Vivint Solar (VSLR) 10-Q 6 Nov 18 2018 Q3 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	9 Months Ended
	Sep. 30, 2018	Nov. 01, 2018
Document And Entity Information [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Sep. 30, 2018
Document Fiscal Year Focus	2,018
Document Fiscal Period Focus	Q3
Trading Symbol	VSLR
Entity Registrant Name	Vivint Solar, Inc.
Entity Central Index Key	1,607,716
Current Fiscal Year End Date	--12-31
Entity Filer Category	Accelerated Filer
Entity Small Business	true
Entity Emerging Growth Company	true
Entity Ex Transition Period	true
Entity Common Stock, Shares Outstanding		119,319,921

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets (Unaudited) - USD ($) $ in Thousands		Sep. 30, 2018	Dec. 31, 2017
Current assets:
Cash and cash equivalents		$ 188,627	$ 108,452
Accounts receivable, net		19,910	19,665
Inventories		15,780	22,597
Prepaid expenses and other current assets		24,662	34,049
Total current assets		248,979	184,763
Restricted cash and cash equivalents		68,341	46,486
Solar energy systems, net		1,858,743	1,673,532
Property and equipment, net		11,082	15,078
Intangible assets, net		676	862
Prepaid tax asset, net			505,883
Other non-current assets, net		28,696	37,325
TOTAL ASSETS	[1]	2,216,517	2,463,929
Current liabilities:
Accounts payable		44,909	40,736
Accounts payable—related party		83	163
Distributions payable to non-controlling interests and redeemable non-controlling interests		11,236	16,437
Accrued compensation		25,789	20,992
Current portion of long-term debt		10,515	13,585
Current portion of deferred revenue		25,480	41,846
Current portion of capital lease obligation		2,305	4,166
Accrued and other current liabilities		37,328	29,675
Total current liabilities		157,645	167,600
Long-term debt, net of current portion		1,143,957	925,964
Deferred revenue, net of current portion		12,728	29,200
Capital lease obligation, net of current portion		648	1,599
Deferred tax liability, net		413,076	342,382
Other non-current liabilities		12,522	13,674
Total liabilities	[1]	1,740,576	1,480,419
Commitments and contingencies (Note 17)
Redeemable non-controlling interests		121,820	122,444
Stockholders’ equity:
Common stock, $0.01 par value—1,000,000 authorized, 119,316 shares issued and outstanding as of September 30, 2018; 1,000,000 authorized, 115,099 shares issued and outstanding as of December 31, 2017		1,193	1,151
Additional paid-in capital		570,506	559,788
Accumulated other comprehensive income		95	6,905
(Accumulated deficit) retained earnings		(266,767)	213,107
Total stockholders’ equity		305,027	780,951
Non-controlling interests		49,094	80,115
Total equity		354,121	861,066
TOTAL LIABILITIES, REDEEMABLE NON-CONTROLLING INTERESTS AND EQUITY		$ 2,216,517	$ 2,463,929
[1]	The Company’s assets as of September 30, 2018 and December 31, 2017 include $1,738.0 million and $1,516.2 million consisting of assets of variable interest entities, or VIEs, that can only be used to settle obligations of the VIEs. These assets include solar energy systems, net, of $1,636.3 million and $1,486.0 million as of September 30, 2018 and December 31, 2017; cash and cash equivalents of $78.9 million and $17.3 million as of September 30, 2018 and December 31, 2017; accounts receivable, net, of $11.1 million and $5.1 million as of September 30, 2018 and December 31, 2017; other non-current assets, net of $9.5 million and $6.8 million as of September 30, 2018 and December 31, 2017; prepaid expenses and other current assets of $1.8 million and $1.0 million as of September 30, 2018 and December 31, 2017; and restricted cash and cash equivalents of $0.4 million and $0 as of September 30, 2018 and December 31, 2017. The Company’s liabilities as of September 30, 2018 and December 31, 2017 included $36.2 million and $58.4 million of liabilities of VIEs whose creditors have no recourse to the Company. These liabilities include distributions payable to non-controlling interests and redeemable non-controlling interests of $11.2 million and $16.4 million as of September 30, 2018 and December 31, 2017; deferred revenue of $11.2 million and $36.0 million as of September 30, 2018 and December 31, 2017; long-term debt of $8.3 million and $0 as of September 30, 2018 and December 31, 2017; accrued and other current liabilities of $4.5 million as of September 30, 2018 and December 31, 2017; and other non-current liabilities of $1.0 million and $1.4 million as of September 30, 2018 and December 31, 2017. For further information see Note 12—Investment Funds.

Condensed Consolidated Balanc_2

Condensed Consolidated Balance Sheets (Unaudited) (Parenthetical) - USD ($) $ in Thousands		Sep. 30, 2018	Dec. 31, 2017
Common stock, par value		$ 0.01	$ 0.01
Common stock, shares authorized		1,000,000,000	1,000,000,000
Common stock, shares issued		119,316,000	115,099,000
Common stock, shares outstanding		119,316,000	115,099,000
Total assets	[1]	$ 2,216,517	$ 2,463,929
Solar energy systems, net		1,858,743	1,673,532
Cash and cash equivalents		188,627	108,452
Accounts receivable, net		19,910	19,665
Other non-current assets, net		28,696	37,325
Restricted cash and cash equivalents		68,341	46,486
Prepaid expenses and other current assets		24,662	34,049
Total liabilities	[1]	1,740,576	1,480,419
Distributions payable to non-controlling interests and redeemable non-controlling interests		11,236	16,437
Accrued and other current liabilities		37,328	29,675
Other non-current liabilities		12,522	13,674
Variable Interest Entities
Total assets		1,737,978	1,516,190
Solar energy systems, net		1,636,300	1,486,023
Cash and cash equivalents		78,906	17,280
Accounts receivable, net		11,052	5,143
Other non-current assets, net		9,529	6,792
Restricted cash and cash equivalents		438	0
Prepaid expenses and other current assets		1,753	952
Total liabilities		36,244	58,382
Distributions payable to non-controlling interests and redeemable non-controlling interests		11,236	16,437
Deferred revenue		11,200	36,000
Long-term debt		8,300	0
Accrued and other current liabilities		4,540	4,478
Other non-current liabilities		$ 982	$ 1,444
[1]	The Company’s assets as of September 30, 2018 and December 31, 2017 include $1,738.0 million and $1,516.2 million consisting of assets of variable interest entities, or VIEs, that can only be used to settle obligations of the VIEs. These assets include solar energy systems, net, of $1,636.3 million and $1,486.0 million as of September 30, 2018 and December 31, 2017; cash and cash equivalents of $78.9 million and $17.3 million as of September 30, 2018 and December 31, 2017; accounts receivable, net, of $11.1 million and $5.1 million as of September 30, 2018 and December 31, 2017; other non-current assets, net of $9.5 million and $6.8 million as of September 30, 2018 and December 31, 2017; prepaid expenses and other current assets of $1.8 million and $1.0 million as of September 30, 2018 and December 31, 2017; and restricted cash and cash equivalents of $0.4 million and $0 as of September 30, 2018 and December 31, 2017. The Company’s liabilities as of September 30, 2018 and December 31, 2017 included $36.2 million and $58.4 million of liabilities of VIEs whose creditors have no recourse to the Company. These liabilities include distributions payable to non-controlling interests and redeemable non-controlling interests of $11.2 million and $16.4 million as of September 30, 2018 and December 31, 2017; deferred revenue of $11.2 million and $36.0 million as of September 30, 2018 and December 31, 2017; long-term debt of $8.3 million and $0 as of September 30, 2018 and December 31, 2017; accrued and other current liabilities of $4.5 million as of September 30, 2018 and December 31, 2017; and other non-current liabilities of $1.0 million and $1.4 million as of September 30, 2018 and December 31, 2017. For further information see Note 12—Investment Funds.

Condensed Consolidated Statemen

Condensed Consolidated Statements of Operations (Unaudited) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Revenue:
Operating leases and incentives	$ 53,470	$ 45,909	$ 139,349	$ 119,711
Solar energy system and product sales	24,346	29,230	87,515	81,537
Total revenue	77,816	75,139	226,864	201,248
Cost of revenue:
Cost of revenue—operating leases and incentives	42,135	34,731	122,188	103,564
Cost of revenue—solar energy system and product sales	17,700	22,168	62,735	63,664
Total cost of revenue	59,835	56,899	184,923	167,228
Gross profit	17,981	18,240	41,941	34,020
Operating expenses:
Sales and marketing	15,841	9,808	40,999	28,037
Research and development	475	896	1,472	2,687
General and administrative	29,803	19,379	71,533	60,259
Amortization of intangible assets	142	139	408	418
Total operating expenses	46,261	30,222	114,412	91,401
Loss from operations	(28,280)	(11,982)	(72,471)	(57,381)
Interest expense, net	18,715	16,148	46,973	47,707
Other (income) expense, net	(1)	195	(6,371)	1,186
Loss before income taxes	(46,994)	(28,325)	(113,073)	(106,274)
Income tax expense	25,698	9,375	79,693	23,932
Net loss	(72,692)	(37,700)	(192,766)	(130,206)
Net loss attributable to non-controlling interests and redeemable non-controlling interests	(64,824)	(44,605)	(190,038)	(155,383)
Net (loss attributable) income available to common stockholders	$ (7,868)	$ 6,905	$ (2,728)	$ 25,177
Net (loss attributable) income available per share to common stockholders:
Basic	$ (0.07)	$ 0.06	$ (0.02)	$ 0.22
Diluted	$ (0.07)	$ 0.06	$ (0.02)	$ 0.21
Weighted-average shares used in computing net (loss attributable) income available per share to common stockholders:
Basic	118,767	114,505	116,871	112,554
Diluted	118,767	119,465	116,871	117,825

Condensed Consolidated Statem_2

Condensed Consolidated Statements of Comprehensive Income (Unaudited) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Statement Of Income And Comprehensive Income [Abstract]
Net (loss attributable) income available to common stockholders	$ (7,868)	$ 6,905	$ (2,728)	$ 25,177
Other comprehensive income (loss):
Unrealized gains (losses) on cash flow hedging instruments (net of tax effect of $1,076, $(331), $2,247 and $(1,076))	2,890	(497)	6,037	(1,612)
Less: Interest (expense) income on derivatives recognized into earnings (net of tax effect of $(145), $62, $6,016 and $5)	(390)	94	16,165	8
Total other comprehensive income (loss)	3,280	(403)	(10,128)	(1,604)
Comprehensive (loss) income	$ (4,588)	$ 6,502	$ (12,856)	$ 23,573

Condensed Consolidated Statem_3

Condensed Consolidated Statements of Comprehensive Income (Unaudited) (Parenthetical) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Statement Of Income And Comprehensive Income [Abstract]
Unrealized losses on cash flow hedging instruments, tax	$ 1,076	$ (331)	$ 2,247	$ (1,076)
Interest expense on derivatives recognized into earnings, tax	$ (145)	$ 62	$ 6,016	$ 5

Condensed Consolidated Statem_4

Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017
CASH FLOWS FROM OPERATING ACTIVITIES:
Net loss	$ (192,766)	$ (130,206)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	50,839	44,671
Amortization of intangible assets	408	418
Deferred income taxes	80,121	98,493
Stock-based compensation	9,884	9,501
Loss on solar energy systems and property and equipment	4,439	5,024
Non-cash interest and other expense	15,317	7,355
Reduction in lease pass-through financing obligation	(3,549)	(3,545)
(Gains) losses on interest rate swaps	(1,279)	1,193
Changes in operating assets and liabilities:
Accounts receivable, net	(245)	(16,859)
Inventories	6,817	(8,517)
Prepaid expenses and other current assets	8,931	16,289
Prepaid tax asset, net		(62,972)
Other non-current assets, net	(8,042)	(5,921)
Accounts payable	941	994
Accrued compensation	4,390	1,500
Deferred revenue	(6,441)	11,673
Accrued and other liabilities	7,177	6,235
Net cash used in operating activities	(23,058)	(24,674)
CASH FLOWS FROM INVESTING ACTIVITIES:
Payments for the cost of solar energy systems	(233,548)	(211,225)
Payments for property and equipment	(129)	(672)
Proceeds from disposals of solar energy systems and property and equipment	2,335	1,952
Purchase of intangible assets	(223)
Proceeds from state tax credits		2,216
Net cash used in investing activities	(231,565)	(207,729)
CASH FLOWS FROM FINANCING ACTIVITIES:
Proceeds from investment by non-controlling interests and redeemable non-controlling interests	194,921	162,291
Distributions paid to non-controlling interests and redeemable non-controlling interests	(41,729)	(33,774)
Proceeds from long-term debt	917,748	306,750
Payments on long-term debt	(693,782)	(164,935)
Payments for debt issuance and deferred offering costs	(21,209)	(13,677)
Proceeds from lease pass-through financing obligation	2,491	2,467
Principal payments on capital lease obligations	(2,663)	(3,413)
Proceeds from issuance of common stock	876	603
Net cash provided by financing activities	356,653	256,312
NET INCREASE IN CASH AND CASH EQUIVALENTS, INCLUDING RESTRICTED AMOUNTS	102,030	23,909
CASH AND CASH EQUIVALENTS, INCLUDING RESTRICTED AMOUNTS—Beginning of period	154,938	123,439
CASH AND CASH EQUIVALENTS, INCLUDING RESTRICTED AMOUNTS—End of period	256,968	147,348
NONCASH INVESTING AND FINANCING ACTIVITIES:
Accrued distributions to non-controlling interests and redeemable non-controlling interests	(5,201)	(4,512)
Costs of solar energy systems included in changes in accounts payable, accounts payable—related party, accrued compensation and accrued and other liabilities	4,682	(1,901)
Vehicles acquired under capital leases	1,079	715
Solar energy system sales
NONCASH INVESTING AND FINANCING ACTIVITIES:
Receivable for state tax credits recorded as a reduction to solar energy system costs	$ 7	$ 82

Organization

Organization	9 Months Ended
	Sep. 30, 2018
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Organization	1 . Organization Vivint Solar, Inc. and its subsidiaries are collectively referred to as the “Company.” The Company most commonly offers solar energy to residential customers through long-term customer contracts, such as power purchase agreements (“PPAs”) and legal-form leases (“Solar Leases”). The Company also offers its customers the option to purchase solar energy systems (“System Sales”) through third-party loan offerings or a cash purchase. The Company enters into customer contracts through a sales organization that primarily uses a direct-to-home sales model. The long-term customer contracts under PPAs and Solar Leases are typically for 20 years and require the customer to make monthly payments to the Company. The Company has formed various investment funds and entered into long-term debt facilities to monetize the recurring customer payments under its long-term customer contracts and the investment tax credits, accelerated tax depreciation and other incentives associated with residential solar energy systems. The Company uses the cash received from the investment funds, long-term debt facilities and cash generated from operations, including System Sales, to finance a portion of the Company’s variable and fixed costs associated with installing solar energy systems.

Summary of Significant Accounti

Summary of Significant Accounting Policies	9 Months Ended
	Sep. 30, 2018
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	2 . Summary of Significant Accounting Policies Basis of Presentation and Principles of Consolidation The accompanying unaudited condensed consolidated financial statements have been prepared in accordance with generally accepted accounting principles in the United States (“GAAP”) and applicable rules and regulations of the Securities and Exchange Commission (“SEC”) regarding interim financial reporting. Certain information and note disclosures normally included in the financial statements prepared in accordance with GAAP have been condensed or omitted pursuant to such rules and regulations. As such, these unaudited condensed consolidated financial statements should be read in conjunction with the consolidated financial statements and accompanying notes included in the Company’s annual report on Form 10-K dated as of March 7, 2018. The unaudited condensed consolidated financial statements were prepared on the same basis as the audited consolidated financial statements and, in the opinion of management, reflect all adjustments (all of which were considered of normal recurring nature) considered necessary to present fairly the Company’s financial results. The results of the nine months ended September 30, 2018 are not necessarily indicative of the results to be expected for the fiscal year ending December 31, 2018 or for any other interim period or other future year. The unaudited condensed consolidated financial statements reflect the accounts and operations of the Company and those of its subsidiaries in which the Company has a controlling financial interest. The Company uses a qualitative approach in assessing the consolidation requirement for variable interest entities (“VIEs”). This approach focuses on determining whether the Company has the power to direct the activities of the VIE that most significantly affect the VIE’s economic performance and whether the Company has the obligation to absorb losses, or the right to receive benefits, that could potentially be significant to the VIE. All of these determinations involve significant management judgments and estimates. The Company has determined that it is the primary beneficiary in the operational VIEs in which it has an equity interest. The Company evaluates its relationships with the VIEs on an ongoing basis to ensure that it continues to be the primary beneficiary. All intercompany transactions and balances have been eliminated in consolidation. For additional information, see Note 12—Investment Funds. Certain prior period amounts have been reclassified to conform to current year presentation. These reclassifications did not have a significant impact on the consolidated financial statements. Use of Estimates The preparation of the condensed consolidated financial statements requires management to make estimates and assumptions that affect the amounts reported in the condensed consolidated financial statements and accompanying notes. The Company regularly makes significant estimates and assumptions including, but not limited to, investment tax credits (“ITCs”); revenue recognition; solar energy systems, net; the impairment analysis of long-lived assets; stock-based compensation; the provision for income taxes; the valuation of derivative financial instruments; the recognition and measurement of loss contingencies; and non-controlling interests and redeemable non-controlling interests. The Company bases its estimates on historical experience and on various other assumptions believed to be reasonable, the results of which form the basis for making judgments about the carrying values of assets and liabilities. Actual results could differ materially from those estimates. Liquidity In order to grow, the Company requires cash to finance the deployment of solar energy systems. As of the date of this filing, the Company will require additional sources of cash beyond current cash balances, and currently available financing facilities to fund long-term planned growth. If the Company is unable to secure additional financing when needed, or upon desirable terms, the Company may be unable to finance installation of customers’ systems in a manner consistent with past performance, cost of capital could increase, or the Company may be required to significantly reduce the scope of operations, any of which would have a material adverse effect on its business, financial condition, results of operations and prospects. While the Company believes additional financing is available and will continue to be available to support current levels of operations, the Company believes it has the ability and intent to reduce operations to the level of available financial resources for at least the next 12 months from the date of this report, if necessary. Revenue from Contracts with Customers The Company adopted ASU 2014-09, Revenue from Contracts with Customers, The Company currently accounts for PPAs, Solar Leases, and associated rebates and incentives as minimum lease payments from operating leases under ASC 840, Leases Leases, The Company has analyzed the impact of Topic 606 on System Sales and other product sales and has concluded that the revenue recognition associated with these product sales did not change in the condensed consolidated financial statements. The Company will continue to show this revenue stream as solar energy system and product sales in the condensed consolidated statement of operations. The Company’s principal performance obligation for System Sales is to design and install a solar energy system that is interconnected to the local power grid and granted permission to operate to the customer. When the solar energy system has been granted permission to operate, the customer retains all of the significant risks and rewards of ownership of the solar energy system. For certain System Sales, the Company provides limited post-sale services to monitor the productivity of the solar energy system for 20 years after it has been placed in service. The Company collects cash during the installation process and recognizes revenue for System Sales and other product sales at the placed in-service date or product delivery date less any revenue allocated to monitoring services. The Company allocates a portion of the transaction price to the monitoring services by estimating the fair market price that the Company would charge for these services if offered separately from the sale of the solar energy system. As of September 30, 2018 and December 31, 2017, the Company had allocated deferred revenue of $3.0 million and $2.1 million to monitoring services that will be recognized over the term of the monitoring services. All costs to obtain and fulfill contracts associated with System Sales and other product sales are expensed as a cost of revenue when the Company has fulfilled its performance obligation and the products have been placed into service or delivered to the customer. The Company has assessed the impact of Topic 606 as it relates to the sales of ITCs through its lease pass-through fund arrangement. The Company has concluded that revenue related to the sale of ITCs through its lease pass-through arrangement is recognized when the related solar energy systems are placed in service as the Company has completed its performance obligation to transfer ITCs to the fund investors at that time. The fund investors contributed cash to the investment fund during the installation process as payment for the ITCs. The transaction price for the ITCs was estimated using the tax credit rate of 30% multiplied by the fair market value of the solar energy systems that were placed into service in the lease pass-through fund. All of the related solar energy systems were placed in service and all related revenue would have been recognized prior to September 30, 2016 under Topic 606. Prior to the adoption of Topic 606, the Company recognized this revenue evenly over the five-year ITC recapture period. This earlier recognition of the ITC lease pass-through revenue decreased revenue for the three and nine months ended September 30, 2018 by $1.6 million and $4.8 million and would have decreased revenue for the three and nine months ended September 30, 2017 by $1.6 million and $4.8 million. As all ITC sales revenue would have been recognized prior to September 30, 2016 under Topic 606, there is no deferred revenue related to ITC sales recorded after the adoption date of January 1, 2018, and there would have been no deferred revenue as of December 31, 2017. As shown below, the cumulative adjustment related to ITC revenue recognized into retained earnings, net of tax, as of January 1, 2018 was $19.2 million. As noted above, the Company adopted Topic 606 on a modified retrospective basis. However, if the Company adjusted the comparative period to reflect the adoption of Topic 606, the following adjustments would have been made to the condensed consolidated statement of operations for the three and nine months ended September 30, 2017 (in thousands, except per share data): Three Months Ended September 30, 2017 Nine Months Ended September 30, 2017 As Previously Revenue As Previously Revenue Reported Adjustment As Adjusted Reported Adjustment As Adjusted Revenue $ 75,139 $ (1,561 ) $ 73,578 $ 201,248 $ (4,790 ) $ 196,458 Income tax expense 9,375 (424 ) 8,951 23,932 (1,299 ) 22,633 Net income available to common shareholders 6,905 (1,137 ) 5,768 25,177 (3,491 ) 21,686 Diluted earnings per share 0.06 (0.01 ) 0.05 0.21 (0.03 ) 0.18 Additionally, the following adjustments would have been made to the condensed consolidated balance sheet as of December 31, 2017 (in thousands): As Previously Revenue Reported Adjustment As Adjusted Current portion of deferred revenue $ 41,846 $ (7,707 ) $ 34,139 Deferred revenue, net of current portion 29,200 (18,690 ) 10,510 Deferred tax liability, net 342,382 7,160 349,542 Retained earnings 213,107 (19,237 ) 193,870 Income Taxes The Company adopted ASU 2016-16, Income Taxes (Topic 740): Intra-Entity Transfers of Assets Other Than Inventory The adoption of ASU 2016-16 had the following effect on the Company’s condensed consolidated statement of operations for the three and nine months ended September 30, 2018 (in thousands, except per share data): Three Months Ended September 30, 2018 Nine Months Ended September 30, 2018 Pre-Adoption Effect of Pre-Adoption Effect of Accounting Adoption As Reported Accounting Adoption As Reported Income tax expense $ 8,514 $ 17,184 $ 25,698 $ 32,893 $ 46,800 $ 79,693 Net loss (55,508 ) (17,184 ) (72,692 ) (145,966 ) (46,800 ) (192,766 ) Net loss attributable to common shareholders 9,316 (17,184 ) (7,868 ) 44,072 (46,800 ) (2,728 ) Basic earnings per share 0.08 (0.15 ) (0.07 ) 0.38 (0.40 ) (0.02 ) Diluted earnings per share 0.08 (0.15 ) (0.07 ) 0.36 (0.38 ) (0.02 ) The Company adopted ASU 2018-02, Income Statement—Reporting Comprehensive Income (Topic 220): Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income , Derivative Financial Instruments The Company adopted ASU 2017-12, Derivatives and Hedging (Topic 815): Targeted Improvements to Accounting for Hedging Activities Restricted Cash The Company adopted ASU 2016-18, Statement of Cash Flows (Topic 230): Restricted Cash (a consensus of the FASB Emerging Issues Task Force) (“ASU 2016-18”) , effective January 1, 2018. This update clarified that transfers between cash and restricted cash are not reported as cash flow activities in the statements of cash flows. As such, restricted cash amounts are included with cash and cash equivalents in the beginning-of-period and end-of-period total amounts on the statements of cash flows. The Company applied this update retrospectively, which resulted in an adjustment to the beginning-of-period and end-of-period total amounts on the condensed consolidated statement of cash flows for the nine months ended September 30, 2017 to include restricted cash balances from those periods. Recent Accounting Pronouncements In July 2018, the Financial Accounting Standards Board (the “FASB”) issued ASU 2018-10 and ASU 2018-11, which clarify aspects of the guidance in ASU 2016-02, Leases (Topic 842) In June 2018, the FASB issued ASU 2018-07, Compensation—Stock Compensation (Topic 718): Improvements to Nonemployee Share-Based Payment Accounting. In August 2018, the FASB issued ASU 2018-15, Intangibles—Goodwill and Other—Internal-Use Software (Subtopic 350-40): Customer’s Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement that is a Service Contract.

Fair Value Measurements

Fair Value Measurements	9 Months Ended
	Sep. 30, 2018
Fair Value Disclosures [Abstract]
Fair Value Measurements	3 . Fair Value Measurements The Company measures and reports its cash equivalents at fair value. The following tables set forth the fair value of the Company’s financial assets and liabilities measured on a recurring basis by level within the fair value hierarchy (in thousands): September 30, 2018 Level 1 Level 2 Level 3 Total Financial Assets Interest rate swaps $ — $ 131 $ — $ 131 December 31, 2017 Level 1 Level 2 Level 3 Total Financial Assets Interest rate swaps $ — $ 14,028 $ — $ 14,028 Financial Liabilities Interest rate swaps $ — $ 1,280 $ — $ 1,280 The interest rate swaps (Level 2) were valued using a discounted cash flow model which incorporates an assessment of the risk of non-performance by the interest rate swap counterparties and the Company. The valuation model uses various observable inputs including contractual terms, interest rate curves, credit spreads and measures of volatility. During the nine months ended September 30, 2018, the Company settled the interest rate swaps associated with its 2016 Term Loan Facility and Aggregation Facility. The settlement of the interest rate swaps on the 2016 Term Loan Facility, which were designated as hedges, resulted in a $22.5 million realized gain that was recorded as a reduction to interest expense. The settlement of the interest rate swaps on the Aggregation Facility, which were not designated as hedges, resulted in a $2.0 million realized gain that was recorded as other income. The carrying values and fair values of the Company’s long-term debt were as follows (in thousands): September 30, 2018 December 31, 2017 Carrying Value Fair Value Carrying Value Fair Value Floating-rate long-term debt $ 521,081 $ 521,080 $ 757,044 $ 757,044 Fixed-rate long-term debt 658,992 674,822 199,063 238,618 Total $ 1,180,073 $ 1,195,902 $ 956,107 $ 995,662 The Company’s outstanding principal balance of long-term debt is carried at cost. The Company estimated the fair values of its floating-rate debt facilities (Level 2) to approximate their carrying values as interest accrues at floating rates based on market rates. The Company’s fixed-rate debt facilities (Level 2) were valued using quoted prices for the fixed rate debt facilities that are publicly traded, or quoted prices for corporate debt with similar terms for debt facilities that are not publicly traded.

Inventories

Inventories	9 Months Ended
	Sep. 30, 2018
Inventory Disclosure [Abstract]
Inventories	4 . Inventories Inventories consisted of the following (in thousands): September 30, December 31, 2018 2017 Solar energy systems held for sale $ 14,801 $ 21,971 Photovoltaic installation products 979 626 Total inventories $ 15,780 $ 22,597 Solar energy systems held for sale are solar energy systems under construction that have yet to be interconnected to the power grid and that will be sold to customers. Solar energy systems held for sale are stated at the lower of cost, on a first-in, first-out basis, or net realizable value. Photovoltaic installation products are stated at the lower of cost, on an average cost basis, or net realizable value.

Solar Energy Systems

Solar Energy Systems	9 Months Ended
	Sep. 30, 2018
Solar Energy Systems Disclosure [Abstract]
Solar Energy Systems	5 . Solar Energy Systems Solar energy systems, net consisted of the following (in thousands): September 30, December 31, 2018 2017 System equipment costs $ 1,604,598 $ 1,437,419 Initial direct costs related to solar energy systems 404,845 336,136 2,009,443 1,773,555 Less: Accumulated depreciation and amortization (178,180 ) (129,640 ) 1,831,263 1,643,915 Solar energy system inventory 27,480 29,617 Solar energy systems, net $ 1,858,743 $ 1,673,532 Solar energy system inventory represents the solar components and materials used in the installation of solar energy systems prior to being installed on customers’ roofs. As such, no depreciation is recorded related to this line item. The Company recorded depreciation and amortization expense related to solar energy systems of $17.0 million and $14.5 million for the three months ended September 30, 2018 and 2017. The Company recorded depreciation and amortization expense related to solar energy systems of $48.5 million and $41.0 million for the nine months ended September 30, 2018 and 2017.

Property and Equipment

Property and Equipment	9 Months Ended
	Sep. 30, 2018
Property Plant And Equipment [Abstract]
Property and Equipment	6 . Property and Equipment Property and equipment, net consisted of the following (in thousands): Estimated September 30, December 31, Useful Lives 2018 2017 Vehicles acquired under capital leases 3-5 years $ 8,957 $ 15,113 Leasehold improvements 1-12 years 12,309 15,071 Furniture and computer and other equipment 3 years 4,171 6,492 25,437 36,676 Less: Accumulated depreciation and amortization (14,355 ) (21,598 ) Property and equipment, net $ 11,082 $ 15,078 The Company recorded depreciation and amortization expense related to property and equipment of $0.9 million and $1.9 million for the three months ended September 30, 2018 and 2017 . The Company recorded depreciation and amortization expense related to property and equipment of $3.9 million and $6.4 million for the nine months ended September 30, 2018 and 2017. The Company leases fleet vehicles that are accounted for as capital leases and are included in property and equipment, net. Of total property and equipment depreciation and amortization, depreciation on vehicles under capital leases of $0.3 million and $0.7 million was capitalized in solar energy systems, net for the three months ended September 30, 2018 and 2017. The Company capitalized depreciation on vehicles under capital leases of $1.6 million and $2.7 million in solar energy systems, net for the nine months ended September 30, 2018 and 2017.

Intangible Assets

Intangible Assets	9 Months Ended
	Sep. 30, 2018
Goodwill And Intangible Assets Disclosure [Abstract]
Intangible Assets	7 . Intangible Assets Intangible assets, net consisted of the following (in thousands): September 30, December 31, 2018 2017 Cost: Internal-use software $ 1,422 $ 1,314 Developed technology 522 522 Trademarks/trade names 201 201 Customer relationships 164 164 Total carrying value 2,309 2,201 Accumulated amortization: Internal-use software (1,076 ) (872 ) Developed technology (307 ) (258 ) Trademarks/trade names (95 ) (79 ) Customer relationships (155 ) (130 ) Total accumulated amortization (1,633 ) (1,339 ) Total intangible assets, net $ 676 $ 862 The Company recorded amortization expense of $0.1 million for each of the three-month periods ended September 30, 2018 and 2017, which was included in amortization of intangible assets. The Company recorded amortization expense of $0.4 million for each of the nine-month periods ended September 30, 2018 and 2017.

Accrued Compensation

Accrued Compensation	9 Months Ended
	Sep. 30, 2018
Accrued Compensation Disclosure [Abstract]
Accrued Compensation	8 . Accrued Compensation Accrued compensation consisted of the following (in thousands): September 30, December 31, 2018 2017 Accrued payroll $ 16,640 $ 13,064 Accrued commissions 9,149 7,928 Total accrued compensation $ 25,789 $ 20,992

Accrued and Other Current Liabi

Accrued and Other Current Liabilities	9 Months Ended
	Sep. 30, 2018
Payables And Accruals [Abstract]
Accrued and Other Current Liabilities	9 . Accrued and Other Current Liabilities Accrued and other current liabilities consisted of the following (in thousands): September 30, December 31, 2018 2017 Accrued unused commitment fees and interest $ 12,220 $ 7,445 Accrued professional fees 5,813 3,977 Current portion of lease pass-through financing obligation 5,017 4,931 Sales, use and property taxes payable 3,227 3,046 Accrued workers' compensation 3,189 1,446 Accrued inventory 2,926 4,122 Workmanship accrual 1,800 1,359 Current portion of deferred rent 935 937 Other accrued expenses 2,201 2,412 Total accrued and other current liabilities $ 37,328 $ 29,675

Debt Obligations

Debt Obligations	9 Months Ended
	Sep. 30, 2018
Debt Disclosure [Abstract]
Debt Obligations	10 . Debt Obligations Debt obligations consisted of the following as of September 30, 2018 (in thousands, except interest rates): Principal Unamortized Debt Unused Borrowings Issuance Costs Net Carrying Value Borrowing Interest Maturity Outstanding Current Long-term Current Long-term Capacity Rate Date Solar asset backed notes, Series 2018-1 $ 466,000 $ (61 ) $ (9,372 ) $ 2,980 $ 453,587 $ — * October 2028 Solar asset backed notes, Series 2018-2 (1)(2) 342,833 (7 ) (7,692 ) 293 334,841 — 5.2 % August 2023 2017 Term loan facility 191,705 (170 ) (4,711 ) 6,615 180,209 — 6.0 January 2035 Forward flow loan facility 11,748 (18 ) (3,445 ) 611 7,674 118,252 5.0 (3) Credit agreement 1,287 (1 ) (124 ) 16 1,146 — 6.5 February 2023 Revolving lines of credit (4) Aggregation facility 30,000 — — — 30,000 345,000 5.4 September 2020 Working capital facility (5) 136,500 — — — 136,500 — 5.3 March 2020 Total debt $ 1,180,073 $ (257 ) $ (25,344 ) $ 10,515 $ 1,143,957 $ 463,252 Debt obligations consisted of the following as of December 31, 2017 (in thousands, except interest rates): Principal Unamortized Debt Unused Borrowings Issuance Costs Net Carrying Value Borrowing Interest Maturity Outstanding Current Long-term Current Long-term Capacity Rate Date 2017 Term loan facility $ 197,764 $ (176 ) $ (4,990 ) $ 6,644 $ 185,954 $ — 6.0 % January 2035 2016 Term loan facility 287,919 (141 ) (7,623 ) 4,962 275,193 — 4.3 August 2021 Subordinated HoldCo facility 197,625 (35 ) (3,451 ) 1,965 192,174 — 9.3 March 2020 Credit agreement 1,299 (2 ) (140 ) 14 1,143 — 6.5 February 2023 Revolving lines of credit (4) Aggregation facility 135,000 — — — 135,000 240,000 4.7 September 2020 Working capital facility (5) 136,500 — — — 136,500 — 4.8 March 2020 Total debt $ 956,107 $ (354 ) $ (16,204 ) $ 13,585 $ 925,964 $ 240,000 * The Series 2018-1 Notes are comprised of Class A and Class B Notes. Class A Notes accrue interest at 4.73%. Class B Notes accrue interest at 7.37%. (1) The Series 2018-2 Notes are comprised of Class A and Class B Notes. Class B Notes accrue interest at a rate of LIBOR plus 4.75%. Class A Notes accrue interest at a variable spread over LIBOR that results in a weighted average spread for all 2018-2 Notes of 2.95%. (2) The interest rate of this facility is partially hedged to an effective interest rate of 6.0% for $326.8 million of the principal borrowings. See Note 11—Derivative Financial Instruments. (3) The maturity date for this facility is 20 years from the end date of the borrowing availability period when all borrowings are aggregated into one term loan, which will be no later than October 31, 2019. (4) Revolving lines of credit are not presented net of unamortized debt issuance costs. (5) Facility is recourse debt, which refers to debt that is collateralized by the Company’s general assets. All of the Company’s other debt obligations are non-recourse, which refers to debt that is only collateralized by specified assets or subsidiaries of the Company. The Company’s debt facilities include customary events of default, conditions to borrowing and covenants, including covenants that restrict, subject to certain exceptions, the Company’s ability to incur indebtedness, incur liens, make investments, make fundamental changes to their business, dispose of assets, make certain types of restricted payments or enter into certain related party transactions. Additionally, the Company is required to maintain certain financial measurements and interest rate swaps for certain debt facilities. These restrictions do not impact the Company’s ability to enter into investment funds, including those that are similar to those entered into previously. The Company’s debt facilities are secured by net cash flows from long-term customer contracts. The Company was in compliance with all debt covenants as of September 30, 2018. Solar Asset Backed Notes, Series 2018-1 In June 2018, a wholly owned subsidiary of the Company issued an aggregate principal amount of $400.0 million of Solar Asset Backed Notes, Series 2018-1, Class A (the “2018-1 Class A Notes”) and an aggregate principal amount of $66.0 million of Solar Asset Backed Notes, Series 2018-1, Class B (the “2018-1 Class B Notes” and together with the 2018-1 Class A Notes, the “2018-1 Notes”). The 2018-1 Class A Notes accrue interest at a fixed rate of 4.73% and have an anticipated repayment date of October 30, 2028. The 2018-1 Class B Notes accrue interest at a fixed rate of 7.37% and have an anticipated repayment date of October 30, 2028. In addition to customary events of default and covenants, the 2018-1 Notes are subject to unscheduled prepayment events that generally are customary in nature for solar securitizations of this type, including (1) asset coverage ratios falling below certain levels, (2) a debt service coverage ratio falling below certain levels, (3) the failure to maintain insurance, and (4) the failure to repay the notes in full prior to the anticipated repayment date for such class of notes. The occurrence of an unscheduled prepayment event or an event of default could result in the more rapid repayment of the 2018-1 Notes, and the occurrence of an event of default could, in certain instances, result in the liquidation of the collateral securing the 2018-1 Notes. The 2018-1 Notes are secured by, and payable solely from the cash flow generated by the membership interests in certain indirectly owned subsidiaries of the Company, each of which subsidiaries is the managing member of a project company that owns a pool of photovoltaic systems and related Solar Leases and PPAs and ancillary rights and agreements that were originated by a wholly owned subsidiary of the Company. As of September 30, 2018, the Company had $13.5 million in required reserves outstanding in collateral accounts with the administrative agent, which are included in restricted cash and cash equivalents. Solar Asset Backed Notes, Series 2018-2 In June 2018, a wholly owned subsidiary of the Company issued an aggregate principal amount of $296.0 million of Solar Asset Backed Notes, Series 2018-2, Class A (the “2018-2 Class A Notes”) and an aggregate principal amount of $49.0 million of Solar Asset Backed Notes, Series 2018-2, Class B (the “2018-2 Class B Notes” and together with the 2018-2 Class A Notes, the “2018-2 Notes”). The 2018-2 Class A Notes accrue interest at a variable spread over the London Interbank Offered Rate (“LIBOR”) that is intended to result in a weighted average spread for all 2018-2 Notes of 2.95%. The 2018-2 Class B Notes accrue interest at a spread over LIBOR of 4.75% or, if no 2018-2 Class A Notes are outstanding, 2.95%. The Company entered into an interest rate swap concurrent with the issuance of the 2018-2 Notes that results in an implied all-in interest rate of approximately 5.95%. See Note 11—Derivative Financial Instruments. The 2018-2 Notes have a stated maturity of August 29, 2023. The 2018-2 Notes have the same events of default, covenants and unscheduled prepayment events as the 2018-1 Notes. In addition, the 2018-2 Notes are subject to unscheduled prepayment events relating to certain change of control events and certain liquidity requirements. As of September 30, 2018, the Company had $23.9 million in required reserves outstanding in collateral accounts with the administrative agent, which are included in restricted cash and cash equivalents. 2016 Term Loan Facility In June 2018, the Company used proceeds from the issuance of the 2018-1 Notes and 2018-2 Notes to pay off the outstanding balance of $282.3 million on the credit facility entered into by a wholly owned subsidiary of the Company in August 2016 (the “2016 Term Loan Facility”) and terminated the credit agreement. The outstanding balance was comprised of $281.8 million of principal and $0.5 million of accrued interest. The termination of the 2016 Term Loan Facility was accounted for as a debt extinguishment. As such, the remaining $6.9 million of unamortized debt issuance costs related to the 2016 Term Loan Facility were recognized in interest expense during the nine months ended September 30, 2018. There was no prepayment fee associated with the termination of the 2016 Term Loan Facility. Subordinated HoldCo Facility In June 2018, the Company used proceeds from the issuance of the 2018-1 Notes and 2018-2 Notes to pay off the outstanding balance of $206.4 million on the credit facility entered into by a wholly owned subsidiary of the Company in March 2016 (the “Subordinated HoldCo Facility”) and terminated the financing agreement. The outstanding balance was comprised of $196.6 million of principal, $3.9 million of accrued interest, and a prepayment fee of $5.9 million, which was calculated as 3.0% of the outstanding principal balance. The termination of the Subordinated HoldCo Facility was accounted for as a debt extinguishment. As such, the remaining $2.9 million of unamortized debt issuance costs related to the Subordinated HoldCo Facility were recognized in interest expense during the nine months ended September 30, 2018. The prepayment fee of $5.9 million was also recognized in interest expense during the nine months ended September 30, 2018. 2017 Term Loan Facility In January 2017, a wholly owned subsidiary of the Company entered into a long-term fixed rate credit agreement (the “2017 Term Loan Facility”). Interest on borrowings accrues at an annual fixed rate equal to 6.0% and is payable in arrears. Certain principal payments are due on a quarterly basis, subject to the occurrence of certain events. As of September 30, 2018, the Company had $19.4 million in required reserves Forward Flow Loan Facility In August 2018, a subsidiary which is indirectly owned by the Company together with investors, entered into a loan agreement (the “Forward Flow Loan Facility”) pursuant to which the Company may borrow up to an aggregate principal amount of $130.0 million. The borrower may make multiple borrowings under the Forward Flow Loan Facility during the availability period, which is expected to continue into late 2019. After the availability period, all outstanding loans under the Forward Flow Loan Facility will be aggregated into a single term loan with a maturity date 20 years after the date of aggregation. Interest on each loan will accrue at an annual rate equal to the U.S. swap rate for the weighted-average life of such loan, plus an applicable margin equal to the greater of (a) 1.9% plus a spread adjustment based on the risk premium on the borrowing date relative to the market index-based risk premium on the closing date and (b) 1.5%. Scheduled principal payments are due on a quarterly basis, at the end of January, April, July and October of each year. Upon the occurrence of certain events, the Company will be required to make prepayments of the loans, including payment of a make-whole amount in certain circumstances. As of September 30, 2018, the Company had $0.4 million in required reserves outstanding in collateral accounts with the administrative agent, which were included in restricted cash and cash equivalents. Credit Agreement In February 2016, a wholly owned subsidiary of the Company entered into a fixed rate credit agreement (the “Credit Agreement”). Principal and interest payments under the Credit Agreement are paid quarterly over the term of the loan. Interest accrues on borrowings at a fixed rate of 6.50%. Aggregation Facility In September 2014, a wholly owned subsidiary of the Company entered into an aggregation credit facility (as amended, the “Aggregation Facility”), pursuant to which the Company may borrow up to an aggregate of $375.0 million and, upon the satisfaction of certain conditions and the approval of the lenders, up to an additional aggregate of $175.0 million in borrowings. Prepayments are permitted under the Aggregation Facility. Under the Aggregation Facility, interest on borrowings accrues at a floating rate equal to either (1)(a) LIBOR or (b) the greatest of (i) the Federal Funds Rate plus 0.5%, (ii) the administrative agent’s prime rate and (iii) LIBOR plus 1% and (2) a margin that varies between 3.25% during the period during which the Company may incur borrowings and 3.75% after such period. As of September 30, 2018, the Company had $1.0 million in required reserves outstanding in collateral accounts with the administrative agent, which were included in restricted cash and cash equivalents. Working Capital Facility In March 2015, a wholly owned subsidiary of the Company entered into a revolving credit agreement (the “Working Capital Facility”) pursuant to which the Company may borrow up to an aggregate principal amount of $150.0 million from certain financial institutions. In addition to the outstanding borrowings as of September 30, 2018, the Company had established letters of credit under the Working Capital Facility for up to $13.5 million related to insurance contracts. Prepayments are permitted under the Working Capital Facility. Interest accrues on borrowings at a floating rate equal to, depending on the type of borrowing, (1) a rate equal to the Eurodollar Rate for the interest period divided by one minus the Eurodollar Reserve Percentage, plus a margin of 3.25%; or (2) the highest of (a) the Federal Funds Rate plus 0.50%, (b) the Citibank prime rate and (c) the one-month interest period Eurodollar rate plus 1.00%, plus a margin of 2.25%. Interest is payable depending on the type of borrowing at the end of (1) the interest period that the Company may elect as a term, not to exceed three months, (2) quarterly or (3) at maturity of the Working Capital Facility. The Company is required to maintain $30.0 million in cash and cash equivalents and certain investments as of the last day of each quarter. As of September 30, 2018, the Company was in compliance with such covenants.

Derivative Financial Instrument

Derivative Financial Instruments	9 Months Ended
	Sep. 30, 2018
Derivative Instruments And Hedging Activities Disclosure [Abstract]
Derivative Financial Instruments	11 . Derivative Financial Instruments Derivative financial instruments consisted of the following at fair value (in thousands): September 30, 2018 Fair Value Balance Sheet Location Derivatives designated as hedging instruments: Interest rate swaps $ 131 Other non-current assets, net December 31, 2017 Fair Value Balance Sheet Location Derivatives designated as hedging instruments: Interest rate swaps $ 14,028 Other non-current assets, net Derivatives not designated as hedging instruments: Interest rate swaps $ 1,280 Other non-current liabilities The Company is exposed to interest rate risk relating to its outstanding debt facilities that have variable interest rates. In connection with the 2016 Term Loan Facility, the Company entered into interest rate swaps to offset changes in the variable interest rate for a portion of the Company’s LIBOR-indexed floating-rate loans. During the nine months ended September 30, 2018, the Company paid off and terminated the 2016 Term Loan Facility and settled all outstanding interest rate swaps associated with the 2016 Term Loan Facility. As a result of settling the interest rate swaps, which were designated as hedges, the Company realized a $22.5 million gain that was recorded as a reduction to interest expense. In connection with the March 2017 amendment of the Aggregation Facility, the Company is required to maintain interest rate swaps such that at least 75% of the outstanding loan balance of the Aggregation Facility is hedged. The Company is required to meet this threshold within 15 business days after the end of each quarterly period. During the second quarter of 2018, the outstanding balance of the Aggregation Facility was paid off, and as a result, the Company settled all outstanding interest rate swaps associated with the Aggregation Facility during that quarter. The settlement of the interest rate swaps, which were not designated as hedges, resulted in a realized gain of $2.0 million that was recorded as other income. As of September 30, 2018, the Company had drawn on the Aggregation Facility again but had not yet opened the required interest rate swaps. The Company entered the required swaps subsequent to period end and is in compliance with the hedging requirement. In connection with the 2018-2 Notes, the Company entered into interest rate swaps to offset changes in the variable interest rate for a portion of these notes. As of September 30, 2018, the notional amount of these interest rate swaps was $326.8 million. The notional amount of the interest rate swaps decreases through the maturity of the 2018-2 Notes, similar to the Company’s estimated semi-annual principal payments on the 2018-2 Notes through August 2023. The interest rate swaps are designated as cash flow hedges, and unrealized gains or losses are recorded in other comprehensive income (“OCI”). The amount of AOCI expected to be reclassified to interest expense within the next 12 months is approximately $1.0 million. The Company will discontinue the hedge accounting designation of these derivatives if interest payments on LIBOR-indexed floating rate loans compared to the payments under the derivatives are no longer highly effective. The Company adopted ASU 2017-12 as of January 1, 2018. Among other changes, this update eliminated the separate measurement of hedge ineffectiveness. The Company adopted this update using a modified retrospective method with a cumulative-effect adjustment to retained earnings as of January 1, 2018. As a result, the Company ceased measuring hedge ineffectiveness beginning January 1, 2018, while prior period measurements remain unchanged. See Note 2—Summary of Significant Accounting Policies. The Company records derivatives at fair value. The (gains) losses on derivatives designated as cash flow hedges recognized in OCI, before tax effect, consisted of the following (in thousands): Three Months Ended September 30, 2018 2017 Derivatives designated as cash flow hedges: Interest rate swaps $ (3,966 ) $ 828 Nine Months Ended September 30, 2018 2017 Derivatives designated as cash flow hedges: Interest rate swaps $ (8,284 ) $ 2,688 The (gains) losses on derivative financial instruments recognized in the condensed consolidated statements of operations, before tax effect, consisted of the following (in thousands): Three Months Ended September 30, 2018 2017 Interest expense, net Other (income) expense, net Interest expense, net Other (income) expense, net Total amounts presented in the income statement line items $ 18,715 $ (1 ) $ 16,148 $ 195 Derivatives designated as cash flow hedges: Interest rate swaps Losses (gains) reclassified from AOCI into income $ 535 $ — $ (156 ) $ — Gains recognized in income - ineffective portion: — — — (120 ) Derivatives not designated as hedging instruments: Interest rate swaps Losses recognized in income — — — 320 Total losses (gains) $ 535 $ — $ (156 ) $ 200 Nine Months Ended September 30, 2018 2017 Interest expense, net Other (income) expense, net Interest expense, net Other (income) expense, net Total amounts presented in the income statement line items $ 46,973 $ (6,371 ) $ 47,707 $ 1,186 Derivatives designated as cash flow hedges: Interest rate swaps Gains reclassified from AOCI into income $ (22,181 ) $ — $ (13 ) $ — Gains recognized in income - ineffective portion: — — — (641 ) Derivatives not designated as hedging instruments: Interest rate swaps (Gains) losses recognized in income — (4,252 ) — 1,834 Total (gains) losses $ (22,181 ) $ (4,252 ) $ (13 ) $ 1,193

Investment Funds

Investment Funds	9 Months Ended
	Sep. 30, 2018
Summarized Financial Data Of Subsidiary [Abstract]
Investment Funds	12 . Investment Funds As of September 30, 2018 and December 31, 2017, the Company had formed investment funds for the purpose of funding the purchase of solar energy systems under long-term customer contracts. The aggregate carrying value of these funds’ assets and liabilities (after elimination of intercompany transactions and balances) in the Company’s condensed consolidated balance sheets were as follows (in thousands): September 30, December 31, 2018 2017 Assets Current assets: Cash and cash equivalents $ 78,906 $ 17,280 Accounts receivable, net 11,052 5,143 Prepaid expenses and other current assets 1,753 952 Total current assets 91,711 23,375 Restricted cash and cash equivalents 438 — Solar energy systems, net 1,636,300 1,486,023 Other non-current assets, net 9,529 6,792 Total assets $ 1,737,978 $ 1,516,190 Liabilities Current liabilities: Distributions payable to non-controlling interests and redeemable non-controlling interests $ 11,236 $ 16,437 Current portion of long-term debt 611 — Current portion of deferred revenue 1,793 9,176 Accrued and other current liabilities 4,540 4,478 Total current liabilities 18,180 30,091 Long-term debt, net of current portion 7,674 — Deferred revenue, net of current portion 9,408 26,847 Other non-current liabilities 982 1,444 Total liabilities $ 36,244 $ 58,382 Under the fund agreements, cash distributions of income and other receipts by the funds, net of agreed-upon expenses and estimated expenses, tax benefits and detriments of income and loss, and tax benefits of tax credits, are assigned to the fund investors and the Company’s subsidiaries as specified in contractual arrangements. As such, the cash held in investment funds is not readily available to the Company due to the timing of distributions. Certain of these fund arrangements have call and put options to acquire the investor’s equity interest as specified in the contractual agreements. Once the investor’s equity interest is acquired by the Company, the assets, liabilities and operations of the investment fund become wholly owned and no longer require an assessment of non-controlling interests. Fund investors for three of the funds are managed indirectly by The Blackstone Group L.P. (the “Sponsor”) and are considered related parties. As of September 30, 2018 and December 31, 2017, the cumulative total of contributions into the VIEs by all investors was $1,459.5 million and $1,264.6 million. Of these contributions, a cumulative total of $110.0 million was contributed by related parties in prior periods. A third-party provider has agreed to perform backup maintenance services for all funds, if necessary. Lease Pass-Through Financing Obligation During 2015, a wholly owned subsidiary of the Company entered into a lease pass-through fund arrangement under which the Company contributed solar energy systems and the investor contributed cash. The net carrying value of the related solar energy systems was $56.4 million and $58.2 million as of September 30, 2018 and December 31, 2017. The Company adopted Topic 606 as of January 1, 2018. The Company has assessed the impact of Topic 606 as it relates to the sales of ITCs through its lease pass-through fund arrangement. The Company has concluded that revenue related to the sale of ITCs through its lease pass-through arrangement is recognized when the related solar energy systems are placed in service as the Company has completed its performance obligation to transfer ITCs to the funds investors at that time. The fund investors contributed cash to the investment fund during the installation process as payment for the ITCs. The transaction price for the ITCs was estimated using the tax credit rate of 30% times the fair market value of the solar energy systems that were placed into service in the lease pass-through fund. All of the related solar energy systems were placed in service and all related revenue would have been recognized prior to September 30, 2016 under Topic 606. Prior to the adoption of Topic 606, the Company recognized this revenue evenly over the five-year ITC recapture period. The Company adopted Topic 606 on a modified retrospective basis with a cumulative adjustment to retained earnings as of January 1, 2018. As all ITC sales revenue would have been recognized prior to September 30, 2016 under Topic 606, the Company removed previously recorded deferred revenue related to ITC sales by recording it to retained earnings as of the adoption date of Topic 606. See Note 2—Summary of Significant Accounting Policies. The Company accounts for the residual of the large upfront payments, net of amounts allocated to the ITCs, and subsequent periodic payments received from the fund investor as a borrowing by recording the proceeds received as a lease pass-through financing obligation, which will be repaid through customer payments that will be received by the investor. Under this approach, the Company continues to account for the arrangement with the customers in its condensed consolidated financial statements, whether the cash generated from the customer arrangements is received by the Company’s wholly owned subsidiary or paid directly to the fund investor. A portion of the amounts received by the fund investor from customer payments is applied to reduce the lease pass-through financing obligation, and the balance is allocated to interest expense. The customer payments are recognized into revenue based on cash receipts during the period as required by GAAP. Interest is calculated on the lease pass-through financing obligation using the effective interest rate method. The effective interest rate is the interest rate that equates the present value of the cash amounts to be received by a fund investor over the master lease term with the present value of the cash amounts paid by the investor to the Company, adjusted for any payments made by the Company. Any additional master lease prepayments by the investor would be recorded as an additional lease pass-through financing obligation, while any refunds of master lease prepayments would reduce the lease pass-through financing obligation. The lease pass-through financing obligation is nonrecourse. As of September 30, 2018, the Company had recorded financing liabilities of $5.3 million related to this fund arrangement, which was the lease pass-through financing obligation recorded in other liabilities. As of December 31, 2017, the Company had recorded financing liabilities of $32.1 million related to this fund arrangement, of which $26.4 million was deferred revenue and $5.8 million was the lease pass-through financing obligation recorded in other liabilities. Guarantees With respect to the investment funds, the Company and the fund investors have entered into guaranty agreements under which the Company guarantees the performance of certain financial obligations of its subsidiaries to the investment funds. These guarantees do not result in the Company being required to make payments to the fund investors unless such payments are mandated by the investment fund governing documents and the investment fund fails to make such payment. Each of the Company’s investment funds and financing subsidiaries maintains separate books and records from each other and from the Company. The assets of each investment fund are not available to satisfy the debts or obligations of any other investment fund, subsidiary or the Company. The Company is contractually obligated to make certain VIE investors whole for losses that the investors may suffer in certain limited circumstances resulting from the disallowance or recapture of ITCs. The Company has concluded that the likelihood of a significant recapture event is remote and consequently has not recorded any liability in the condensed consolidated financial statements for any potential recapture exposure. The maximum potential future payments that the Company could have to make under this obligation would depend on the Internal Revenue Service (“IRS”) successfully asserting upon audit that the fair market values of the solar energy systems sold or transferred to the funds as determined by the Company exceeded the allowable basis for the systems for purposes of claiming ITCs. The fair market values of the solar energy systems and related ITCs are determined and the ITCs are allocated to the fund investors in accordance with the funds’ governing agreements. Due to uncertainties associated with estimating the timing and amounts of distributions, the likelihood of an event that may trigger repayment, forfeiture or recapture of ITCs to such investors, and the fact that the Company cannot determine how the IRS will evaluate system values used in claiming ITCs, the Company cannot determine the potential maximum future payments that are required under these guarantees. As of September 30, 2018, the Company has not made any payments under these guarantees. However, several recent investment funds, the 2018-1 Notes and the 2018-2 Notes have required the Company to prepay insurance premiums to cover the risk of ITC recapture. The Company amortizes this prepaid insurance expense over the ITC recapture period. The Company had prepaid insurance balances of $8.6 million and $2.4 million as of September 30, 2018 and December 31, 2017. From time to time, the Company incurs penalties for non-performance, which non-performance may include, but is not limited to, delays in the installation process and interconnection to the power grid of solar energy systems and other factors. Based on the terms of the investment fund agreements, the Company will either reimburse a portion of the fund investor’s capital or pay the fund investor a non-performance fee. No distributions were paid to reimburse fund investors during the three months ended September 30, 2018. Distributions paid to reimburse fund investors totaled $11.9 million during nine months ended September 30, 2018. As of September 30, 2018, As a result of the guaranty arrangements in certain funds, the Company was required to hold a minimum cash balance of $10.0 million as of September 30, 2018 and December 31, 2017, which is classified as restricted cash and cash equivalents.

Redeemable Non-Controlling Inte

Redeemable Non-Controlling Interests and Equity	9 Months Ended
	Sep. 30, 2018
Equity [Abstract]
Redeemable Non-Controlling Interests and Equity	13 . Redeemable Non-Controlling Interests and Equity Common Stock The Company had reserved shares of common stock for issuance as follows (in thousands): September 30, December 31, 2018 2017 Shares available for grant under equity incentive plans 13,242 12,774 Restricted stock units issued and outstanding 6,653 6,688 Stock options issued and outstanding 3,792 3,837 Long-term incentive plan 2,706 2,706 Total 26,393 26,005 Redeemable Non-Controlling Interests, Equity and Non-Controlling Interests The changes in redeemable non-controlling interests were as follows (in thousands): Balance as of December 31, 2017 $ 122,444 Contributions from redeemable non-controlling interests 72,078 Distributions to redeemable non-controlling interests (7,663 ) Net loss (65,039 ) Balance as of September 30, 2018 $ 121,820 The changes in stockholders’ equity and non-controlling interests were as follows (in thousands): Total Stockholders' Non-Controlling Equity Interests Total Equity Balance as of December 31, 2017 $ 780,951 $ 80,115 $ 861,066 Cumulative-effect adjustment from adoption of new ASUs (473,828 ) — (473,828 ) Stock-based compensation expense 9,884 — 9,884 Issuance of common stock 876 — 876 Contributions from non-controlling interests — 122,843 122,843 Distributions to non-controlling interests — (28,865 ) (28,865 ) Total other comprehensive loss (10,128 ) — (10,128 ) Net loss (2,728 ) (124,999 ) (127,727 ) Balance as of September 30, 2018 $ 305,027 $ 49,094 $ 354,121 Accumulated Other Comprehensive Income The changes in AOCI are related to the Company’s cash flow hedges. The changes in AOCI, net of tax, were as follows (in thousands): Accumulated Other Comprehensive Income Balance as of December 31, 2017 $ 6,905 Cumulative-effect adjustment from adoption of new ASUs 3,318 Other comprehensive income before reclassifications 6,037 Less: Amounts reclassified from AOCI 16,165 Balance as of September 30, 2018 $ 95 Redeemable Non-Controlling Interests and Non-Controlling Interests Seven of the investment funds include a right for the non-controlling interest holder to require the Company’s wholly owned subsidiary to purchase all of its membership interests in the fund (each, a “Put Option”). The purchase price for the fund investor’s interest in the seven investment funds under the Put Options is the greater of fair market value at the time the option is exercised and a specified amount, ranging from $2.1 million to $4.1 million. The Put Options for these seven investment funds are exercisable beginning on the date that specified conditions are met for each respective fund. None of the Put Options are expected to become exercisable prior to 2021. Because the Put Options represent redemption features that are not solely within the control of the Company, the non-controlling interests in these investment funds are presented outside of permanent equity. Redeemable non-controlling interests are recorded using the greater of their carrying value at each reporting date (which is impacted by attribution under the hypothetical liquidation at book value (“HLBV”) method) or their estimated redemption value in each reporting period. In all investment funds except one, the Company’s wholly owned subsidiary has the right to require the non-controlling interest holder to sell all of its membership units to the Company’s wholly owned subsidiary (each, a “Call Option”). The purchase price for the fund investors’ interests under the Call Options varies by fund, but is generally the greater of a specified amount, which ranges from approximately $1.2 million to $7.0 million, the fair market value of such interest at the time the option is exercised, or an amount that causes the fund investor to achieve a specified return on investment. The Call Options are exercisable beginning on the date that specified conditions are met for each respective fund. None of the Call Options are expected to become exercisable prior to 2020.

Equity Compensation Plans

Equity Compensation Plans	9 Months Ended
	Sep. 30, 2018
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Equity Compensation Plans	14 . Equity Compensation Plans Equity Incentive Plans 2014 Equity Incentive Plan The Company currently grants equity awards through its 2014 Equity Incentive Plan (the “2014 Plan”). Under the 2014 Plan, the Company may grant stock options, restricted stock, restricted stock units (“RSUs”), stock appreciation rights, performance stock units, performance shares and performance awards to its employees, directors and consultants, and its parent and subsidiary corporations’ employees and consultants. As of September 30, 2018, a total of 13.2 million shares of common stock were available to grant under the 2014 Plan, subject to adjustment in the case of certain events. The number of shares available to grant under the 2014 Plan is subject to an annual increase on the first day of each year. In accordance with the annual increase, an additional 4.6 million shares became available to grant in January 2018 under the 2014 Plan. Equity Award Modifications Sales Leader Awards In July 2018, the Company modified 0.4 million performance-based equity awards for members of its sales leadership team as it was considered improbable that the performance targets would be met. As a result of the modification, the awards are now considered probable of being met, and expense is being recorded accordingly. This was accounted for as a modification; however, there was no incremental expense arising from the modification. Stock Options Stock Option Activity Stock option activity for the nine months ended September 30, 2018 was as follows (in thousands, except term and per share amounts): Weighted- Weighted- Average Shares Average Remaining Aggregate Underlying Exercise Contractual Intrinsic Options Price Term (in years) Value Outstanding—December 31, 2017 3,837 $ 2.01 $ 8,522 Granted 827 3.93 Exercised (780 ) 1.12 Cancelled (92 ) 2.27 Outstanding—September 30, 2018 3,792 $ 2.60 7.1 $ 10,447 Options vested and exercisable—September 30, 2018 1,840 $ 2.06 5.9 $ 6,290 RSUs RSU activity for the nine months ended September 30, 2018 was as follows (awards in thousands): Weighted- Average Number of Grant Date Awards Fair Value Outstanding at December 31, 2017 6,688 $ 3.20 Granted 3,986 4.13 Vested (3,436 ) 2.98 Forfeited (585 ) 3.42 Outstanding at September 30, 2018 6,653 $ 3.85 Stock-Based Compensation Expense Stock-based compensation was included in operating expenses as follows (in thousands): Three Months Ended Nine Months Ended September 30, September 30, 2018 2017 2018 2017 Cost of revenue $ 361 $ 164 $ 984 $ 738 Sales and marketing 754 601 2,668 2,710 General and administrative 1,956 1,421 6,125 5,763 Research and development 32 63 107 290 Total stock-based compensation $ 3,103 $ 2,249 $ 9,884 $ 9,501 Unrecognized stock-based compensation expense for stock options and RSUs as of September 30, 2018 was as follows (in thousands, except years): Unrecognized Weighted- Stock-Based Average Period Compensation of Recognition Expense (in years) RSUs $ 20,105 1.8 Stock options 2,516 1.8 Total unrecognized stock-based compensation expense $ 22,621

Income Taxes

Income Taxes	9 Months Ended
	Sep. 30, 2018
Income Tax Disclosure [Abstract]
Income Taxes	15 . Income Taxes The income tax expense for the three months ended September 30, 2018 and 2017 was calculated on a discrete basis resulting in a consolidated quarterly effective income tax rate of (54.7)% and (33.1)%. For the nine months ended September 30, 2018 and 2017 the Company’s consolidated effective income tax rate was (70.5)% and (22.5)% .The variations between the consolidated effective income tax rate and the U.S. federal statutory rate for the three and nine months ended September 30, 2018 and 2017 were primarily attributable to the net effects of adopting ASU 2016-16, non-controlling interests and redeemable non-controlling interests, federal investment tax credits and the TCJA reducing the federal corporate income tax rate from 35% to 21% beginning in 2018. The TCJA made significant changes to the U.S. tax code, which include, but are not limited to, a reduced U.S. federal corporate tax rate, a provision that limits the amount of deductible interest expense, full expensing of acquired property, limitations on the utilization of net operating loss carryforwards, the repeal of the domestic production activity deduction, limitations on the deductibility of certain executive compensation, and the tax year of income inclusion. The Company recorded a provisional net tax benefit of $187.5 million related to the remeasurement of its deferred tax balances to reflect the corporate rate reduction in the period ended December 31, 2017. Although the Company is able to make a reasonable estimate of the impacts of the TCJA, it continues to analyze the temporary differences that existed on the date of enactment and the other previously mentioned provisions that come into effect for tax years starting after 2017 to determine if these items would impact the effective tax rate. The impact of the TCJA may differ from the Company’s estimates, possibly materially, due to, among other things, changes in interpretations and assumptions the Company has made, guidance that may be issued and actions the Company may take as a result of the TCJA. The Company sells solar energy systems to the investment funds for income tax purposes. As the investment funds are consolidated by the Company, the gain on the sale of the solar energy systems is eliminated in the condensed consolidated financial statements. However, this gain is recognized for tax reporting purposes. With the adoption of ASU 2016-16, the Company now accounts for the income tax consequences of these intra-entity transfers, both current and deferred, as a component of income tax expense and deferred tax liability, net during the period in which the transfers occur. Prior to the adoption of ASU 2016-16, any tax expense incurred related to these intra-entity sales was deferred and amortized over the estimated useful life of the underlying solar energy systems, which was estimated to be 30 years. Accordingly, the Company had recorded a prepaid tax asset, net, of $505.9 million as of December 31, 2017, which was removed as of January 1, 2018 when the Company adopted ASU 2016-16. See Note 2—Summary of Significant Accounting Policies. Uncertain Tax Positions As of September 30, 2018 and December 31, 2017, the Company had no unrecognized tax benefits. There was no interest or penalties accrued for any uncertain tax positions as of September 30, 2018 and December 31, 2017. The Company does not have any tax positions for which it is reasonably possible the total amount of gross unrecognized benefits will increase or decrease within the next 12 months. The Company is subject to taxation and files income tax returns in the United States, and various state and local jurisdictions. The U.S. and state jurisdictions in which the Company operates have statutes of limitations that generally range from three to four years. The Company’s federal, state and local income tax returns starting with the 2015 tax year are subject to audit. The Company’s 2014 income tax returns for four states are also subject to audit.

Related Party Transactions

Related Party Transactions	9 Months Ended
	Sep. 30, 2018
Related Party Transactions [Abstract]
Related Party Transactions	16 . Related Party Transactions The Company’s condensed consolidated statements of operations included the following related party transactions (in thousands): Three Months Ended Nine Months Ended September 30, September 30, 2018 2017 2018 2017 Cost of revenue—operating leases and incentives $ — $ 70 $ — $ 701 Sales and marketing 340 697 1,651 1,959 General and administrative — 15 — 139 Vivint Services The Company has negotiated and entered into a number of agreements with its sister company, Vivint, Inc. (“Vivint”). Some of those agreements related to the Company’s use of certain of Vivint’s information technology and infrastructure services; however, the Company stopped using such services in July 2017. In August 2017, the Company entered into a sales dealer agreement with Vivint, pursuant to which each company will act as a non-exclusive dealer for the other party to market, promote and sell each other’s products. The agreement has an initial term of two years and replaces substantially all of the activities being undertaken under the parties’ former marketing and customer relations agreement. The Company and Vivint also agreed to extend the term of the non-solicitation provisions under an existing non-competition agreement to match the term of the sales dealer agreement. The Company incurred fees under agreements with Vivint of $6.1 million and $0.7 million for the three months ended September 30, 2018 and 2017, which reflect the amount of services provided by Vivint on behalf of the Company. The Company incurred fees under these agreements of $11.4 million and $1.8 million for the nine months ended September 30, 2018 and 2017. Payables to Vivint recorded in accounts payable—related party were $0.1 million and $0.2 million as of September 30, 2018 and December 31, 2017. These payables include amounts due to Vivint related primarily to the sales dealer agreement. Advances Receivable — Net amounts due from direct-sales personnel were $5.7 million and $6.6 million as of September 30, 2018 and December 31, 2017. The Company provided a reserve of $1.0 million as of September 30, 2018 and December 31, 2017 related to advances to direct-sales personnel who have terminated their employment agreement with the Company. Investment Funds Fund investors for three of the investment funds are indirectly managed by the Sponsor and accordingly are considered related parties. The Company accrued equity distributions to these entities of $1.8 million and $1.2 million as of September 30, 2018 and December 31, 2017, included in distributions payable to non-controlling and redeemable non-controlling interests. See Note 12—Investment Funds.

Commitments and Contingencies

Commitments and Contingencies	9 Months Ended
	Sep. 30, 2018
Commitments And Contingencies Disclosure [Abstract]
Commitments and Contingencies	17 . Commitments and Contingencies Non-Cancellable Operating Leases The Company has entered into operating lease agreements for corporate and operating facilities, warehouses and related equipment in states in which the Company conducts operations. The aggregate expense incurred under these operating leases was $3.6 million and $4.0 million for the three months ended September 30, 2018 and 2017. The aggregate expense incurred under these operating leases was $11.3 million and $12.4 million for the nine months ended September 30, 2018 and 2017. Letters of Credit As of September 30, 2018, the Company had established letters of credit under the Working Capital Facility for up to $13.5 million related to insurance contracts. See Note 10—Debt Obligations. Indemnification Obligations From time to time, the Company enters into contracts that contingently require it to indemnify parties against claims. These contracts primarily relate to provisions in the Company’s services agreements with related parties that may require the Company to indemnify the related parties against services rendered; and certain agreements with the Company’s officers and directors under which the Company may be required to indemnify such persons for liabilities. In addition, under the terms of the agreements related to the Company’s investment funds and other material contracts, the Company may also be required to indemnify fund investors and other third parties for liabilities. For further information see Note 12—Investment Funds. Residual Commission Payments The Company pays a portion of sales commissions to its sales representatives on a deferred basis. The amount deferred is based on the value of the system sold by the sales representative and payment is based on the sales representative remaining employed by the Company. As this amount is earned over time, it is not considered an initial direct cost of obtaining the contract due to the requirement that the sales representative remain in the Company’s service. As a result, the amount that is earned over time is expensed by the Company over the deferment period. As of September 30, 2018, the total estimated obligation that is currently not recorded in the Company’s condensed consolidated financial statements, but that will be earned and expensed over the deferment period was $12.5 million. Legal Proceedings In September 2015, two of the Company’s customers, on behalf of themselves and a purported class, named the Company in a putative class action, Case No. BCV-15-100925 (Cal. Super. Ct., Kern County), alleging violation of California Business and Professions Code Section 17200 and requesting relief pursuant to Section 1689 of the California Civil Code. The complaint sought: (1) rescission of their PPAs along with restitution to the plaintiffs individually and (2) declaratory and injunctive relief. In October 2015, the Company moved to compel arbitration of the plaintiffs’ claims pursuant to the provisions set forth in the PPAs, which the Court granted and dismissed the class claims without prejudice. The plaintiffs appealed the Court’s order. On July 26, 2017, the Court of Appeal for the Fifth Appellate District ruled that all issues concerning the interpretation, validity, or enforceability of the PPAs, including the arbitrability of class claims, must be submitted to arbitration. The appellate court vacated the portion of the trial court's order dismissing class claims, requiring that issue to be determined by an arbitrator. The case proceeded in arbitration administered by JAMS. In June 2018, the parties reached a settlement with the two individual plaintiffs. In March 2016, the Company filed suit in the Court of Chancery State of Delaware against SunEdison and SEV Merger Sub Inc. alleging that SunEdison willfully breached its obligations under the Merger Agreement pursuant to which the Company was to be acquired and breached its implied covenant of good faith and fair dealing. In April 2016, SunEdison filed for Chapter 11 bankruptcy, which stayed prosecution of the Company’s litigation in the Delaware court. In September 2016, the Company submitted a proof of claim in the bankruptcy case for an unsecured claim in the initial amount of $1.0 billion, which was subject to dispute, for damages for breach of the Merger Agreement. In April 2018, the Company reached a settlement with the litigation trustee in the bankruptcy case under which the Company’s claim will be allowed in the amount of $590.0 million. This settlement resolves both the lawsuit in the Delaware Chancery Court and the dispute about the amount of the Company’s unsecured creditor claim in the bankruptcy. In April 2018, the Company received an initial distribution of $2.1 million and expects to receive further distributions as assets are distributed to unsecured creditors under the court-approved plan of reorganization in the SunEdison bankruptcy case. While the exact amount to be distributed for this claim is unknown at this time, the payout is expected to be a small fraction of the $590.0 million claim. In November 2016, a customer of the Company filed a putative class action lawsuit in Superior Court in Alameda County, California, purportedly on behalf of all customers of a particular Company sales representative in California, claiming that the representative’s sales practices were improper under California consumer protection law. The Company moved to dismiss that action to compel arbitration. In March 2017, the original plaintiff filed an amended complaint adding an additional plaintiff, purporting to expand the proposed class to include all customers who are eligible for the California Alternate Rates for Energy program, and adding claims of misconduct in the Company’s sales practices apart from the individual representative identified in the original complaint. The Company moved to compel arbitration of the new plaintiff’s claims as well. The Company disputed the allegations in both the original and amended complaints. In January 2018, the parties reached a settlement with the two individual plaintiffs. Under the settlement, in addition to certain changes to its sales process and immaterial compensation payments to the individual plaintiffs, the Company agreed to pay attorneys’ fees. On May 29, 2018, the court entered an order requiring the Company to pay attorneys’ fees and costs, both of which have now been paid, and which were immaterial to the Company’s results of operations. In March 2018, the New Mexico Attorney General’s office filed an action against the Company and several of its officers alleging violation of state consumer protection statutes and other claims. The Company disputes the allegations in the lawsuit and intends to defend itself in the action. The Company is unable to estimate a range of loss, if any, were there to be an adverse final decision. If an unfavorable outcome were to occur in this case, it is possible that the impact could be material to the Company’s results of operations in the period(s) in which any such outcome becomes probable and estimable. In June 2018, four of the Company’s customers, on behalf of themselves and a purported class, named the Company in a putative class action alleging violations of the Consumers Legal Remedies Act and California Business and Professions Code Section 17200 and requesting relief pursuant to Section 1689 of the California Civil Code. The complaint sought (1) rescission of their PPAs along with restitution to the plaintiffs individually and (2) declaratory and injunctive relief. The Company disputes the allegations in the complaint and intends to vigorously defend itself. The Company is unable to estimate the amount or range of potential loss, if any, at this time. In July 2018, an individual filed a putative class action lawsuit in the U.S. District Court for the District of Columbia, purportedly on behalf of himself and other persons who received certain telephone calls. The lawsuit alleges that the Company violated the Telephone Consumer Protection Act and some of its implementing regulations. The complaint seeks statutory penalties for each alleged violation. The Company disputes the allegations in the complaint and intends to vigorously defend itself in the litigation. The Company is unable to estimate the amount or range of potential loss, if any, at this time. In October 2018, a former employee filed a representative action pursuant to California’s Private Attorneys General Act alleging that the Company violated California labor and employment laws by, among other things, failing to provide its employees with rest and meal breaks. The Company disputes the allegations in the complaint and is in the process of retaining counsel to represent it in the litigation. The Company is unable to estimate a range of loss, if any, at this time. If an unfavorable outcome were to occur in the case, it is possible that the impact could be material to the Company’s results of operations in the period(s) in which any such outcome becomes probable and estimable. In October 2018, a former sales representative filed a representative action pursuant to California’s Private Attorneys General Act alleging that the Company violated California labor and employment laws by, among other things, failing to properly compensate its direct sellers and reimburse them for business expenses. The Company disputes the allegations in the complaint and is in the process of retaining counsel to represent it in the litigation. The Company is unable to estimate a range of loss, if any, at this time. If an unfavorable outcome were to occur in the case, it is possible that the impact could be material to the Company’s results of operations in the period(s) in which any such outcome becomes probable and estimable. In addition to the matters discussed above, in the normal course of business, the Company has from time to time been named as a party to various legal claims, actions and complaints. While the outcome of these matters cannot be predicted with certainty, the Company does not currently believe that the outcome of any of these claims will have a material adverse effect, individually or in the aggregate, on its consolidated financial position, results of operations or cash flows. The Company accrues for losses that are probable and can be reasonably estimated. The Company evaluates the adequacy of its legal reserves based on its assessment of many factors, including interpretations of the law and assumptions about the future outcome of each case based on available information.

Basic and Diluted Net (Loss) In

Basic and Diluted Net (Loss) Income Per Share	9 Months Ended
	Sep. 30, 2018
Earnings Per Share [Abstract]
Basic and Diluted Net (Loss) Income Per Share	18 . Basic and Diluted Net (Loss) Income Per Share The following table sets forth the computation of the Company’s basic and diluted net (loss attributable) income available per share to common stockholders for the three and nine months ended September 30, 2018 and 2017 (in thousands, except per share amounts): Three Months Ended Nine Months Ended September 30, September 30, 2018 2017 2018 2017 Numerator: Net (loss attributable) income available to common stockholders $ (7,868 ) $ 6,905 $ (2,728 ) $ 25,177 Denominator: Shares used in computing net (loss attributable) income available per share to common stockholders, basic 118,767 114,505 116,871 112,554 Weighted-average effect of potentially dilutive shares to purchase common stock — 4,960 — 5,271 Shares used in computing net (loss attributable) income available per share to common stockholders, diluted 118,767 119,465 116,871 117,825 Net (loss attributable) income available per share to common stockholders: Basic $ (0.07 ) $ 0.06 $ (0.02 ) $ 0.22 Diluted $ (0.07 ) $ 0.06 $ (0.02 ) $ 0.21 For the three and nine months ended September 30, 2018, the Company incurred a net loss attributable to common stockholders. As such, the potentially dilutive shares were anti-dilutive and were not considered in the weighted-average number of common shares outstanding for the period. For the three and nine months ended September 30, 2017, 0.2 million shares and 0.8 million shares were excluded from the dilutive share calculations as the effect on net income per share would have been anti-dilutive.

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	9 Months Ended
	Sep. 30, 2018
Accounting Policies [Abstract]
Basis of Presentation and Principles of Consolidation	Basis of Presentation and Principles of Consolidation The accompanying unaudited condensed consolidated financial statements have been prepared in accordance with generally accepted accounting principles in the United States (“GAAP”) and applicable rules and regulations of the Securities and Exchange Commission (“SEC”) regarding interim financial reporting. Certain information and note disclosures normally included in the financial statements prepared in accordance with GAAP have been condensed or omitted pursuant to such rules and regulations. As such, these unaudited condensed consolidated financial statements should be read in conjunction with the consolidated financial statements and accompanying notes included in the Company’s annual report on Form 10-K dated as of March 7, 2018. The unaudited condensed consolidated financial statements were prepared on the same basis as the audited consolidated financial statements and, in the opinion of management, reflect all adjustments (all of which were considered of normal recurring nature) considered necessary to present fairly the Company’s financial results. The results of the nine months ended September 30, 2018 are not necessarily indicative of the results to be expected for the fiscal year ending December 31, 2018 or for any other interim period or other future year. The unaudited condensed consolidated financial statements reflect the accounts and operations of the Company and those of its subsidiaries in which the Company has a controlling financial interest. The Company uses a qualitative approach in assessing the consolidation requirement for variable interest entities (“VIEs”). This approach focuses on determining whether the Company has the power to direct the activities of the VIE that most significantly affect the VIE’s economic performance and whether the Company has the obligation to absorb losses, or the right to receive benefits, that could potentially be significant to the VIE. All of these determinations involve significant management judgments and estimates. The Company has determined that it is the primary beneficiary in the operational VIEs in which it has an equity interest. The Company evaluates its relationships with the VIEs on an ongoing basis to ensure that it continues to be the primary beneficiary. All intercompany transactions and balances have been eliminated in consolidation. For additional information, see Note 12—Investment Funds. Certain prior period amounts have been reclassified to conform to current year presentation. These reclassifications did not have a significant impact on the consolidated financial statements.
Use of Estimates	Use of Estimates The preparation of the condensed consolidated financial statements requires management to make estimates and assumptions that affect the amounts reported in the condensed consolidated financial statements and accompanying notes. The Company regularly makes significant estimates and assumptions including, but not limited to, investment tax credits (“ITCs”); revenue recognition; solar energy systems, net; the impairment analysis of long-lived assets; stock-based compensation; the provision for income taxes; the valuation of derivative financial instruments; the recognition and measurement of loss contingencies; and non-controlling interests and redeemable non-controlling interests. The Company bases its estimates on historical experience and on various other assumptions believed to be reasonable, the results of which form the basis for making judgments about the carrying values of assets and liabilities. Actual results could differ materially from those estimates.
Liquidity	Liquidity In order to grow, the Company requires cash to finance the deployment of solar energy systems. As of the date of this filing, the Company will require additional sources of cash beyond current cash balances, and currently available financing facilities to fund long-term planned growth. If the Company is unable to secure additional financing when needed, or upon desirable terms, the Company may be unable to finance installation of customers’ systems in a manner consistent with past performance, cost of capital could increase, or the Company may be required to significantly reduce the scope of operations, any of which would have a material adverse effect on its business, financial condition, results of operations and prospects. While the Company believes additional financing is available and will continue to be available to support current levels of operations, the Company believes it has the ability and intent to reduce operations to the level of available financial resources for at least the next 12 months from the date of this report, if necessary.
Revenue from Contracts with Customers	Revenue from Contracts with Customers The Company adopted ASU 2014-09, Revenue from Contracts with Customers, The Company currently accounts for PPAs, Solar Leases, and associated rebates and incentives as minimum lease payments from operating leases under ASC 840, Leases Leases, The Company has analyzed the impact of Topic 606 on System Sales and other product sales and has concluded that the revenue recognition associated with these product sales did not change in the condensed consolidated financial statements. The Company will continue to show this revenue stream as solar energy system and product sales in the condensed consolidated statement of operations. The Company’s principal performance obligation for System Sales is to design and install a solar energy system that is interconnected to the local power grid and granted permission to operate to the customer. When the solar energy system has been granted permission to operate, the customer retains all of the significant risks and rewards of ownership of the solar energy system. For certain System Sales, the Company provides limited post-sale services to monitor the productivity of the solar energy system for 20 years after it has been placed in service. The Company collects cash during the installation process and recognizes revenue for System Sales and other product sales at the placed in-service date or product delivery date less any revenue allocated to monitoring services. The Company allocates a portion of the transaction price to the monitoring services by estimating the fair market price that the Company would charge for these services if offered separately from the sale of the solar energy system. As of September 30, 2018 and December 31, 2017, the Company had allocated deferred revenue of $3.0 million and $2.1 million to monitoring services that will be recognized over the term of the monitoring services. All costs to obtain and fulfill contracts associated with System Sales and other product sales are expensed as a cost of revenue when the Company has fulfilled its performance obligation and the products have been placed into service or delivered to the customer. The Company has assessed the impact of Topic 606 as it relates to the sales of ITCs through its lease pass-through fund arrangement. The Company has concluded that revenue related to the sale of ITCs through its lease pass-through arrangement is recognized when the related solar energy systems are placed in service as the Company has completed its performance obligation to transfer ITCs to the fund investors at that time. The fund investors contributed cash to the investment fund during the installation process as payment for the ITCs. The transaction price for the ITCs was estimated using the tax credit rate of 30% multiplied by the fair market value of the solar energy systems that were placed into service in the lease pass-through fund. All of the related solar energy systems were placed in service and all related revenue would have been recognized prior to September 30, 2016 under Topic 606. Prior to the adoption of Topic 606, the Company recognized this revenue evenly over the five-year ITC recapture period. This earlier recognition of the ITC lease pass-through revenue decreased revenue for the three and nine months ended September 30, 2018 by $1.6 million and $4.8 million and would have decreased revenue for the three and nine months ended September 30, 2017 by $1.6 million and $4.8 million. As all ITC sales revenue would have been recognized prior to September 30, 2016 under Topic 606, there is no deferred revenue related to ITC sales recorded after the adoption date of January 1, 2018, and there would have been no deferred revenue as of December 31, 2017. As shown below, the cumulative adjustment related to ITC revenue recognized into retained earnings, net of tax, as of January 1, 2018 was $19.2 million. As noted above, the Company adopted Topic 606 on a modified retrospective basis. However, if the Company adjusted the comparative period to reflect the adoption of Topic 606, the following adjustments would have been made to the condensed consolidated statement of operations for the three and nine months ended September 30, 2017 (in thousands, except per share data): Three Months Ended September 30, 2017 Nine Months Ended September 30, 2017 As Previously Revenue As Previously Revenue Reported Adjustment As Adjusted Reported Adjustment As Adjusted Revenue $ 75,139 $ (1,561 ) $ 73,578 $ 201,248 $ (4,790 ) $ 196,458 Income tax expense 9,375 (424 ) 8,951 23,932 (1,299 ) 22,633 Net income available to common shareholders 6,905 (1,137 ) 5,768 25,177 (3,491 ) 21,686 Diluted earnings per share 0.06 (0.01 ) 0.05 0.21 (0.03 ) 0.18 Additionally, the following adjustments would have been made to the condensed consolidated balance sheet as of December 31, 2017 (in thousands): As Previously Revenue Reported Adjustment As Adjusted Current portion of deferred revenue $ 41,846 $ (7,707 ) $ 34,139 Deferred revenue, net of current portion 29,200 (18,690 ) 10,510 Deferred tax liability, net 342,382 7,160 349,542 Retained earnings 213,107 (19,237 ) 193,870
Income Taxes	Income Taxes The Company adopted ASU 2016-16, Income Taxes (Topic 740): Intra-Entity Transfers of Assets Other Than Inventory The adoption of ASU 2016-16 had the following effect on the Company’s condensed consolidated statement of operations for the three and nine months ended September 30, 2018 (in thousands, except per share data): Three Months Ended September 30, 2018 Nine Months Ended September 30, 2018 Pre-Adoption Effect of Pre-Adoption Effect of Accounting Adoption As Reported Accounting Adoption As Reported Income tax expense $ 8,514 $ 17,184 $ 25,698 $ 32,893 $ 46,800 $ 79,693 Net loss (55,508 ) (17,184 ) (72,692 ) (145,966 ) (46,800 ) (192,766 ) Net loss attributable to common shareholders 9,316 (17,184 ) (7,868 ) 44,072 (46,800 ) (2,728 ) Basic earnings per share 0.08 (0.15 ) (0.07 ) 0.38 (0.40 ) (0.02 ) Diluted earnings per share 0.08 (0.15 ) (0.07 ) 0.36 (0.38 ) (0.02 ) The Company adopted ASU 2018-02, Income Statement—Reporting Comprehensive Income (Topic 220): Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income ,
Derivative Financial Instruments	Derivative Financial Instruments The Company adopted ASU 2017-12, Derivatives and Hedging (Topic 815): Targeted Improvements to Accounting for Hedging Activities
Restricted Cash	Restricted Cash The Company adopted ASU 2016-18, Statement of Cash Flows (Topic 230): Restricted Cash (a consensus of the FASB Emerging Issues Task Force) (“ASU 2016-18”) , effective January 1, 2018. This update clarified that transfers between cash and restricted cash are not reported as cash flow activities in the statements of cash flows. As such, restricted cash amounts are included with cash and cash equivalents in the beginning-of-period and end-of-period total amounts on the statements of cash flows. The Company applied this update retrospectively, which resulted in an adjustment to the beginning-of-period and end-of-period total amounts on the condensed consolidated statement of cash flows for the nine months ended September 30, 2017 to include restricted cash balances from those periods.
Recent Accounting Pronouncements	Recent Accounting Pronouncements In July 2018, the Financial Accounting Standards Board (the “FASB”) issued ASU 2018-10 and ASU 2018-11, which clarify aspects of the guidance in ASU 2016-02, Leases (Topic 842) In June 2018, the FASB issued ASU 2018-07, Compensation—Stock Compensation (Topic 718): Improvements to Nonemployee Share-Based Payment Accounting. In August 2018, the FASB issued ASU 2018-15, Intangibles—Goodwill and Other—Internal-Use Software (Subtopic 350-40): Customer’s Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement that is a Service Contract.

Summary of Significant Accoun_3

Summary of Significant Accounting Policies (Tables)	9 Months Ended
	Sep. 30, 2018
ASU 2014-09
Schedule of Accounting Standards Update Adjustments to Financial Statements	As noted above, the Company adopted Topic 606 on a modified retrospective basis. However, if the Company adjusted the comparative period to reflect the adoption of Topic 606, the following adjustments would have been made to the condensed consolidated statement of operations for the three and nine months ended September 30, 2017 (in thousands, except per share data): Three Months Ended September 30, 2017 Nine Months Ended September 30, 2017 As Previously Revenue As Previously Revenue Reported Adjustment As Adjusted Reported Adjustment As Adjusted Revenue $ 75,139 $ (1,561 ) $ 73,578 $ 201,248 $ (4,790 ) $ 196,458 Income tax expense 9,375 (424 ) 8,951 23,932 (1,299 ) 22,633 Net income available to common shareholders 6,905 (1,137 ) 5,768 25,177 (3,491 ) 21,686 Diluted earnings per share 0.06 (0.01 ) 0.05 0.21 (0.03 ) 0.18 Additionally, the following adjustments would have been made to the condensed consolidated balance sheet as of December 31, 2017 (in thousands): As Previously Revenue Reported Adjustment As Adjusted Current portion of deferred revenue $ 41,846 $ (7,707 ) $ 34,139 Deferred revenue, net of current portion 29,200 (18,690 ) 10,510 Deferred tax liability, net 342,382 7,160 349,542 Retained earnings 213,107 (19,237 ) 193,870
ASU 2016-16
Schedule of Accounting Standards Update Adjustments to Financial Statements	The adoption of ASU 2016-16 had the following effect on the Company’s condensed consolidated statement of operations for the three and nine months ended September 30, 2018 (in thousands, except per share data): Three Months Ended September 30, 2018 Nine Months Ended September 30, 2018 Pre-Adoption Effect of Pre-Adoption Effect of Accounting Adoption As Reported Accounting Adoption As Reported Income tax expense $ 8,514 $ 17,184 $ 25,698 $ 32,893 $ 46,800 $ 79,693 Net loss (55,508 ) (17,184 ) (72,692 ) (145,966 ) (46,800 ) (192,766 ) Net loss attributable to common shareholders 9,316 (17,184 ) (7,868 ) 44,072 (46,800 ) (2,728 ) Basic earnings per share 0.08 (0.15 ) (0.07 ) 0.38 (0.40 ) (0.02 ) Diluted earnings per share 0.08 (0.15 ) (0.07 ) 0.36 (0.38 ) (0.02 )

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	9 Months Ended
	Sep. 30, 2018
Fair Value Disclosures [Abstract]
Schedule of Fair Value of Financial Assets and Liabilities Measured on Recurring Basis	The Company measures and reports its cash equivalents at fair value. The following tables set forth the fair value of the Company’s financial assets and liabilities measured on a recurring basis by level within the fair value hierarchy (in thousands): September 30, 2018 Level 1 Level 2 Level 3 Total Financial Assets Interest rate swaps $ — $ 131 $ — $ 131 December 31, 2017 Level 1 Level 2 Level 3 Total Financial Assets Interest rate swaps $ — $ 14,028 $ — $ 14,028 Financial Liabilities Interest rate swaps $ — $ 1,280 $ — $ 1,280
Schedule of Carrying Values and Fair Values of Company's Long-term Debt	The carrying values and fair values of the Company’s long-term debt were as follows (in thousands): September 30, 2018 December 31, 2017 Carrying Value Fair Value Carrying Value Fair Value Floating-rate long-term debt $ 521,081 $ 521,080 $ 757,044 $ 757,044 Fixed-rate long-term debt 658,992 674,822 199,063 238,618 Total $ 1,180,073 $ 1,195,902 $ 956,107 $ 995,662

Inventories (Tables)

Inventories (Tables)	9 Months Ended
	Sep. 30, 2018
Inventory Disclosure [Abstract]
Summary of Inventories	Inventories consisted of the following (in thousands): September 30, December 31, 2018 2017 Solar energy systems held for sale $ 14,801 $ 21,971 Photovoltaic installation products 979 626 Total inventories $ 15,780 $ 22,597

Solar Energy Systems (Tables)

Solar Energy Systems (Tables)	9 Months Ended
	Sep. 30, 2018
Solar Energy Systems Disclosure [Abstract]
Solar Energy Systems	Solar energy systems, net consisted of the following (in thousands): September 30, December 31, 2018 2017 System equipment costs $ 1,604,598 $ 1,437,419 Initial direct costs related to solar energy systems 404,845 336,136 2,009,443 1,773,555 Less: Accumulated depreciation and amortization (178,180 ) (129,640 ) 1,831,263 1,643,915 Solar energy system inventory 27,480 29,617 Solar energy systems, net $ 1,858,743 $ 1,673,532

Property and Equipment (Tables)

Property and Equipment (Tables)	9 Months Ended
	Sep. 30, 2018
Property Plant And Equipment [Abstract]
Summary of Property and Equipment Net	Property and equipment, net consisted of the following (in thousands): Estimated September 30, December 31, Useful Lives 2018 2017 Vehicles acquired under capital leases 3-5 years $ 8,957 $ 15,113 Leasehold improvements 1-12 years 12,309 15,071 Furniture and computer and other equipment 3 years 4,171 6,492 25,437 36,676 Less: Accumulated depreciation and amortization (14,355 ) (21,598 ) Property and equipment, net $ 11,082 $ 15,078

Intangible Assets (Tables)

Intangible Assets (Tables)	9 Months Ended
	Sep. 30, 2018
Goodwill And Intangible Assets Disclosure [Abstract]
Summary of Intangible Assets, Net	Intangible assets, net consisted of the following (in thousands): September 30, December 31, 2018 2017 Cost: Internal-use software $ 1,422 $ 1,314 Developed technology 522 522 Trademarks/trade names 201 201 Customer relationships 164 164 Total carrying value 2,309 2,201 Accumulated amortization: Internal-use software (1,076 ) (872 ) Developed technology (307 ) (258 ) Trademarks/trade names (95 ) (79 ) Customer relationships (155 ) (130 ) Total accumulated amortization (1,633 ) (1,339 ) Total intangible assets, net $ 676 $ 862

Accrued Compensation (Tables)

Accrued Compensation (Tables)	9 Months Ended
	Sep. 30, 2018
Accrued Compensation Disclosure [Abstract]
Summary of Accrued Compensation	Accrued compensation consisted of the following (in thousands): September 30, December 31, 2018 2017 Accrued payroll $ 16,640 $ 13,064 Accrued commissions 9,149 7,928 Total accrued compensation $ 25,789 $ 20,992

Accrued and Other Current Lia_2

Accrued and Other Current Liabilities (Tables)	9 Months Ended
	Sep. 30, 2018
Payables And Accruals [Abstract]
Schedule of Accrued and Other Current Liabilities	Accrued and other current liabilities consisted of the following (in thousands): September 30, December 31, 2018 2017 Accrued unused commitment fees and interest $ 12,220 $ 7,445 Accrued professional fees 5,813 3,977 Current portion of lease pass-through financing obligation 5,017 4,931 Sales, use and property taxes payable 3,227 3,046 Accrued workers' compensation 3,189 1,446 Accrued inventory 2,926 4,122 Workmanship accrual 1,800 1,359 Current portion of deferred rent 935 937 Other accrued expenses 2,201 2,412 Total accrued and other current liabilities $ 37,328 $ 29,675

Debt Obligations (Tables)

Debt Obligations (Tables)	9 Months Ended
	Sep. 30, 2018
Debt Disclosure [Abstract]
Schedule of Debt	Debt obligations consisted of the following as of September 30, 2018 (in thousands, except interest rates): Principal Unamortized Debt Unused Borrowings Issuance Costs Net Carrying Value Borrowing Interest Maturity Outstanding Current Long-term Current Long-term Capacity Rate Date Solar asset backed notes, Series 2018-1 $ 466,000 $ (61 ) $ (9,372 ) $ 2,980 $ 453,587 $ — * October 2028 Solar asset backed notes, Series 2018-2 (1)(2) 342,833 (7 ) (7,692 ) 293 334,841 — 5.2 % August 2023 2017 Term loan facility 191,705 (170 ) (4,711 ) 6,615 180,209 — 6.0 January 2035 Forward flow loan facility 11,748 (18 ) (3,445 ) 611 7,674 118,252 5.0 (3) Credit agreement 1,287 (1 ) (124 ) 16 1,146 — 6.5 February 2023 Revolving lines of credit (4) Aggregation facility 30,000 — — — 30,000 345,000 5.4 September 2020 Working capital facility (5) 136,500 — — — 136,500 — 5.3 March 2020 Total debt $ 1,180,073 $ (257 ) $ (25,344 ) $ 10,515 $ 1,143,957 $ 463,252 Debt obligations consisted of the following as of December 31, 2017 (in thousands, except interest rates): Principal Unamortized Debt Unused Borrowings Issuance Costs Net Carrying Value Borrowing Interest Maturity Outstanding Current Long-term Current Long-term Capacity Rate Date 2017 Term loan facility $ 197,764 $ (176 ) $ (4,990 ) $ 6,644 $ 185,954 $ — 6.0 % January 2035 2016 Term loan facility 287,919 (141 ) (7,623 ) 4,962 275,193 — 4.3 August 2021 Subordinated HoldCo facility 197,625 (35 ) (3,451 ) 1,965 192,174 — 9.3 March 2020 Credit agreement 1,299 (2 ) (140 ) 14 1,143 — 6.5 February 2023 Revolving lines of credit (4) Aggregation facility 135,000 — — — 135,000 240,000 4.7 September 2020 Working capital facility (5) 136,500 — — — 136,500 — 4.8 March 2020 Total debt $ 956,107 $ (354 ) $ (16,204 ) $ 13,585 $ 925,964 $ 240,000 * The Series 2018-1 Notes are comprised of Class A and Class B Notes. Class A Notes accrue interest at 4.73%. Class B Notes accrue interest at 7.37%. (1) The Series 2018-2 Notes are comprised of Class A and Class B Notes. Class B Notes accrue interest at a rate of LIBOR plus 4.75%. Class A Notes accrue interest at a variable spread over LIBOR that results in a weighted average spread for all 2018-2 Notes of 2.95%. (2) The interest rate of this facility is partially hedged to an effective interest rate of 6.0% for $326.8 million of the principal borrowings. See Note 11—Derivative Financial Instruments. (3) The maturity date for this facility is 20 years from the end date of the borrowing availability period when all borrowings are aggregated into one term loan, which will be no later than October 31, 2019. (4) Revolving lines of credit are not presented net of unamortized debt issuance costs. (5) Facility is recourse debt, which refers to debt that is collateralized by the Company’s general assets. All of the Company’s other debt obligations are non-recourse, which refers to debt that is only collateralized by specified assets or subsidiaries of the Company.

Derivative Financial Instrume_2

Derivative Financial Instruments (Tables)	9 Months Ended
	Sep. 30, 2018
Derivative Instruments And Hedging Activities Disclosure [Abstract]
Schedule of Derivative Financial Instruments at Fair Value	Derivative financial instruments consisted of the following at fair value (in thousands): September 30, 2018 Fair Value Balance Sheet Location Derivatives designated as hedging instruments: Interest rate swaps $ 131 Other non-current assets, net December 31, 2017 Fair Value Balance Sheet Location Derivatives designated as hedging instruments: Interest rate swaps $ 14,028 Other non-current assets, net Derivatives not designated as hedging instruments: Interest rate swaps $ 1,280 Other non-current liabilities
Schedule of (Gains) Losses on Derivative Financial Instruments Recognized in OCI and Condensed Consolidated Statements of Operations Before Tax Effect	The (gains) losses on derivatives designated as cash flow hedges recognized in OCI, before tax effect, consisted of the following (in thousands): Three Months Ended September 30, 2018 2017 Derivatives designated as cash flow hedges: Interest rate swaps $ (3,966 ) $ 828 Nine Months Ended September 30, 2018 2017 Derivatives designated as cash flow hedges: Interest rate swaps $ (8,284 ) $ 2,688 The (gains) losses on derivative financial instruments recognized in the condensed consolidated statements of operations, before tax effect, consisted of the following (in thousands): Three Months Ended September 30, 2018 2017 Interest expense, net Other (income) expense, net Interest expense, net Other (income) expense, net Total amounts presented in the income statement line items $ 18,715 $ (1 ) $ 16,148 $ 195 Derivatives designated as cash flow hedges: Interest rate swaps Losses (gains) reclassified from AOCI into income $ 535 $ — $ (156 ) $ — Gains recognized in income - ineffective portion: — — — (120 ) Derivatives not designated as hedging instruments: Interest rate swaps Losses recognized in income — — — 320 Total losses (gains) $ 535 $ — $ (156 ) $ 200 Nine Months Ended September 30, 2018 2017 Interest expense, net Other (income) expense, net Interest expense, net Other (income) expense, net Total amounts presented in the income statement line items $ 46,973 $ (6,371 ) $ 47,707 $ 1,186 Derivatives designated as cash flow hedges: Interest rate swaps Gains reclassified from AOCI into income $ (22,181 ) $ — $ (13 ) $ — Gains recognized in income - ineffective portion: — — — (641 ) Derivatives not designated as hedging instruments: Interest rate swaps (Gains) losses recognized in income — (4,252 ) — 1,834 Total (gains) losses $ (22,181 ) $ (4,252 ) $ (13 ) $ 1,193

Investment Funds (Tables)

Investment Funds (Tables)	9 Months Ended
	Sep. 30, 2018
Schedule Of Investments [Abstract]
Aggregate Carrying Value of Funds Assets and Liabilities	As of September 30, 2018 and December 31, 2017, the Company had formed investment funds for the purpose of funding the purchase of solar energy systems under long-term customer contracts. The aggregate carrying value of these funds’ assets and liabilities (after elimination of intercompany transactions and balances) in the Company’s condensed consolidated balance sheets were as follows (in thousands): September 30, December 31, 2018 2017 Assets Current assets: Cash and cash equivalents $ 78,906 $ 17,280 Accounts receivable, net 11,052 5,143 Prepaid expenses and other current assets 1,753 952 Total current assets 91,711 23,375 Restricted cash and cash equivalents 438 — Solar energy systems, net 1,636,300 1,486,023 Other non-current assets, net 9,529 6,792 Total assets $ 1,737,978 $ 1,516,190 Liabilities Current liabilities: Distributions payable to non-controlling interests and redeemable non-controlling interests $ 11,236 $ 16,437 Current portion of long-term debt 611 — Current portion of deferred revenue 1,793 9,176 Accrued and other current liabilities 4,540 4,478 Total current liabilities 18,180 30,091 Long-term debt, net of current portion 7,674 — Deferred revenue, net of current portion 9,408 26,847 Other non-current liabilities 982 1,444 Total liabilities $ 36,244 $ 58,382

Redeemable Non-Controlling In_2

Redeemable Non-Controlling Interests and Equity (Tables)	9 Months Ended
	Sep. 30, 2018
Noncontrolling Interest [Abstract]
Schedule of Reserved Shares of Common Stock for Issuance	The Company had reserved shares of common stock for issuance as follows (in thousands): September 30, December 31, 2018 2017 Shares available for grant under equity incentive plans 13,242 12,774 Restricted stock units issued and outstanding 6,653 6,688 Stock options issued and outstanding 3,792 3,837 Long-term incentive plan 2,706 2,706 Total 26,393 26,005
Schedule of Changes in Redeemable Non-Controlling Interests	The changes in redeemable non-controlling interests were as follows (in thousands): Balance as of December 31, 2017 $ 122,444 Contributions from redeemable non-controlling interests 72,078 Distributions to redeemable non-controlling interests (7,663 ) Net loss (65,039 ) Balance as of September 30, 2018 $ 121,820
Schedule of Changes in Total Stockholders' Equity and Non-Controlling Interests	The changes in stockholders’ equity and non-controlling interests were as follows (in thousands): Total Stockholders' Non-Controlling Equity Interests Total Equity Balance as of December 31, 2017 $ 780,951 $ 80,115 $ 861,066 Cumulative-effect adjustment from adoption of new ASUs (473,828 ) — (473,828 ) Stock-based compensation expense 9,884 — 9,884 Issuance of common stock 876 — 876 Contributions from non-controlling interests — 122,843 122,843 Distributions to non-controlling interests — (28,865 ) (28,865 ) Total other comprehensive loss (10,128 ) — (10,128 ) Net loss (2,728 ) (124,999 ) (127,727 ) Balance as of September 30, 2018 $ 305,027 $ 49,094 $ 354,121
Schedule Changes in Accumulated Other Comprehensive Income Related to Cash Flow Hedges	The changes in AOCI are related to the Company’s cash flow hedges. The changes in AOCI, net of tax, were as follows (in thousands): Accumulated Other Comprehensive Income Balance as of December 31, 2017 $ 6,905 Cumulative-effect adjustment from adoption of new ASUs 3,318 Other comprehensive income before reclassifications 6,037 Less: Amounts reclassified from AOCI 16,165 Balance as of September 30, 2018 $ 95

Equity Compensation Plans (Tabl

Equity Compensation Plans (Tables)	9 Months Ended
	Sep. 30, 2018
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Summary of Stock Option Activity	Stock option activity for the nine months ended September 30, 2018 was as follows (in thousands, except term and per share amounts): Weighted- Weighted- Average Shares Average Remaining Aggregate Underlying Exercise Contractual Intrinsic Options Price Term (in years) Value Outstanding—December 31, 2017 3,837 $ 2.01 $ 8,522 Granted 827 3.93 Exercised (780 ) 1.12 Cancelled (92 ) 2.27 Outstanding—September 30, 2018 3,792 $ 2.60 7.1 $ 10,447 Options vested and exercisable—September 30, 2018 1,840 $ 2.06 5.9 $ 6,290
RSU Activity	RSU activity for the nine months ended September 30, 2018 was as follows (awards in thousands): Weighted- Average Number of Grant Date Awards Fair Value Outstanding at December 31, 2017 6,688 $ 3.20 Granted 3,986 4.13 Vested (3,436 ) 2.98 Forfeited (585 ) 3.42 Outstanding at September 30, 2018 6,653 $ 3.85
Summary of Stock-Based Compensation Expense	Stock-based compensation was included in operating expenses as follows (in thousands): Three Months Ended Nine Months Ended September 30, September 30, 2018 2017 2018 2017 Cost of revenue $ 361 $ 164 $ 984 $ 738 Sales and marketing 754 601 2,668 2,710 General and administrative 1,956 1,421 6,125 5,763 Research and development 32 63 107 290 Total stock-based compensation $ 3,103 $ 2,249 $ 9,884 $ 9,501
Summary of Unrecognized Stock-Based Compensation Expense	Unrecognized stock-based compensation expense for stock options and RSUs as of September 30, 2018 was as follows (in thousands, except years): Unrecognized Weighted- Stock-Based Average Period Compensation of Recognition Expense (in years) RSUs $ 20,105 1.8 Stock options 2,516 1.8 Total unrecognized stock-based compensation expense $ 22,621

Related Party Transactions (Tab

Related Party Transactions (Tables)	9 Months Ended
	Sep. 30, 2018
Related Party Transactions [Abstract]
Components of Related Party Transactions	The Company’s condensed consolidated statements of operations included the following related party transactions (in thousands): Three Months Ended Nine Months Ended September 30, September 30, 2018 2017 2018 2017 Cost of revenue—operating leases and incentives $ — $ 70 $ — $ 701 Sales and marketing 340 697 1,651 1,959 General and administrative — 15 — 139

Basic and Diluted Net (Loss) _2

Basic and Diluted Net (Loss) Income Per Share (Tables)	9 Months Ended
	Sep. 30, 2018
Earnings Per Share [Abstract]
Computation of Basic and Diluted Net (Loss) Income Per Share to Common Stockholders	The following table sets forth the computation of the Company’s basic and diluted net (loss attributable) income available per share to common stockholders for the three and nine months ended September 30, 2018 and 2017 (in thousands, except per share amounts): Three Months Ended Nine Months Ended September 30, September 30, 2018 2017 2018 2017 Numerator: Net (loss attributable) income available to common stockholders $ (7,868 ) $ 6,905 $ (2,728 ) $ 25,177 Denominator: Shares used in computing net (loss attributable) income available per share to common stockholders, basic 118,767 114,505 116,871 112,554 Weighted-average effect of potentially dilutive shares to purchase common stock — 4,960 — 5,271 Shares used in computing net (loss attributable) income available per share to common stockholders, diluted 118,767 119,465 116,871 117,825 Net (loss attributable) income available per share to common stockholders: Basic $ (0.07 ) $ 0.06 $ (0.02 ) $ 0.22 Diluted $ (0.07 ) $ 0.06 $ (0.02 ) $ 0.21

Organization - Additional Infor

Organization - Additional Information (Details)	Sep. 30, 2018
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Contractual term of customers	20 years

Summary of Significant Accoun_4

Summary of Significant Accounting Policies - Additional Information (Details) - USD ($)	Jan. 02, 2018	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Jan. 01, 2018	Dec. 31, 2017
Summary Of Significant Accounting Policies [Line Items]
Investment tax credit percentage of qualified assets				30.00%
Recapture period of revenue recognition				5 years
Effect of adopting new accounting pronouncements				$ 473,828,000
ASU 2014-09
Summary Of Significant Accounting Policies [Line Items]
Cumulative effect adjustment, retained earnings	$ 19,200,000
ASU 2016-16
Summary Of Significant Accounting Policies [Line Items]
Cumulative effect adjustment, retained earnings	493,100,000
Cumulative effect adjustment, deferred tax liability, net	12,800,000
ASU 2018-02
Summary Of Significant Accounting Policies [Line Items]
Cumulative effect adjustment, retained earnings	1,500,000
ASU 2017-12
Summary Of Significant Accounting Policies [Line Items]
Cumulative effect adjustment, retained earnings	$ 1,800,000
Calculated under Revenue Guidance in Effect before Topic 606
Summary Of Significant Accounting Policies [Line Items]
Deferred revenue							$ 0
Effect of adopting new accounting pronouncements		$ 1,600,000	$ 1,600,000	4,800,000	$ 4,800,000
Difference between Revenue Guidance in Effect before and after Topic 606
Summary Of Significant Accounting Policies [Line Items]
Deferred revenue						$ 0
Monitoring Services
Summary Of Significant Accounting Policies [Line Items]
Deferred revenue		$ 3,000,000		$ 3,000,000			$ 2,100,000

Summary of Significant Accoun_5

Summary of Significant Accounting Policies - Adjustments made to Condensed Consolidated Statement of Operations (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Revenue	$ 77,816	$ 75,139	$ 226,864	$ 201,248
Income tax expense	25,698	9,375	79,693	23,932
Net (loss attributable) income available to common stockholders	$ (7,868)	$ 6,905	$ (2,728)	$ 25,177
Diluted	$ (0.07)	$ 0.06	$ (0.02)	$ 0.21
Difference between Revenue Guidance in Effect before and after Topic 606 | ASU 2014-09
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Revenue		$ (1,561)		$ (4,790)
Income tax expense		(424)		(1,299)
Net (loss attributable) income available to common stockholders		$ (1,137)		$ (3,491)
Diluted		$ (0.01)		$ (0.03)
As Adjusted | ASU 2014-09
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Revenue		$ 73,578		$ 196,458
Income tax expense		8,951		22,633
Net (loss attributable) income available to common stockholders		$ 5,768		$ 21,686
Diluted		$ 0.05		$ 0.18

Summary of Significant Accoun_6

Summary of Significant Accounting Policies - Adjustments made to Condensed Consolidated Balance Sheet (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Current portion of deferred revenue	$ 25,480	$ 41,846
Deferred revenue, net of current portion	12,728	29,200
Deferred tax liability, net	413,076	342,382
Retained earnings	$ (266,767)	213,107
Difference between Revenue Guidance in Effect before and after Topic 606 | ASU 2014-09
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Current portion of deferred revenue		(7,707)
Deferred revenue, net of current portion		(18,690)
Deferred tax liability, net		7,160
Retained earnings		(19,237)
As Adjusted | ASU 2014-09
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Current portion of deferred revenue		34,139
Deferred revenue, net of current portion		10,510
Deferred tax liability, net		349,542
Retained earnings		$ 193,870

Summary of Significant Accoun_7

Summary of Significant Accounting Policies - Adoption of ASU 2016-16 Effect on Condensed Consolidated Statement of Operations (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Income tax expense	$ 25,698	$ 9,375	$ 79,693	$ 23,932
Net loss	(72,692)	(37,700)	(192,766)	(130,206)
Net (loss attributable) income available to common stockholders	$ (7,868)	$ 6,905	$ (2,728)	$ 25,177
Basic earnings per share	$ (0.07)	$ 0.06	$ (0.02)	$ 0.22
Diluted earnings per share	$ (0.07)	$ 0.06	$ (0.02)	$ 0.21
Pre-Adoption Accounting | ASU 2016-16
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Income tax expense	$ 8,514		$ 32,893
Net loss	(55,508)		(145,966)
Net (loss attributable) income available to common stockholders	$ 9,316		$ 44,072
Basic earnings per share	$ 0.08		$ 0.38
Diluted earnings per share	$ 0.08		$ 0.36
Effect of Adoption | ASU 2016-16
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Income tax expense	$ 17,184		$ 46,800
Net loss	(17,184)		(46,800)
Net (loss attributable) income available to common stockholders	$ (17,184)		$ (46,800)
Basic earnings per share	$ (0.15)		$ (0.40)
Diluted earnings per share	$ (0.15)		$ (0.38)

Fair Value Measurements - Sched

Fair Value Measurements - Schedule of Fair Value of Financial Assets and Liabilities Measured on Recurring Basis (Details) - Interest Rate Swaps - Fair Value Measurements, Recurring Basis - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Financial Assets	$ 131	$ 14,028
Financial Liabilities		1,280
Level 2
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Financial Assets	$ 131	14,028
Financial Liabilities		$ 1,280

Fair Value Measurements - Addit

Fair Value Measurements - Additional Information (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Realized gain on interest rate swaps			$ 1,279	$ (1,193)
Interest Expense
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Realized gain on interest rate swaps	$ (535)	$ 156	22,181	13
Other Income
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Realized gain on interest rate swaps		$ (200)	4,252	$ (1,193)
2016 Term Loan Facility | Derivatives Designated as Hedging Instruments | Interest Expense
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Realized gain on interest rate swaps			22,500
Aggregation Facility | Derivatives Designated as Hedging Instruments | Other Income
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Realized gain on interest rate swaps			$ 2,000

Fair Value Measurements - Sch_2

Fair Value Measurements - Schedule of Carrying Values and Fair Values of Long-term Debt (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Long-term debt, Carrying Value	$ 1,180,073	$ 956,107
Long-term debt, Fair Value	1,195,902	995,662
Floating-rate Long-term Debt
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Long-term debt, Carrying Value	521,081	757,044
Long-term debt, Fair Value	521,080	757,044
Fixed-rate Long-term Debt
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Long-term debt, Carrying Value	658,992	199,063
Long-term debt, Fair Value	$ 674,822	$ 238,618

Inventories - Summary of Invent

Inventories - Summary of Inventories (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Inventory Disclosure [Abstract]
Solar energy systems held for sale	$ 14,801	$ 21,971
Photovoltaic installation products	979	626
Total inventories	$ 15,780	$ 22,597

Solar Energy Systems (Details)

Solar Energy Systems (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Property Subject To Or Available For Operating Lease [Line Items]
Solar energy systems, gross	$ 2,009,443	$ 1,773,555
Less: Accumulated depreciation and amortization	(178,180)	(129,640)
Solar energy systems, net excluding inventory	1,831,263	1,643,915
Solar energy system inventory	27,480	29,617
Solar energy systems, net	1,858,743	1,673,532
System Equipment Costs
Property Subject To Or Available For Operating Lease [Line Items]
Solar energy systems, gross	1,604,598	1,437,419
Initial Direct Costs Related to Solar Energy Systems
Property Subject To Or Available For Operating Lease [Line Items]
Solar energy systems, gross	$ 404,845	$ 336,136

Solar Energy Systems - Addition

Solar Energy Systems - Additional Information (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Property Subject To Or Available For Operating Lease [Line Items]
Depreciation and amortization expense			$ 50,839,000	$ 44,671,000
Solar Energy System Inventory
Property Subject To Or Available For Operating Lease [Line Items]
Depreciation			0
Solar Energy Systems
Property Subject To Or Available For Operating Lease [Line Items]
Depreciation and amortization expense	$ 17,000,000	$ 14,500,000	$ 48,500,000	$ 41,000,000

Property and Equipment - Summar

Property and Equipment - Summary of Property and Equipment Net (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2018	Dec. 31, 2017
Property Plant And Equipment [Line Items]
Property, gross	$ 25,437	$ 36,676
Less: Accumulated depreciation and amortization	(14,355)	(21,598)
Property and equipment, net	11,082	15,078
Vehicles Acquired Under Capital Leases
Property Plant And Equipment [Line Items]
Property, gross	8,957	15,113
Leasehold Improvements
Property Plant And Equipment [Line Items]
Property, gross	$ 12,309	15,071
Furniture and Computer and Other Equipment
Property Plant And Equipment [Line Items]
Property and Equipment, Estimated Useful Lives	3 years
Property, gross	$ 4,171	$ 6,492
Minimum | Vehicles Acquired Under Capital Leases
Property Plant And Equipment [Line Items]
Property and Equipment, Estimated Useful Lives	3 years
Minimum | Leasehold Improvements
Property Plant And Equipment [Line Items]
Property and Equipment, Estimated Useful Lives	1 year
Maximum | Vehicles Acquired Under Capital Leases
Property Plant And Equipment [Line Items]
Property and Equipment, Estimated Useful Lives	5 years
Maximum | Leasehold Improvements
Property Plant And Equipment [Line Items]
Property and Equipment, Estimated Useful Lives	12 years

Property and Equipment - Additi

Property and Equipment - Additional Information (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Property Plant And Equipment [Line Items]
Depreciation and amortization expense			$ 50,839	$ 44,671
Solar Energy Systems
Property Plant And Equipment [Line Items]
Depreciation and amortization expense	$ 17,000	$ 14,500	48,500	41,000
Property and equipment
Property Plant And Equipment [Line Items]
Depreciation and amortization expense	900	1,900	3,900	6,400
Vehicles Acquired Under Capital Leases | Solar Energy Systems
Property Plant And Equipment [Line Items]
Depreciation and amortization expense	$ 300	$ 700	$ 1,600	$ 2,700

Intangible Assets - Summary of

Intangible Assets - Summary of Intangible Assets, Net (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Finite Lived Intangible Assets [Line Items]
Intangible assets, carrying value	$ 2,309	$ 2,201
Intangible assets, accumulated amortization	(1,633)	(1,339)
Total intangible assets, net	676	862
Internal-use software
Finite Lived Intangible Assets [Line Items]
Intangible assets, carrying value	1,422	1,314
Intangible assets, accumulated amortization	(1,076)	(872)
Developed Technology
Finite Lived Intangible Assets [Line Items]
Intangible assets, carrying value	522	522
Intangible assets, accumulated amortization	(307)	(258)
Trademarks/Trade Names
Finite Lived Intangible Assets [Line Items]
Intangible assets, carrying value	201	201
Intangible assets, accumulated amortization	(95)	(79)
Customer Relationships
Finite Lived Intangible Assets [Line Items]
Intangible assets, carrying value	164	164
Intangible assets, accumulated amortization	$ (155)	$ (130)

Intangible Assets - Additional

Intangible Assets - Additional Information (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Goodwill And Intangible Assets Disclosure [Abstract]
Amortization of intangible assets	$ 142	$ 139	$ 408	$ 418

Accrued Compensation - Summary

Accrued Compensation - Summary of Accrued Compensation (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Accrued Compensation Disclosure [Abstract]
Accrued payroll	$ 16,640	$ 13,064
Accrued commissions	9,149	7,928
Total accrued compensation	$ 25,789	$ 20,992

Accrued and Other Current Lia_3

Accrued and Other Current Liabilities - Schedule of Accrued and Other Current Liabilities (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Payables And Accruals [Abstract]
Accrued unused commitment fees and interest	$ 12,220	$ 7,445
Accrued professional fees	5,813	3,977
Current portion of lease pass-through financing obligation	5,017	4,931
Sales, use and property taxes payable	3,227	3,046
Accrued workers' compensation	3,189	1,446
Accrued inventory	2,926	4,122
Workmanship accrual	1,800	1,359
Current portion of deferred rent	935	937
Other accrued expenses	2,201	2,412
Total accrued and other current liabilities	$ 37,328	$ 29,675

Debt Obligations - Schedule of

Debt Obligations - Schedule of Debt Obligations (Details) - USD ($) $ in Thousands		1 Months Ended	9 Months Ended		12 Months Ended
		Jun. 30, 2018	Sep. 30, 2018		Dec. 31, 2017
Debt Instrument [Line Items]
Principal Borrowings Outstanding			$ 1,180,073		$ 956,107
Unamortized Debt Issuance Costs, Current			(257)		(354)
Unamortized Debt Issuance Costs, Long-term			(25,344)		(16,204)
Current portion of long-term debt			10,515		13,585
Long-term debt, net of current portion			1,143,957		925,964
Unused Borrowing Capacity			463,252		240,000
Solar Asset Backed Notes, Series 2018-1
Debt Instrument [Line Items]
Principal Borrowings Outstanding			466,000
Unamortized Debt Issuance Costs, Current			(61)
Unamortized Debt Issuance Costs, Long-term			(9,372)
Current portion of long-term debt			2,980
Long-term debt, net of current portion			$ 453,587
Maturity Date			Oct. 31, 2028
2017 Term Loan Facility
Debt Instrument [Line Items]
Principal Borrowings Outstanding			$ 191,705		197,764
Unamortized Debt Issuance Costs, Current			(170)		(176)
Unamortized Debt Issuance Costs, Long-term			(4,711)		(4,990)
Current portion of long-term debt			6,615		6,644
Long-term debt, net of current portion			$ 180,209		$ 185,954
Interest Rate			6.00%		6.00%
Maturity Date			Jan. 31, 2035		Jan. 31, 2035
Solar Asset Backed Notes, Series 2018-2
Debt Instrument [Line Items]
Principal Borrowings Outstanding	[1],[2]		$ 342,833
Unamortized Debt Issuance Costs, Current	[1],[2]		(7)
Unamortized Debt Issuance Costs, Long-term	[1],[2]		(7,692)
Current portion of long-term debt	[1],[2]		293
Long-term debt, net of current portion	[1],[2]		$ 334,841
Interest Rate	[1],[2]		5.20%
Maturity Date		Aug. 29, 2023	Aug. 31, 2023	[1],[2]
Forward Flow Loan Facility
Debt Instrument [Line Items]
Principal Borrowings Outstanding			$ 11,748
Unamortized Debt Issuance Costs, Current			(18)
Unamortized Debt Issuance Costs, Long-term			(3,445)
Current portion of long-term debt			611
Long-term debt, net of current portion			7,674
Unused Borrowing Capacity			$ 118,252
Interest Rate			5.00%
Credit Agreement
Debt Instrument [Line Items]
Principal Borrowings Outstanding			$ 1,287		$ 1,299
Unamortized Debt Issuance Costs, Current			(1)		(2)
Unamortized Debt Issuance Costs, Long-term			(124)		(140)
Current portion of long-term debt			16		14
Long-term debt, net of current portion			$ 1,146		$ 1,143
Interest Rate			6.50%		6.50%
Maturity Date			Feb. 28, 2023		Feb. 28, 2023
Aggregation Facility
Debt Instrument [Line Items]
Principal Borrowings Outstanding	[3]		$ 30,000		$ 135,000
Long-term debt, net of current portion	[3]		30,000		135,000
Unused Borrowing Capacity	[3]		$ 345,000		$ 240,000
Interest Rate	[3]		5.40%		4.70%
Maturity Date	[3]		Sep. 30, 2020		Sep. 30, 2020
Working Capital Facility
Debt Instrument [Line Items]
Principal Borrowings Outstanding	[3],[4]		$ 136,500		$ 136,500
Long-term debt, net of current portion	[3],[4]		$ 136,500		$ 136,500
Interest Rate	[3],[4]		5.30%		4.80%
Maturity Date	[3],[4]		Mar. 31, 2020		Mar. 31, 2020
2016 Term Loan Facility
Debt Instrument [Line Items]
Principal Borrowings Outstanding					$ 287,919
Unamortized Debt Issuance Costs, Current					(141)
Unamortized Debt Issuance Costs, Long-term					(7,623)
Current portion of long-term debt					4,962
Long-term debt, net of current portion					$ 275,193
Interest Rate					4.30%
Maturity Date					Aug. 31, 2021
Subordinated HoldCo Facility
Debt Instrument [Line Items]
Principal Borrowings Outstanding					$ 197,625
Unamortized Debt Issuance Costs, Current					(35)
Unamortized Debt Issuance Costs, Long-term					(3,451)
Current portion of long-term debt					1,965
Long-term debt, net of current portion					$ 192,174
Interest Rate					9.30%
Maturity Date					Mar. 31, 2020
[1]	The Series 2018-2 Notes are comprised of Class A and Class B Notes. Class B Notes accrue interest at a rate of LIBOR plus 4.75%. Class A Notes accrue interest at a variable spread over LIBOR that results in a weighted average spread for all 2018-2 Notes of 2.95
[2]	The interest rate of this facility is partially hedged to an effective interest rate of 6.0% for $326.8 million of the principal borrowings. See Note 11—Derivative Financial Instruments.
[3]	Revolving lines of credit are not presented net of unamortized debt issuance costs.
[4]	Facility is recourse debt, which refers to debt that is collateralized by the Company’s general assets. All of the Company’s other debt obligations are non-recourse, which refers to debt that is only collateralized by specified assets or subsidiaries of the Company.

Debt Obligations - Schedule o_2

Debt Obligations - Schedule of Debt Obligations (Parenthetical) (Details) - USD ($)		1 Months Ended		9 Months Ended
		Aug. 31, 2018	Jun. 30, 2018	Sep. 30, 2018		Dec. 31, 2017
Debt Instrument [Line Items]
Principal borrowings outstanding				$ 1,180,073,000		$ 956,107,000
Solar Asset Backed Notes, Series 2018-1
Debt Instrument [Line Items]
Principal borrowings outstanding				$ 466,000,000
Maturity Date				Oct. 31, 2028
Solar Asset Backed Notes, Series 2018-1 | Class A Notes
Debt Instrument [Line Items]
Interest Rate			4.73%	4.73%
Principal borrowings outstanding			$ 400,000,000
Maturity Date			Oct. 30, 2028
Solar Asset Backed Notes, Series 2018-1 | Class B Notes
Debt Instrument [Line Items]
Interest Rate			7.37%	7.37%
Principal borrowings outstanding			$ 66,000,000
Maturity Date			Oct. 30, 2028
Solar Asset Backed Notes, Series 2018-2
Debt Instrument [Line Items]
Interest Rate	[1],[2]			5.20%
Principal borrowings outstanding	[1],[2]			$ 342,833,000
Maturity Date			Aug. 29, 2023	Aug. 31, 2023	[1],[2]
Solar Asset Backed Notes, Series 2018-2 | Interest Rate Swaps
Debt Instrument [Line Items]
Effective interest rate of principal borrowings			5.95%	6.00%
Principal borrowings outstanding				$ 326,800,000
Solar Asset Backed Notes, Series 2018-2 | L I B O R Plus | Weighted Average
Debt Instrument [Line Items]
Debt instrument interest rate			2.95%
Solar Asset Backed Notes, Series 2018-2 | Class A Notes
Debt Instrument [Line Items]
Principal borrowings outstanding			$ 296,000,000
Solar Asset Backed Notes, Series 2018-2 | Class A Notes | L I B O R Plus | Weighted Average
Debt Instrument [Line Items]
Debt instrument interest rate			2.95%	2.95%
Solar Asset Backed Notes, Series 2018-2 | Class B Notes
Debt Instrument [Line Items]
Principal borrowings outstanding			$ 49,000,000
Solar Asset Backed Notes, Series 2018-2 | Class B Notes | L I B O R Plus
Debt Instrument [Line Items]
Debt instrument interest rate				4.75%
Solar Asset Backed Notes, Series 2018-2 | Class B Notes | L I B O R Plus | Weighted Average
Debt Instrument [Line Items]
Debt instrument interest rate			4.75%
Forward Flow Loan Facility
Debt Instrument [Line Items]
Interest Rate				5.00%
Debt instrument interest rate		1.50%
Principal borrowings outstanding				$ 11,748,000
Debt instrument maturity period		20 years		20 years
Forward Flow Loan Facility | Maximum
Debt Instrument [Line Items]
Maturity Date				Oct. 31, 2019
[1]	The Series 2018-2 Notes are comprised of Class A and Class B Notes. Class B Notes accrue interest at a rate of LIBOR plus 4.75%. Class A Notes accrue interest at a variable spread over LIBOR that results in a weighted average spread for all 2018-2 Notes of 2.95
[2]	The interest rate of this facility is partially hedged to an effective interest rate of 6.0% for $326.8 million of the principal borrowings. See Note 11—Derivative Financial Instruments.

Debt Obligations - Additional I

Debt Obligations - Additional Information (Details) - USD ($)		1 Months Ended		9 Months Ended		12 Months Ended
		Aug. 31, 2018	Jun. 30, 2018	Sep. 30, 2018		Dec. 31, 2017	Jan. 31, 2017	Mar. 31, 2015	Sep. 30, 2014
Debt Instrument [Line Items]
Principal Borrowings Outstanding				$ 1,180,073,000		$ 956,107,000
Restricted cash and cash equivalents				68,341,000		46,486,000
Letter of credit related to insurance contracts				13,500,000
Minimum
Debt Instrument [Line Items]
Restricted cash and cash equivalents				10,000,000		10,000,000
Solar Asset Backed Notes, Series 2018-1
Debt Instrument [Line Items]
Principal Borrowings Outstanding				$ 466,000,000
Revolving credit facility maturity date				Oct. 31, 2028
Solar Asset Backed Notes, Series 2018-1 | Required Reserves
Debt Instrument [Line Items]
Restricted cash and cash equivalents				$ 13,500,000
Solar Asset Backed Notes, Series 2018-1 | Class A Notes
Debt Instrument [Line Items]
Principal Borrowings Outstanding			$ 400,000,000
Interest Rate			4.73%	4.73%
Revolving credit facility maturity date			Oct. 30, 2028
Solar Asset Backed Notes, Series 2018-1 | Class B Notes
Debt Instrument [Line Items]
Principal Borrowings Outstanding			$ 66,000,000
Interest Rate			7.37%	7.37%
Revolving credit facility maturity date			Oct. 30, 2028
Solar Asset Backed Notes, Series 2018-2
Debt Instrument [Line Items]
Principal Borrowings Outstanding	[1],[2]			$ 342,833,000
Interest Rate	[1],[2]			5.20%
Revolving credit facility maturity date			Aug. 29, 2023	Aug. 31, 2023	[1],[2]
Solar Asset Backed Notes, Series 2018-2 | Interest Rate Swaps
Debt Instrument [Line Items]
Principal Borrowings Outstanding				$ 326,800,000
Effective interest rate of principal borrowings			5.95%	6.00%
Solar Asset Backed Notes, Series 2018-2 | L I B O R Plus | Weighted Average
Debt Instrument [Line Items]
Debt instrument interest rate			2.95%
Solar Asset Backed Notes, Series 2018-2 | Required Reserves
Debt Instrument [Line Items]
Restricted cash and cash equivalents				$ 23,900,000
Solar Asset Backed Notes, Series 2018-2 | Class A Notes
Debt Instrument [Line Items]
Principal Borrowings Outstanding			$ 296,000,000
Solar Asset Backed Notes, Series 2018-2 | Class A Notes | L I B O R Plus | Weighted Average
Debt Instrument [Line Items]
Debt instrument interest rate			2.95%	2.95%
Solar Asset Backed Notes, Series 2018-2 | Class B Notes
Debt Instrument [Line Items]
Principal Borrowings Outstanding			$ 49,000,000
Solar Asset Backed Notes, Series 2018-2 | Class B Notes | L I B O R Plus
Debt Instrument [Line Items]
Debt instrument interest rate				4.75%
Solar Asset Backed Notes, Series 2018-2 | Class B Notes | L I B O R Plus | Weighted Average
Debt Instrument [Line Items]
Debt instrument interest rate			4.75%
2016 Term Loan Facility
Debt Instrument [Line Items]
Principal Borrowings Outstanding						$ 287,919,000
Interest Rate						4.30%
Revolving credit facility maturity date						Aug. 31, 2021
Payment of outstanding balance of debt			$ 282,300,000
Payment of outstanding balance of debt principal			281,800,000
Payment of outstanding balance of debt accrued interest			500,000
Unamortized debt issuance costs recognized in interest expense				$ 6,900,000
Prepayment fee			0
Subordinated HoldCo Facility
Debt Instrument [Line Items]
Principal Borrowings Outstanding						$ 197,625,000
Interest Rate						9.30%
Revolving credit facility maturity date						Mar. 31, 2020
Payment of outstanding balance of debt			206,400,000
Payment of outstanding balance of debt principal			196,600,000
Payment of outstanding balance of debt accrued interest			3,900,000
Unamortized debt issuance costs recognized in interest expense				2,900,000
Prepayment fee			$ 5,900,000
Percentage of principal prepayments fee			3.00%
Subordinated HoldCo Facility | Interest Expense
Debt Instrument [Line Items]
Prepayment fee				5,900,000
2017 Term Loan Facility
Debt Instrument [Line Items]
Principal Borrowings Outstanding				$ 191,705,000		$ 197,764,000
Interest Rate				6.00%		6.00%
Revolving credit facility maturity date				Jan. 31, 2035		Jan. 31, 2035
Interest on borrowings accrue at an annual fixed rate and payable in arrears							6.00%
Debt instrument, frequency of periodic payment				quarterly basis
2017 Term Loan Facility | Required Reserves
Debt Instrument [Line Items]
Restricted cash and cash equivalents				$ 19,400,000
Forward Flow Loan Facility
Debt Instrument [Line Items]
Principal Borrowings Outstanding				$ 11,748,000
Interest Rate				5.00%
Debt instrument interest rate		1.50%
Maximum borrowing amount under credit agreement		$ 130,000,000
Debt instrument maturity period		20 years		20 years
Debt Instrument interest rate description				Interest on each loan will accrue at an annual rate equal to the U.S. swap rate for the weighted-average life of such loan, plus an applicable margin equal to the greater of (a) 1.9% plus a spread adjustment based on the risk premium on the borrowing date relative to the market index-based risk premium on the closing date and (b) 1.5%. Scheduled principal payments are due on a quarterly basis, at the end of January, April, July and October of each year.
Forward Flow Loan Facility | Maximum
Debt Instrument [Line Items]
Revolving credit facility maturity date				Oct. 31, 2019
Forward Flow Loan Facility | Market Index-Based Risk Premium
Debt Instrument [Line Items]
Debt instrument interest rate		1.90%
Forward Flow Loan Facility | Required Reserves
Debt Instrument [Line Items]
Restricted cash and cash equivalents				$ 400,000
Aggregation Facility
Debt Instrument [Line Items]
Principal Borrowings Outstanding	[3]			$ 30,000,000		$ 135,000,000
Interest Rate	[3]			5.40%		4.70%
Revolving credit facility maturity date	[3]			Sep. 30, 2020		Sep. 30, 2020
Maximum borrowing amount under credit agreement									$ 375,000,000
Additional borrowing capacity									$ 175,000,000
Aggregation Facility | Minimum
Debt Instrument [Line Items]
Debt instrument interest rate				3.25%
Aggregation Facility | Maximum
Debt Instrument [Line Items]
Debt instrument interest rate				3.75%
Aggregation Facility | L I B O R Plus
Debt Instrument [Line Items]
Debt instrument interest rate				1.00%
Aggregation Facility | Federal Funds Rate Plus
Debt Instrument [Line Items]
Debt instrument interest rate				0.50%
Aggregation Facility | Required Reserves
Debt Instrument [Line Items]
Restricted cash and cash equivalents				$ 1,000,000
Working Capital Facility
Debt Instrument [Line Items]
Principal Borrowings Outstanding	[3],[4]			$ 136,500,000		$ 136,500,000
Interest Rate	[3],[4]			5.30%		4.80%
Revolving credit facility maturity date	[3],[4]			Mar. 31, 2020		Mar. 31, 2020
Debt instrument interest rate				2.25%
Maximum borrowing amount under credit agreement								$ 150,000,000
Debt Instrument interest rate description				(1) a rate equal to the Eurodollar Rate for the interest period divided by one minus the Eurodollar Reserve Percentage, plus a margin of 3.25%; or (2) the highest of (a) the Federal Funds Rate plus 0.50%, (b) the Citibank prime rate and (c) the one-month interest period Eurodollar rate plus 1.00%, plus a margin of 2.25%. Interest is payable depending on the type of borrowing at the end of (1) the interest period that the Company may elect as a term, not to exceed three months, (2) quarterly or (3) at maturity of the Working Capital Facility.
Letter of credit related to insurance contracts				$ 13,500,000
Minimum cash balance requirement				$ 30,000,000
Working Capital Facility | Federal Funds Rate Plus
Debt Instrument [Line Items]
Debt instrument interest rate				0.50%
Working Capital Facility | Eurodollar Reserve Percentage Plus
Debt Instrument [Line Items]
Debt instrument interest rate				3.25%
Working Capital Facility | Euro Dollar Rate Plus
Debt Instrument [Line Items]
Debt instrument interest rate				1.00%
[1]	The Series 2018-2 Notes are comprised of Class A and Class B Notes. Class B Notes accrue interest at a rate of LIBOR plus 4.75%. Class A Notes accrue interest at a variable spread over LIBOR that results in a weighted average spread for all 2018-2 Notes of 2.95
[2]	The interest rate of this facility is partially hedged to an effective interest rate of 6.0% for $326.8 million of the principal borrowings. See Note 11—Derivative Financial Instruments.
[3]	Revolving lines of credit are not presented net of unamortized debt issuance costs.
[4]	Facility is recourse debt, which refers to debt that is collateralized by the Company’s general assets. All of the Company’s other debt obligations are non-recourse, which refers to debt that is only collateralized by specified assets or subsidiaries of the Company.

Derivative Financial Instrume_3

Derivative Financial Instruments - Schedule of Derivative Financial Instruments at Fair Value (Details) - Interest Rate Swaps - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Derivatives Designated as Hedging Instruments | Other Noncurrent Assets, Net
Derivatives Fair Value [Line Items]
Fair Value	$ 131	$ 14,028
Derivatives Not Designated as Hedging Instruments | Other Noncurrent Liabilities
Derivatives Fair Value [Line Items]
Fair Value		$ 1,280

Derivative Financial Instrume_4

Derivative Financial Instruments - Additional Information (Details) - USD ($)	3 Months Ended		6 Months Ended	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Jun. 30, 2018	Sep. 30, 2018	Sep. 30, 2017	Mar. 31, 2018
Derivatives Fair Value [Line Items]
Realized gain on interest rate swaps				$ 1,279,000	$ (1,193,000)
Interest Expense
Derivatives Fair Value [Line Items]
Realized gain on interest rate swaps	$ (535,000)	$ 156,000		22,181,000	13,000
Other Income
Derivatives Fair Value [Line Items]
Realized gain on interest rate swaps		$ (200,000)		4,252,000	$ (1,193,000)
2016 Term Loan Facility | Derivatives Designated as Hedging Instruments | Interest Expense
Derivatives Fair Value [Line Items]
Realized gain on interest rate swaps				22,500,000
Amended Bank Of America Aggregation Credit Facility | Interest Rate Swaps
Derivatives Fair Value [Line Items]
Percentage of outstanding term loans in interest rate hedged						75.00%
Threshold period			15 days
Amended Bank Of America Aggregation Credit Facility | Derivatives Not Designated as Hedging Instruments | Other Income
Derivatives Fair Value [Line Items]
Realized gain on interest rate swaps			$ 2,000,000
2018-2 Notes | Interest Rate Swaps
Derivatives Fair Value [Line Items]
Notional amount	$ 326,800,000			326,800,000
Accumulated other comprehensive income, expected amount of cash flow hedge to be reclassified to interest expense within the next 12 months				$ 1,000,000

Derivative Financial Instrume_5

Derivative Financial Instruments - Schedule of (Gains) Losses on Derivative Financial Instruments Recognized in OCI and Condensed Consolidated Statements of Operations Before Tax Effect (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Derivative Instruments, Gain (Loss) [Line Items]
Total amounts presented in the income statement line items, Interest expense	$ 18,715	$ 16,148	$ 46,973	$ 47,707
(Gains) losses on interest rate swaps			(1,279)	1,193
Total amounts presented in the income statement line items, Other (income) expense, net	(1)	195	(6,371)	1,186
Interest Expense, Net
Derivative Instruments, Gain (Loss) [Line Items]
(Gains) losses on interest rate swaps	535	(156)	(22,181)	(13)
Other (Income) Expense, Net
Derivative Instruments, Gain (Loss) [Line Items]
(Gains) losses on interest rate swaps		200	(4,252)	1,193
Derivatives Designated as Hedging Instruments | Cash Flow Hedging | Interest Rate Swaps | Interest Expense, Net
Derivative Instruments, Gain (Loss) [Line Items]
Losses (gains) reclassified from AOCI into income	535	(156)	(22,181)	(13)
Derivatives Designated as Hedging Instruments | Cash Flow Hedging | Interest Rate Swaps | Other (Income) Expense, Net
Derivative Instruments, Gain (Loss) [Line Items]
Losses (Gains) recognized in income - ineffective portion		(120)		(641)
Derivatives Designated as Hedging Instruments | Cash Flow Hedging | Interest Rate Swaps | Other Comprehensive Income
Derivative Instruments, Gain (Loss) [Line Items]
(Gains) losses recognized in OCI	$ (3,966)	828	(8,284)	2,688
Derivatives Not Designated as Hedging Instruments | Interest Rate Swaps | Other (Income) Expense, Net
Derivative Instruments, Gain (Loss) [Line Items]
Losses (Gains) recognized in income - ineffective portion		$ 320	$ (4,252)	$ 1,834

Investment Funds - Additional I

Investment Funds - Additional Information (Details) - USD ($)	3 Months Ended	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2018	Dec. 31, 2017
Investment Holdings [Line Items]
Summary of investment fund		As of September 30, 2018 and December 31, 2017, the Company had formed investment funds for the purpose of funding the purchase of solar energy systems under long-term customer contracts.
Investors cash contribution to variable interest equity	$ 1,459,500,000	$ 1,459,500,000	$ 1,264,600,000
Solar energy systems, net	1,858,743,000	$ 1,858,743,000	1,673,532,000
Recapture period of revenue recognition		5 years
Prepaid insurance balance	8,600,000	$ 8,600,000	2,400,000
Distributions paid to reimburse fund investors	0	11,900,000
Accrued distribution	0	0
Restricted cash	68,341,000	68,341,000	46,486,000
Minimum
Investment Holdings [Line Items]
Restricted cash	10,000,000	10,000,000	10,000,000
Variable Interest Entities
Investment Holdings [Line Items]
Solar energy systems, net	1,636,300,000	1,636,300,000	1,486,023,000
Deferred revenue	11,200,000	11,200,000	36,000,000
Investment tax credit repayment		0
Restricted cash	438,000	438,000	0
Calculated under Revenue Guidance in Effect before Topic 606
Investment Holdings [Line Items]
Deferred revenue			0
Financing Obligation
Investment Holdings [Line Items]
Solar energy systems, net	56,400,000	$ 56,400,000	58,200,000
Investment tax credit rate		30.00%
Financing liabilities	5,300,000	$ 5,300,000	32,100,000
Deferred revenue			26,400,000
Financing Obligation | Other Liabilities
Investment Holdings [Line Items]
Lease pass-through financing obligation	5,300,000	$ 5,300,000	$ 5,800,000
Financing Obligation | Calculated under Revenue Guidance in Effect before Topic 606
Investment Holdings [Line Items]
Recapture period of revenue recognition		5 years
Investor
Investment Holdings [Line Items]
Investors cash contribution to variable interest equity	$ 110,000,000	$ 110,000,000

Investment Funds - Aggregate Ca

Investment Funds - Aggregate Carrying Value of Funds Assets and Liabilities (Details) - USD ($) $ in Thousands		Sep. 30, 2018	Dec. 31, 2017
Current assets:
Cash and cash equivalents		$ 188,627	$ 108,452
Accounts receivable, net		19,910	19,665
Prepaid expenses and other current assets		24,662	34,049
Total current assets		248,979	184,763
Restricted cash and cash equivalents		68,341	46,486
Solar energy systems, net		1,858,743	1,673,532
Other non-current assets, net		28,696	37,325
TOTAL ASSETS	[1]	2,216,517	2,463,929
Current liabilities:
Distributions payable to non-controlling interests and redeemable non-controlling interests		11,236	16,437
Current portion of long-term debt		10,515	13,585
Current portion of deferred revenue		25,480	41,846
Accrued and other current liabilities		37,328	29,675
Total current liabilities		157,645	167,600
Long-term debt, net of current portion		1,143,957	925,964
Deferred revenue, net of current portion		12,728	29,200
Other non-current liabilities		12,522	13,674
Total liabilities	[1]	1,740,576	1,480,419
Variable Interest Entities
Current assets:
Cash and cash equivalents		78,906	17,280
Accounts receivable, net		11,052	5,143
Prepaid expenses and other current assets		1,753	952
Total current assets		91,711	23,375
Restricted cash and cash equivalents		438	0
Solar energy systems, net		1,636,300	1,486,023
Other non-current assets, net		9,529	6,792
TOTAL ASSETS		1,737,978	1,516,190
Current liabilities:
Distributions payable to non-controlling interests and redeemable non-controlling interests		11,236	16,437
Current portion of long-term debt		611
Current portion of deferred revenue		1,793	9,176
Accrued and other current liabilities		4,540	4,478
Total current liabilities		18,180	30,091
Long-term debt, net of current portion		7,674
Deferred revenue, net of current portion		9,408	26,847
Other non-current liabilities		982	1,444
Total liabilities		$ 36,244	$ 58,382
[1]	The Company’s assets as of September 30, 2018 and December 31, 2017 include $1,738.0 million and $1,516.2 million consisting of assets of variable interest entities, or VIEs, that can only be used to settle obligations of the VIEs. These assets include solar energy systems, net, of $1,636.3 million and $1,486.0 million as of September 30, 2018 and December 31, 2017; cash and cash equivalents of $78.9 million and $17.3 million as of September 30, 2018 and December 31, 2017; accounts receivable, net, of $11.1 million and $5.1 million as of September 30, 2018 and December 31, 2017; other non-current assets, net of $9.5 million and $6.8 million as of September 30, 2018 and December 31, 2017; prepaid expenses and other current assets of $1.8 million and $1.0 million as of September 30, 2018 and December 31, 2017; and restricted cash and cash equivalents of $0.4 million and $0 as of September 30, 2018 and December 31, 2017. The Company’s liabilities as of September 30, 2018 and December 31, 2017 included $36.2 million and $58.4 million of liabilities of VIEs whose creditors have no recourse to the Company. These liabilities include distributions payable to non-controlling interests and redeemable non-controlling interests of $11.2 million and $16.4 million as of September 30, 2018 and December 31, 2017; deferred revenue of $11.2 million and $36.0 million as of September 30, 2018 and December 31, 2017; long-term debt of $8.3 million and $0 as of September 30, 2018 and December 31, 2017; accrued and other current liabilities of $4.5 million as of September 30, 2018 and December 31, 2017; and other non-current liabilities of $1.0 million and $1.4 million as of September 30, 2018 and December 31, 2017. For further information see Note 12—Investment Funds.

Redeemable Non-Controlling In_3

Redeemable Non-Controlling Interests and Equity - Schedule of Reserved Shares of Common Stock for Issuance (Details) - shares	Sep. 30, 2018	Dec. 31, 2017
Equity [Abstract]
Shares available for grant under equity incentive plans	13,242,000	12,774,000
Restricted stock units issued and outstanding	6,653,000	6,688,000
Stock options issued and outstanding	3,792,000	3,837,000
Long-term incentive plan	2,706,000	2,706,000
Total	26,393,000	26,005,000

Redeemable Non-Controlling In_4

Redeemable Non-Controlling Interests and Equity - Schedule of Changes in Redeemable Non-Controlling Interests (Details) $ in Thousands	9 Months Ended
	Sep. 30, 2018USD ($)
Redeemable Noncontrolling Interest [Line Items]
Balance at beginning of period	$ 122,444
Contributions from redeemable non-controlling interests	72,078
Distributions to redeemable non-controlling interests	(7,663)
Balance at end of period	121,820
Redeemable Non Controlling Interests
Redeemable Noncontrolling Interest [Line Items]
Net loss	$ (65,039)

Redeemable Non-Controlling In_5

Redeemable Non-Controlling Interests and Equity - Schedule of Changes in Total Stockholders' Equity and Non-Controlling Interests (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Balance at beginning of year			$ 861,066
Balance at beginning of year			780,951
Balance at beginning of year			80,115
Cumulative-effect adjustment from adoption of new ASUs			(473,828)
Stock-based compensation expense			9,884	$ 9,501
Issuance of common stock			876
Contributions from non-controlling interests			122,843
Distributions to non-controlling interests			(28,865)
Total other comprehensive loss	$ 3,280	$ (403)	(10,128)	(1,604)
Net loss	(72,692)	(37,700)	(192,766)	(130,206)
Net income (loss)	(7,868)	6,905	(2,728)	25,177
Net income (loss)	(64,824)	$ (44,605)	(190,038)	$ (155,383)
Balance at end of year	354,121		354,121
Balance at end of year	305,027		305,027
Balance at end of year	49,094		49,094
Profit Loss Excluding Redeemable Noncontrolling Interest
Net loss			(127,727)
Total Stockholders' Equity
Balance at beginning of year			780,951
Cumulative-effect adjustment from adoption of new ASUs			(473,828)
Stock-based compensation expense			9,884
Issuance of common stock			876
Total other comprehensive loss			(10,128)
Net income (loss)			(2,728)
Balance at end of year	305,027		305,027
Non-controlling Interests
Balance at beginning of year			80,115
Contributions from non-controlling interests			122,843
Distributions to non-controlling interests			(28,865)
Net income (loss)			(124,999)
Balance at end of year	$ 49,094		$ 49,094

Redeemable Non-Controlling In_6

Redeemable Non-Controlling Interests and Equity - Changes in Accumulated Other Comprehensive Income Related to Cash Flow Hedges (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Equity [Abstract]
Balance as of December 31, 2017			$ 6,905
Cumulative-effect adjustment from adoption of new ASUs	$ 3,318		3,318
Other comprehensive income before reclassifications	2,890	$ (497)	6,037	$ (1,612)
Less: Amounts reclassified from AOCI	(390)	$ 94	16,165	$ 8
Balance as of September 30, 2018	$ 95		$ 95

Redeemable Non-Controlling In_7

Redeemable Non-Controlling Interests, Equity and Preferred Stock - Additional Information (Details)	9 Months Ended
	Sep. 30, 2018USD ($)
Put Option
Redeemable Noncontrolling Interest [Line Items]
Fund options expected to exercise	$ 0
Put Option | Minimum
Redeemable Noncontrolling Interest [Line Items]
Purchase price for investors' interest in funds under Put Options	2,100,000
Put Option | Maximum
Redeemable Noncontrolling Interest [Line Items]
Purchase price for investors' interest in funds under Put Options	4,100,000
Call Option
Redeemable Noncontrolling Interest [Line Items]
Fund options expected to exercise	0
Call Option | Minimum
Redeemable Noncontrolling Interest [Line Items]
Purchase price for investors' interest in funds under Put Options	1,200,000
Call Option | Maximum
Redeemable Noncontrolling Interest [Line Items]
Purchase price for investors' interest in funds under Put Options	$ 7,000,000

Equity Compensation Plans - Add

Equity Compensation Plans - Additional Information (Details) - USD ($) $ in Thousands	1 Months Ended
	Jul. 31, 2018	Jan. 31, 2018	Sep. 30, 2018	Dec. 31, 2017
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Shares available for grant under equity incentive plans			13,242,000	12,774,000
Performance-Based Equity Awards
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Modified performance of sales leadership team	$ 400
Incremental expense arising from modification	$ 0
2014 Equity Incentive Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Shares available for grant under equity incentive plans			13,200,000
Number of additional shares available for issuance		4,600,000

Equity Compensation Plans - Sum

Equity Compensation Plans - Summary of Stock Option Activity (Details) - USD ($) $ / shares in Units, $ in Thousands	9 Months Ended
	Sep. 30, 2018	Dec. 31, 2017
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Shares Underlying Options, Outstanding, Balance	3,837,000
Shares Underlying Options, Granted	827,000
Shares Underlying Options, Exercised	(780,000)
Shares Underlying Options, Cancelled	(92,000)
Shares Underlying Options, Outstanding, Balance	3,792,000
Shares Underlying Options, Options vested and exercisable	1,840,000
Weighted-Average Exercise Price, Outstanding, Balance	$ 2.01
Weighted-Average Exercise Price, Granted	3.93
Weighted-Average Exercise Price, Exercised	1.12
Weighted-Average Exercise Price, Cancelled	2.27
Weighted-Average Exercise Price, Outstanding, Balance	2.60
Weighted-Average Exercise Price, Options vested and exercisable	$ 2.06
Weighted-Average Remaining Contractual Term, Outstanding, Balance	7 years 1 month 6 days
Weighted-Average Remaining Contractual Term, Options vested and exercisable	5 years 10 months 24 days
Aggregate Intrinsic Value	$ 10,447	$ 8,522
Aggregate Intrinsic Value, Options vested and exercisable	$ 6,290

Equity Compensation Plans - RSU

Equity Compensation Plans - RSU Activity (Details)	9 Months Ended
	Sep. 30, 2018$ / sharesshares
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Number of Awards, Outstanding at December 31, 2017 | shares	6,688,000
Number of Awards, Granted | shares	3,986,000
Number of Awards, Vested | shares	(3,436,000)
Number of Awards, Forfeited | shares	(585,000)
Number of Awards, Outstanding at September 30, 2018 | shares	6,653,000
Weighted Average Grant Date Fair Value, Outstanding at December 31, 2017 | $ / shares	$ 3.20
Weighted Average Grant Date Fair Value, Granted | $ / shares	4.13
Weighted Average Grant Date Fair Value, Vested | $ / shares	2.98
Weighted Average Grant Date Fair Value, Forfeited | $ / shares	3.42
Weighted Average Grant Date Fair Value, Outstanding at September 30, 2018 | $ / shares	$ 3.85

Equity Compensation Plans - S_2

Equity Compensation Plans - Summary of Stock-Based Compensation Expense (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Schedule Of Stock Options [Line Items]
Stock-based compensation expense	$ 3,103	$ 2,249	$ 9,884	$ 9,501
Cost of Revenue
Schedule Of Stock Options [Line Items]
Stock-based compensation expense	361	164	984	738
Sales and Marketing
Schedule Of Stock Options [Line Items]
Stock-based compensation expense	754	601	2,668	2,710
General and Administrative
Schedule Of Stock Options [Line Items]
Stock-based compensation expense	1,956	1,421	6,125	5,763
Research and Development
Schedule Of Stock Options [Line Items]
Stock-based compensation expense	$ 32	$ 63	$ 107	$ 290

Equity Compensation Plans - S_3

Equity Compensation Plans - Summary of Unrecognized Stock-Based Compensation Expense (Details) $ in Thousands	9 Months Ended
	Sep. 30, 2018USD ($)
Schedule Of Stock Options [Line Items]
Unrecognized Stock-Based Compensation Expense	$ 22,621
RSUs
Schedule Of Stock Options [Line Items]
Unrecognized Stock-Based Compensation Expense, other than stock options	$ 20,105
Weighted- Average Period of Recognition	1 year 9 months 18 days
Stock Options
Schedule Of Stock Options [Line Items]
Unrecognized Stock-Based Compensation Expense, stock options	$ 2,516
Weighted- Average Period of Recognition	1 year 9 months 18 days

Income Taxes - Additional Infor

Income Taxes - Additional Information (Details) - USD ($)	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Income Tax Disclosure [Abstract]
Effective income tax rate	(54.70%)	(33.10%)	(70.50%)	(22.50%)
Income tax benefit, statutory federal rate			21.00%		35.00%
Net tax benefits related to remeasurement of deferred tax balances			$ 187,500,000
Useful life of assets			30 years
Prepaid tax asset, net					$ 505,883,000
Unrecognized tax benefits	$ 0		$ 0		0
Unrecognized tax benefits, income tax penalties and interest accrued	$ 0		$ 0		$ 0

Related Party Transactions - Co

Related Party Transactions - Components of Related Party Transactions (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Related Party Transaction [Line Items]
Cost of revenue—operating leases and incentives	$ 42,135	$ 34,731	$ 122,188	$ 103,564
Sales and marketing	15,841	9,808	40,999	28,037
General and administrative	29,803	19,379	71,533	60,259
Related Party
Related Party Transaction [Line Items]
Cost of revenue—operating leases and incentives		70		701
Sales and marketing	$ 340	697	$ 1,651	1,959
General and administrative		$ 15		$ 139

Related Party Transactions - Ad

Related Party Transactions - Additional Information (Details) - USD ($) $ in Thousands	1 Months Ended	3 Months Ended		9 Months Ended		12 Months Ended
	Aug. 31, 2017	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Related Party Transaction [Line Items]
Accounts payable—related party		$ 83		$ 83		$ 163
Accrued equity distributions		11,236		11,236		16,437
Related Party
Related Party Transaction [Line Items]
Amounts due from direct-sales personnel		5,700		5,700		6,600
Provision for advances to direct-sales personnel				1,000		1,000
Accrued equity distributions		1,800		1,800		$ 1,200
Vivint Services
Related Party Transaction [Line Items]
Fees incurred in conjunction with agreements entered		$ 6,100	$ 700	$ 11,400	$ 1,800
Initial term of agreement period	2 years

Commitments and Contingencies -

Commitments and Contingencies - Additional Information (Details) - USD ($) $ in Millions	1 Months Ended		3 Months Ended		9 Months Ended
	Apr. 30, 2018	Sep. 30, 2016	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Other Commitments [Line Items]
Aggregate operating lease expense			$ 3.6	$ 4	$ 11.3	$ 12.4
Standby letter of credit outstanding			13.5		13.5
Total estimated obligation earned over deferment period			$ 12.5		$ 12.5
Sun Edison Inc
Other Commitments [Line Items]
Unsecured claim initial amount		$ 1,000
Claim amount received from other party	$ 590
Received initial distribution amount	$ 2.1

Basic and Diluted Net (Loss) _3

Basic and Diluted Net (Loss) Income Per Share - Computation of Basic and Diluted Net (Loss) Income Per Share to Common Stockholders (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Numerator:
Net (loss attributable) income available to common stockholders	$ (7,868)	$ 6,905	$ (2,728)	$ 25,177
Denominator:
Shares used in computing net (loss attributable) income available per share to common stockholders, basic	118,767	114,505	116,871	112,554
Weighted-average effect of potentially dilutive shares to purchase common stock		4,960		5,271
Shares used in computing net (loss attributable) income available per share to common stockholders, diluted	118,767	119,465	116,871	117,825
Net (loss attributable) income available per share to common stockholders:
Basic	$ (0.07)	$ 0.06	$ (0.02)	$ 0.22
Diluted	$ (0.07)	$ 0.06	$ (0.02)	$ 0.21

Basic and Diluted Net (Loss) _4

Basic and Diluted Net (Loss) Income Per Share - Additional Information (Details) - shares shares in Millions	3 Months Ended	9 Months Ended
	Sep. 30, 2017	Sep. 30, 2017
Earnings Per Share [Abstract]
Number of shares excluded from dilutive shares	0.2	0.8