DESCRIPTION OF BUSINESS AND BASIS OF PRESENTATION	9 Months Ended
DESCRIPTION OF BUSINESS AND BASIS OF PRESENTATION	Sep. 30, 2021
Organization, Consolidation and Presentation of Financial Statements [Abstract]
DESCRIPTION OF BUSINESS AND BASIS OF PRESENTATION	DESCRIPTION OF BUSINESS AND BASIS OF PRESENTATION Description of Business Enphase Energy, Inc. (the “Company”) is a global energy technology company. The Company delivers smart, easy-to-use solutions that manage solar generation, storage and communication on one platform. The Company revolutionized the solar industry with its microinverter technology and produces a fully integrated solar-plus-storage solution. Basis of Presentation and Consolidation The accompanying condensed consolidated financial statements are presented in accordance with accounting principles generally accepted in the United States (“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 consolidation. Unaudited Interim Financial Information These accompanying unaudited condensed consolidated financial statements have been prepared pursuant to the rules and regulations of 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, stockholders’ equity and cash flows for the interim periods indicated. The results of operations for the three and nine months ended September 30, 2021 are not necessarily indicative of the operating results for the full year. 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, allowance for doubtful accounts, stock-based compensation, deferred compensation arrangements, inventory valuation, accrued warranty obligations, fair value of investments, debt derivatives, convertible notes and contingent consideration, fair value of acquired intangible assets and goodwill, useful lives of acquired intangible assets and property and equipment, incremental borrowing rate for right-of-use assets and lease liability, legal contingencies, and tax valuation allowance. 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. In light of ongoing semiconductor supply and logistics constraints, and the evolving COVID-19 pandemic, management has considered their impact on the Company’s critical and significant accounting estimates on the date of issuance of these financial statements. These estimates may change, as new events occur and additional information is obtained, and are recognized in the consolidated financial statements as soon as they become known. Actual results could differ from those estimates and any such differences may be material to the Company’s condensed financial statements. The year-end condensed consolidated balance sheet data was derived from audited financial statements but does not include all disclosures required by accounting principles generally accepted in the U.S. The Company filed audited consolidated financial statements, which included all information and notes necessary for such a complete presentation in conjunction with its Annual Report on Form 10-K filed with the Securities and Exchange Commission (the “SEC”) on February 16, 2021 (the “Form 10‑K”). Summary of Significant Accounting Policies Except for the accounting policy for repurchase of common stock, added as a result of the common stock repurchased, and cash, cash equivalents and marketable securities, added as a result of investments made by the Company during the nine months ended September 30, 2021, there have been no significant changes to the Company’s significant accounting policies in Note 2, “Summary of Significant Accounting Policies,” of the notes to consolidated financial statements included in Part II, Item 8 of the Company’s Annual Report on Form 10-K for the fiscal year ended December 31, 2020. Common Stock Repurchase The Company accounts for repurchase of common stock under ASC 505 and charged the entire cost of repurchase to the accumulated deficit in the condensed consolidated balance sheet as of September 30, 2021. Cash, Cash Equivalents and Marketable Securities The Company classifies investments in marketable securities as available-for-sale investments and records these marketable securities at fair value. The Company determines the appropriate classification of marketable securities at the time of purchase and reevaluates such designation at each balance sheet date. All highly liquid investments with original maturities of 90 days or less from the date of purchase are classified as cash equivalents, while all others are presented within current assets since these investments represent funds available for current operations and the Company has the ability and intent, if necessary, to liquidate any of these investments within one year in order to meet liquidity needs or to grow the business, including for potential business acquisitions or other strategic transactions. Marketable securities are recorded at fair value, with the unrealized gains or losses unrelated to credit loss factors included in accumulated other comprehensive income (loss), net of tax. Realized gains and losses and declines in value determined to be other than temporary based on the specific identification method are reported in other income (expense), net in the condensed consolidated statements of operations. The Company periodically reviews whether the securities may be other-than-temporarily impaired, including whether or not (i) the Company has the intent to sell the security or (ii) it is more likely than not that the Company will be required to sell the security before its anticipated recovery. If one of these factors is met, the Company records an impairment loss associated with the impaired investment. The impairment loss will be recorded as a write-down of investments in the condensed consolidated balance sheets and a realized loss within other income (expense), net in the condensed consolidated statements of operations. There were no credit-related impairments recognized on the Company’s investments in marketable securities during the periods presented. Recently Issued Accounting Pronouncements Not Yet Effective In August 2020, the FASB issued Accounting Standards Update (“ASU”) 2020-06, “Debt - Debt with Conversion and Other Options (subtopic 470-20) and Derivatives and Hedging - Contracts in Entity’s Own Equity (subtopic 815-40),” which reduces the number of accounting models in ASC 470-20 that require separate accounting for embedded conversion features. As a result, a convertible debt instrument will be accounted for as a single liability measured at its amortized cost as long as no other features require bifurcation and recognition as derivatives. By removing those separation models, the effective interest rate of convertible debt instruments will be closer to the coupon interest rate. Further, the diluted net income per share calculation for convertible instruments will require the Company to use the if-converted method. The treasury stock method should no longer be used to calculate diluted net income per share for convertible instruments. The Company will adopt the new guidance in the annual period beginning January 1, 2022, on a modified retrospective basis. On the date of adoption, the Company expects to record a net decrease to Additional paid-in capital by approximately $207.9 million, net of tax to remove the equity component separately recorded for the conversion features associated with the convertible debt instruments and equity component associated with the issuance costs, an increase of approximately $244.5 million in the carrying value of its convertible debt instrument to reflect the full principal amount of the Notes outstanding net of issuance costs, a decrease to deferred tax liability of approximately $62.3 million, and a decrease of approximately $25.7 million, net of tax to Accumulated deficit. These estimates could change as the Company continues to progress with the implementation of the standard.