Quarterly Results of Operations (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								6 Months Ended	9 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	Jun. 30, 2018	Sep. 30, 2018	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Total revenue	$ 240,120	$ 204,960	$ 170,538	$ 144,363	$ 152,265	$ 144,546	$ 130,622	$ 105,109			$ 759,981	$ 532,542	$ 477,107
Net loss	(49,515)	(47,524)	(71,727)	(91,420)	(56,035)	(82,815)	(73,610)	(75,155)			(260,186)	(287,615)	(320,839)
Net income attributable to common stockholders	$ (5,888)	$ (2,896)	$ 7,409	$ 28,032	$ 69,254	$ 28,007	$ 18,346	$ 9,882			$ 26,657	$ 125,489	$ 75,129
Net income (loss) per share available to common shareholders, basic (in dollars per share)	$ (0.05)	$ (0.03)	$ 0.07	$ 0.26	$ 0.65	$ 0.26	$ 0.17	$ 0.09			$ 0.24	$ 1.19	$ 0.73
Net income (loss) per share available to common shareholders, diluted (in dollars per share)	$ (0.05)	$ (0.02)	$ 0.06	$ 0.25	$ 0.63	$ 0.26	$ 0.17	$ 0.09			$ 0.23	$ 1.16	$ 0.72
Net cash used in operating activities											$ (62,461)	$ (96,103)	$ (200,141)
Accounting Standards Update 2014-09
Net cash used in operating activities									$ 53,500	$ 103,000
Customer agreements and incentives
Cost of solar energy systems and product sales	$ 65,317	$ 63,195	$ 57,769	$ 54,576	$ 51,234	$ 47,299	$ 45,289	$ 42,613			240,857	186,435	154,244
Solar energy systems and product sales
Total revenue											355,515	298,266	285,481
Cost of solar energy systems and product sales	$ 89,040	$ 76,179	$ 64,268	$ 64,579	$ 74,174	$ 69,588	$ 60,938	$ 49,431			$ 294,066	$ 254,131	$ 239,381