SolarCity 10-Q 12 Nov 13 2013 Q3 Quarterly report Financial data

Document_and_Entity_Informatio

Document and Entity Information	9 Months Ended
	Sep. 30, 2013
Document And Entity Information [Abstract]	'
Document Type	'10-Q
Amendment Flag	'false
Document Period End Date	30-Sep-13
Document Fiscal Year Focus	'2013
Document Fiscal Period Focus	'Q3
Trading Symbol	'SCTY
Entity Registrant Name	'SOLARCITY CORP
Entity Central Index Key	'0001408356
Current Fiscal Year End Date	'--12-31
Entity Filer Category	'Non-accelerated Filer
Entity Common Stock, Shares Outstanding	83,129,286

Condensed_Consolidated_Balance

Condensed Consolidated Balance Sheets (USD $)	Sep. 30, 2013		Dec. 31, 2012
In Thousands, unless otherwise specified
Current assets:	'		'
Cash and cash equivalents	$132,986		$160,080
Restricted cash	3,269		7,516
Accounts receivable (net of allowances for doubtful accounts of $819 and $220 as of September 30, 2013 and December 31, 2012, respectively)	32,791		25,145
Rebates receivable	19,158		17,501
Inventories	90,753		87,903
Deferred income tax asset	7,762		5,770
Prepaid expenses and other current assets	25,527		11,502
Total current assets	312,246		315,417
Restricted cash	1,701		2,810
Solar energy systems, leased and to be leased - net	1,491,941		1,002,184
Property and equipment - net	20,471		18,635
Goodwill and intangible assets - net	105,351		626
Other assets	28,625		22,170
Total assets	1,960,335	[1]	1,361,842	[1]
Current liabilities:	'		'
Accounts payable	134,123		62,986
Distributions payable to noncontrolling interests	17,634		12,028
Current portion of deferred U.S. Treasury grants income	15,404		11,376
Accrued and other current liabilities	51,800		52,334
Customer deposits	9,208		8,753
Current portion of deferred revenue	52,989		31,516
Current portion of long-term debt	9,158		20,613
Current portion of lease pass-through financing obligation	29,629		13,622
Current portion of sale-leaseback financing obligation	410		389
Total current liabilities	320,355		213,617
Deferred revenue, net of current portion	326,884		204,396
Long-term debt, net of current portion	132,149		83,533
Long-term deferred tax liability	7,791		5,790
Lease pass-through financing obligation, net of current portion	103,128		125,884
Sale-leaseback financing obligation, net of current portion	14,444		14,755
Deferred U.S. Treasury grants income, net of current portion	411,316		286,884
Other liabilities and deferred credits	182,288		112,056
Total liabilities	1,498,355	[1]	1,046,915	[1]
Commitments and contingencies (Note 13)	'		'
Stockholders' equity:	'		'
Common stock	8		7
Additional paid-in capital	469,053		325,705
Accumulated deficit	-162,915		-111,392
Total stockholders' equity	306,146		214,320
Noncontrolling interests in subsidiaries	155,834		100,607
Total equity	461,980		314,927
Total liabilities and equity	$1,960,335		$1,361,842
[1]	The Company's consolidated assets as of September 30, 2013 and December 31, 2012 include $651,218 and $562,531, respectively, being assets of variable interest entities, or VIEs, that can only be used to settle obligations of the VIEs. These assets include solar energy systems, leased and to be leased, net, of $612,186 and $530,230 as of September 30, 2013 and December 31, 2012, respectively; cash and cash equivalents of $14,938 and $16,065 as of September 30, 2013 and December 31, 2012, respectively; restricted cash, long-term of $193 and $0 as of September 30, 2013 and 2012, respectively; accounts receivable, net, of $4,629 and $1,681 as of September 30, 2013 and December 31, 2012, respectively; prepaid expenses and other assets of $1,794 and $2,603 as of September 30, 2013 and December 31, 2012, respectively; and rebates receivable of $14,660 and $8,985 as of September 30, 2013 and December 31, 2012, respectively; other assets of $2,818 and $2,800 as of September 30, 2013 and 2012, respectively. The Company's consolidated liabilities as of September 30, 2013 and December 31, 2012 included $32,392 and $19,853, respectively, being liabilities of VIEs whose creditors have no recourse to the Company. These liabilities include distributions payable to noncontrolling interests of $17,634 and $12,028 as of September 30, 2013 and December 31, 2012, respectively; customer deposits of $6,266 and $4,162 as of September 30, 2013 and December 31, 2012, respectively; accounts payable of $0 and $9 as of September 30, 2013 and December 31, 2012, respectively; accrued and other payables of $739 and $938 as of September 30, 2013 and December 31, 2012, respectively; other liabilities of $1,911 and $0 as of September 30, 2013 and December 31, 2012, respectively; and bank borrowings of $5,842 and $2,716 as of September 30, 2013 and December 31, 2012, respectively.

Condensed_Consolidated_Balance1

Condensed Consolidated Balance Sheets (Parenthetical) (USD $)	Sep. 30, 2013		Dec. 31, 2012
In Thousands, except Share data, unless otherwise specified
Allowances for doubtful accounts	$819		$220
Common stock, par value	$0.00		$0.00
Common stock, shares authorized	1,000,000,000		1,000,000,000
Common stock, shares issued	83,129,000		74,913,000
Common stock, shares outstanding	83,129,000		74,913,000
Total assets	1,960,335	[1]	1,361,842	[1]
Solar energy systems, leased and to be leased, net	1,491,941		1,002,184
Cash and cash equivalents	132,986		160,080
Restricted cash	1,701		2,810
Accounts receivable, net	32,791		25,145
Prepaid expenses and other assets	25,527		11,502
Other assets	28,625		22,170
Total liabilities	1,498,355	[1]	1,046,915	[1]
Distributions payable to noncontrolling interests	17,634		12,028
Customer deposits	9,208		8,753
Accounts payable	134,123		62,986
Accrued and other payables	51,800		52,334
Other liabilities	182,288		112,056
Variable Interest Entities [Member]	'		'
Total assets	651,218		562,531
Solar energy systems, leased and to be leased, net	612,186		530,230
Cash and cash equivalents	14,938		16,065
Restricted cash	193		0
Accounts receivable, net	4,629		1,681
Prepaid expenses and other assets	1,794		2,603
Rebates receivable	14,660		8,985
Other assets	2,818		2,800
Total liabilities	32,392		19,853
Distributions payable to noncontrolling interests	17,634		12,028
Customer deposits	6,266		4,162
Accounts payable	0		9
Accrued and other payables	739		938
Other liabilities	1,911		0
Bank borrowings	$5,842		$2,716
[1]	The Company's consolidated assets as of September 30, 2013 and December 31, 2012 include $651,218 and $562,531, respectively, being assets of variable interest entities, or VIEs, that can only be used to settle obligations of the VIEs. These assets include solar energy systems, leased and to be leased, net, of $612,186 and $530,230 as of September 30, 2013 and December 31, 2012, respectively; cash and cash equivalents of $14,938 and $16,065 as of September 30, 2013 and December 31, 2012, respectively; restricted cash, long-term of $193 and $0 as of September 30, 2013 and 2012, respectively; accounts receivable, net, of $4,629 and $1,681 as of September 30, 2013 and December 31, 2012, respectively; prepaid expenses and other assets of $1,794 and $2,603 as of September 30, 2013 and December 31, 2012, respectively; and rebates receivable of $14,660 and $8,985 as of September 30, 2013 and December 31, 2012, respectively; other assets of $2,818 and $2,800 as of September 30, 2013 and 2012, respectively. The Company's consolidated liabilities as of September 30, 2013 and December 31, 2012 included $32,392 and $19,853, respectively, being liabilities of VIEs whose creditors have no recourse to the Company. These liabilities include distributions payable to noncontrolling interests of $17,634 and $12,028 as of September 30, 2013 and December 31, 2012, respectively; customer deposits of $6,266 and $4,162 as of September 30, 2013 and December 31, 2012, respectively; accounts payable of $0 and $9 as of September 30, 2013 and December 31, 2012, respectively; accrued and other payables of $739 and $938 as of September 30, 2013 and December 31, 2012, respectively; other liabilities of $1,911 and $0 as of September 30, 2013 and December 31, 2012, respectively; and bank borrowings of $5,842 and $2,716 as of September 30, 2013 and December 31, 2012, respectively.

Condensed_Consolidated_Stateme

Condensed Consolidated Statements of Operations (USD $)	3 Months Ended		9 Months Ended
In Thousands, except Share data, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Revenue:	'	'	'	'
Operating leases	$24,796	$13,917	$60,493	$33,584
Solar energy systems sales	23,804	18,057	56,044	69,805
Total revenue	48,600	31,974	116,537	103,389
Cost of revenue:	'	'	'	'
Operating leases	8,423	2,323	21,149	8,615
Solar energy systems	22,640	13,900	49,676	57,924
Total cost of revenue	31,063	16,223	70,825	66,539
Gross profit	17,537	15,751	45,712	36,850
Operating expenses:	'	'	'	'
Sales and marketing	24,310	18,145	63,533	49,976
General and administrative	21,893	12,554	59,687	31,904
Total operating expenses	46,203	30,699	123,220	81,880
Loss from operations	-28,666	-14,948	-77,508	-45,030
Interest expense, net	5,781	6,587	17,521	14,922
Other expense, net	123	7,466	425	17,895
Loss before income taxes	-34,570	-29,001	-95,454	-77,847
Income tax benefit (provision)	-23	-42	57	-107
Net loss	-34,593	-29,043	-95,397	-77,954
Net (loss) income attributable to noncontrolling interests	-37,949	9,028	-43,874	-16,806
Net income (loss) attributable to stockholders	3,356	-38,071	-51,523	-61,148
Net income ( loss) attributable to common stockholders	'	'	'	'
Basic	3,356	-38,071	-51,523	-61,148
Diluted	$3,356	($38,071)	($51,523)	($61,148)
Net income ( loss) per share attributable to common stockholders	'	'	'	'
Basic	$0.04	($3.41)	($0.67)	($5.63)
Diluted	$0.04	($3.41)	($0.67)	($5.63)
Weighted-average shares used to compute net income (loss) per share attributable to common stockholders	'	'	'	'
Basic	79,918,110	11,161,789	77,228,677	10,867,584
Diluted	88,054,393	11,161,789	77,228,677	10,867,584

Condensed_Consolidated_Stateme1

Condensed Consolidated Statements of Cash Flows (USD $)	9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012
Operating activities:	'	'
Net loss	($95,397)	($77,954)
Adjustments to reconcile net loss to net cash provided by (used in) operating activities:	'	'
Loss on disposal of property and equipment	30	10
Depreciation and amortization net of amortization of deferred U.S. Treasury grant income	26,275	14,277
Interest on lease pass-through financing obligation	10,035	8,948
Stock-based compensation	17,166	7,749
Revaluation of convertible redeemable preferred stock warrants	'	16,713
Revaluation of preferred stock forward contract	'	350
Deferred income taxes	9	9
Reduction in lease pass-through financing obligation	-25,525	-12,057
Changes in operating assets and liabilities:	'	'
Restricted cash	1,454	-6,709
Accounts receivable	-7,646	-29,977
Rebates receivable	-1,657	-2,825
Inventories	-2,850	29,829
Prepaid expenses and other current assets	-17,449	2,615
Other assets	-3,411	-7,218
Accounts payable	71,137	-75,967
Accrued and other liabilities	66,635	41,137
Customer deposits	455	-3,884
Deferred revenue	143,682	90,564
Net cash provided by (used in) operating activities	182,943	-4,390
Investing activities:	'	'
Payments for the cost of solar energy systems, leased and to be leased	-507,695	-290,371
Purchase of property and equipment	-5,827	-7,400
Acquisition of business, net of cash acquired	-3,758	'
Net cash used in investing activities	-517,280	-297,771
Financing activities:	'	'
Borrowings under long-term debt	57,161	119,008
Repayments of long-term debt	-24,690	-32,168
Borrowings under bank line of credit	'	19,418
Repayments of bank line of credit	'	-25,000
Repayments of sale-leaseback financing obligation	-290	-268
Proceeds from lease pass-through financing obligation	31,233	138,775
Repayment of capital lease obligations	-1,594	-27,356
Proceeds from investment by noncontrolling interests in subsidiaries	221,175	63,532
Distributions paid to noncontrolling interests in a subsidiaries	-117,017	-137,276
Proceeds from U.S. Treasury grants	123,816	99,916
Net cash provided by financing activities before equity issuances	289,794	218,581
Equity issuances:	'	'
Proceeds from exercise of stock options	9,415	1,409
Proceeds from issuance of convertible redeemable preferred stock	'	80,868
Proceeds from issuance of convertible redeemable preferred stock warrants	'	150
Proceeds from exercise of common stock warrants	8,034	'
Net cash provided by equity issuances	17,449	82,427
Net cash provided by financing activities	307,243	301,008
Net decrease in cash and cash equivalents	-27,094	-1,153
Cash and cash equivalents, beginning of period	160,080	50,471
Cash and cash equivalents, end of period	132,986	49,318
Supplemental disclosures of cash flow information:	'	'
Cash paid during the period for interest	4,924	4,932
Cash paid during the period for taxes	'	$2,689

Organization

Organization	9 Months Ended
	Sep. 30, 2013
Accounting Policies [Abstract]	'
Organization	'
	1. Organization
	SolarCity Corporation, or the Company, was incorporated as a Delaware corporation on June 21, 2006. The Company is engaged in the design, installation and sale or lease of solar energy systems to residential and commercial customers, or sale of electricity generated by solar energy systems to customers. The Company’s headquarters are located in San Mateo, California.

Summary_of_Significant_Account

Summary of Significant Accounting Policies and Procedures	9 Months Ended
	Sep. 30, 2013
Accounting Policies [Abstract]	'
Summary of Significant Accounting Policies and Procedures	'
	2. Summary of Significant Accounting Policies and Procedures
	Basis of Presentation and Principles of Consolidation
	The accompanying unaudited condensed consolidated financial statements, in the opinion of management, include all adjustments (consisting only of normal recurring adjustments) which the Company considers necessary for a fair statement of the results of operations for the interim periods covered and the consolidated financial position of the Company at the date of the balance sheets. This Quarterly Report on Form 10-Q should be read in conjunction with the Company’s audited consolidated financial statements contained in the Company’s Annual Report on Form 10-K, which was filed with the Securities and Exchange Commission on March 27, 2013. The interim results presented herein are not necessarily indicative of the results of operations that may be expected for the full fiscal year ending December 31, 2013, or any other future period. As noted in Note 4, the Company acquired Paramount Energy on September 6, 2013. The acquisition was accounted for as a business combination and has been consolidated in the Company’s condensed consolidated financial statements.
	The 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. In accordance with the provisions of Financial Accounting Standards Board, or FASB, Accounting Standards Codification Section 810, or ASC 810, Consolidation, the Company consolidates any variable interest entity, or VIE, of which it is the primary beneficiary. The typical condition for a controlling financial interest ownership is holding a majority of the voting interests of an entity; however, a controlling financial interest may also exist in entities, such as variable interest entities, through arrangements that do not involve controlling voting interests. ASC 810 requires a variable interest holder to consolidate a VIE if that party has the power to direct the activities of a VIE that most significantly impact the VIE’s economic performance, and the obligation to absorb losses of the VIE that could potentially be significant to the VIE or the right to receive benefits from the VIE that could potentially be significant to the VIE. The Company does not consolidate a VIE in which it has a majority ownership interest when the Company is not considered the primary beneficiary. The Company has determined that it is the primary beneficiary in a number of VIEs—refer to Note 8, VIE Arrangements. 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.
	Reclassifications
	Prior period goodwill balance was reclassified in the condensed consolidated financial statements and accompanying notes in order to enhance their comparability to the current period balances. The reclassifications did not impact prior period results of operations or cash flows.
	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, the estimates which affect the estimated selling price of undelivered elements for revenue recognition purposes, the collectibility of accounts receivable, the valuation of inventories, the estimated total costs for long-term contracts used as a basis of determining percentage of completion for such contracts, the estimated fair value and residual values of solar energy systems subject to leases, accounting for business combinations, the estimates fair values and useful lives of acquired intangible assets, the estimated fair value of noncontrolling interests from business acquisitions, the useful lives of solar energy systems, property and equipment and intangible assets, the determination of accrued liabilities, the discount rates used to estimate the fair value of investment tax credits, the valuation of stock-based compensation, and the determination of valuation allowances associated with deferred tax assets. 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.
	Fair Value of Financial Instruments
	ASC 820, Fair Value Measurements, clarifies that fair value is an exit price, representing the amount that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants. As such, fair value is a market-based measurement that should be determined based on assumptions that market participants would use in pricing an asset or liability.
	ASC 820 requires that the valuation techniques used to measure fair value must maximize the use of observable inputs and minimize the use of unobservable inputs. ASC 820 establishes a three tier value hierarchy, which prioritizes inputs that may be used to measure fair value as follows:
		•		Level 1—Observable inputs that reflect quoted prices for identical assets or liabilities in active markets.
		•		Level 2—Observable inputs other than Level 1 prices, such as quoted prices for similar assets or liabilities; quoted prices in markets that are not active; or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the assets or liabilities.
		•		Level 3—Unobservable inputs that are supported by little or no market activity and that are significant to the fair value of the assets or liabilities.
	As of September 30, 2013 and December 31, 2012, there were no fair value measurements of assets and liabilities subsequent to initial recognition.
	The Company’s financial instruments include customer deposits, distributions payable to noncontrolling interests, borrowings under lines of credit, and long-term debt. The carrying values of its financial instruments other than its long-term debt approximate their fair values due to the fact that they were short-term in nature at September 30, 2013 and December 31, 2012 (Level 1). The Company estimates the fair value of its long-term debt based on rates currently offered for debt of similar maturities and terms (Level 3). The Company has estimated the fair value of its long-term debt to approximate its carrying value.
	Business Combinations
	The Company accounts for business acquisitions under ASC 805, Business Combinations. The cost of an acquisition is measured at the fair value of the assets given, equity instruments issued, and liabilities assumed at the acquisition date. Costs that are directly attributable to the acquisition are expensed as incurred. Identifiable assets, including intangible assets, acquired and liabilities, including contingent liabilities, assumed in the acquisition are measured initially at their fair values at the acquisition date. Any noncontrolling interests in the acquired business are also initially measured at fair value. The Company recognizes goodwill if the aggregate fair value of the total purchase consideration and the noncontrolling interests is in excess of the aggregate fair value of the identifiable assets acquired and the liabilities assumed.
	Long-Lived Assets
	The Company’s long-lived assets include property and equipment, solar energy systems leased and to be leased, and intangible assets acquired through business combinations. Intangible assets with definite useful lives are amortized over their estimated useful lives, which range from 3 to 30 years. The Company evaluates long-lived assets for impairment whenever events or changes in circumstances indicate that the carrying value of a long-lived asset, or group of assets as appropriate, may not be recoverable. If the aggregate undiscounted future net cash flows from a long-lived asset is less than its carrying value, then the Company would recognize an impairment loss based on the discounted future net cash flows.
	Goodwill
	Goodwill represents the difference between the purchase price and the aggregate fair value of the identifiable assets acquired and the liabilities assumed in a business combination. The Company tests goodwill for impairment annually, in the fourth quarter of each fiscal year, and whenever events or changes in circumstances indicate that the carrying value of goodwill may exceed its fair value, at the consolidated-level, which is the sole reporting unit. When assessing goodwill for impairment, the Company considers its market capitalization adjusted for a control premium and, if necessary, the Company’s discounted cash flow model, which involves significant assumptions and estimates, including the Company’s future financial performance, weighted-average cost of capital, and interpretation of currently enacted tax laws. Circumstances that could indicate impairment and require the Company to perform an impairment test include a significant decline in the Company’s financial results, a significant decline in the Company’s market capitalization relative to its net book value, an unanticipated change in competition or the Company’s market share, a significant change in the Company’s strategic plans, and an adverse action by a regulator.
	Warranties
	The Company warrants its products for various periods against defects in material or installation workmanship. The Company generally provides a warranty on the generating and non-generating parts of the solar energy systems it sells of typically between five to twenty years. The manufacturer’s warranty on the solar energy systems’ components, which is typically passed through to customers, has a warranty period ranging from one to twenty-five years. The changes in the accrued warranty balance, recorded as a component of accrued and other current liabilities on the condensed consolidated balance sheets, consisted of the following (in thousands):
			As of and for the
			Nine Months Ended
			September 30, 2013
	Balance – beginning of the period		$	4,019
	Provision charged to warranty expense			2,168
	Less warranty claims			(206	)
	Balance – end of the period		$	5,981
	Solar Energy Systems Performance Guarantees
	The Company guarantees certain specified minimum solar energy production output for systems leased to customers. The Company monitors the solar energy systems to ensure that these outputs are being achieved. The Company evaluates if any amounts are due to its customers. As of December 31, 2012 and September 30, 2013, the Company had recorded liabilities of $0.6 million and $0.9 million, respectively, as accrued and other current liabilities in the condensed consolidated financial statements, relating to these guarantees based on the Company’s assessment of its exposure.
	Deferred U.S. Treasury Grants Income
	The Company is eligible for U.S. Treasury grants received or receivable on eligible property as defined under Section 1603 of the American Recovery and Reinvestment Act of 2009, as amended by the Tax Relief Unemployment Insurance Reauthorization and Job Creation Act of December 2010, which includes solar energy system installations, upon approval by the U.S. Treasury Department. For solar energy systems under lease pass-through arrangements the Company reduces the financing obligation and records deferred income for the U.S. Treasury grants which are paid directly to the investors upon receipt of the grants by the investors. The benefit of the U.S. Treasury grants is recorded as deferred income and is amortized on a straight-line basis over the estimated useful lives of the related solar energy systems of 30 years. The amortization of the deferred income is recorded as a reduction to depreciation expense which is a component of the cost of revenue of operating leases in the condensed consolidated statement of operations. A catch up adjustment is recorded in the period in which the grant is approved by the U.S. Treasury Department or received by lease pass-through investors to recognize the portion of the grant that matches proportionally the amortization for the period between the date of placement in service of the solar energy systems and approval by the U.S. Treasury Department or receipt by lease pass-through investors of the associated grant. The changes in deferred U.S. Treasury grants income during the nine months ended September 30, 2013 were as follows (in thousands):
	Balance as of December 31, 2012		$	298,260
	U.S. Treasury grants received and receivable by the company			121,318
	U.S. Treasury grants received by investors under lease pass-through arrangements			18,590
	Amortized during the period as a credit to depreciation expense			(11,448	)
	Balance as of September 30, 2013		$	426,720
	Of the balance outstanding as of September 30, 2013, $411.3 million is presented as noncurrent deferred U.S. Treasury grants income in the condensed consolidated balance sheets.
	Deferred Investment Tax Credits Revenue
	The Company’s solar energy systems are eligible for investment tax credits, or ITCs, that accrue to eligible property under the Internal Revenue Code. Under Section 50(d)(5) of the Internal Revenue Code and the related regulations, a lessor of qualifying property may elect to treat the lessee as the owner of such property for the purposes of claiming government ITCs associated with such property. These regulations enable the ITCs to be separated from the ownership of the property and allow the transfer of these ITCs. Under the lease pass-through structures, the Company can make a tax election to pass through the ITCs to the investor, who is the legal lessee of the property. The Company is therefore able to monetize the ITCs to investors who can utilize them in return for cash payments. The Company considers the monetization of ITCs to constitute one of the key elements of realizing the value associated with solar energy systems. The Company therefore views the proceeds from the monetization of ITCs to be a component of revenue generated from the solar energy systems.
	For lease pass-through structures, the Company allocates a portion of the aggregate payments received from the investor to the estimated fair value of the assigned ITCs and the balance to the future customer lease payments that are also assigned to the investors. The estimated fair value of the ITCs are determined by discounting the estimated cash flows impact of the ITCs using an appropriate discount rate that reflects a market interest rate.
	The Company recognizes the revenue associated with the monetization of ITCs in accordance with ASC 605-10-S99, Revenue Recognition-Overall-SEC Materials. The revenue associated with the monetization of the ITCs is recognized when (1) persuasive evidence of an arrangement exists, (2) delivery has occurred or services have been rendered, (3) the sales price is fixed or determinable, and (4) collection of the related receivable is reasonably assured. The ITCs are subject to recapture under the Internal Revenue Code if the underlying solar energy system either ceases to be a qualifying property or undergoes a change in ownership within five years of its placed in service date. The recapture amount decreases on the anniversary of the placed in service date. As the Company has an obligation to ensure the solar energy system is in service and operational for a term of five years to avoid any recapture of the ITCs, the Company recognizes revenue as the recapture provisions lapse assuming the other aforementioned revenue recognition criteria have been met. The monetized ITCs are initially recorded as deferred revenue on the condensed consolidated balance sheet and subsequently one-fifth of the monetized ITCs is recognized as revenue in the condensed consolidated statement of operations on each anniversary of the solar energy system’s placed in service date over the next five years.
	The Company guarantees its fund investors that in the event of a subsequent recapture of the ITCs by the taxing authority due to the Company’s noncompliance with the applicable ITC guidelines, the Company will compensate the investor for any recaptured credits. The Company has concluded that the likelihood of a recapture event is remote and consequently has not recorded any liability in the condensed consolidated financial statements for any potential recapture exposure.
	The balance of deferred investment tax credits revenue, which is included as part of deferred revenue in the condensed consolidated balance sheets, as of September 30, 2013 and December 31, 2012 was $76.3 million and $0, respectively. No revenue has been recognized in the condensed consolidated statements of operations to date related to the monetization of investment tax credits.
	Comprehensive Income (Loss)
	The Company accounts for comprehensive income (loss) in accordance with ASC 220, Comprehensive Income. Under ASC 220, the Company is required to report comprehensive income (loss), which includes the Company’s net loss, as well as other comprehensive income (loss). There were no differences between comprehensive loss as defined by ASC 220 and net loss as reported in the Company’s accompanying condensed consolidated statements of operations for the periods presented.
	Segment Information
	Operating segments are defined as components of a company about which separate financial information is available that is evaluated regularly by the chief operating decision maker, or decision making group, in deciding how to allocate resources and in assessing performance. The Company’s chief operating decision maker is the executive team, comprising the chief executive officer, the chief operating officer, the chief revenue officer, and the chief financial officer. Based on the financial information presented to and reviewed by the chief operating decision maker in deciding how to allocate the resources and in assessing the performance of the Company, the Company has determined that it has a single operating and reporting segment, solar energy and energy efficiency products and services. The Company’s principal operations, revenue and decision-making functions are located in the United States.
	Basic and Diluted Net Income (Loss) Per Share
	The Company’s basic net income (loss) per share attributable to common stockholders is calculated by dividing the net income (loss) attributable to common stockholders by the weighted-average number of shares of common stock outstanding for the period. Prior to the Company’s initial public offering of its common stock, the Company’s convertible redeemable preferred stock was entitled to receive dividends of up to $0.01 per share when and if dividends were declared on the common stock and thereafter participate pro rata on an as converted basis with the common stock holders on any distributions to common stockholders. They were therefore participating securities. As a result, the Company calculates the net income (loss) per share using the two-class method. Accordingly, the net income (loss) attributable to common stockholders is derived from the net income (loss) for the period and, in periods in which the Company has net income attributable to common stockholders, an adjustment is made for the noncumulative dividends and allocations of earnings to participating securities based on their outstanding shareholder rights. Under the two-class method, the net loss attributable to common stockholders is not allocated to the convertible redeemable preferred stock as the convertible redeemable preferred stock did not have a contractual obligation to share in the Company’s losses.
	The diluted net income (loss) per share attributable to common stockholders is computed by giving effect to all potential common stock equivalents outstanding for the period determined using the treasury stock method or the as-if converted method as applicable. In periods when the Company incurred a net loss attributable to common stockholders, convertible redeemable preferred stock, stock options, restricted stock units, warrants to purchase common stock, and warrants to purchase convertible redeemable preferred stock were considered to be common stock equivalents but have been excluded from the calculation of diluted net loss per share attributable to common stockholders as their effect is antidilutive.
	Recently Issued Accounting Standard
	In July 2013, the FASB issued Accounting Standards Update, or ASU, No. 2013-11, Income Taxes (Topic 740): Presentation of an Unrecognized Tax Benefit When a Net Operating Loss Carryforward, a Similar Tax Loss, or a Tax Credit Carryforward Exists, to specify when an unrecognized tax benefit should be presented as a liability versus an offset against a deferred tax asset. The ASU is effective prospectively for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2013. The Company is currently assessing the impact of the ASU on the Company’s consolidated financial statements.

Acquisitions

Acquisitions	9 Months Ended
	Sep. 30, 2013
Business Combinations [Abstract]	'
Acquisitions	'
	3. Acquisitions
	Paramount Energy
	On September 6, 2013, the Company purchased certain assets of Paramount Energy Solutions, LLC, or Paramount Energy. Paramount Energy was a leading direct-to-consumer marketer and was one of the Company’s channel partners through a customer referral arrangement. The acquired assets included Paramount Energy’s interest in a financing fund that Paramount Energy had formed with an investor that is also an investor in five of SolarCity’s existing financing funds, executed end user customer agreements together with associated solar energy systems in various stages of completion and various databases and arrangements used by Paramount Energy in its acquisition of new customers. The acquisition will enable the Company to develop and offer its solar energy systems directly to a broader customer base and to better compete with other energy producers, as well as drive a lower cost of customer acquisition. In connection with the acquisition, the former chief executive officer of Paramount Energy joined the Company as the Chief Revenue Officer. The purchase consideration comprised of $3.7 million in cash and 3,674,565 shares of the Company’s common stock inclusive of 379,146 shares held in escrow until September 2014 to cover any general representations and warranties, with an aggregate fair value of $108.8 million based on the closing price of the Company’s common stock on the acquisition date. Additionally the Company is obligated to pay to the sellers an additional $4.3 million following the close of the acquisition.
	The following table summarizes the determination of the fair value of the purchase consideration in the acquired business as of the acquisition date (in thousands). The Company is in the process of determining the final value of deferred consideration, which includes estimated costs incurred by Paramount Energy in the installation of certain solar energy systems during a specified period and future contributions into the fund by the investor associated with certain other solar energy systems:
	Cash	$	3,700
	Common stock		108,804
	Deferred consideration		4,259
	Total purchase consideration	$	116,763
	The following table summarizes the preliminary assessment of the fair value of the assets acquired, liabilities assumed and noncontrolling interests as of the acquisition date (in thousands). The Company is in the process of obtaining third-party valuations of solar energy systems under construction, solar energy systems, leased and to be leased, intangible assets and noncontrolling interests. Accordingly, the preliminary amounts of these assets, noncontrolling interest and goodwill reflected in the table below are subject to change:
	Cash	$	12
	Deposits		12
	Prepaid costs		764
	Solar energy systems under construction		7,473
	Solar energy systems, leased and to be leased		3,793
	Property and equipment		96
	Intangible assets		56,571
	Deferred revenue		(279	)
	Total identifiable net assets at fair value		68,442
	Noncontrolling interest		(549	)
	Goodwill		48,870
	Total purchase consideration	$	116,763
	The noncontrolling interest represents the estimated fair value of an investor’s interest in a financing fund acquired as part of the business acquisition. The Company has determined that it is the primary beneficiary of this fund and accordingly consolidates the financial position and results of operations of the fund in the condensed consolidated financial statements.
	The goodwill recognized is attributable primarily to expected synergies, anticipated costs savings and efficiencies, and the assembled workforce of Paramount Energy. The full amount of goodwill is deductible for tax purposes.
	The following table summarizes the preliminary acquired intangible assets as of the acquisition date:
		Fair Value			Weighted-
					Average
					Useful Life
		(in thousands)			(in years)
	Marketing database	$	17,427			5
	PowerSaver agreement		17,077			10
	Solar energy systems backlog		10,280			30
	Non-compete agreement		6,959			5
	Mortgage database		4,628			3
	Funding commitment by fund investor		200			5
	Total	$	56,571
	Pro Forma Financial Information
	Pro forma financial information is not presented as the acquisition is not material to the condensed consolidated statements of operations. The revenue and earnings of the acquired business were not material to the condensed consolidated financial statements.

Goodwill_and_Intangible_Assets

Goodwill and Intangible Assets	9 Months Ended
	Sep. 30, 2013
Goodwill And Intangible Assets Disclosure [Abstract]	'
Goodwill and Intangible Assets	'
	4. Goodwill and Intangible Assets
	Intangible Assets
	The following is a summary of acquired intangible assets as of September 30, 2013 (in thousands):
		Gross		Accumulated		Transfer to solar		Net
				Amortization		energy systems –
						leased and to be
						leased
	Marketing database	$	17,427	$	242		—	$	17,185
	PowerSaver agreement		17,077		118		—		16,959
	Solar energy systems backlog		10,280		—		149		10,131
	Mortgage database		4,628		107		—		4,521
	Non-compete agreement		6,959		97		—		6,862
	Funding commitment		200		3		—		197
	Total	$	56,571	$	567		149	$	55,855
	Marketing Database
	The marketing database is a comprehensive platform for targeted marketing, including a prospective customer scoring engine, a marketing campaign manager tool, and monthly updates. The prospect scoring engine improves the results of marketing initiatives by predicting customer leads in the database that will respond favorably to a particular marketing campaign. The marketing campaign manager tool monitors the results of marketing campaigns and provides feedback for optimizing future marketing campaigns.
	PowerSaver Agreement
	Under the PowerSaver program, Fannie Mae makes available additional loans of up to $25,000 to eligible Fannie Mae borrowers. These additional loan amounts can only be used for energy efficiency projects that includes the installation of solar energy systems. This program provides an additional source of financing for customers that are interested in adopting a solar energy solution and therefore would help broaden the Company’s customer base. Under the PowerSaver agreement, SolarCity is provided the exclusive right to market solar energy systems to the customers of Paramount Mortgage, an affiliate of Paramount Energy.
	Solar Energy Systems Backlog
	Solar energy systems backlog represents the value attributable to contractual arrangements entered into by Paramount with its customers to install solar energy systems for which installation work was yet to commence as of the acquisition date. These arrangements were assumed by SolarCity. This amount will be transferred to the cost of solar energy systems, leased and to be leased, as the solar energy systems are installed and placed in service, and subsequently depreciated as cost of solar energy systems over the estimated useful lives of the solar energy systems of 30 years.
	Non-Compete Agreement
	The former CEO of Paramount Energy became the Company’s new Chief Revenue Officer and executed a five-year non-compete agreement.
	Mortgage Database
	The mortgage database contains data pertaining to households that the Company can directly market to.
	All intangible assets, with the exception of the solar energy systems backlog, are amortized over their expected useful life. No intangible assets were impaired during the nine months ended September 30, 2013.
	Estimated aggregate future amortization expense for intangible assets, excluding the solar energy systems backlog, is as follows (in thousands):
	Three months ending December 31, 2013	$	2,042
	2014		8,168
	2015		8,168
	2016		7,674
	2017		6,625
	2018		5,055
	Thereafter		7,992
	Total	$	45,724
	The value of solar energy systems backlog is transferred to the cost of leased solar energy systems as the Company completes the installation of the systems represented in the backlog.
	Goodwill
	The changes to the carrying value of goodwill during the nine months ended September 30, 2013 and the year ended December 31, 2012 are as follows (in thousands):
		2013		2012
	Balance – beginning of the period	$	626	$	626
	Acquisition of Paramount Energy		48,870		—
	Balance – end of the period	$	49,496	$	626
	The Company has not recorded any impairment charges related to goodwill for any period.

Selected_Balance_Sheet_Compone

Selected Balance Sheet Components	9 Months Ended
	Sep. 30, 2013
Text Block [Abstract]	'
Selected Balance Sheet Components	'
	5. Selected Balance Sheet Components
	Selected components of the condensed consolidated balance sheets were as follows (in thousands):
			September 30,			December 31,
			2013			2012
	Inventories:
	Raw materials		$	80,080		$	69,726
	Work in progress			10,673			18,177
	Total		$	90,753		$	87,903
	Solar Energy Systems, Leased and To Be Leased – Net:
	Solar energy systems leased to customers(1)		$	1,320,697		$	895,020
	Initial direct costs related to solar energy systems leased to customers			81,888			54,095
				1,402,585			949,115
	Less accumulated depreciation and amortization			(74,204	)		(43,024	)
				1,328,381			906,091
	Solar energy systems under construction			93,353			43,747
	Solar energy systems to be leased to customers			70,207			52,346
	Solar energy systems, leased and to be leased – net		$	1,491,941		$	1,002,184
	Other Liabilities and Deferred Credits:
	Deferred gain on sale-leaseback transactions, net of current portion		$	56,856		$	59,243
	Amounts received from lease pass-through investors for monetization of investment tax credits for systems not installed			77,812			18,111
	Deferred rent expense			4,304			4,443
	Capital lease obligation			27,506			28,688
	Other noncurrent liabilities			15,810			1,571
	Total		$	182,288		$	112,056
	-1	Included under solar energy systems leased to customers as of September 30, 2013 and December 31, 2012 was $66.4 million, related to capital leased assets, with an accumulated depreciation of $4.6 million and $2.6 million, respectively.

LongTerm_Debt

Long-Term Debt	9 Months Ended
	Sep. 30, 2013
Debt Disclosure [Abstract]	'
Long-Term Debt	'
	6. Long-Term Debt
	Working Capital Financing
	On May 26, 2010, a subsidiary of the Company entered into a financing agreement with a bank to obtain funding for working capital. The amount borrowed under the financing agreement was determined based on the estimated present value of expected future lease rentals to be generated by solar energy systems owned by the subsidiary and leased to customers, but could not exceed $16.3 million. The working capital financing was funded in four tranches and was available for drawdown through March 31, 2011. Each tranche bears interest at an annual rate of 2.00% plus the swap rate applicable to the average life of the scheduled rent receipts for the tranche. The working capital financing is secured by substantially all of the assets of the subsidiary and is nonrecourse to the Company’s other assets. The working capital financing matures on December 31, 2024.
	Through September 30, 2013, the Company had borrowed an aggregate of $13.3 million, net of fees, under the working capital financing. Of the amounts borrowed, $10.3 million, net of fees, was outstanding, of which $9.1 million is included in the condensed consolidated balance sheets under long-term debt, net of current portion, as of September 30, 2013. For the amounts outstanding as of September 30, 2013, the interest rates ranged between 5.48% and 5.65%. The Company was in compliance with all debt covenants as of September 30, 2013.
	Vehicle Loans
	The Company has entered into various vehicle loan agreements with various financial institutions. The vehicle loans are secured by the vehicles financed and mature between October 2013 and September 2018. Total vehicle loans payable as of September 30, 2013 was $8.6 million, of which $5.0 million is included in the condensed consolidated balance sheets under long-term debt, net of current portion. For the amounts outstanding as of September 30, 2013, the interest rates ranged between 0.00% and 7.49%. The Company was in compliance with all debt covenants as of September 30, 2013. Of the outstanding balance as of September 30, 2013, $2.7 million was repaid in November 2013.
	Inventory Financing
	On March 8, 2012, the Company entered into a $58.5 million loan agreement with a syndicate of banks to finance the purchase of inventory. The borrowed funds bore interest at an annual rate of LIBOR plus 3.75% and was secured by the Company’s inventory. The inventory financing was fully repaid in August 2013.
	Term Loans
	On February 8, 2013, a subsidiary of the Company entered into an agreement with a bank for a term loan of $10 million. The loan proceeds were used to finance the Company’s acquisition of a fund investor’s interests in three of the Company’s financing funds. The loan bears interest at an annual rate equal to the lower of (i) the sum of LIBOR plus 3.25% and (ii) an interest rate cap of 6.50%. As of September 30, 2013, the interest rate for the loan was 3.43%. The loan is secured by the assets of certain of the Company’s subsidiaries and is nonrecourse to the Company’s other assets. The loan matures on January 31, 2015. Through September 30, 2013, the Company had borrowed an aggregate of $9.5 million, net of fees, under the loan. Of the amounts borrowed, $6.8 million, net of fees, was outstanding, of which $5.1 million is included in the condensed consolidated balance sheets under long-term debt, net of current portion, as of September 30, 2013. The Company was in compliance with all debt covenants as of September 30, 2013.
	On June 7, 2013, a subsidiary of the Company entered into an agreement with a syndicate of banks for a term loan of $100.0 million for working capital financing. The loan bears interest at an annual rate equal to LIBOR plus 3.25%. As of September 30, 2013, the interest rates ranged between 3.50% and 3.67%. The loan is secured by the assets and future cash inflows of the subsidiary and is nonrecourse to the Company’s other assets. The loan matures on June 7, 2015. Through September 30, 2013, the Company had borrowed an aggregate of $38.1 million, net of fees, under the loan. Of the amounts borrowed, $38.1 million, net of fees, was outstanding, of which $35.7 million is included in the condensed consolidated balance sheets under long-term debt, net of current portion, as of September 30, 2013. The Company was in compliance with all debt covenants as of September 30, 2013.

Borrowings_under_Bank_Lines_of

Borrowings under Bank Lines of Credit	9 Months Ended
	Sep. 30, 2013
Debt Disclosure [Abstract]	'
Borrowings under Bank Lines of Credit	'
	7. Borrowings under Bank Lines of Credit
	Credit Facility for SolarStrong
	On November 21, 2011, a subsidiary of the Company entered into an agreement with a bank for a credit facility of up to $350 million. The facility is used to partially fund the Company’s SolarStrong initiative, which is a five-year plan to build solar power projects for privatized U.S. military housing communities across the country. The facility is drawn down in tranches as defined in the agreement, with the interest rates determined as amounts are drawn down. As of September 30, 2013, the interest rates for the facility ranged between 6.78% and of 7.27%. The facility is collateralized by the assets of the SolarStrong initiative and is nonrecourse to the Company’s other assets. The facility matures in 2032. As of September 30, 2013, $5.6 million, net of fees, was outstanding under the facility, of which $5.4 million is included in the condensed consolidated balance sheets under long-term debt, net of current portion. The Company was in compliance with all debt covenants as of September 30, 2013.
	Revolving Credit Facility
	In September 2012, the Company entered into a revolving credit agreement with a syndicate of banks to obtain funding for working capital, letters of credit, and general corporate needs. The revolving credit agreement has a $75.0 million committed facility. The facility bears interest at an annual rate equal to LIBOR plus 3.875% or, at the Company’s option, 2.875% plus the higher of (i) the federal funds rate plus 0.50%, (ii) Bank of America’s published “prime rate”, and (iii) LIBOR plus 1.00%. The fee for letters of credit is 3.875% per annum, and the fee for undrawn commitments is 0.375% per annum. The facility is secured by certain of the Company’s machinery and equipment, accounts receivables, inventory, and other assets, excluding certain inventory pledged to other lenders. The facility was to mature in September 2014, at which date it may have been extended by an additional year if the Company satisfied certain financial conditions. As of September 30, 2013, $71.9 million, net of fees, was outstanding under the facility, all of which is included in the condensed consolidated balance sheets under long-term debt. For the amounts outstanding as of September 30, 2013, the interest rate ranged between 4.05% and 4.06%. The Company was in compliance with all debt covenants as of September 30, 2013. This facility was amended and restated in November 2013 to increase the committed facility from $75.0 to $160.5 million, extend the maturity date to December 31, 2016 and lower the rate at which the facility bears interest to LIBOR plus 3.25% or, at the Company’s option, 2.25% plus the higher of (i) the federal funds rate plus 0.50%, (ii) Bank of America’s published “prime rate”, and (iii) LIBOR plus 1.00%.

VIE_Arrangements

VIE Arrangements	9 Months Ended
	Sep. 30, 2013
Text Block [Abstract]	'
VIE Arrangements	'
	8. VIE Arrangements
	Since 2008, wholly owned subsidiaries of the Company and fund investors have formed and contributed cash or assets into various financing funds and entered into related agreements. Additionally the Company acquired a financing fund through a business acquisition in the period ended September 30, 2013. As of September 30, 2013, the VIE investors had contributed $763.5 million into the VIEs.
	The Company has determined it is the primary beneficiary of these VIEs by reference to the power and benefits criterion under ASC 810. The Company has considered the provisions within the contractual arrangements, which grant it power to manage and make decisions that affect the operation of these VIEs, including determining the solar energy systems and associated customer leases to be sold or contributed to the VIE, preparation and approval of budgets. The Company considers that the rights granted to the other investors under the contractual arrangements are more protective in nature rather than participating rights.
	As the primary beneficiary of these VIEs, the Company consolidates in its financial statements the financial position, results of operations, and cash flows of these funds, and all intercompany balances and transactions between the Company and the financing funds are eliminated in the condensed consolidated financial statements.
	Under the related agreements, cash distributions of income and other receipts by the fund, net of agreed-upon expenses and estimated expenses, tax benefits and detriments of income and loss, and tax benefits of tax credits are allocated to the fund investor and Company’s subsidiary as specified in contractual arrangements. Generally, the Company’s subsidiary has the option to acquire the investor’s equity interest at the higher of market value or an amount based upon a formula specified in the contractual agreements.
	Upon the sale or liquidation of the fund, distributions would occur in the order and priority specified in the contractual agreements.
	Pursuant to management services, maintenance, and warranty arrangements, the Company has been contracted to provide services such as warranty support, accounting, lease servicing, and performance reporting. In some instances the Company has guaranteed payments to the fund investors as specified in the contractual agreements. The funds’ creditors have no recourse to the general credit of the Company or to that of other funds. As of September 30, 2013, the assets of one of the VIEs with a carrying value of $29.2 million have been pledged as collateral for the VIE’s borrowings under the SolarStrong facility. None of the assets of the other VIEs have been pledged as collateral for the VIEs’ obligations.
	The Company has aggregated the financial information of the financing funds in the table below. The aggregate carrying values of these funds’ assets and liabilities (after elimination of intercompany transactions and balances) in the Company’s condensed consolidated balance sheets as of September 30, 2013 and December 31, 2012, were as follows (in thousands):
		September 30,		December 31,
		2013		2012
	Assets
	Current assets
	Cash and cash equivalents	$	14,938	$	16,065
	Restricted cash, short term		—		167
	Accounts receivable, net		4,629		1,681
	Prepaid expenses and other assets		1,794		2,603
	Rebates receivable		14,660		8,985
	Total current assets		36,021		29,501
	Restricted cash, long term		193		—
	Solar energy systems, leased and to be leased, net		612,186		530,230
	Other assets		2,818		2,800
	Total assets	$	651,218	$	562,531
	Liabilities
	Current liabilities
	Accounts payable	$	—	$	9
	Customer deposits		6,266		4,162
	Distributions payable to noncontrolling interests		17,634		12,028
	Current portion of deferred U.S. Treasury grants income		6,619		6,710
	Current portion of deferred revenue		12,422		11,324
	Accrued and other liabilities		739		938
	Current portion of bank borrowings		242		131
	Total current liabilities		43,922		35,302
	Bank borrowings, net of current portion		5,600		2,585
	Deferred revenue, net of current portion		179,996		160,093
	Deferred U.S. Treasury grant income, net of current portion		180,748		184,470
	Other liabilities		1,911		—
	Total liabilities	$	412,177	$	382,450

Equity

Equity	9 Months Ended
	Sep. 30, 2013
Equity [Abstract]	'
Equity	'
	9. Equity
	Changes in total stockholder’s equity and noncontrolling interests in the nine months ended September 30, 2013 were as follows (in thousands):
		Total			Noncontrolling			Total
		Stockholders’			Interests in			Equity
		Equity			Subsidiaries
	Balance, December 31, 2012	$	214,320		$	100,607		$	314,927
	Issuance of common stock upon exercise of stock options for cash		9,415			—			9,415
	Issuance of common stock upon exercise of common stock warrants for cash		8,034			—			8,034
	Contributions from noncontrolling interests		—			221,175			221,175
	Stock-based compensation expense		17,166			—			17,166
	Issuance of common stock upon acquisition of Paramount Energy, net of issuance costs		108,734			—			108,734
	Net loss		(51,523	)		(43,874	)		(95,397	)
	Noncontrolling interests arising from business combination		—			549			549
	Distributions to noncontrolling interests		—			(122,623	)		(122,623	)
	Balance, September 30, 2013	$	306,146		$	155,834		$	461,980
	On May 8, 2013, a fund investor exercised its warrants to purchase 1,485,010 shares of the Company’s common stock for $8.0 million.
	On September 6, 2013, the Company issued 3,674,565 shares of its common stock to Paramount GR Holdings, LLC pursuant to its acquisition of Paramount Energy (see Note 3, Acquisition).

Stock_Option_Plans

Stock Option Plans	9 Months Ended
	Sep. 30, 2013
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]	'
Stock Option Plans	'
	10. Stock Option Plans
	Under the Company’s 2012 Equity Incentive Plan, the Company may grant options to purchase or directly issue incentive stock options and nonstatutory stock options, respectively, of common stock to employees, directors, and consultants. Incentive stock options may be granted at a price per share not less than 100% of the fair market value at date of grant. If the incentive stock option is granted to a 10% stockholder, then the purchase or exercise price per share shall not be less than 110% of the fair market value per share of common stock on the grant date. Nonstatutory stock options may be granted at a price per share not less than 100% of the fair market value at date of grant. Options granted are exercisable over a maximum term of 10 years from the date of grant and generally vest over a period of four years.
	In September 2012, the Company adopted a director compensation plan for future non-employee directors. Under the director compensation plan, each individual who joins the board of directors as a non-employee director following the adoption of the plan will receive an initial stock option grant to purchase 30,000 shares of common stock at the time of initial election or appointment and additional triennial stock option grants to purchase 15,000 shares of common stock, as well as an annual cash retainer of $15,000, all of which are subject to continued service on the board of directors. Such non-employee directors who serve on committees of the board of directors will receive various specified additional equity awards and cash retainers.
	A summary of stock option activity for the nine months ended September 30, 2013 is as follows (in thousands, except per share amounts):
		Common Stock			Weighted-			Weighted-			Aggregate
		Options			Average			Average			Intrinsic
					Exercise			Remaining			Value
					Price			Contractual
								Term
	Outstanding – December 31, 2012		14,903		$	4.8			7.67		$	107,653
	Granted (weighted-average fair value of $27.76)		3,416			35.48			—			—
	Exercised		(3,052	)		3.09			—			—
	Canceled		(1,069	)		12.56			—			—
	Outstanding – September 30, 2013		14,198		$	11.96			7.67		$	335,924
	Options vested and exercisable – September 30, 2013		6,834		$	4.22			6.72		$	208,408
	Options vested and expected to vest – September 30, 2013		12,989		$	10.81			7.55		$	320,757
	The aggregate intrinsic value of options exercised was $39.9 million and $2.1 million during the three months ended September 30, 2013 and 2012, respectively, and $91.9 million and $7.7 million during the nine months ended September 30, 2013 and 2012, respectively. The grant date fair market value of options that vested was $53.9 million and $3.6 million for the three months ended September 30, 2013 and 2012, respectively, and $121.2 million and $9.0 million for the nine months ended September 30, 2013 and 2012, respectively.
	As of September 30, 2013, there was $74.8 million of total unrecognized stock-based compensation expense, net of estimated forfeitures, related to nonvested stock options, which are expected to be recognized over the weighted-average period of 2.93 years.
	Under ASC 718, Stock Compensation, the Company estimates the fair value of stock options granted on each grant date using the Black-Scholes option valuation model and applies the ratable method of expense attribution. The fair values were estimated on each grant date with the following weighted-average assumptions:
		Three Months Ended						Nine Months Ended
		September 30,						September 30,
		2013			2012			2013			2012
	Dividend yield		0	%		0	%		0	%		0	%
	Annual risk-free rate of return		1.56	%		0.93	%		1.31	%		1.08	%
	Expected volatility		80.21	%		90.82	%		88.33	%		88.16	%
	Expected term (years)		5.83			6.29			6.02			6.16
	The expected volatility was calculated based on the average historical volatilities of publicly traded peer companies, determined by the Company. The risk-free interest rate used was based on the U.S. Treasury yield curve in effect at the time of grant for the expected term of the stock options to be valued. The expected dividend yield was zero, as the Company does not anticipate paying a dividend within the relevant time frame. The expected term was estimated using the simplified method allowed under ASC 718.
	As part of the requirements of ASC 718, the Company is required to estimate potential forfeitures of stock grants and adjust stock-based compensation expense accordingly. The estimate of forfeitures will be adjusted over the requisite service period to the extent that actual forfeitures differ, or are expected to differ, from such estimates. Changes in estimated forfeitures will be recognized in the period of change and will also impact the amount of stock-based compensation expenses to be recognized in future periods.
	The amount of stock-based compensation expense recognized was $8.2 million and $3.0 million during the three months ended September 30, 2013 and 2012, respectively, and $17.2 million and $7.7 million during the nine months ended September 30, 2013 and 2012, respectively. The Company capitalized costs of $2.0 million and $0.7 million for the three months ended September 30, 2013 and 2012, respectively, and $4.7 million and $1.9 million for the nine months ended September 30, 2013 and 2012, respectively, as a component of work-in-progress within inventory and solar energy systems leased and to be leased to customers.
	Stock-based compensation expense was included in cost of revenue and operating expenses as follows (in thousands):
		Three Months Ended						Nine Months Ended
		September 30,						September 30,
		2013			2012			2013			2012
	Cost of revenue	$	245		$	120		$	548		$	321
	Sales and marketing		1,317			352			2,643			880
	General and administrative		4,589			1,856			9,277			4,615

Income_Taxes

Income Taxes	9 Months Ended
	Sep. 30, 2013
Income Tax Disclosure [Abstract]	'
Income Taxes	'
	11. Income Taxes
	The Company accounts for income taxes using the asset and liability method. Under this method, deferred income tax assets and liabilities are determined based upon the difference between the condensed consolidated financial statement carrying amounts and the tax basis of assets and liabilities and are measured using the enacted tax rate expected to apply to taxable income in the years in which the differences are expected to be reversed.
	The income tax expense for the three months ended September 30, 2013 and 2012 were determined based on the Company’s estimated consolidated effective income tax rates of 0.07% and 0.13%, respectively. The income tax expense for the nine months ended September 30, 2013 and 2012 were determined based on the Company’s estimated consolidated effective income tax rates of negative 0.06% and 0.13%, respectively. The differences between the estimated consolidated effective income tax rate and the U.S. federal statutory rate were primarily attributable to a valuation allowance and the current amortization of the prepaid income taxes due to inter-company sales held within the consolidated group.
	As part of the asset monetization strategy, the Company has agreements to sell solar energy systems to the solar financing fund joint ventures. The gain on the sale of the assets has been eliminated in the condensed consolidated financial statements. These transactions are treated as inter-company sales and as such, tax is not recognized on the sale until the Company no longer benefits from the underlying asset. Since the systems remain within the consolidated group, the tax expense incurred related to these sales is being deferred and amortized over the estimated useful life of the underlying systems which has been estimated to be 30 years. The deferral of the tax expense results in recording of a prepaid tax expense that is included in the condensed consolidated balance sheets as other assets. As of September 30, 2013 and December 31, 2012, the Company recorded a long-term prepaid tax expense, net of amortization of $2.0 million. The amortization of the prepaid tax expense in each period makes up the major component of the tax expense.
	Uncertain Tax Positions
	The Company is subject to taxation and files income tax returns in the U.S., various state, local, and foreign jurisdictions. Due to the Company’s net losses, substantially all of its federal, state, local, and foreign income tax returns since inception are still subject to audit.

Related_Party_Transactions

Related Party Transactions	9 Months Ended
	Sep. 30, 2013
Related Party Transactions [Abstract]	'
Related Party Transactions	'
	12. Related Party Transactions
	The Company’s operations for the three and nine months ended September 30, 2013 and 2012 included the following related party transactions (in thousands):
		Three Months Ended				Nine Months Ended
		September 30,				September 30,
		2013		2012		2013		2012
	Net Revenue, Systems:
	Solar energy systems sales to related parties	$	—	$	234	$	17	$	417
	Expenditures:
	Purchases of inventory from a related party	$	975	$	—	$	975	$	—
	Referral fees paid or payable to a related party (included in sales and marketing)	$	25	$	—	$	25	$	—
	Related party balances as of September 30, 2013 and December 31, 2012 comprised of (in thousands):
		September 30,		December 31,
		2013		2012
	Due from a related party (included in accounts receivable)	$	—	$	932
	Due to a related party (included in accounts payable)	$	974	$	—
	Deferred revenue from a related party (included in current portion of deferred revenue)	$	831	$	—

Commitments_and_Contingencies

Commitments and Contingencies	9 Months Ended
	Sep. 30, 2013
Commitments And Contingencies Disclosure [Abstract]	'
Commitments and Contingencies	'
	13. Commitments and Contingencies
	Noncancelable Operating Leases
	The Company leases office and warehouse facilities under noncancelable operating leases primarily for its United States based warehouse locations. In addition, the Company leases equipment under noncancelable operating leases.
	Indemnification and Guaranteed Returns
	The Company is contractually committed to compensate certain fund investors for any losses that they may suffer in certain limited circumstances resulting from reductions in U.S. Treasury grants or investment tax credits (“ITCs”). Generally such obligations would arise as a result of reductions to the value of the underlying solar energy systems as assessed by the U.S. Treasury Department for purposes of claiming the Treasury grants or as assessed by the Internal Revenue Service (IRS) for purposes of claiming ITCs or grants. At each reporting period end, the Company assesses and recognizes, when applicable, the potential exposure from this obligation based on all the information available at that time, including any guidelines issued by the U.S. Treasury Department on solar energy system valuations for purposes of making claims under the U.S. Treasury grant program or any audits undertaken by the IRS. The Company believes that any payments to the fund investors in excess of the amounts already recorded by the Company arising from this obligation are not probable based on the facts known at the reporting date.
	The maximum potential future payments that the Company would have to make under this obligation would depend on the difference between the fair values of the solar energy systems sold or transferred to the funds as determined by the Company and the values that the U.S. Treasury Department would determine as fair value for the systems for purposes of claiming the U.S. Treasury grants or the values the IRS would determine as the fair values of the systems for purposes of claiming the ITCs or grants. The Company claims U.S. Treasury grants based on guidelines provided by the U.S. Treasury department and the statutory regulations from the IRS. The Company uses fair values determined with the assistance of an independent third party appraisal as the basis for determining the ITCs that are passed through to and claimed by the investors. Since the Company cannot determine future revisions to the U.S. Treasury guidelines governing system values or how the IRS will evaluate system values used in claiming ITCs, the Company is unable to reliably estimate the maximum potential future payments that it could have to make under the Company’s contractual investor obligation as of each reporting date.
	The Company is eligible to receive certain state or local government incentives that are associated with renewable energy generation. The amount of the incentive that can be claimed is based on the projected or actual systems size and/or the amount of solar energy produced by the solar energy system. The Company also currently participates in one state incentives program in which the incentive is based on either the fair market value or the tax basis of the solar energy systems placed in service. The state and local incentives are either shared between the Company and the fund investors based on a predefined allocation percentage or retained fully by either party, in either case as determined by the contractual terms of each financing fund. The Company is not contractually obligated to indemnify any fund investor for any losses they may incur due to a shortfall in the amount of the state or local incentives actually received.
	The Company is contractually required to make payments to one fund investor to ensure the fund investor achieves a specified minimum internal rate of return. The fund investor has already received a significant portion of the projected economic benefits from U.S. Treasury grant distributions and tax depreciation benefits. The contractual provisions of this financing fund state that the financing fund has an indefinite term unless the members agree to dissolve the financing fund. Based on the Company’s current financial projections regarding the amount and timing of future distributions to the fund investor, the Company does not expect to make any payments as a result of this guarantee and has not accrued any liabilities related to this guarantee. The amount of potential future payments under this guarantee is dependent on the amount and timing of future distributions to the fund investor and future tax benefits that accrue to the fund investor. Due to uncertainties surrounding estimating the amounts of these factors, the Company is unable to estimate the maximum potential payments under this guarantee. As of September 30, 2013, the fund investor had achieved its annual minimum internal rate of return as determined in accordance with the contractual provisions of the financing fund.
	In July 2012, the Company, in addition to other companies related to the solar industry, received subpoenas from the U.S. Department of Treasury’s Office of the Inspector General to deliver certain documents in the Company’s possession that are dated, created, revised or referred to since January 1, 2007 that relate to the Company’s applications for U.S. Treasury grants or communications with certain other solar development companies or certain firms that appraise solar energy property for U.S Treasury grant application purposes. The Inspector General and the Civil Division of the U.S. Department of Justice are investigating the administration and implementation of the U.S Treasury grant program, including possible misrepresentations concerning the fair market value of the solar energy systems submitted for grant under that program made in grant applications by the Company. If at the conclusion of the investigation the Inspector General concludes that misrepresentations were made, the Department of Justice could decide to bring a civil action to recover amounts it believes were improperly paid to the Company. If the Department of Justice was successful in asserting this action, the Company could then be required to pay material damages and penalties for any funds received based on such misrepresentations (which in turn, could require the Company to make indemnity payments to certain fund investors). The Company is unable to estimate the possible loss, if any, associated with this investigation as documentation is still being produced by the Company for further review by the Inspector General in connection with their ongoing investigation.
	From time to time, claims have been asserted, and may in the future be asserted, including claims from regulatory authorities related to labor practices or other matters. Such assertions arise in the normal course of the Company’s operations. The resolution of any such assertions and claims cannot be predicted with certainty.

Basic_and_Diluted_Net_Income_L

Basic and Diluted Net Income (Loss) Per Share	9 Months Ended
	Sep. 30, 2013
Earnings Per Share [Abstract]	'
Basic and Diluted Net Income (Loss) Per Share	'
	14. Basic and Diluted Net Income (Loss) Per Share
	The following table sets forth the computation of the Company’s basic and diluted net income (loss) per share for the three and nine months ended September 30, 2013 and 2012 (in thousands, except share and per share amounts):
		Three Months Ended					Nine Months Ended
		September 30,					September 30,
		2013		2012			2013			2012
	Net income (loss) attributable to common stockholders, basic	$	3,356	$	(38,071	)	$	(51,523	)	$	(61,148	)
	Net income (loss) attributable to common stockholders, diluted	$	3,356	$	(38,071	)	$	(51,523	)	$	(61,148	)
	Weighted-average shares used to compute net income (loss) per share attributable to common stockholders, basic		79,918,110		11,161,789			77,228,677			10,867,584
	Dilutive effect of common stock options		8,128,037		—			—			—
	Dilutive effect of restricted stock units		8,246		—			—			—
	Weighted-average shares used to compute net income (loss) per share attributable to common stockholders, diluted		88,054,393		11,161,789			77,228,677			10,867,584
	Net income (loss) per share attributable to common stockholders, basic	$	0.04	$	(3.41	)	$	(0.67	)	$	(5.63	)
	Net income (loss) per share attributable to common stockholders, diluted	$	0.04	$	(3.41	)	$	(0.67	)	$	(5.63	)
	The following outstanding shares of common stock equivalents were excluded from the computation of diluted net income (loss) per share for the periods presented because including them would have been antidilutive:
		Three Months Ended					Nine Months Ended
		September 30,					September 30,
		2013		2012			2013			2012
	Convertible redeemable preferred stock		—		45,392,867			—			45,392,867
	Preferred stock warrants and common stock warrants		—		1,816,650			690,829			1,816,650
	Common stock options		1,936,485		14,859,208			14,564,924			14,611,371
	Restricted stock units		—		—			19,026			—

Subsequent_Events

Subsequent Events	9 Months Ended
	Sep. 30, 2013
Subsequent Events [Abstract]	'
Subsequent Events	'
	15. Subsequent Events
	Pending Acquisition of Zep Solar
	In October 2013, the Company entered into an agreement to acquire all of the outstanding capital stock of Zep Solar, Inc., or Zep Solar, for shares of the Company’s common stock valued at approximately $158 million. Zep Solar contract manufactures solar energy system mounting and grounding products and also licenses this patented technology to other third parties.
	Issuance of Common Stock and Convertible Senior Notes
	In October 2013, the Company issued 3,910,000 shares of common stock at a price of $46.54 per share and $230.0 million of 2.75% convertible senior notes maturing on November 1, 2018. As a result of the issuances, the Company received $398.0 million, net of underwriting discounts and commissions but before offering expenses. The notes are convertible to the Company’s common stock at any time until maturity at an initial conversion rate of 16.2165 shares per $1,000 of principal, which is equivalent to an initial conversion price of $61.67 per share.

Summary_of_Significant_Account1

Summary of Significant Accounting Policies and Procedures (Policies)	9 Months Ended
	Sep. 30, 2013
Accounting Policies [Abstract]	'
Basis of Presentation and Principles of Consolidation	'
	Basis of Presentation and Principles of Consolidation
	The accompanying unaudited condensed consolidated financial statements, in the opinion of management, include all adjustments (consisting only of normal recurring adjustments) which the Company considers necessary for a fair statement of the results of operations for the interim periods covered and the consolidated financial position of the Company at the date of the balance sheets. This Quarterly Report on Form 10-Q should be read in conjunction with the Company’s audited consolidated financial statements contained in the Company’s Annual Report on Form 10-K, which was filed with the Securities and Exchange Commission on March 27, 2013. The interim results presented herein are not necessarily indicative of the results of operations that may be expected for the full fiscal year ending December 31, 2013, or any other future period. As noted in Note 4, the Company acquired Paramount Energy on September 6, 2013. The acquisition was accounted for as a business combination and has been consolidated in the Company’s condensed consolidated financial statements.
	The 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. In accordance with the provisions of Financial Accounting Standards Board, or FASB, Accounting Standards Codification Section 810, or ASC 810, Consolidation, the Company consolidates any variable interest entity, or VIE, of which it is the primary beneficiary. The typical condition for a controlling financial interest ownership is holding a majority of the voting interests of an entity; however, a controlling financial interest may also exist in entities, such as variable interest entities, through arrangements that do not involve controlling voting interests. ASC 810 requires a variable interest holder to consolidate a VIE if that party has the power to direct the activities of a VIE that most significantly impact the VIE’s economic performance, and the obligation to absorb losses of the VIE that could potentially be significant to the VIE or the right to receive benefits from the VIE that could potentially be significant to the VIE. The Company does not consolidate a VIE in which it has a majority ownership interest when the Company is not considered the primary beneficiary. The Company has determined that it is the primary beneficiary in a number of VIEs—refer to Note 8, VIE Arrangements. 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.
Reclassifications	'
	Reclassifications
	Prior period goodwill balance was reclassified in the condensed consolidated financial statements and accompanying notes in order to enhance their comparability to the current period balances. The reclassifications did not impact prior period results of operations or cash flows.
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, the estimates which affect the estimated selling price of undelivered elements for revenue recognition purposes, the collectibility of accounts receivable, the valuation of inventories, the estimated total costs for long-term contracts used as a basis of determining percentage of completion for such contracts, the estimated fair value and residual values of solar energy systems subject to leases, accounting for business combinations, the estimates fair values and useful lives of acquired intangible assets, the estimated fair value of noncontrolling interests from business acquisitions, the useful lives of solar energy systems, property and equipment and intangible assets, the determination of accrued liabilities, the discount rates used to estimate the fair value of investment tax credits, the valuation of stock-based compensation, and the determination of valuation allowances associated with deferred tax assets. 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.
Fair Value of Financial Instruments	'
	Fair Value of Financial Instruments
	ASC 820, Fair Value Measurements, clarifies that fair value is an exit price, representing the amount that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants. As such, fair value is a market-based measurement that should be determined based on assumptions that market participants would use in pricing an asset or liability.
	ASC 820 requires that the valuation techniques used to measure fair value must maximize the use of observable inputs and minimize the use of unobservable inputs. ASC 820 establishes a three tier value hierarchy, which prioritizes inputs that may be used to measure fair value as follows:
		•		Level 1—Observable inputs that reflect quoted prices for identical assets or liabilities in active markets.
		•		Level 2—Observable inputs other than Level 1 prices, such as quoted prices for similar assets or liabilities; quoted prices in markets that are not active; or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the assets or liabilities.
		•		Level 3—Unobservable inputs that are supported by little or no market activity and that are significant to the fair value of the assets or liabilities.
	As of September 30, 2013 and December 31, 2012, there were no fair value measurements of assets and liabilities subsequent to initial recognition.
	The Company’s financial instruments include customer deposits, distributions payable to noncontrolling interests, borrowings under lines of credit, and long-term debt. The carrying values of its financial instruments other than its long-term debt approximate their fair values due to the fact that they were short-term in nature at September 30, 2013 and December 31, 2012 (Level 1). The Company estimates the fair value of its long-term debt based on rates currently offered for debt of similar maturities and terms (Level 3). The Company has estimated the fair value of its long-term debt to approximate its carrying value.
Business Combinations	'
	Business Combinations
	The Company accounts for business acquisitions under ASC 805, Business Combinations. The cost of an acquisition is measured at the fair value of the assets given, equity instruments issued, and liabilities assumed at the acquisition date. Costs that are directly attributable to the acquisition are expensed as incurred. Identifiable assets, including intangible assets, acquired and liabilities, including contingent liabilities, assumed in the acquisition are measured initially at their fair values at the acquisition date. Any noncontrolling interests in the acquired business are also initially measured at fair value. The Company recognizes goodwill if the aggregate fair value of the total purchase consideration and the noncontrolling interests is in excess of the aggregate fair value of the identifiable assets acquired and the liabilities assumed.
Long-Lived Assets	'
	Long-Lived Assets
	The Company’s long-lived assets include property and equipment, solar energy systems leased and to be leased, and intangible assets acquired through business combinations. Intangible assets with definite useful lives are amortized over their estimated useful lives, which range from 3 to 30 years. The Company evaluates long-lived assets for impairment whenever events or changes in circumstances indicate that the carrying value of a long-lived asset, or group of assets as appropriate, may not be recoverable. If the aggregate undiscounted future net cash flows from a long-lived asset is less than its carrying value, then the Company would recognize an impairment loss based on the discounted future net cash flows.
Goodwill	'
	Goodwill
	Goodwill represents the difference between the purchase price and the aggregate fair value of the identifiable assets acquired and the liabilities assumed in a business combination. The Company tests goodwill for impairment annually, in the fourth quarter of each fiscal year, and whenever events or changes in circumstances indicate that the carrying value of goodwill may exceed its fair value, at the consolidated-level, which is the sole reporting unit. When assessing goodwill for impairment, the Company considers its market capitalization adjusted for a control premium and, if necessary, the Company’s discounted cash flow model, which involves significant assumptions and estimates, including the Company’s future financial performance, weighted-average cost of capital, and interpretation of currently enacted tax laws. Circumstances that could indicate impairment and require the Company to perform an impairment test include a significant decline in the Company’s financial results, a significant decline in the Company’s market capitalization relative to its net book value, an unanticipated change in competition or the Company’s market share, a significant change in the Company’s strategic plans, and an adverse action by a regulator.
Warranties	'
	Warranties
	The Company warrants its products for various periods against defects in material or installation workmanship. The Company generally provides a warranty on the generating and non-generating parts of the solar energy systems it sells of typically between five to twenty years. The manufacturer’s warranty on the solar energy systems’ components, which is typically passed through to customers, has a warranty period ranging from one to twenty-five years. The changes in the accrued warranty balance, recorded as a component of accrued and other current liabilities on the condensed consolidated balance sheets, consisted of the following (in thousands):
			As of and for the
			Nine Months Ended
			September 30, 2013
	Balance – beginning of the period		$	4,019
	Provision charged to warranty expense			2,168
	Less warranty claims			(206	)
	Balance – end of the period		$	5,981
Solar Energy Systems Performance Guarantees	'
	Solar Energy Systems Performance Guarantees
	The Company guarantees certain specified minimum solar energy production output for systems leased to customers. The Company monitors the solar energy systems to ensure that these outputs are being achieved. The Company evaluates if any amounts are due to its customers. As of December 31, 2012 and September 30, 2013, the Company had recorded liabilities of $0.6 million and $0.9 million, respectively, as accrued and other current liabilities in the condensed consolidated financial statements, relating to these guarantees based on the Company’s assessment of its exposure.
Deferred U.S. Treasury Grants Income	'
	Deferred U.S. Treasury Grants Income
	The Company is eligible for U.S. Treasury grants received or receivable on eligible property as defined under Section 1603 of the American Recovery and Reinvestment Act of 2009, as amended by the Tax Relief Unemployment Insurance Reauthorization and Job Creation Act of December 2010, which includes solar energy system installations, upon approval by the U.S. Treasury Department. For solar energy systems under lease pass-through arrangements the Company reduces the financing obligation and records deferred income for the U.S. Treasury grants which are paid directly to the investors upon receipt of the grants by the investors. The benefit of the U.S. Treasury grants is recorded as deferred income and is amortized on a straight-line basis over the estimated useful lives of the related solar energy systems of 30 years. The amortization of the deferred income is recorded as a reduction to depreciation expense which is a component of the cost of revenue of operating leases in the condensed consolidated statement of operations. A catch up adjustment is recorded in the period in which the grant is approved by the U.S. Treasury Department or received by lease pass-through investors to recognize the portion of the grant that matches proportionally the amortization for the period between the date of placement in service of the solar energy systems and approval by the U.S. Treasury Department or receipt by lease pass-through investors of the associated grant. The changes in deferred U.S. Treasury grants income during the nine months ended September 30, 2013 were as follows (in thousands):
	Balance as of December 31, 2012		$	298,260
	U.S. Treasury grants received and receivable by the company			121,318
	U.S. Treasury grants received by investors under lease pass-through arrangements			18,590
	Amortized during the period as a credit to depreciation expense			(11,448	)
	Balance as of September 30, 2013		$	426,720
	Of the balance outstanding as of September 30, 2013, $411.3 million is presented as noncurrent deferred U.S. Treasury grants income in the condensed consolidated balance sheets.
Deferred Investment Tax Credits Revenue	'
	Deferred Investment Tax Credits Revenue
	The Company’s solar energy systems are eligible for investment tax credits, or ITCs, that accrue to eligible property under the Internal Revenue Code. Under Section 50(d)(5) of the Internal Revenue Code and the related regulations, a lessor of qualifying property may elect to treat the lessee as the owner of such property for the purposes of claiming government ITCs associated with such property. These regulations enable the ITCs to be separated from the ownership of the property and allow the transfer of these ITCs. Under the lease pass-through structures, the Company can make a tax election to pass through the ITCs to the investor, who is the legal lessee of the property. The Company is therefore able to monetize the ITCs to investors who can utilize them in return for cash payments. The Company considers the monetization of ITCs to constitute one of the key elements of realizing the value associated with solar energy systems. The Company therefore views the proceeds from the monetization of ITCs to be a component of revenue generated from the solar energy systems.
	For lease pass-through structures, the Company allocates a portion of the aggregate payments received from the investor to the estimated fair value of the assigned ITCs and the balance to the future customer lease payments that are also assigned to the investors. The estimated fair value of the ITCs are determined by discounting the estimated cash flows impact of the ITCs using an appropriate discount rate that reflects a market interest rate.
	The Company recognizes the revenue associated with the monetization of ITCs in accordance with ASC 605-10-S99, Revenue Recognition-Overall-SEC Materials. The revenue associated with the monetization of the ITCs is recognized when (1) persuasive evidence of an arrangement exists, (2) delivery has occurred or services have been rendered, (3) the sales price is fixed or determinable, and (4) collection of the related receivable is reasonably assured. The ITCs are subject to recapture under the Internal Revenue Code if the underlying solar energy system either ceases to be a qualifying property or undergoes a change in ownership within five years of its placed in service date. The recapture amount decreases on the anniversary of the placed in service date. As the Company has an obligation to ensure the solar energy system is in service and operational for a term of five years to avoid any recapture of the ITCs, the Company recognizes revenue as the recapture provisions lapse assuming the other aforementioned revenue recognition criteria have been met. The monetized ITCs are initially recorded as deferred revenue on the condensed consolidated balance sheet and subsequently one-fifth of the monetized ITCs is recognized as revenue in the condensed consolidated statement of operations on each anniversary of the solar energy system’s placed in service date over the next five years.
	The Company guarantees its fund investors that in the event of a subsequent recapture of the ITCs by the taxing authority due to the Company’s noncompliance with the applicable ITC guidelines, the Company will compensate the investor for any recaptured credits. The Company has concluded that the likelihood of a recapture event is remote and consequently has not recorded any liability in the condensed consolidated financial statements for any potential recapture exposure.
	The balance of deferred investment tax credits revenue, which is included as part of deferred revenue in the condensed consolidated balance sheets, as of September 30, 2013 and December 31, 2012 was $76.3 million and $0, respectively. No revenue has been recognized in the condensed consolidated statements of operations to date related to the monetization of investment tax credits.
Comprehensive Income (Loss)	'
	Comprehensive Income (Loss)
	The Company accounts for comprehensive income (loss) in accordance with ASC 220, Comprehensive Income. Under ASC 220, the Company is required to report comprehensive income (loss), which includes the Company’s net loss, as well as other comprehensive income (loss). There were no differences between comprehensive loss as defined by ASC 220 and net loss as reported in the Company’s accompanying condensed consolidated statements of operations for the periods presented.
Segment Information	'
	Segment Information
	Operating segments are defined as components of a company about which separate financial information is available that is evaluated regularly by the chief operating decision maker, or decision making group, in deciding how to allocate resources and in assessing performance. The Company’s chief operating decision maker is the executive team, comprising the chief executive officer, the chief operating officer, the chief revenue officer, and the chief financial officer. Based on the financial information presented to and reviewed by the chief operating decision maker in deciding how to allocate the resources and in assessing the performance of the Company, the Company has determined that it has a single operating and reporting segment, solar energy and energy efficiency products and services. The Company’s principal operations, revenue and decision-making functions are located in the United States.
Basic and Diluted Net Income (Loss) Per Share	'
	Basic and Diluted Net Income (Loss) Per Share
	The Company’s basic net income (loss) per share attributable to common stockholders is calculated by dividing the net income (loss) attributable to common stockholders by the weighted-average number of shares of common stock outstanding for the period. Prior to the Company’s initial public offering of its common stock, the Company’s convertible redeemable preferred stock was entitled to receive dividends of up to $0.01 per share when and if dividends were declared on the common stock and thereafter participate pro rata on an as converted basis with the common stock holders on any distributions to common stockholders. They were therefore participating securities. As a result, the Company calculates the net income (loss) per share using the two-class method. Accordingly, the net income (loss) attributable to common stockholders is derived from the net income (loss) for the period and, in periods in which the Company has net income attributable to common stockholders, an adjustment is made for the noncumulative dividends and allocations of earnings to participating securities based on their outstanding shareholder rights. Under the two-class method, the net loss attributable to common stockholders is not allocated to the convertible redeemable preferred stock as the convertible redeemable preferred stock did not have a contractual obligation to share in the Company’s losses.
	The diluted net income (loss) per share attributable to common stockholders is computed by giving effect to all potential common stock equivalents outstanding for the period determined using the treasury stock method or the as-if converted method as applicable. In periods when the Company incurred a net loss attributable to common stockholders, convertible redeemable preferred stock, stock options, restricted stock units, warrants to purchase common stock, and warrants to purchase convertible redeemable preferred stock were considered to be common stock equivalents but have been excluded from the calculation of diluted net loss per share attributable to common stockholders as their effect is antidilutive.
Recently Issued Accounting Standard	'
	Recently Issued Accounting Standard
	In July 2013, the FASB issued Accounting Standards Update, or ASU, No. 2013-11, Income Taxes (Topic 740): Presentation of an Unrecognized Tax Benefit When a Net Operating Loss Carryforward, a Similar Tax Loss, or a Tax Credit Carryforward Exists, to specify when an unrecognized tax benefit should be presented as a liability versus an offset against a deferred tax asset. The ASU is effective prospectively for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2013. The Company is currently assessing the impact of the ASU on the Company’s consolidated financial statements.

Summary_of_Significant_Account2

Summary of Significant Accounting Policies and Procedures (Tables)	9 Months Ended
	Sep. 30, 2013
Accounting Policies [Abstract]	'
Schedule of Changes in Accrued Warranty Balance	'
	The changes in the accrued warranty balance, recorded as a component of accrued and other current liabilities on the condensed consolidated balance sheets, consisted of the following (in thousands):
		As of and for the
		Nine Months Ended
		September 30, 2013
	Balance – beginning of the period	$	4,019
	Provision charged to warranty expense		2,168
	Less warranty claims		(206	)
	Balance – end of the period	$	5,981
Schedule of Changes in Deferred U.S. Treasury Grants Income	'
	The changes in deferred U.S. Treasury grants income during the nine months ended September 30, 2013 were as follows (in thousands):
	Balance as of December 31, 2012	$	298,260
	U.S. Treasury grants received and receivable by the company		121,318
	U.S. Treasury grants received by investors under lease pass-through arrangements		18,590
	Amortized during the period as a credit to depreciation expense		(11,448	)
	Balance as of September 30, 2013	$	426,720

Acquisitions_Tables

Acquisitions (Tables)	9 Months Ended
	Sep. 30, 2013
Business Combinations [Abstract]	'
Schedule of Determination of Fair Value Purchase Consideration in Acquired Business	'
	The following table summarizes the determination of the fair value of the purchase consideration in the acquired business as of the acquisition date (in thousands). The Company is in the process of determining the final value of deferred consideration, which includes estimated costs incurred by Paramount Energy in the installation of certain solar energy systems during a specified period and future contributions into the fund by the investor associated with certain other solar energy systems:
	Cash	$	3,700
	Common stock		108,804
	Deferred consideration		4,259
	Total purchase consideration	$	116,763
Summary of Preliminary Assessment of Fair Value of Assets Acquired, Liabilities Assumed and Noncontrolling Interests	'
	The following table summarizes the preliminary assessment of the fair value of the assets acquired, liabilities assumed and noncontrolling interests as of the acquisition date (in thousands). The Company is in the process of obtaining third-party valuations of solar energy systems under construction, solar energy systems, leased and to be leased, intangible assets and noncontrolling interests. Accordingly, the preliminary amounts of these assets, noncontrolling interest and goodwill reflected in the table below are subject to change:
	Cash	$	12
	Deposits		12
	Prepaid costs		764
	Solar energy systems under construction		7,473
	Solar energy systems, leased and to be leased		3,793
	Property and equipment		96
	Intangible assets		56,571
	Deferred revenue		(279	)
	Total identifiable net assets at fair value		68,442
	Noncontrolling interest		(549	)
	Goodwill		48,870
	Total purchase consideration	$	116,763
Summary of Preliminary Intangible Assets Acquired	'
	The following table summarizes the preliminary acquired intangible assets as of the acquisition date:
		Fair Value			Weighted-
					Average
					Useful Life
		(in thousands)			(in years)
	Marketing database	$	17,427			5
	PowerSaver agreement		17,077			10
	Solar energy systems backlog		10,280			30
	Non-compete agreement		6,959			5
	Mortgage database		4,628			3
	Funding commitment by fund investor		200			5
	Total	$	56,571

Goodwill_and_Intangible_Assets1

Goodwill and Intangible Assets (Tables)	9 Months Ended
	Sep. 30, 2013
Goodwill And Intangible Assets Disclosure [Abstract]	'
Summary of Acquired Intangible Assets	'
	The following is a summary of acquired intangible assets as of September 30, 2013 (in thousands):
		Gross		Accumulated		Transfer to solar		Net
				Amortization		energy systems –
						leased and to be
						leased
	Marketing database	$	17,427	$	242		—	$	17,185
	PowerSaver agreement		17,077		118		—		16,959
	Solar energy systems backlog		10,280		—		149		10,131
	Mortgage database		4,628		107		—		4,521
	Non-compete agreement		6,959		97		—		6,862
	Funding commitment		200		3		—		197
	Total	$	56,571	$	567		149	$	55,855
Summary of Estimated Aggregate Future Amortization Expense for Intangible Assets	'
	Estimated aggregate future amortization expense for intangible assets, excluding the solar energy systems backlog, is as follows (in thousands):
	Three months ending December 31, 2013	$	2,042
	2014		8,168
	2015		8,168
	2016		7,674
	2017		6,625
	2018		5,055
	Thereafter		7,992
	Total	$	45,724
Summary of Carrying Value of Goodwill	'
	The changes to the carrying value of goodwill during the nine months ended September 30, 2013 and the year ended December 31, 2012 are as follows (in thousands):
		2013		2012
	Balance – beginning of the period	$	626	$	626
	Acquisition of Paramount Energy		48,870		—
	Balance – end of the period	$	49,496	$	626

Selected_Balance_Sheet_Compone1

Selected Balance Sheet Components (Tables)	9 Months Ended
	Sep. 30, 2013
Text Block [Abstract]	'
Components of Balance Sheet	'
	Selected components of the condensed consolidated balance sheets were as follows (in thousands):
			September 30,			December 31,
			2013			2012
	Inventories:
	Raw materials		$	80,080		$	69,726
	Work in progress			10,673			18,177
	Total		$	90,753		$	87,903
	Solar Energy Systems, Leased and To Be Leased – Net:
	Solar energy systems leased to customers(1)		$	1,320,697		$	895,020
	Initial direct costs related to solar energy systems leased to customers			81,888			54,095
				1,402,585			949,115
	Less accumulated depreciation and amortization			(74,204	)		(43,024	)
				1,328,381			906,091
	Solar energy systems under construction			93,353			43,747
	Solar energy systems to be leased to customers			70,207			52,346
	Solar energy systems, leased and to be leased – net		$	1,491,941		$	1,002,184
	Other Liabilities and Deferred Credits:
	Deferred gain on sale-leaseback transactions, net of current portion		$	56,856		$	59,243
	Amounts received from lease pass-through investors for monetization of investment tax credits for systems not installed			77,812			18,111
	Deferred rent expense			4,304			4,443
	Capital lease obligation			27,506			28,688
	Other noncurrent liabilities			15,810			1,571
	Total		$	182,288		$	112,056
	-1	Included under solar energy systems leased to customers as of September 30, 2013 and December 31, 2012 was $66.4 million, related to capital leased assets, with an accumulated depreciation of $4.6 million and $2.6 million, respectively.

VIE_Arrangements_Tables

VIE Arrangements (Tables)	9 Months Ended
	Sep. 30, 2013
Text Block [Abstract]	'
Carrying Values of Assets and Liabilities of Subsidiary in Condensed Consolidated Balance Sheets	'
	The Company has aggregated the financial information of the financing funds in the table below. The aggregate carrying values of these funds’ assets and liabilities (after elimination of intercompany transactions and balances) in the Company’s condensed consolidated balance sheets as of September 30, 2013 and December 31, 2012, were as follows (in thousands):
		September 30,		December 31,
		2013		2012
	Assets
	Current assets
	Cash and cash equivalents	$	14,938	$	16,065
	Restricted cash, short term		—		167
	Accounts receivable, net		4,629		1,681
	Prepaid expenses and other assets		1,794		2,603
	Rebates receivable		14,660		8,985
	Total current assets		36,021		29,501
	Restricted cash, long term		193		—
	Solar energy systems, leased and to be leased, net		612,186		530,230
	Other assets		2,818		2,800
	Total assets	$	651,218	$	562,531
	Liabilities
	Current liabilities
	Accounts payable	$	—	$	9
	Customer deposits		6,266		4,162
	Distributions payable to noncontrolling interests		17,634		12,028
	Current portion of deferred U.S. Treasury grants income		6,619		6,710
	Current portion of deferred revenue		12,422		11,324
	Accrued and other liabilities		739		938
	Current portion of bank borrowings		242		131
	Total current liabilities		43,922		35,302
	Bank borrowings, net of current portion		5,600		2,585
	Deferred revenue, net of current portion		179,996		160,093
	Deferred U.S. Treasury grant income, net of current portion		180,748		184,470
	Other liabilities		1,911		—
	Total liabilities	$	412,177	$	382,450

Equity_Tables

Equity (Tables)	9 Months Ended
	Sep. 30, 2013
Equity [Abstract]	'
Schedule of Changes in Total Stockholder's Equity and Noncontrolling Interests	'
	Changes in total stockholder’s equity and noncontrolling interests in the nine months ended September 30, 2013 were as follows (in thousands):
		Total			Noncontrolling			Total
		Stockholders’			Interests in			Equity
		Equity			Subsidiaries
	Balance, December 31, 2012	$	214,320		$	100,607		$	314,927
	Issuance of common stock upon exercise of stock options for cash		9,415			—			9,415
	Issuance of common stock upon exercise of common stock warrants for cash		8,034			—			8,034
	Contributions from noncontrolling interests		—			221,175			221,175
	Stock-based compensation expense		17,166			—			17,166
	Issuance of common stock upon acquisition of Paramount Energy, net of issuance costs		108,734			—			108,734
	Net loss		(51,523	)		(43,874	)		(95,397	)
	Noncontrolling interests arising from business combination		—			549			549
	Distributions to noncontrolling interests		—			(122,623	)		(122,623	)
	Balance, September 30, 2013	$	306,146		$	155,834		$	461,980

Stock_Option_Plans_Tables

Stock Option Plans (Tables)	9 Months Ended
	Sep. 30, 2013
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]	'
Summary of Stock Option Activity	'
	A summary of stock option activity for the nine months ended September 30, 2013 is as follows (in thousands, except per share amounts):
		Common Stock			Weighted-			Weighted-			Aggregate
		Options			Average			Average			Intrinsic
					Exercise			Remaining			Value
					Price			Contractual
								Term
	Outstanding – December 31, 2012		14,903		$	4.8			7.67		$	107,653
	Granted (weighted-average fair value of $27.76)		3,416			35.48			—			—
	Exercised		(3,052	)		3.09			—			—
	Canceled		(1,069	)		12.56			—			—
	Outstanding – September 30, 2013		14,198		$	11.96			7.67		$	335,924
	Options vested and exercisable – September 30, 2013		6,834		$	4.22			6.72		$	208,408
	Options vested and expected to vest – September 30, 2013		12,989		$	10.81			7.55		$	320,757
Summary of Fair Value of Stock Options Granted Using Weighted-Average Assumptions	'
	The fair values were estimated on each grant date with the following weighted-average assumptions:
		Three Months Ended						Nine Months Ended
		September 30,						September 30,
		2013			2012			2013			2012
	Dividend yield		0	%		0	%		0	%		0	%
	Annual risk-free rate of return		1.56	%		0.93	%		1.31	%		1.08	%
	Expected volatility		80.21	%		90.82	%		88.33	%		88.16	%
	Expected term (years)		5.83			6.29			6.02			6.16
Summary of Stock-Based Compensation Expense Recognized	'
	Stock-based compensation expense was included in cost of revenue and operating expenses as follows (in thousands):
		Three Months Ended						Nine Months Ended
		September 30,						September 30,
		2013			2012			2013			2012
	Cost of revenue	$	245		$	120		$	548		$	321
	Sales and marketing		1,317			352			2,643			880
	General and administrative		4,589			1,856			9,277			4,615

Related_Party_Transactions_Tab

Related Party Transactions (Tables)	9 Months Ended
	Sep. 30, 2013
Related Party Transactions [Abstract]	'
Components of Related Party Transactions	'
	The Company’s operations for the three and nine months ended September 30, 2013 and 2012 included the following related party transactions (in thousands):
		Three Months Ended				Nine Months Ended
		September 30,				September 30,
		2013		2012		2013		2012
	Net Revenue, Systems:
	Solar energy systems sales to related parties	$	—	$	234	$	17	$	417
	Expenditures:
	Purchases of inventory from a related party	$	975	$	—	$	975	$	—
	Referral fees paid or payable to a related party (included in sales and marketing)	$	25	$	—	$	25	$	—
Summary of Related Party Balances	'
	Related party balances as of September 30, 2013 and December 31, 2012 comprised of (in thousands):
		September 30,		December 31,
		2013		2012
	Due from a related party (included in accounts receivable)	$	—	$	932
	Due to a related party (included in accounts payable)	$	974	$	—
	Deferred revenue from a related party (included in current portion of deferred revenue)	$	831	$	—

Basic_and_Diluted_Net_Income_L1

Basic and Diluted Net Income (Loss) Per Share (Tables)	9 Months Ended
	Sep. 30, 2013
Earnings Per Share [Abstract]	'
Computation of Company's Basic and Diluted Net Income (Loss) Per Share	'
	The following table sets forth the computation of the Company’s basic and diluted net income (loss) per share for the three and nine months ended September 30, 2013 and 2012 (in thousands, except share and per share amounts):
		Three Months Ended					Nine Months Ended
		September 30,					September 30,
		2013		2012			2013			2012
	Net income (loss) attributable to common stockholders, basic	$	3,356	$	(38,071	)	$	(51,523	)	$	(61,148	)
	Net income (loss) attributable to common stockholders, diluted	$	3,356	$	(38,071	)	$	(51,523	)	$	(61,148	)
	Weighted-average shares used to compute net income (loss) per share attributable to common stockholders, basic		79,918,110		11,161,789			77,228,677			10,867,584
	Dilutive effect of common stock options		8,128,037		—			—			—
	Dilutive effect of restricted stock units		8,246		—			—			—
	Weighted-average shares used to compute net income (loss) per share attributable to common stockholders, diluted		88,054,393		11,161,789			77,228,677			10,867,584
	Net income (loss) per share attributable to common stockholders, basic	$	0.04	$	(3.41	)	$	(0.67	)	$	(5.63	)
	Net income (loss) per share attributable to common stockholders, diluted	$	0.04	$	(3.41	)	$	(0.67	)	$	(5.63	)
Schedule of Outstanding Shares of Common Stock Equivalents Excluded from Computation of Diluted Net Income (Loss) Per Share	'
	The following outstanding shares of common stock equivalents were excluded from the computation of diluted net income (loss) per share for the periods presented because including them would have been antidilutive:
		Three Months Ended					Nine Months Ended
		September 30,					September 30,
		2013		2012			2013			2012
	Convertible redeemable preferred stock		—		45,392,867			—			45,392,867
	Preferred stock warrants and common stock warrants		—		1,816,650			690,829			1,816,650
	Common stock options		1,936,485		14,859,208			14,564,924			14,611,371
	Restricted stock units		—		—			19,026			—

Organization_Additional_Inform

Organization - Additional Information (Detail)	9 Months Ended
	Sep. 30, 2013
Organization Consolidation And Presentation Of Financial Statements [Abstract]	'
Delaware corporation incorporation date	21-Jun-06

Summary_of_Significant_Account3

Summary of Significant Accounting Policies and Procedures - Additional Information (Detail) (USD $)	9 Months Ended
	Sep. 30, 2013	Dec. 31, 2012
Summary Of Significant Accounting Policies And Recent Accounting Pronouncements [Line Items]	'	'
Fair value measurements of assets and liabilities on non recurring basis	$0	$0
Company generally provides a warranty on the generating and non-generating parts of the solar energy systems	'Five to twenty years	'
Liability recorded relating to guarantees	900,000	600,000
Noncurrent deferred Treasury grants income	411,316,000	286,884,000
Deferred investment tax credits revenue	$76,300,000	$0
Manufacturer [Member]	'	'
Summary Of Significant Accounting Policies And Recent Accounting Pronouncements [Line Items]	'	'
Company generally provides a warranty on the generating and non-generating parts of the solar energy systems	'One to twenty-five years	'
Minimum [Member]	'	'
Summary Of Significant Accounting Policies And Recent Accounting Pronouncements [Line Items]	'	'
Estimated useful lives	'3 years	'
Maximum [Member]	'	'
Summary Of Significant Accounting Policies And Recent Accounting Pronouncements [Line Items]	'	'
Estimated useful lives	'30 years	'
Convertible redeemable preferred stock [Member]	'	'
Summary Of Significant Accounting Policies And Recent Accounting Pronouncements [Line Items]	'	'
Convertible redeemable preferred stock entitled to receive dividends	$0.01	'
U.S. Treasury Grants [Member]	'	'
Summary Of Significant Accounting Policies And Recent Accounting Pronouncements [Line Items]	'	'
Estimated useful lives	'30 years	'

Summary_of_Significant_Account4

Summary of Significant Accounting Policies and Procedures - Schedule of Changes in Accrued Warranty Balance (Detail) (USD $)	9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2013
Movement in Standard Product Warranty Accrual [Roll Forward]	'
Balance - beginning of the period	$4,019
Provision charged to warranty expense	2,168
Less warranty claims	-206
Balance - end of the period	$5,981

Summary_of_Significant_Account5

Summary of Significant Accounting Policies and Procedures - Schedule of Changes in Deferred U.S. Treasury Grants Income (Detail) (U.S. Treasury Grants [Member], USD $)	9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2013
U.S. Treasury Grants [Member]	'
Deferred Grant [Line Items]	'
Balance as of December 31, 2012	$298,260
U.S. Treasury grants received and receivable by the company	121,318
U.S. Treasury grants received by investors under lease pass-through arrangements	18,590
Amortized during the period as a credit to depreciation expense	-11,448
Balance as of September 30, 2013	$426,720

Acquisitions_Additional_Inform

Acquisitions - Additional Information (Detail) (USD $)	1 Months Ended	9 Months Ended
	Sep. 06, 2013	Sep. 30, 2013
Business Combinations [Abstract]	'	'
Assets acquisition	$3,700,000	$3,700,000
Common stock issued for acquisition	3,674,565	'
Common stock shares held in escrow	379,146	'
Common stock shares held in escrow, period	30-Sep-14	'
Aggregate fair value of common stock on acquisition date	108,800,000	'
Amount payable related to future acquisition	$4,300,000	$4,259,000

Acquisitions_Schedule_of_Deter

Acquisitions - Schedule of Determination of Fair Value Purchase Consideration in Acquired Business (Detail) (USD $)	1 Months Ended	9 Months Ended
In Thousands, unless otherwise specified	Sep. 06, 2013	Sep. 30, 2013
Business Combinations [Abstract]	'	'
Cash	$3,700	$3,700
Common stock	'	108,804
Deferred consideration	4,300	4,259
Total purchase consideration	'	$116,763

Acquisitions_Summary_of_Prelim

Acquisitions - Summary of Preliminary Assessment of Fair Value of Assets Acquired, Liabilities Assumed and Noncontrolling Interests (Detail) (USD $)	Sep. 30, 2013	Dec. 31, 2012	Dec. 31, 2011
In Thousands, unless otherwise specified
Business Acquisition [Line Items]	'	'	'
Cash	$12	'	'
Deposits	12	'	'
Prepaid costs	764	'	'
Property and equipment	96	'	'
Intangible assets	56,571	'	'
Deferred revenue	-279	'	'
Total identifiable net assets at fair value	68,442	'	'
Noncontrolling interest	-549	'	'
Goodwill	49,496	626	626
Total purchase consideration	116,763	'	'
Solar energy systems under construction [Member]	'	'	'
Business Acquisition [Line Items]	'	'	'
Property and equipment	7,473	'	'
Solar energy systems, leased and to be leased [Member]	'	'	'
Business Acquisition [Line Items]	'	'	'
Property and equipment	$3,793	'	'

Acquisitions_Summary_of_Prelim1

Acquisitions - Summary of Preliminary Intangible Assets Acquired (Detail) (USD $)	9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2013
Acquired Finite-Lived Intangible Assets [Line Items]	'
Acquired intangible assets, fair value	$56,571
Marketing database [Member]	'
Acquired Finite-Lived Intangible Assets [Line Items]	'
Acquired intangible assets, fair value	17,427
Acquired intangible assets, Weighted-average useful life	'5 years
PowerSaver agreement [Member]	'
Acquired Finite-Lived Intangible Assets [Line Items]	'
Acquired intangible assets, fair value	17,077
Acquired intangible assets, Weighted-average useful life	'10 years
Solar energy systems backlog [Member]	'
Acquired Finite-Lived Intangible Assets [Line Items]	'
Acquired intangible assets, fair value	10,280
Acquired intangible assets, Weighted-average useful life	'30 years
Non-compete agreement [Member]	'
Acquired Finite-Lived Intangible Assets [Line Items]	'
Acquired intangible assets, fair value	6,959
Acquired intangible assets, Weighted-average useful life	'5 years
Mortgage database [Member]	'
Acquired Finite-Lived Intangible Assets [Line Items]	'
Acquired intangible assets, fair value	4,628
Acquired intangible assets, Weighted-average useful life	'3 years
Funding commitment [Member]	'
Acquired Finite-Lived Intangible Assets [Line Items]	'
Acquired intangible assets, fair value	$200
Acquired intangible assets, Weighted-average useful life	'5 years

Goodwill_and_Intangible_Assets2

Goodwill and Intangible Assets - Summary of Acquired Intangible Assets (Detail) (USD $)	Sep. 30, 2013
In Thousands, unless otherwise specified
Finite-Lived Intangible Assets [Line Items]	'
Intangible assets acquired, Gross	$56,571
Accumulated Amortization	567
Intangible asset, Transfer to solar energy systems - leased and to be leased	149
Intangible asset, Net	55,855
Marketing database [Member]	'
Finite-Lived Intangible Assets [Line Items]	'
Intangible assets acquired, Gross	17,427
Accumulated Amortization	242
Intangible asset, Net	17,185
PowerSaver agreement [Member]	'
Finite-Lived Intangible Assets [Line Items]	'
Intangible assets acquired, Gross	17,077
Accumulated Amortization	118
Intangible asset, Net	16,959
Solar energy systems backlog [Member]	'
Finite-Lived Intangible Assets [Line Items]	'
Intangible assets acquired, Gross	10,280
Intangible asset, Transfer to solar energy systems - leased and to be leased	149
Intangible asset, Net	10,131
Mortgage database [Member]	'
Finite-Lived Intangible Assets [Line Items]	'
Intangible assets acquired, Gross	4,628
Accumulated Amortization	107
Intangible asset, Net	4,521
Non-compete agreement [Member]	'
Finite-Lived Intangible Assets [Line Items]	'
Intangible assets acquired, Gross	6,959
Accumulated Amortization	97
Intangible asset, Net	6,862
Funding commitment [Member]	'
Finite-Lived Intangible Assets [Line Items]	'
Intangible assets acquired, Gross	200
Accumulated Amortization	3
Intangible asset, Net	$197

Goodwill_and_Intangible_Assets3

Goodwill and Intangible Assets - Additional Information (Detail) (USD $)	9 Months Ended
	Sep. 30, 2013
PowerSaver agreement [Member]	'
Finite-Lived Intangible Assets [Line Items]	'
Maximum available additional loan capacity	25,000
Solar energy systems backlog [Member]	'
Finite-Lived Intangible Assets [Line Items]	'
Estimated useful lives of solar energy systems	'30 years
Non-compete agreement [Member]	'
Finite-Lived Intangible Assets [Line Items]	'
Non-compete agreement, terms	'The former CEO of Paramount Energy became the Companybs new Chief Revenue Officer and executed a five-year non-compete agreement.

Goodwill_and_Intangible_Assets4

Goodwill and Intangible Assets - Summary of Estimated Aggregate Future Amortization Expense for Intangible Assets (Detail) (USD $)	Sep. 30, 2013
In Thousands, unless otherwise specified
Finite Lived Intangible Assets Future Amortization Expense [Abstract]	'
Three months ending December 31, 2013	$2,042
2014	8,168
2015	8,168
2016	7,674
2017	6,625
2018	5,055
Thereafter	7,992
Total	$45,724

Goodwill_and_Intangible_Assets5

Goodwill and Intangible Assets - Summary of Carrying Value of Goodwill (Detail) (USD $)	9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2013	Dec. 31, 2011
Goodwill And Intangible Assets Disclosure [Abstract]	'	'
Balance - beginning of the period	$626	$626
Acquisition of Paramount Energy	48,870	'
Balance - end of the period	$49,496	$626

Selected_Balance_Sheet_Compone2

Selected Balance Sheet Components - Components of Balance Sheet (Detail) (USD $)	Sep. 30, 2013	Dec. 31, 2012
In Thousands, unless otherwise specified
Inventories:	'	'
Raw materials	$80,080	$69,726
Work in progress	10,673	18,177
Total	90,753	87,903
Solar Energy Systems, Leased and To Be Leased - Net:	'	'
Solar energy systems leased to customers	1,320,697	895,020
Initial direct costs related to solar energy systems leased to customers	81,888	54,095
Solar energy systems, leased and to be leased, gross	1,402,585	949,115
Less accumulated depreciation and amortization	-74,204	-43,024
Solar energy systems, leased and to be leased gross, less accumulated depreciation and amortization	1,328,381	906,091
Solar energy systems under construction	93,353	43,747
Solar energy systems to be leased to customers	70,207	52,346
Solar energy systems, leased and to be leased - net	1,491,941	1,002,184
Deferred gain on sale-leaseback transactions, net of current portion	56,856	59,243
Amounts received from lease pass-through investors for monetization of investment tax credits for systems not installed	77,812	18,111
Deferred rent expense	4,304	4,443
Capital lease obligation	27,506	28,688
Other noncurrent liabilities	15,810	1,571
Total	$182,288	$112,056

Selected_Balance_Sheet_Compone3

Selected Balance Sheet Components - Components of Balance Sheet (Parenthetical) (Detail) (USD $)	Sep. 30, 2013	Dec. 31, 2012
In Millions, unless otherwise specified
Solar Energy Systems Leased To Customers [Abstract]	'	'
Capital leased assets	$66.40	$66.40
Accumulated depreciation	$4.60	$2.60

LongTerm_Debt_Additional_Infor

Long-Term Debt - Additional Information (Detail) (USD $)	Sep. 30, 2013	Dec. 31, 2012	Oct. 31, 2013	Sep. 30, 2013	26-May-10	Sep. 30, 2013	Nov. 30, 2013	Sep. 30, 2013	Sep. 30, 2013
			Subsequent Event [Member]	Working Capital Financing [Member]	Working Capital Financing [Member]	Vehicle Loans [Member]	Vehicle Loans [Member]	Vehicle Loans [Member]	Vehicle Loans [Member]
				Loans			Subsequent Event [Member]	Minimum [Member]	Maximum [Member]
Line Of Credit Facility Covenant Compliance [Line Items]	'	'	'	'	'	'	'	'	'
Maximum amount to be borrowed under financing agreement	'	'	'	'	$16,300,000	'	'	'	'
Number of funded tranches	'	'	'	4	'	'	'	'	'
Loan tranches interest rate description	'	'	'	'Each tranche bears interest at an annual rate of 2.00% plus the swap rate applicable to the average life of the scheduled rent receipts for the tranche.	'	'	'	'	'
Basis interest rate	'	'	'	2.00%	'	'	'	'	'
Maturity date of loan	'	'	1-Nov-18	31-Dec-24	'	'	'	'	'
Amount borrowed under facility	'	'	'	13,300,000	'	'	'	'	'
Outstanding amount under facility	'	'	'	10,300,000	'	'	'	'	'
Long-term debt, net of current portion	132,149,000	83,533,000	'	9,100,000	'	'	'	'	'
Interest rate of amounts borrowed, minimum	'	'	'	5.48%	'	'	'	'	'
Interest rate of amounts borrowed, maximum	'	'	'	5.65%	'	'	'	'	'
Maturity of loan, minimum	'	'	'	'	'	'2013	'	'	'
Maturity of loan, maximum	'	'	'	'	'	'2018	'	'	'
Total vehicle loans payable	'	'	'	'	'	8,600,000	'	'	'
Total vehicle loans payable, net of current portion	'	'	'	'	'	5,000,000	'	'	'
Loans payable interest rate	'	'	'	'	'	'	'	0.00%	7.49%
Outstanding balance repaid	'	'	'	'	'	'	$2,700,000	'	'

LongTerm_Debt_Additional_Infor1

Long-Term Debt - Additional Information 1 (Detail) (USD $)	0 Months Ended			0 Months Ended	9 Months Ended
	Mar. 08, 2012	Feb. 08, 2013	Sep. 30, 2013	Jun. 07, 2013	Sep. 30, 2013	Sep. 30, 2013	Sep. 30, 2013
	Inventory Financing [Member]	Term Loans [Member]	Term Loans [Member]	Working Capital Loans Facility [Member]	Working Capital Loans Facility [Member]	Working Capital Loans Facility [Member]	Working Capital Loans Facility [Member]
						Minimum [Member]	Maximum [Member]
Line Of Credit Facility Covenant Compliance [Line Items]	'	'	'	'	'	'	'
Term loan facility	$58,500,000	'	'	'	'	'	'
Facility interest rate description	'LIBOR plus 3.75%	'LIBOR plus 3.25%	'	'LIBOR plus 3.25%	'	'	'
Basis interest rate	3.75%	3.25%	'	3.25%	'	'	'
Term loan by subsidiary, amount	'	10,000,000	'	100,000,000	'	'	'
Loan facility interest rate	'	6.50%	3.43%	'	'	3.50%	3.67%
Maturity of loan	'	31-Jan-15	'	'	7-Jun-15	'	'
Loan facility outstanding amount	'	'	9,500,000	'	38,100,000	'	'
Long-term debt	'	'	6,800,000	'	38,100,000	'	'
Long-term debt, net of current portion	'	'	$5,100,000	'	$35,700,000	'	'

Borrowings_under_Bank_Lines_of1

Borrowings under Bank Lines of Credit - Additional Information (Detail) (USD $)

9 Months Ended

0 Months Ended

9 Months Ended

9 Months Ended

0 Months Ended

In Millions, unless otherwise specified

Sep. 30, 2013

Sep. 30, 2013

Sep. 30, 2013

Sep. 30, 2012

Sep. 30, 2013

Sep. 30, 2013

Sep. 30, 2013

Sep. 30, 2013

Nov. 21, 2011

Sep. 30, 2013

Sep. 30, 2013

Nov. 30, 2013

Nov. 30, 2013

Nov. 30, 2013

Nov. 30, 2013

Revolving Credit Facility [Member]

Revolving Credit Facility [Member]

Revolving Credit Facility [Member]

Syndicated Revolving Bank Facility One [Member]

Syndicated Revolving Bank Facility One [Member]

Syndicated Revolving Bank Facility One [Member]

Federal Funds [Member]

Subsidiary [Member]

Subsidiary [Member]

Subsidiary [Member]

Subsidiary [Member]

Subsequent Event [Member]

Subsequent Event [Member]

Subsequent Event [Member]

Subsequent Event [Member]

Minimum [Member]

Maximum [Member]

Prime Rate [Member]

Revolving Credit Facility [Member]

Revolving Credit Facility [Member]

Revolving Credit Facility [Member]

Revolving Credit Facility [Member]

Minimum [Member]

Maximum [Member]

Revolving Credit Facility [Member]

Syndicated Revolving Bank Facility One [Member]

Syndicated Revolving Bank Facility One [Member]

Federal Funds [Member]

LIBOR [Member]

Prime Rate [Member]

Revolving Credit Facility [Member]

Revolving Credit Facility [Member]

Revolving Credit Facility [Member]

LIBOR [Member]

Line Of Credit Facility Covenant Compliance [Line Items]

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Maximum credit facility for subsidiary

'

'

'

'

'

'

'

'

$350

'

'

'

$160.50

'

'

Borrowed funds interest rate

4.05%

4.06%

1.00%

'

3.88%

2.88%

0.50%

'

'

6.78%

7.27%

1.00%

3.25%

2.25%

0.50%

Long-term debt, outstanding under the facility

'

'

'

'

'

'

'

5.6

'

'

'

'

'

'

'

Long-term debt, net of current portion

'

'

'

'

'

'

'

5.4

'

'

'

'

'

'

'

Debt repayment period

'

'

'

'

'

'

'

'2032

'

'

'

'

'

'

'

Revolving line of credit facility

'

'

'

75

'

'

'

'

'

'

'

'

'

'

'

Credit facility interest rate terms

'

'

'

'Company entered into a revolving credit agreement with a syndicate of banks to obtain funding for working capital, letters of credit, and general corporate needs. The revolving credit agreement has a $75.0 million committed facility. The facility bears interest at an annual rate equal to LIBOR plus 3.875% or, at the Company's option, 2.875% plus the higher of (i) the federal funds rate plus 0.50%, (ii) Bank of America's published "prime rate", and (iii) LIBOR plus 1.00%.

'

'

'

'

'

'

'

'

'This facility was amended and restated in November 2013 to increase the committed facility from $75.0 to $160.5 million, extend the maturity date to December 31, 2016 and lower the rate at which the facility bears interest to LIBOR plus 3.25% or, at the Companybs option, 2.25% plus the higher of (i) the federal funds rate plus 0.50%, (ii) Bank of Americabs published bprime rateb, and (iii) LIBOR plus 1.00%.

'

'

Percentage of fee for letters of credit

'

'

'

'

3.88%

'

'

'

'

'

'

'

'

'

'

Percentage of fee for undrawn commitments

'

'

'

0.38%

'

'

'

'

'

'

'

'

'

'

'

Facility maturity date

'

'

'

30-Sep-14

'

'

'

'

'

'

'

'

31-Dec-16

'

'

Borrowed and outstanding under revolving credit agreement, net of lender fees

'

'

'

'

$71.90

'

'

'

'

'

'

'

'

'

'

VIE_Arrangements_Additional_In

VIE Arrangements - Additional Information (Detail) (USD $)	9 Months Ended
In Millions, unless otherwise specified	Sep. 30, 2013
Related Party Transactions [Abstract]	'
Investors contribution to variable interest equity	$763.50
Carrying value of the assets	$29.20

VIE_Arrangements_Carrying_Valu

VIE Arrangements - Carrying Values of Assets and Liabilities of Subsidiary in Condensed Consolidated Balance Sheets (Detail) (USD $)	Sep. 30, 2013		Dec. 31, 2012		Sep. 30, 2012	Dec. 31, 2011
In Thousands, unless otherwise specified
Current assets	'		'		'	'
Cash and cash equivalents	$132,986		$160,080		$49,318	$50,471
Restricted cash, short term	3,269		7,516		'	'
Accounts receivable, net	32,791		25,145		'	'
Prepaid expenses and other assets	25,527		11,502		'	'
Rebates receivable	19,158		17,501		'	'
Total current assets	312,246		315,417		'	'
Restricted cash, long term	1,701		2,810		'	'
Solar energy systems, leased and to be leased, net	1,491,941		1,002,184		'	'
Other assets	28,625		22,170		'	'
Total assets	1,960,335	[1]	1,361,842	[1]	'	'
Current liabilities	'		'		'	'
Accounts payable	134,123		62,986		'	'
Customer deposits	9,208		8,753		'	'
Current portion of deferred U.S. Treasury grants income	15,404		11,376		'	'
Current portion of deferred revenue	52,989		31,516		'	'
Total current liabilities	320,355		213,617		'	'
Deferred revenue, net of current portion	326,884		204,396		'	'
Deferred U.S. Treasury grant income, net of current portion	411,316		286,884		'	'
Other liabilities	182,288		112,056		'	'
Total liabilities	1,498,355	[1]	1,046,915	[1]	'	'
Subsidiary of Common Parent [Member]	'		'		'	'
Current assets	'		'		'	'
Cash and cash equivalents	14,938		16,065		'	'
Restricted cash, short term	'		167		'	'
Accounts receivable, net	4,629		1,681		'	'
Prepaid expenses and other assets	1,794		2,603		'	'
Rebates receivable	14,660		8,985		'	'
Total current assets	36,021		29,501		'	'
Restricted cash, long term	193		'		'	'
Solar energy systems, leased and to be leased, net	612,186		530,230		'	'
Other assets	2,818		2,800		'	'
Total assets	651,218		562,531		'	'
Current liabilities	'		'		'	'
Accounts payable	'		9		'	'
Customer deposits	6,266		4,162		'	'
Distributions payable to noncontrolling interests	17,634		12,028		'	'
Current portion of deferred U.S. Treasury grants income	6,619		6,710		'	'
Current portion of deferred revenue	12,422		11,324		'	'
Accrued and other liabilities	739		938		'	'
Current portion of bank borrowings	242		131		'	'
Total current liabilities	43,922		35,302		'	'
Bank borrowings, net of current portion	5,600		2,585		'	'
Deferred revenue, net of current portion	179,996		160,093		'	'
Deferred U.S. Treasury grant income, net of current portion	180,748		184,470		'	'
Other liabilities	1,911		'		'	'
Total liabilities	$412,177		$382,450		'	'
[1]	The Company's consolidated assets as of September 30, 2013 and December 31, 2012 include $651,218 and $562,531, respectively, being assets of variable interest entities, or VIEs, that can only be used to settle obligations of the VIEs. These assets include solar energy systems, leased and to be leased, net, of $612,186 and $530,230 as of September 30, 2013 and December 31, 2012, respectively; cash and cash equivalents of $14,938 and $16,065 as of September 30, 2013 and December 31, 2012, respectively; restricted cash, long-term of $193 and $0 as of September 30, 2013 and 2012, respectively; accounts receivable, net, of $4,629 and $1,681 as of September 30, 2013 and December 31, 2012, respectively; prepaid expenses and other assets of $1,794 and $2,603 as of September 30, 2013 and December 31, 2012, respectively; and rebates receivable of $14,660 and $8,985 as of September 30, 2013 and December 31, 2012, respectively; other assets of $2,818 and $2,800 as of September 30, 2013 and 2012, respectively. The Company's consolidated liabilities as of September 30, 2013 and December 31, 2012 included $32,392 and $19,853, respectively, being liabilities of VIEs whose creditors have no recourse to the Company. These liabilities include distributions payable to noncontrolling interests of $17,634 and $12,028 as of September 30, 2013 and December 31, 2012, respectively; customer deposits of $6,266 and $4,162 as of September 30, 2013 and December 31, 2012, respectively; accounts payable of $0 and $9 as of September 30, 2013 and December 31, 2012, respectively; accrued and other payables of $739 and $938 as of September 30, 2013 and December 31, 2012, respectively; other liabilities of $1,911 and $0 as of September 30, 2013 and December 31, 2012, respectively; and bank borrowings of $5,842 and $2,716 as of September 30, 2013 and December 31, 2012, respectively.

Equity_Schedule_of_Changes_in_

Equity - Schedule of Changes in Total Stockholder's Equity and Noncontrolling Interests (Detail) (USD $)	3 Months Ended		9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Schedule of Capitalization, Equity [Line Items]	'	'	'	'
Beginning balance	'	'	$314,927	'
Issuance of common stock upon exercise of stock options for cash	'	'	9,415	'
Issuance of common stock upon exercise of common stock warrants for cash	'	'	8,034	'
Contributions from noncontrolling interests	'	'	221,175	'
Stock-based compensation expense	8,200	300	17,166	7,700
Issuance of common stock upon acquisition of Paramount Energy, net of issuance costs	'	'	108,734	'
Net loss	'	'	-95,397	'
Noncontrolling interests arising from business combination	'	'	549	'
Distributions to noncontrolling interests	'	'	-122,623	'
Ending balance	461,980	'	461,980	'
Total Stockholders' Equity [Member]	'	'	'	'
Schedule of Capitalization, Equity [Line Items]	'	'	'	'
Beginning balance	'	'	214,320	'
Issuance of common stock upon exercise of stock options for cash	'	'	9,415	'
Issuance of common stock upon exercise of common stock warrants for cash	'	'	8,034	'
Stock-based compensation expense	'	'	17,166	'
Issuance of common stock upon acquisition of Paramount Energy, net of issuance costs	'	'	108,734	'
Net loss	'	'	-51,523	'
Ending balance	306,146	'	306,146	'
Noncontrolling Interests in Subsidiaries [Member]	'	'	'	'
Schedule of Capitalization, Equity [Line Items]	'	'	'	'
Beginning balance	'	'	100,607	'
Contributions from noncontrolling interests	'	'	221,175	'
Net loss	'	'	-43,874	'
Noncontrolling interests arising from business combination	'	'	549	'
Distributions to noncontrolling interests	'	'	-122,623	'
Ending balance	$155,834	'	$155,834	'

Equity_Additional_Information_

Equity - Additional Information (Detail) (USD $)	1 Months Ended
In Thousands, except Share data, unless otherwise specified	Sep. 06, 2013	Sep. 30, 2013	Dec. 31, 2012	8-May-13
				Warrants Exercised [Member]
Schedule of Capitalization, Equity [Line Items]	'	'	'	'
Common stock shares purchased	'	83,129,000	74,913,000	1,485,010
Common stock value	'	$8	$7	$8,000
Common stock issued for acquisition	3,674,565	'	'	'

Stock_Option_Plans_Additional_

Stock Option Plans - Additional Information (Detail) (USD $)	3 Months Ended		9 Months Ended				1 Months Ended			9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2013	Sep. 20, 2012	Sep. 30, 2012	Sep. 30, 2012	Sep. 30, 2013
					Incentive Stock Option Plan [Member]	Nonstatutory Stock Incentive Plans [Member]	Director Compensation Plan [Member]	Initial Appointment [Member]	Additional Stock Options [Member]	Minimum [Member]
								Director Compensation Plan [Member]	Director Compensation Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'	'	'	'	'	'	'	'	'	'
Granted stock options at fair market value on grant date	'	'	'	'	'Not less than 100%	'Not less than 100%	'	'	'	'
Purchase or exercise price	'	'	'	'	110.00%	'	'	'	'	'
Exercisable options granted	'	'	'	'	'10 years	'	'	'	'	'4 years
Percentage of fair market value at date of grant	'	'	'	'	100.00%	'	'	'	'	'
Holding percent of stockholder	'	'	'	'	10.00%	'	'	'	'	'
Stock option grant to purchase shares of common stock	'	'	3,416,000	'	'	'	'	30,000	15,000	'
Annual cash retainer	'	'	'	'	'	'	$15,000	'	'	'
Aggregate intrinsic value of options exercised	39,900,000	2,100,000	91,900,000	7,700,000	'	'	'	'	'	'
Grant date fair market value of options that vested	53,900,000	3,600,000	121,200,000	9,000,000	'	'	'	'	'	'
Unrecognized compensation cost, net of estimated forfeitures	74,800,000	'	74,800,000	'	'	'	'	'	'	'
Weighted average period	'	'	'2 years 11 months 5 days	'	'	'	'	'	'	'
Expected dividend yield	0.00%	0.00%	0.00%	0.00%	'	'	'	'	'	'
Stock-based compensation expense	8,200,000	300,000	17,166,000	7,700,000	'	'	'	'	'	'
Capitalized stock-based compensation expense	$2,000,000	$700,000	$4,700,000	$1,900,000	'	'	'	'	'	'

Stock_Option_Plans_Summary_of_

Stock Option Plans - Summary of Stock Option Activity (Detail) (USD $)	3 Months Ended		9 Months Ended		12 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012	Dec. 31, 2012
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]	'	'	'	'	'
Common Stock Options, Outstanding, Balance	'	'	14,903	'	'
Common Stock Options, Granted	'	'	3,416	'	'
Common Stock Options, Exercised	'	'	-3,052	'	'
Common Stock Options, Canceled	'	'	-1,069	'	'
Common Stock Options, Outstanding, Balance	14,198	'	14,198	'	14,903
Common Stock Options vested and exercisable	6,834	'	6,834	'	'
Common Stock Options vested and expected to vest	12,989	'	12,989	'	'
Weighted-Average Exercise Price, Outstanding, Balance	'	'	$4.80	'	'
Weighted-Average Exercise Price, Granted	'	'	$35.48	'	'
Weighted-Average Exercise Price, Exercised	'	'	$3.09	'	'
Weighted-Average Exercise Price, Canceled	'	'	$12.56	'	'
Weighted-Average Exercise Price, Outstanding, Balance	$11.96	'	$11.96	'	$4.80
Weighted-Average Exercise Price, Options vested and exercisable	$4.22	'	$4.22	'	'
Weighted-Average Exercise Price, Options vested and expected to vest	$10.81	'	$10.81	'	'
Weighted-Average Remaining Contractual Term, Granted	'	'	'	'	'
Weighted-Average Remaining Contractual Term, Exercised	'	'	'	'	'
Weighted-Average Remaining Contractual Term, Canceled	'	'	'	'	'
Weighted-Average Remaining Contractual Term, Outstanding	'	'	'7 years 8 months 1 day	'	'7 years 8 months 1 day
Weighted-Average Remaining Contractual Term, Options vested and exercisable	'	'	'6 years 8 months 19 days	'	'
Weighted-Average Remaining Contractual Term, Options vested and expected to vest	'	'	'7 years 6 months 18 days	'	'
Aggregate Intrinsic Value, Outstanding, Balance	'	'	$107,653	'	'
Aggregate Intrinsic Value, Granted	'	'	'	'	'
Aggregate Intrinsic Value, Exercised	39,900	2,100	91,900	7,700	'
Aggregate Intrinsic Value, Canceled	'	'	'	'	'
Aggregate Intrinsic Value, Outstanding, Balance	335,924	'	335,924	'	107,653
Aggregate Intrinsic Value, Options vested and exercisable	208,408	'	208,408	'	'
Aggregate Intrinsic Value, Options vested and expected to vest	$320,757	'	$320,757	'	'

Stock_Option_Plans_Summary_of_1

Stock Option Plans - Summary of Stock Option Activity (Parenthetical) (Detail) (USD $)	9 Months Ended
	Sep. 30, 2013
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]	'
Weighted-average fair value, granted	$27.76

Stock_Option_Plans_Summary_of_2

Stock Option Plans - Summary of Fair Value of Stock Options Granted Using Weighted-Average Assumptions (Detail)	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]	'	'	'	'
Dividend yield	0.00%	0.00%	0.00%	0.00%
Annual risk-free rate of return	1.56%	0.93%	1.31%	1.08%
Expected volatility	80.21%	90.82%	88.33%	88.16%
Expected term (years)	'5 years 9 months 29 days	'6 years 3 months 15 days	'6 years 7 days	'6 years 1 month 28 days

Stock_Option_Plans_Summary_of_3

Stock Option Plans - Summary of Stock Based Compensation Expense Recognized (Detail) (USD $)	3 Months Ended		9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Cost of revenue [Member]	'	'	'	'
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'	'	'	'
Stock-based compensation expense	$245	$120	$548	$321
Sales and marketing [Member]	'	'	'	'
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'	'	'	'
Stock-based compensation expense	1,317	352	2,643	880
General and administrative [Member]	'	'	'	'
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'	'	'	'
Stock-based compensation expense	$4,589	$1,856	$9,277	$4,615

Income_Taxes_Additional_Inform

Income Taxes - Additional Information (Detail) (USD $)	3 Months Ended		9 Months Ended
In Millions, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012	Dec. 31, 2012
Income Tax Disclosure [Abstract]	'	'	'	'	'
Estimated consolidated effective income tax rates	0.07%	0.13%	0.06%	0.13%	'
Estimated useful life for amortization of tax expense	'	'	'30 years	'	'
Long-term prepaid tax expense	$2	'	$2	'	$2

Related_Party_Transactions_Com

Related Party Transactions - Components of Related Party Transactions (Detail) (USD $)	3 Months Ended		9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Net Revenue, Systems:	'	'	'	'
Solar energy systems sales to related parties	'	$234	$17	$417
Expenditures:	'	'	'	'
Purchases of inventory from a related party	975	'	975	'
Referral fees paid or payable to a related party (included in sales and marketing)	$25	'	$25	'

Related_Party_Transactions_Sum

Related Party Transactions - Summary of Related Party Balances (Detail) (USD $)	Sep. 30, 2013	Dec. 31, 2012
In Thousands, unless otherwise specified
Related Party Transactions [Abstract]	'	'
Due from a related party (included in accounts receivable)	'	$932
Due to a related party (included in accounts payable)	974	'
Deferred revenue from a related party (included in current portion of deferred revenue)	$831	'

Basic_and_Diluted_Net_Income_L2

Basic and Diluted Net Income (Loss) Per Share - Computation of Company's Basic and Diluted Net Income (Loss) Per Share (Detail) (USD $)	3 Months Ended		9 Months Ended
In Thousands, except Share data, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Schedule Of Earnings Per Share Basic And Diluted [Line Items]	'	'	'	'
Net income (loss) attributable to common stockholders, basic	$3,356	($38,071)	($51,523)	($61,148)
Net income (loss) attributable to common stockholders, diluted	$3,356	($38,071)	($51,523)	($61,148)
Weighted-average shares used to compute net income (loss) per share attributable to common stockholders, basic	79,918,110	11,161,789	77,228,677	10,867,584
Weighted-average shares used to compute net income (loss) per share attributable to common stockholders, diluted	88,054,393	11,161,789	77,228,677	10,867,584
Net income (loss) per share attributable to common stockholders, basic	$0.04	($3.41)	($0.67)	($5.63)
Net income (loss) per share attributable to common stockholders, diluted	$0.04	($3.41)	($0.67)	($5.63)
Common stock options [Member]	'	'	'	'
Schedule Of Earnings Per Share Basic And Diluted [Line Items]	'	'	'	'
Dilutive effect of common stock	8,128,037	'	'	'
Restricted stock units [Member]	'	'	'	'
Schedule Of Earnings Per Share Basic And Diluted [Line Items]	'	'	'	'
Dilutive effect of common stock	8,246	'	'	'

Basic_and_Diluted_Net_Income_L3

Basic and Diluted Net Income (Loss) Per Share - Schedule of Outstanding Shares of Common Stock Equivalents Excluded from Computation of Diluted Net Income (Loss) Per Share (Detail)	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Convertible redeemable preferred stock [Member]	'	'	'	'
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]	'	'	'	'
Common stock equivalents excluded from the computation of diluted net loss per share	'	45,392,867	'	45,392,867
Preferred stock warrants and common stock warrants [Member]	'	'	'	'
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]	'	'	'	'
Common stock equivalents excluded from the computation of diluted net loss per share	'	1,816,650	690,829	1,816,650
Common stock options [Member]	'	'	'	'
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]	'	'	'	'
Common stock equivalents excluded from the computation of diluted net loss per share	1,936,485	14,859,208	14,564,924	14,611,371
Restricted stock units [Member]	'	'	'	'
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]	'	'	'	'
Common stock equivalents excluded from the computation of diluted net loss per share	'	'	19,026	'

Subsequent_Events_Additional_I

Subsequent Events - Additional Information (Detail) (USD $)	Sep. 30, 2013	Dec. 31, 2012	Oct. 31, 2013	Oct. 31, 2013
			Subsequent Event [Member]	Subsequent Event [Member]
				Zep Solar [Member]
Subsequent Event [Line Items]	'	'	'	'
Date of acquisition	'	'	'	31-Oct-13
Common stock value	$8,000	$7,000	'	$158,000,000
Stock of shares, new issues	'	'	3,910,000	'
Common stock, share price	'	'	$46.54	'
Convertible senior notes	'	'	230,000,000	'
Convertible senior notes, interest rate	'	'	2.75%	'
Convertible senior notes, maturity date	'	'	1-Nov-18	'
Issuance of common stock, value	'	'	398,000,000	'
Convertible senior notes conversion, shares issued per principal amount	'	'	16.2165	'
Initial conversion price equivalent, base principal amount	'	'	$1,000	'
Conversion price per share	'	'	$61.67	'