Stock-Based Compensation - Summary of Stock-Based Compensation Expense (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Compensation expense recognized	$ 5,547	$ 5,515	$ 16,242	$ 11,389
Cost of customer agreements and incentives
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Compensation expense recognized	667	1,110	1,279	1,861
Cost of solar energy systems and product sales
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Compensation expense recognized	186	156	357	270
Sales and marketing
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Compensation expense recognized	834	807	4,984	2,724
Research and development
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Compensation expense recognized	311	186	605	335
General and administration
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Compensation expense recognized	$ 3,549	$ 3,256	$ 9,017	$ 6,199