Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Operating activities:
Net loss	$ (260,186)	$ (287,615)	$ (320,839)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization, net of amortization of deferred grants	156,007	128,687	98,493
Deferred income taxes	9,322	12,353	56,263
Stock-based compensation expense	27,856	22,042	18,723
Interest on pass-through financing obligations	19,205	12,629	12,757
Reduction in pass-through financing obligations	(25,005)	(18,295)	(44,913)
Other noncash losses and expenses	25,484	24,471	15,705
Changes in operating assets and liabilities:
Accounts receivable	(5,707)	(9,409)	(1,973)
Inventories	14,960	(27,101)	4,042
Prepaid and other assets	(75,924)	(51,633)	(52,226)
Accounts payable	8,848	47,837	(40,336)
Accrued expenses and other liabilities	15,286	9,219	24,868
Deferred revenue	27,393	40,712	29,295
Net cash used in operating activities	(62,461)	(96,103)	(200,141)
Investing activities:
Payments for the costs of solar energy systems	(806,365)	(769,363)	(678,258)
Purchases of property and equipment	(4,951)	(7,956)	(12,544)
Business acquisition	0	0	(5,000)
Net cash used in investing activities	(811,316)	(777,319)	(695,802)
Financing activities:
Proceeds from state tax credits, net of recapture	10,887	13,773	9,081
Payment of debt fees	(24,849)	(14,392)	(13,741)
Proceeds from pass-through financing and other obligations	217,082	6,221	16,047
Payment of finance lease obligations	(9,025)	(9,836)	(12,759)
Contributions received from noncontrolling interests and redeemable noncontrolling interests	345,147	594,921	573,542
Distributions paid to noncontrolling interests and redeemable noncontrolling interests	(78,398)	(54,530)	(39,542)
Acquisition of noncontrolling interests	0	(35,386)	0
Proceeds from exercises of stock options, net of withholding taxes paid on restricted stock units	12,592	1,035	7,364
Offering costs paid related to initial public offering	0	0	(437)
Net cash provided by financing activities	936,386	890,849	899,145
Net change in cash and restricted cash	62,609	17,427	3,202
Cash and restricted cash, beginning of period	241,790	224,363	221,161
Cash and restricted cash, end of period	304,399	241,790	224,363
Supplemental disclosures of cash flow information
Cash paid for interest	76,313	42,194	26,191
Cash paid for taxes	0	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	27,169	19,625	18,547
Purchases of solar energy systems included in non-recourse debt	0	12,873	0
Right-of-use assets obtained in exchange for finance lease liabilities	14,302	650	12,961
Recourse Debt
Financing activities:
Proceeds from issuance of debt	17,000	170,400	458,400
Repayment of debt	(17,000)	(167,400)	(411,400)
Non Recourse Debt
Financing activities:
Proceeds from issuance of debt	980,544	748,806	335,666
Repayment of debt	$ (517,594)	$ (362,763)	$ (23,076)