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Document and Entity Information - shares	3 Months Ended
Document and Entity Information - shares	Mar. 31, 2015	Apr. 30, 2015
Document and Entity Information [Abstract]
Entity Registrant Name	Enphase Energy, Inc.
Entity Central Index Key	0001463101
Document Type	10-Q
Document Period End Date	Mar. 31, 2015
Amendment Flag	false
Document Fiscal Year Focus	2015
Document Fiscal Period Focus	Q1
Current Fiscal Year End	--12-31
Entity Filer Category	Accelerated Filer
Entity Common Stock, Shares Outstanding		44,155,790

Condensed Consolidated Balance Sheets (Unaudited) - USD ($) $ in Thousands	Mar. 31, 2015	Dec. 31, 2014
Current assets:
Cash and cash equivalents	$ 27,127	$ 42,032
Accounts receivable, net of allowances of $533 and $569 at March 31, 2015 and December 31, 2014, respectively	45,870	45,119
Inventory	34,746	21,590
Prepaid expenses and other assets	7,087	6,155
Total current assets	114,830	114,896
Property and equipment, net	31,197	30,824
Goodwill	3,745	3,745
Intangibles, net	1,704	1,811
Other assets	2,014	916
Total assets	153,490	152,192
Current liabilities:
Accounts payable	30,954	22,316
Accrued liabilities	20,230	26,036
Deferred revenues	3,558	2,747
Warranty obligations, current portion (includes $1,534 and $1,125 measured at fair value at March 31, 2015 and December 31, 2014, respectively)	7,550	7,607
Total current liabilities	62,292	58,706
Long-term liabilities:
Deferred revenues, noncurrent	18,217	16,612
Warranty obligations, noncurrent (includes $3,249 and $2,437 measured at fair value at March 31, 2015 and December 31, 2014, respectively)	26,613	26,333
Other liabilities	2,387	3,589
Total liabilities	109,509	105,240
Commitments and contingencies
Stockholders’ equity:
Preferred stock, $0.00001 par value, 10,000 shares authorized; none issued and outstanding	0	0
Common stock, $0.00001 par value, 100,000 shares authorized; 44,117 and 43,756 shares issued and outstanding at March 31, 2015 and December 31, 2014, respectively	0	0
Additional paid-in capital	211,687	208,022
Accumulated deficit	(167,311)	(160,991)
Accumulated other comprehensive loss	(395)	(79)
Total stockholders’ equity	43,981	46,952
Total liabilities and stockholders’ equity	$ 153,490	$ 152,192

Condensed Consolidated Balance Sheets (Unaudited ) (Parenthetical) - USD ($) $ in Thousands	Mar. 31, 2015	Dec. 31, 2014
Statement of Financial Position [Abstract]
Allowances, accounts receivable	$ 533	$ 569
Warranty obligations, current at fair value	1,534	1,125
Warranty obligations, non-current at fair value	$ 3,249	$ 2,437
Preferred stock, par value (in usd per share)	$ 0.00001	$ 0.00001
Preferred stock, shares authorized (in shares)	10,000,000	10,000,000
Preferred stock, shares issued (in shares)	0	0
Preferred stock, shares outstanding (in shares)	0	0
Common stock, par value (in usd per share)	$ 0.00001	$ 0.00001
Common stock, shares authorized (in shares)	100,000,000	100,000,000
Common stock, shares issued (in shares)	44,117,000	43,756,000
Common stock, shares outstanding (in shares)	44,117,000	43,756,000

Condensed Consolidated Statements of Operations (Unaudited) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
Income Statement [Abstract]
Net revenues	$ 86,653	$ 57,580
Cost of revenues	58,629	38,925
Gross profit	28,024	18,655
Operating expenses:
Research and development	13,430	9,086
Sales and marketing	11,937	8,828
General and administrative	8,205	6,526
Total operating expenses	33,572	24,440
Loss from operations	(5,548)	(5,785)
Other income (expense), net:
Interest expense	(78)	(449)
Other (expense) income	(527)	107
Total other expense, net	(605)	(342)
Loss before income taxes	(6,153)	(6,127)
Provision for income taxes	(167)	(109)
Net loss	$ (6,320)	$ (6,236)
Net loss per share, basic and diluted (in usd per share)	$ (0.14)	$ (0.15)
Shares used in computing net loss per share, basic and diluted (in shares)	43,950	42,205

Condensed Consolidated Statements of Comprehensive Loss (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
Statement of Comprehensive Income [Abstract]
Net loss	$ (6,320)	$ (6,236)
Other comprehensive (loss) income:
Foreign currency translation adjustments	(316)	1
Comprehensive loss	$ (6,636)	$ (6,235)

- Definition

The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

+ References + Details

Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
Cash flows from operating activities:
Net loss	$ (6,320)	$ (6,236)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	2,532	1,910
Provision for doubtful accounts	0	26
Net loss on disposal of assets	191	6
Non-cash interest expense	39	102
Stock-based compensation	2,988	2,013
Revaluation of contingent consideration liability	104	0
Changes in operating assets and liabilities:
Accounts receivable	(751)	3,608
Inventory	(13,156)	2,467
Prepaid expenses and other assets	(2,069)	(977)
Accounts payable, accrued and other liabilities	2,305	1,159
Warranty obligations	223	296
Deferred revenues	2,416	(93)
Net cash (used in) provided by operating activities	(11,498)	4,281
Cash flows from investing activities:
Purchases of property and equipment	(3,611)	(2,172)
Net cash used in investing activities	(3,611)	(2,172)
Cash flows from financing activities:
Repayments of term loans	0	(866)
Proceeds from issuance of common stock under employee stock plans	677	454
Net cash provided by (used in) financing activities	677	(412)
Effect of exchange rate changes on cash	(473)	48
Net (decrease) increase in cash and cash equivalents	(14,905)	1,745
Cash and cash equivalents—Beginning of period	42,032	38,190
Cash and cash equivalents—End of period	27,127	39,935
Supplemental disclosures of non-cash investing and financing activities:
Purchases of property and equipment included in accounts payable	$ 1,269	$ 497

OVERVIEW AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES	3 Months Ended
OVERVIEW AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES	Mar. 31, 2015
Organization, Consolidation and Presentation of Financial Statements [Abstract]
OVERVIEW AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES	OVERVIEW AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES Description of Business Enphase Energy, Inc. and subsidiaries (the “Company”) designs, develops, and sells microinverter systems for the solar photovoltaic industry. The Company was incorporated in 2006 and began selling its products in 2008. The Company’s microinverter system consists of (i) an Enphase microinverter and related accessories that convert direct current (“DC”) power to grid-compliant alternating current (“AC”) power; (ii) an Envoy communications gateway device that collects and transmits performance information from each solar module to the Company’s hosted data center; and (iii) the Enlighten web-based software platform that collects and processes this information to enable customers to monitor and manage their solar power systems. The Company sells microinverter systems primarily to distributors who resell them to solar installers. The Company also sells directly to large installers as well as through original equipment manufacturers (“OEMs”) and strategic partners. The Company also offers operations and maintenance services for photovoltaic (“PV”) systems including preventive and corrective maintenance, solar panel cleaning and solar system commissioning. Basis of Presentation and Consolidation The accompanying condensed consolidated financial statements are presented in accordance with accounting principles generally accepted in the U.S, or GAAP. The condensed consolidated financial statements include the accounts of the Company and its wholly-owned subsidiaries. All intercompany balances and transactions have been eliminated in the consolidation. Unaudited Interim Financial Information These accompanying unaudited condensed consolidated financial statements have been prepared pursuant to the rules and regulations of the Securities and Exchange Commission (the “SEC”) for interim financial reporting. In the opinion of management, these unaudited condensed consolidated financial statements reflect all adjustments, consisting of normal recurring items, considered necessary to present fairly the Company's financial condition, results of operations, comprehensive income (loss) and cash flows for the interim periods indicated. The results of operations for the three months ended March 31, 2015 are not necessarily indicative of the operating results for the full year. Certain information and footnote disclosures typically included in annual consolidated financial statements have been condensed or omitted. Accordingly, these unaudited interim condensed consolidated financial statements should be read in conjunction with the consolidated financial statements and related notes included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2014. There have been no material changes in the Company’s significant accounting policies during the three months ended March 31, 2015 as compared to the significant accounting policies described in the Company’s Annual Report on Form 10-K for the year ended December 31, 2014. Reference is made to the disclosures therein for a summary of all of the Company’s significant accounting policies. Use of Estimates The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of income and expenses during the reporting period. Significant estimates and assumptions reflected in the financial statements include revenue recognition, inventory valuation and accrued warranty obligations. These estimates are based on information available as of the date of the financial statements; therefore, actual results could differ materially from management’s estimates using different assumptions or under different conditions. Recent Accounting Pronouncements Not Yet Effective In May 2014, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) No. 2014-09 (Topic 606), Revenue from Contracts with Customers, which will replace most existing revenue recognition guidance under US GAAP. The updated standard’s core principle is that revenue is recognized when promised goods or services are transferred to customers in an amount that reflects the consideration to which an entity expects to be entitled in exchange for those goods or services. The standard generally requires an entity to identify performance obligations in its contracts, estimate the amount of variable consideration to be received in the transaction price, allocate the transaction price to each separate performance obligation, and recognize revenue as obligations are satisfied. In addition, the updated standard requires additional disclosure about the nature, amount, timing and uncertainty of revenue and cash flows arising from customer contracts. ASU 2014-09 is effective for annual and interim periods beginning after December 15, 2016. Early adoption is not permitted. Accordingly, the ASU will be effective for the Company beginning in the first quarter of 2017. The Company is currently evaluating the impact of the adoption on its consolidated financial statements.

INVENTORY

3 Months Ended

Mar. 31, 2015

Inventory Disclosure [Abstract]

INVENTORY

Inventory as of March 31, 2015 and December 31, 2014 consists of the following (in thousands):



	March 31, 2015		December 31, 2014
Raw materials	$	4,179	$	3,429
Finished goods	30,567		18,161
Total inventory	$	34,746	$	21,590

WARRANTY OBLIGATIONS

3 Months Ended

Mar. 31, 2015

Product Warranties Disclosures [Abstract]

WARRANTY OBLIGATIONS

The Company’s warranty activities during the three months ended March 31, 2015 and 2014 were as follows (in thousands):



	Three Months Ended March 31,
	2015			2014
Warranty obligations, beginning of period	$	33,940		$	30,432
Accruals for warranties issued during period	1,105			613
Changes in estimates	58			1,400
Settlements	(1,151		)	(1,733		)
Increase due to accretion expense	161			20
Other	50			(4		)
Warranty obligations, end of period	$	34,163		$	30,728
Less current portion	$	(7,550	)	$	(5,894	)
Noncurrent	$	26,613		$	24,834

For the three months ended March 31, 2014, warranty expense included net changes in estimates of $1.4 million to reflect higher than originally estimated replacement unit costs related to the Company’s second generation microinverter.

As of March 31, 2015, the $34.2 million in warranty obligations included $4.8 million measured at fair value (see Note 4—Fair Value Measurements).

FAIR VALUE MEASUREMENTS

3 Months Ended

Mar. 31, 2015

Fair Value Disclosures [Abstract]

FAIR VALUE MEASUREMENTS

The accounting guidance defines fair value as the price that would be received from selling an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date. When determining the fair value measurements for assets and liabilities recorded at fair value, the Company considers the principal or most advantageous market in which it would transact and considers assumptions that market participants would use when pricing the asset or liability, such as inherent risk, transfer restrictions, and risk of nonperformance.

The fair value hierarchy requires an entity to maximize the use of observable inputs and minimize the use of unobservable inputs when measuring fair value. An asset’s or liability’s categorization within the fair value hierarchy is based upon the lowest level of input that is significant to the fair value measurement. Three levels of inputs may be used to measure fair value:


•	Level 1—Valuations based on quoted prices in active markets for identical assets or liabilities that the Company is able to access. Since valuations are based on quoted prices that are readily and regularly available in an active market, valuation of such assets or liabilities do not entail a significant degree of judgment.


•	Level 2—Valuations based on one or more quoted prices in markets that are not active or for which all significant inputs are observable, either directly or indirectly.


•	Level 3—Valuations based on inputs that are unobservable and significant to the overall fair value measurement.

The following table presents the Company’s assets and liabilities that were measured at fair value on a recurring basis and its categorization within the fair value hierarchy at March 31, 2015 and December 31, 2014 (in thousands):



	Fair Value Hierarchy	March 31, 2015		December 31, 2014
Assets:
Foreign currency forward contracts	Level 2	$	59	$	76

Liabilities:
Foreign currency forward contracts	Level 2	$	—	$	—
Warranty obligations	Level 3	4,783		3,562
Contingent consideration	Level 3	2,404		2,300

Derivative Instruments

The Company utilizes foreign currency forward contracts from time to time to reduce the impact of foreign currency fluctuations arising from both sales and purchases denominated in Euros and the British Pound Sterling. At March 31, 2015 and December 31, 2014, the notional amounts of the Company’s foreign currency forward contracts outstanding were $1.3 million and $1.5 million, respectively. For the three months ended March 31, 2015 and 2014, the Company recorded net gains of $148,000 and $50,000, respectively, related to foreign currency forward contracts in other income (expense), net.

Fair Value Option for Warranty Obligations Related to Microinverters Sold Since January 1, 2014

The Company estimates the fair value of warranty obligations by calculating the warranty obligations in the same manner as for sales prior to January 1, 2014 and applying an expected present value technique to that result. The expected present value technique, an income approach, converts future amounts into a single current discounted amount. In addition to the key estimates of failure rates, claim rates and replacement costs, the Company used certain Level 3 inputs which are unobservable and significant to the overall fair value measurement. Such additional assumptions included a discount rate based on the Company’s credit-adjusted risk-free rate and compensation comprised of a profit element and risk premium required of a market participant to assume the obligation.

The following table provides information regarding changes in nonfinancial liabilities related to the Company’s warranty obligations measured at fair value on a recurring basis using significant unobservable inputs (Level 3) for the periods indicated (in thousands):



	Three Months Ended March 31,
	2015			2014
Balance at beginning of period	$	3,562		$	—
Accruals for warranties issued during period	1,047			571
Changes in estimates	—			—
Settlements	(36		)	—
Increase due to accretion expense	161			20
Other	49			(4		)
Balance at end of period	$	4,783		$	587

Contingent Consideration Liability

The contingent consideration liability relates to the Company’s December 2014 acquisition of substantially all of the assets of Next Phase Solar, Inc. (“NPS”). The selling party may be entitled to receive two contingent payments, each based on achievement of defined revenue targets for the two annual periods subsequent to the acquisition date. The range of undiscounted amounts the Company could be required to pay for each contingent payment is between zero and $2.8 million. The amounts are payable, if at all, in early 2016 and 2017 based on achievement of defined 2015 and 2016 revenue targets, respectively.

The Company is required to reevaluate the fair value of the contingent consideration liability at each reporting period based on new developments and record changes in fair value until such consideration is satisfied through payment upon the achievement of the specified revenue targets or is no longer payable due to failure to achieve the specified revenue targets. The fair value of the contingent consideration liability was estimated by applying the income approach. That measure is based on significant Level 3 inputs not observable in the market. Key assumptions include (i) probability adjusted level of revenues and the resultant payout; and (ii) a risk-adjusted discount rate was estimated using a capital asset pricing model, which reflects an expected rate of return required by a market participant holding a financial instrument with risk attributes similar to the Company’s contingent consideration liability.

The following table provides information regarding changes in financial liabilities related to the contingent consideration liability measured at fair value on a recurring basis using significant unobservable inputs (Level 3) for the three months ended March 31, 2015 (in thousands):



Balance—December 31, 2014	$	2,300
Revaluations	104
Balance—March 31, 2015	$	2,404

The increase in fair value of the contingent consideration liability for the three months ended March 31, 2015 was attributed to the shorter discount period between the current balance sheet date and the contingent payment due dates.

Quantitative and Qualitative Information about Level 3 Fair Value Measurements

As of March 31, 2015, the significant unobservable inputs used in the fair value measurement of the Company’s liabilities designated as Level 3 are as follows:



Item Measured at Fair Value	Valuation Technique	Description of Significant Unobservable Input	Percent Used (Weighted-Average)
Warranty obligations for microinverters sold since January 1, 2014	Discounted cash flows	Profit element and risk premium	17%
	Discounted cash flows	Credit-adjusted risk-free rate	18%

Contingent consideration liability	Probability-weighted discounted cash flows	Risk-adjusted discount rate	18%

Sensitivity of Level 3 Inputs

Warranty Obligations

Each of the significant unobservable inputs is independent of the other. The profit element and risk premium are estimated based on requirements of a third-party participant willing to assume the Company’s warranty obligations. The discount rate is determined by reference to the Company’s own credit standing at the fair value measurement date. Increasing or decreasing the profit element and risk premium input by 100 basis points would not have a material impact on the fair value measurement of the liability. Increasing the discount rate by 100 basis points would result in a $0.2 million reduction of the liability. Decreasing the discount rate by 100 basis points would result in a $0.2 million increase to the liability.

Contingent Consideration Liability

Changes in assumed probability adjustments with respect to achievement of target metric can materially impact the fair value measurement of contingent consideration as of the acquisition date and for each subsequent period. Assumptions about the probability and amount of payout will require less subjectivity over the course of the earnout period as management refines estimates based on actual events. Due to the short duration of the earnout period of two years, increasing or decreasing the risk-adjusted discount rate by 100 basis points would not have a material impact on the fair value measurement of the contingent consideration liability.

- Definition

The entire disclosure for the fair value of financial instruments (as defined), including financial assets and financial liabilities (collectively, as defined), and the measurements of those instruments as well as disclosures related to the fair value of non-financial assets and liabilities. Such disclosures about the financial instruments, assets, and liabilities would include: (1) the fair value of the required items together with their carrying amounts (as appropriate); (2) for items for which it is not practicable to estimate fair value, disclosure would include: (a) information pertinent to estimating fair value (including, carrying amount, effective interest rate, and maturity, and (b) the reasons why it is not practicable to estimate fair value; (3) significant concentrations of credit risk including: (a) information about the activity, region, or economic characteristics identifying a concentration, (b) the maximum amount of loss the entity is exposed to based on the gross fair value of the related item, (c) policy for requiring collateral or other security and information as to accessing such collateral or security, and (d) the nature and brief description of such collateral or security; (4) quantitative information about market risks and how such risks are managed; (5) for items measured on both a recurring and nonrecurring basis information regarding the inputs used to develop the fair value measurement; and (6) for items presented in the financial statement for which fair value measurement is elected: (a) information necessary to understand the reasons for the election, (b) discussion of the effect of fair value changes on earnings, (c) a description of [similar groups] items for which the election is made and the relation thereof to the balance sheet, the aggregate carrying value of items included in the balance sheet that are not eligible for the election; (7) all other required (as defined) and desired information.

+ References + Details

GOODWILL AND INTANGIBLE ASSETS

3 Months Ended

Mar. 31, 2015

Goodwill and Intangible Assets Disclosure [Abstract]

GOODWILL AND INTANGIBLE ASSETS



	March 31, 2015							December 31, 2014
	Gross		Accumulated Amortization			Net		Gross		Accumulated Amortization			Net
Goodwill	$	3,745	$	—		$	3,745	$	3,745	$	—		$	3,745

Other indefinite-lived intangibles	$	286	$	—		$	286	$	286	$	—		$	286

Intangibles assets with finite lives:
Customer relationships	900		(45		)	855		900		—			900
Patents	750		(187		)	563		750		(125		)	625
Total	$	1,650	$	(232	)	$	1,418	$	1,650	$	(125	)	$	1,525

In July 2014, the Company purchased certain patents related to system interconnection and photovoltaic AC module construction. The patents are being amortized over their legal life of 3 years. The customer relationship intangible resulted from the Company’s NPS acquisition and is being amortized on a straight-line basis over its estimated useful life of 5 years.

For the three months ended March 31, 2015, amortization expense related to intangible assets was $0.1 million. As of March 31, 2015, estimated future amortization expense related to finite-lived intangible assets was as follows:



Year	(In thousands)
2015 (remaining 9 months)	$	323
2016	430
2017	305
2018	180
2019	180
Total	$	1,418

- Definition

The entire disclosure for the aggregate amount of goodwill and a description of intangible assets, which may include (a) for amortizable intangible assets (also referred to as finite-lived intangible assets), the carrying amount, the amount of any significant residual value, and the weighted-average amortization period, (b) for intangible assets not subject to amortization (also referred to as indefinite-lived intangible assets), the carrying amount, and (c) the amount of research and development assets acquired and written off in the period, including the line item in the income statement in which the amounts written off are aggregated, if not readily apparent from the income statement. Also discloses (a) for amortizable intangibles assets in total and by major class, the gross carrying amount and accumulated amortization, the total amortization expense for the period, and the estimated aggregate amortization expense for each of the five succeeding fiscal years, (b) for intangible assets not subject to amortization the carrying amount in total and by major class, and (c) for goodwill, in total and for each reportable segment, the changes in the carrying amount of goodwill during the period (including the aggregate amount of goodwill acquired, the aggregate amount of impairment losses recognized, and the amount of goodwill included in the gain (loss) on disposal of a reporting unit). If any part of goodwill has not been allocated to a reportable segment, discloses the unallocated amount and the reasons for not allocating. For each impairment loss recognized related to an intangible asset (excluding goodwill), discloses: (a) a description of the impaired intangible asset and the facts and circumstances leading to the impairment, (b) the amount of the impairment loss and the method for determining fair value, (c) the caption in the income statement or the statement of activities in which the impairment loss is aggregated, and (d) the segment in which the impaired intangible asset is reported. For each goodwill impairment loss recognized, discloses: (a) a description of the facts and circumstances leading to the impairment, (b) the amount of the impairment loss and the method of determining the fair value of the associated reporting unit, and (c) if a recognized impairment loss is an estimate not finalized and the reasons why the estimate is not final. May also disclose the nature and amount of any significant adjustments made to a previous estimate of an impairment loss.

+ References + Details

COMMITMENTS AND CONTINGENCIES	3 Months Ended
COMMITMENTS AND CONTINGENCIES	Mar. 31, 2015
Commitments and Contingencies Disclosure [Abstract]
COMMITMENTS AND CONTINGENCIES	COMMITMENTS AND CONTINGENCIES Contingencies —The Company is not currently involved in any material legal proceedings. The Company may become involved in various legal proceedings and claims that arise in the ordinary course of business. Such matters are subject to uncertainty and there can be no assurance that such legal proceedings will not have a material adverse effect on its business, results of operations, financial position or cash flows.

STOCK-BASED COMPENSATION

3 Months Ended

Mar. 31, 2015

Disclosure of Compensation Related Costs, Share-based Payments [Abstract]

STOCK-BASED COMPENSATION

The Company has adopted certain equity incentive and stock purchase plans as described in the consolidated financial statements and related notes included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2014.

Equity Awards Activity

Stock Options

The following is a summary of stock option activity for the three months ended March 31, 2015 (in thousands, except per share data):



	Number of Shares Outstanding		Weighted- Average Exercise Price per Share
Outstanding at December 31, 2014	8,632		$	4.75
Granted	197		12.17
Exercised	(188	)	3.65
Canceled	(45	)	9.83
Outstanding at March 31, 2015	8,596		4.92

The intrinsic value of options exercised in the three months ended March 31, 2015 was $1.8 million. As of March 31, 2015, the intrinsic value of options outstanding was $71.7 million based on the closing price of the Company’s stock as of March 31, 2015.

Restricted Stock Units

The following is a summary of restricted stock unit activity for the three months ended March 31, 2015 (in thousands, except per share data):



	RSUs		Weighted Average Fair Value per Share at Grant Date
Outstanding at December 31, 2014	1,345		$	8.25
Granted	450		13.05
Vested	(172	)	8.04
Canceled	—
Outstanding at March 31, 2015	1,623		9.60

The total fair value of restricted stock units that vested in the three months ended March 31, 2015 was $2.5 million. As of March 31, 2015, the intrinsic value of restricted stock units outstanding was $21.4 million based on the closing price of the Company’s stock as of March 31, 2015.

Stock-Based Compensation Expense

Compensation cost for all stock-based awards expected to vest is measured at fair value on the date of grant and recognized ratably over the requisite service period. The following table summarizes the components of total stock-based compensation expense included in the condensed consolidated statements of operations for the periods presented (in thousands):



	Three Months Ended March 31,
	2015		2014
Cost of revenues	$	264	$	149
Research and development	1,079		613
Sales and marketing	765		532
General and administrative	880		719
Total	$	2,988	$	2,013

The following table summarizes stock-based compensation associated with each type of award for the periods presented (in thousands):



	Three Months Ended March 31,
	2015		2014
Stock options and restricted stock units	$	2,526	$	1,839
Employee stock purchase plan	462		174
Total	$	2,988	$	2,013

The following table presents the weighted-average grant date fair value of options granted for the periods presented and the assumptions used to estimate those values using a Black-Scholes option pricing model:



	Three Months Ended March 31,
	2015			2014
Weighted average grant date fair value	$	6.89		$	3.99
Expected term (in years)	4.6			4.6
Expected volatility	71.1		%	62.2		%
Annual risk-free rate of return	1.3		%	1.4		%
Dividend yield	0.0		%	0.0		%

The fair value of restricted stock units granted is determined based on the price of the Company’s common stock on the date of grant.

As of March 31, 2015, there was approximately $24.4 million of total unrecognized compensation cost related to unvested equity awards expected to be recognized over a weighted-average period of 2.8 years.

INCOME TAXES	3 Months Ended
INCOME TAXES	Mar. 31, 2015
Income Tax Disclosure [Abstract]
INCOME TAXES	INCOME TAXES The Company has used the discrete tax approach in calculating the tax expense for the three months ended March 31, 2015 and 2014 due to the fact that a relatively small change in the Company’s projected pre-tax net income (loss) could result in a volatile effective tax rate. Under the discrete method, the Company determines its tax (expense) benefit based upon actual results as if the interim period was an annual period. For the three months ended March 31, 2015, the Company recorded a tax provision of $167,000 on a pretax loss of $6.2 million. For the three months ended March 31, 2014, the Company recorded a tax provision of $109,000 on a pretax loss of $6.1 million. The tax provisions recorded were primarily related to income taxes in profitable jurisdictions outside of the U.S.

NET LOSS PER SHARE

3 Months Ended

Mar. 31, 2015

Earnings Per Share [Abstract]

NET LOSS PER SHARE

The following table presents the computation of basic and diluted net loss per share (in thousands, except per share data):



	Three Months Ended March 31,
	2015			2014
Numerator:
Net loss	$	(6,320	)	$	(6,236	)
Denominator:
Weighted average number of common shares outstanding	43,950			42,205

Net loss per share, basic and diluted	$	(0.14	)	$	(0.15	)

As the Company incurred a net loss for all periods presented, potential dilutive securities from employee stock options, restricted stock units and warrants have been excluded from the diluted net loss per share computations because the effect of including such shares would have been anti-dilutive. The following table sets forth the potentially dilutive securities excluded from the computation of the diluted net loss per share (in thousands):



	Three Months Ended March 31,
	2015	2014
Employee stock options	8,627	8,489
Restricted stock units	1,433	732
Warrants to purchase common stock	111	293
Total	10,171	9,514

OVERVIEW AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Policies)	3 Months Ended
	Mar. 31, 2015
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of Presentation and Consolidation	Basis of Presentation and Consolidation The accompanying condensed consolidated financial statements are presented in accordance with accounting principles generally accepted in the U.S, or GAAP. The condensed consolidated financial statements include the accounts of the Company and its wholly-owned subsidiaries. All intercompany balances and transactions have been eliminated in the consolidation.
Unaudited Interim Financial Information	Unaudited Interim Financial Information These accompanying unaudited condensed consolidated financial statements have been prepared pursuant to the rules and regulations of the Securities and Exchange Commission (the “SEC”) for interim financial reporting. In the opinion of management, these unaudited condensed consolidated financial statements reflect all adjustments, consisting of normal recurring items, considered necessary to present fairly the Company's financial condition, results of operations, comprehensive income (loss) and cash flows for the interim periods indicated. The results of operations for the three months ended March 31, 2015 are not necessarily indicative of the operating results for the full year. Certain information and footnote disclosures typically included in annual consolidated financial statements have been condensed or omitted. Accordingly, these unaudited interim condensed consolidated financial statements should be read in conjunction with the consolidated financial statements and related notes included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2014.
Use of Estimates	Use of Estimates The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of income and expenses during the reporting period. Significant estimates and assumptions reflected in the financial statements include revenue recognition, inventory valuation and accrued warranty obligations. These estimates are based on information available as of the date of the financial statements; therefore, actual results could differ materially from management’s estimates using different assumptions or under different conditions.
Income Taxes	The Company has used the discrete tax approach in calculating the tax expense for the three months ended March 31, 2015 and 2014 due to the fact that a relatively small change in the Company’s projected pre-tax net income (loss) could result in a volatile effective tax rate. Under the discrete method, the Company determines its tax (expense) benefit based upon actual results as if the interim period was an annual period.

- Definition

Disclosure of accounting policy for income taxes, which may include its accounting policies for recognizing and measuring deferred tax assets and liabilities and related valuation allowances, recognizing investment tax credits, operating loss carryforwards, tax credit carryforwards, and other carryforwards, methodologies for determining its effective income tax rate and the characterization of interest and penalties in the financial statements.

+ References + Details

INVENTORY (Tables)

3 Months Ended

Mar. 31, 2015

Inventory Disclosure [Abstract]

Summary of Inventory

Inventory as of March 31, 2015 and December 31, 2014 consists of the following (in thousands):



	March 31, 2015		December 31, 2014
Raw materials	$	4,179	$	3,429
Finished goods	30,567		18,161
Total inventory	$	34,746	$	21,590

WARRANTY OBLIGATIONS (Tables)

3 Months Ended

Mar. 31, 2015

Product Warranties Disclosures [Abstract]

Summary of Warranty Activities

The Company’s warranty activities during the three months ended March 31, 2015 and 2014 were as follows (in thousands):



	Three Months Ended March 31,
	2015			2014
Warranty obligations, beginning of period	$	33,940		$	30,432
Accruals for warranties issued during period	1,105			613
Changes in estimates	58			1,400
Settlements	(1,151		)	(1,733		)
Increase due to accretion expense	161			20
Other	50			(4		)
Warranty obligations, end of period	$	34,163		$	30,728
Less current portion	$	(7,550	)	$	(5,894	)
Noncurrent	$	26,613		$	24,834

FAIR VALUE MEASUREMENTS (Tables)

3 Months Ended

Mar. 31, 2015

Fair Value Disclosures [Abstract]

Schedule of Assets and Liabilities Measured at Fair Value on a Recurring Basis



	Fair Value Hierarchy	March 31, 2015		December 31, 2014
Assets:
Foreign currency forward contracts	Level 2	$	59	$	76

Liabilities:
Foreign currency forward contracts	Level 2	$	—	$	—
Warranty obligations	Level 3	4,783		3,562
Contingent consideration	Level 3	2,404		2,300

Schedule of Changes in Nonfinancial Liabilities Related to Warrant Obligations Measured at Fair Value on a Recurring Basis Using Significant Unobservable Inputs



	Three Months Ended March 31,
	2015			2014
Balance at beginning of period	$	3,562		$	—
Accruals for warranties issued during period	1,047			571
Changes in estimates	—			—
Settlements	(36		)	—
Increase due to accretion expense	161			20
Other	49			(4		)
Balance at end of period	$	4,783		$	587

Summary of Changes in Financial Liabilities Related to Contingent Consideration Measured at Fair Value on a Recurring Basis Using Significant Unobservable Inputs



Balance—December 31, 2014	$	2,300
Revaluations	104
Balance—March 31, 2015	$	2,404

Summary of Significant Unobservable Inputs used in the Fair Value Measurement of Liabilities Designated as Level 3

As of March 31, 2015, the significant unobservable inputs used in the fair value measurement of the Company’s liabilities designated as Level 3 are as follows:



Item Measured at Fair Value	Valuation Technique	Description of Significant Unobservable Input	Percent Used (Weighted-Average)
Warranty obligations for microinverters sold since January 1, 2014	Discounted cash flows	Profit element and risk premium	17%
	Discounted cash flows	Credit-adjusted risk-free rate	18%

Contingent consideration liability	Probability-weighted discounted cash flows	Risk-adjusted discount rate	18%

GOODWILL AND INTANGIBLE ASSETS (Tables)

3 Months Ended

Mar. 31, 2015

Goodwill and Intangible Assets Disclosure [Abstract]

Schedule of Goodwill and Intangible Assets



	March 31, 2015							December 31, 2014
	Gross		Accumulated Amortization			Net		Gross		Accumulated Amortization			Net
Goodwill	$	3,745	$	—		$	3,745	$	3,745	$	—		$	3,745

Other indefinite-lived intangibles	$	286	$	—		$	286	$	286	$	—		$	286

Intangibles assets with finite lives:
Customer relationships	900		(45		)	855		900		—			900
Patents	750		(187		)	563		750		(125		)	625
Total	$	1,650	$	(232	)	$	1,418	$	1,650	$	(125	)	$	1,525

Schedule of Estimated Future Amortization Expense Related to Finite-Lived Intangible Assets



Year	(In thousands)
2015 (remaining 9 months)	$	323
2016	430
2017	305
2018	180
2019	180
Total	$	1,418

STOCK-BASED COMPENSATION (Tables)

3 Months Ended

Mar. 31, 2015

Disclosure of Compensation Related Costs, Share-based Payments [Abstract]

Summary of Stock Option Activity

The following is a summary of stock option activity for the three months ended March 31, 2015 (in thousands, except per share data):



	Number of Shares Outstanding		Weighted- Average Exercise Price per Share
Outstanding at December 31, 2014	8,632		$	4.75
Granted	197		12.17
Exercised	(188	)	3.65
Canceled	(45	)	9.83
Outstanding at March 31, 2015	8,596		4.92

Summary of Restricted Stock Unit Activity

The following is a summary of restricted stock unit activity for the three months ended March 31, 2015 (in thousands, except per share data):



	RSUs		Weighted Average Fair Value per Share at Grant Date
Outstanding at December 31, 2014	1,345		$	8.25
Granted	450		13.05
Vested	(172	)	8.04
Canceled	—
Outstanding at March 31, 2015	1,623		9.60

Summary of the Components of Total Stock-Based Compensation Expense

The following table summarizes the components of total stock-based compensation expense included in the condensed consolidated statements of operations for the periods presented (in thousands):



	Three Months Ended March 31,
	2015		2014
Cost of revenues	$	264	$	149
Research and development	1,079		613
Sales and marketing	765		532
General and administrative	880		719
Total	$	2,988	$	2,013

Summary of Stock-Based Compensation Associated with Each Type of Award

The following table summarizes stock-based compensation associated with each type of award for the periods presented (in thousands):



	Three Months Ended March 31,
	2015		2014
Stock options and restricted stock units	$	2,526	$	1,839
Employee stock purchase plan	462		174
Total	$	2,988	$	2,013

Summary of the Weighted-Average Grant Date Fair Value of Options Granted



	Three Months Ended March 31,
	2015			2014
Weighted average grant date fair value	$	6.89		$	3.99
Expected term (in years)	4.6			4.6
Expected volatility	71.1		%	62.2		%
Annual risk-free rate of return	1.3		%	1.4		%
Dividend yield	0.0		%	0.0		%

NET LOSS PER SHARE (Tables)

3 Months Ended

Mar. 31, 2015

Earnings Per Share [Abstract]

Schedule of Computation of Basic and Diluted Net Loss Per Share

The following table presents the computation of basic and diluted net loss per share (in thousands, except per share data):



	Three Months Ended March 31,
	2015			2014
Numerator:
Net loss	$	(6,320	)	$	(6,236	)
Denominator:
Weighted average number of common shares outstanding	43,950			42,205

Net loss per share, basic and diluted	$	(0.14	)	$	(0.15	)

Schedule of Potentially Dilutive Securities Excluded from the Computation of Diluted Net Loss Per Share

The following table sets forth the potentially dilutive securities excluded from the computation of the diluted net loss per share (in thousands):



	Three Months Ended March 31,
	2015	2014
Employee stock options	8,627	8,489
Restricted stock units	1,433	732
Warrants to purchase common stock	111	293
Total	10,171	9,514

INVENTORY - Summary of Inventory (Details) - USD ($) $ in Thousands	Mar. 31, 2015	Dec. 31, 2014
Schedule of inventory
Raw materials	$ 4,179	$ 3,429
Finished goods	30,567	18,161
Total inventory	$ 34,746	$ 21,590

WARRANTY OBLIGATIONS - Summary of Warranty Activities (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014	Mar. 31, 2015	Dec. 31, 2014	Mar. 31, 2014
Changes in the Company's product warranty liability
Warranty obligations, beginning of period	$ 33,940	$ 30,432
Accruals for warranties issued during period	1,105	613
Changes in estimates	58	1,400
Settlements	(1,151)	(1,733)
Increase due to accretion expense	161	20
Other	50	(4)
Warranty obligations, end of period	$ 33,940	$ 30,432	$ 34,163	$ 33,940	$ 30,728
Less current portion			(7,550)	(7,607)	(5,894)
Noncurrent			$ 26,613	$ 26,333	$ 24,834

WARRANTY OBLIGATIONS - Narrative (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014	Dec. 31, 2014	Dec. 31, 2013
Product Warranty Liability [Line Items]
Changes in warranty estimates	$ 58	$ 1,400
Warranty obligations	34,163	30,728	$ 33,940	$ 30,432
Recurring \| Warranty obligations for microinverters sold since January 1, 2014 \| Level 3
Product Warranty Liability [Line Items]
Fair value liabilities	$ 4,783	$ 587	$ 3,562	$ 0

FAIR VALUE MEASUREMENTS - Schedule of Assets and Liabilities Measured at Fair Value on a Recurring Basis (Details) - Recurring - USD ($) $ in Thousands	Mar. 31, 2015	Dec. 31, 2014	Mar. 31, 2014	Dec. 31, 2013
Level 2
Assets:
Foreign currency forward contracts	$ 59	$ 76
Liabilities:
Foreign currency forward contracts	0	0
Warranty obligations \| Level 3
Liabilities:
Fair value liabilities	4,783	3,562	$ 587	$ 0
Contingent consideration \| Level 3
Liabilities:
Fair value liabilities	$ 2,404	$ 2,300

FAIR VALUE MEASUREMENTS - Narrative (Details)	3 Months Ended
FAIR VALUE MEASUREMENTS - Narrative (Details)	Mar. 31, 2015 USD ($)	Mar. 31, 2014 USD ($)	Dec. 31, 2014 USD ($) payment
Derivative [Line Items]
Contingent consideration earnout period	2 years
Not designated as hedging instrument \| Foreign exchange forward
Derivative [Line Items]
Notional amount of foreign currency	$ 1,300,000		$ 1,500,000
Net gain on foreign currency	148,000	$ 50,000
Discounted cash flows \| Recurring \| Level 3 \| Contingent consideration
Derivative [Line Items]
Decrease to fair value measurement as a result of 100 basis point increase	200,000
Increase to fair value measurement as a result of 100 basis point decrease	$ 200,000
Next Phase Solar, Inc.
Derivative [Line Items]
Number of contingent payments \| payment			2
Contingent payment, low range of undiscounted amounts			$ 0
Contingent payment, high range of undiscounted amounts			$ 2,800,000

FAIR VALUE MEASUREMENTS - Schedule of Changes in Nonfinancial Liabilities Related to Warrant Obligations Measured at Fair Value on a Recurring Basis Using Significant Unobservable Inputs (Details) - Level 3 - Recurring - Warranty obligations - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance at beginning of period	$ 3,562	$ 0
Accruals for warranties issued during period	1,047	571
Changes in estimates	0	0
Settlements	(36)	0
Increase due to accretion expense	161	20
Other	49	(4)
Balance at end of period	$ 4,783	$ 587

FAIR VALUE MEASUREMENTS - Summary of Changes in Financial Liabilities Related to Contingent Consideration Measured at Fair Value on a Recurring Basis Using Significant Unobservable Inputs (Details) - Next Phase Solar, Inc. - Contingent consideration - Recurring - Level 3 $ in Thousands	3 Months Ended
	Mar. 31, 2015 USD ($)
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance at beginning of period	$ 2,300
Revaluations	104
Balance at end of period	$ 2,404

FAIR VALUE MEASUREMENTS - Summary of Significant Unobservable Inputs used in the Fair Value Measurement of Liabilities Designated as Level 3 (Details) - Discounted cash flows - Recurring - Level 3	3 Months Ended
	Mar. 31, 2015
Warranty obligations for microinverters sold since January 1, 2014
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Profit element and risk premium	17.00%
Credit-adjusted risk-free rate	18.00%
Contingent consideration liability
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Risk-adjusted discount rate	18.00%

GOODWILL AND INTANGIBLE ASSETS - Schedule of Goodwill and Intangible Assets (Details) - USD ($) $ in Thousands	Mar. 31, 2015	Dec. 31, 2014
Finite-Lived Intangible Assets [Line Items]
Goodwill, gross	$ 3,745	$ 3,745
Goodwill	3,745	3,745
Other indefinite-lived intangibles	286	286
Intangibles assets with finite lives:
Intangibles assets with finite lives, gross	1,650	1,650
Intangibles assets with finite lives, accumulated amortization	(232)	(125)
Total	1,418	1,525
Customer relationships
Intangibles assets with finite lives:
Intangibles assets with finite lives, gross	900	900
Intangibles assets with finite lives, accumulated amortization	(45)	0
Total	855	900
Patents
Intangibles assets with finite lives:
Intangibles assets with finite lives, gross	750	750
Intangibles assets with finite lives, accumulated amortization	(187)	(125)
Total	$ 563	$ 625

GOODWILL AND INTANGIBLE ASSETS - Narrative (Details) - USD ($) $ in Millions	1 Months Ended	3 Months Ended
	Jul. 31, 2014	Mar. 31, 2015
Finite-Lived Intangible Assets [Line Items]
Amortization expense related to intangible assets		$ 0.1
Patents
Finite-Lived Intangible Assets [Line Items]
Useful life	3 years
Customer relationships
Finite-Lived Intangible Assets [Line Items]
Useful life	5 years

GOODWILL AND INTANGIBLE ASSETS - Schedule of Estimated Future Amortization Expense Related to Finite-Lived Intangible Assets (Details) - USD ($) $ in Thousands	Mar. 31, 2015	Dec. 31, 2014
Goodwill and Intangible Assets Disclosure [Abstract]
2015 (remaining 9 months)	$ 323
2016	430
2017	305
2018	180
2019	180
Total	$ 1,418	$ 1,525

STOCK-BASED COMPENSATION - Summary of Stock Option Activity (Details) shares in Thousands	3 Months Ended
	Mar. 31, 2015 $ / shares shares
Number of Shares Outstanding
Outstanding, beginning balance (in shares) \| shares	8,632
Granted (in shares) \| shares	197
Exercised (in shares) \| shares	(188)
Canceled (in shares) \| shares	(45)
Outstanding, ending balance (in shares) \| shares	8,596
Weighted- Average Exercise Price per Share
Outstanding, beginning balance (in usd per share) \| $ / shares	$ 4.75
Granted (in usd per share) \| $ / shares	12.17
Exercised (in usd per share) \| $ / shares	3.65
Canceled (in usd per share) \| $ / shares	9.83
Outstanding, ending balance (in usd per share) \| $ / shares	$ 4.92

STOCK-BASED COMPENSATION - Narrative (Details) $ in Millions	3 Months Ended
	Mar. 31, 2015 USD ($)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Intrinsic value of options exercised during period	$ 1.8
Intrinsic value of options outstanding	71.7
Total unrecognized compensation cost	$ 24.4
Weighted-average recognition period for unrecognized compensation cost	2 years 9 months 6 days
Restricted stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Fair value of stock vested during period	$ 2.5
Intrinsic value of restricted stock units outstanding	$ 21.4

STOCK-BASED COMPENSATION - Summary of Restricted Stock Unit Activity (Details) - Restricted stock units shares in Thousands	3 Months Ended
	Mar. 31, 2015 $ / shares shares
RSUs
Outstanding, beginning balance (in shares) \| shares	1,345
Granted (in shares) \| shares	450
Vested (in shares) \| shares	(172)
Canceled (in shares) \| shares	0
Outstanding, ending balance (in shares) \| shares	1,623
Weighted Average Fair Value per Share at Grant Date
Outstanding, beginning balance (in usd per share) \| $ / shares	$ 8.25
Granted (in usd per share) \| $ / shares	13.05
Vested (in usd per share) \| $ / shares	8.04
Canceled (in usd per share) \| $ / shares
Outstanding, ending balance (in usd per share) \| $ / shares	$ 9.60

STOCK-BASED COMPENSATION - Summary of the Components of Total Stock-Based Compensation Expense (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
Allocation of Stock-based Compensation Expense Included in the Consolidated Statement of Operations [Abstract]
Total stock-based compensation expense	$ 2,988	$ 2,013
Cost of revenues
Allocation of Stock-based Compensation Expense Included in the Consolidated Statement of Operations [Abstract]
Total stock-based compensation expense	264	149
Research and development
Allocation of Stock-based Compensation Expense Included in the Consolidated Statement of Operations [Abstract]
Total stock-based compensation expense	1,079	613
Sales and marketing
Allocation of Stock-based Compensation Expense Included in the Consolidated Statement of Operations [Abstract]
Total stock-based compensation expense	765	532
General and administrative
Allocation of Stock-based Compensation Expense Included in the Consolidated Statement of Operations [Abstract]
Total stock-based compensation expense	$ 880	$ 719

STOCK-BASED COMPENSATION - Summary of Stock-Based Compensation Associated with Each Type of Award (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock-based compensation expense	$ 2,988	$ 2,013
Stock options and restricted stock units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock-based compensation expense	2,526	1,839
Employee stock purchase plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock-based compensation expense	$ 462	$ 174

STOCK-BASED COMPENSATION - Summary of the Weighted-Average Grant Date Fair Value of Options Granted (Details) - Stock options - $ / shares	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
The fair value of each option granted during the periods
Weighted average grant date fair value (in usd per share)	$ 6.89	$ 3.99
Expected term (in years)	4 years 7 months 6 days	4 years 7 months 6 days
Expected volatility	71.10%	62.20%
Annual risk-free rate of return	1.30%	1.40%
Dividend yield	0.00%	0.00%

INCOME TAXES - Narrative (Details) - USD ($) $ in Thousands	3 Months Ended
INCOME TAXES - Narrative (Details) - USD ($) $ in Thousands	Mar. 31, 2015	Mar. 31, 2014
Income Tax Disclosure [Abstract]
Provision for income taxes	$ 167	$ 109
Loss before income taxes	$ 6,153	$ 6,127

NET LOSS PER SHARE - Schedule of Computation of Basic and Diluted Net Loss Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
Numerator:
Net loss	$ (6,320)	$ (6,236)
Denominator:
Weighted average number of common shares outstanding (in shares)	43,950	42,205
Net loss per share, basic and diluted (in usd per share)	$ (0.14)	$ (0.15)

- Definition

The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

+ References + Details

NET LOSS PER SHARE - Schedule of Potentially Dilutive Securities Excluded from the Computation of Diluted Net Loss Per Share (Details) - shares shares in Thousands	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
The potential common shares outstanding that were excluded from the computation of diluted net loss per share attributable to common stockholders
Total (in shares)	10,171	9,514
Employee stock options
The potential common shares outstanding that were excluded from the computation of diluted net loss per share attributable to common stockholders
Total (in shares)	8,627	8,489
Restricted stock units
The potential common shares outstanding that were excluded from the computation of diluted net loss per share attributable to common stockholders
Total (in shares)	1,433	732
Warrants to purchase common stock
The potential common shares outstanding that were excluded from the computation of diluted net loss per share attributable to common stockholders
Total (in shares)	111	293