Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017
Operating activities:
Net loss	$ (163,147)	$ (148,765)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization, net of amortization of deferred grants	73,980	61,654
Deferred income taxes	12,582	16,179
Stock-based compensation expense	16,242	11,389
Interest on pass-through financing obligations	7,002	6,274
Reduction in pass-through financing obligations	(10,142)	(8,142)
Other noncash losses and expenses	12,131	10,152
Changes in operating assets and liabilities:
Accounts receivable	(13,044)	(10,254)
Inventories	13,123	14,582
Prepaid and other assets	(20,474)	(16,067)
Accounts payable	(32,840)	2,636
Accrued expenses and other liabilities	(2,039)	(6,511)
Deferred revenue	(4,555)	17,702
Net cash used in operating activities	(111,181)	(49,171)
Investing activities:
Payments for the costs of solar energy systems	(346,962)	(339,979)
Purchases of property and equipment	(2,762)	(4,464)
Net cash used in investing activities	(349,724)	(344,443)
Financing activities:
Proceeds from state tax credits, net of recapture	10,434	13,171
Payment of debt fees	(9,133)	(4,955)
Proceeds from pass-through financing and other obligations	151,632	3,062
Payment of finance lease obligations	(4,081)	(5,262)
Contributions received from noncontrolling interests and redeemable noncontrolling interests	167,468	303,545
Distributions paid to noncontrolling interests and redeemable noncontrolling interests	(33,301)	(24,635)
Proceeds from exercises of stock options, net of withholding taxes paid on restricted stock units	4,944	(425)
Net cash provided by financing activities	489,518	402,196
Net change in cash and restricted cash	28,613	8,582
Cash and restricted cash, beginning of period	241,790	224,363
Cash and restricted cash, end of period	270,403	232,945
Supplemental disclosures of cash flow information
Cash paid for interest	33,509	17,434
Cash paid for taxes	0	0
Supplemental disclosures of noncash investing and financing activities
Purchases of solar energy systems and property and equipment included in accounts payable and accrued expenses	22,472	25,284
Purchases of solar energy systems included in non-recourse debt	0	12,873
Distributions payable to noncontrolling interests and redeemable noncontrolling interests	15,063	13,212
Right-of-use assets obtained in exchange for new finance lease liabilities	3,662	94
Recourse debt
Financing activities:
Proceeds from issuance of debt	2,000	91,400
Repayment of debt	(2,000)	(88,400)
Non-recourse debt
Financing activities:
Proceeds from issuance of debt	250,232	199,525
Repayment of debt	$ (48,677)	$ (84,830)