546	$ 130,622	$ 105,109	$ 759,981	$ 532,542	$ 477,107
Customer agreements and incentives
Revenue, Major Customer [Line Items]
Customer agreements and incentives									404,466	234,276	191,626
Customer agreements
Revenue, Major Customer [Line Items]
Customer agreements and incentives									272,672	210,753	155,870
Incentives
Revenue, Major Customer [Line Items]
Customer agreements and incentives									131,794	23,523	35,756
Solar energy systems and product sales
Revenue, Major Customer [Line Items]
Total revenue									355,515	298,266	285,481
Solar energy systems
Revenue, Major Customer [Line Items]
Total revenue									186,512	113,953	127,727
Products
Revenue, Major Customer [Line Items]
Total revenue									$ 169,003	$ 184,313	$ 157,754