SIGNIFICANT ACCOUNTING POLICIES (Policies)	9 Months Ended
SIGNIFICANT ACCOUNTING POLICIES (Policies)	Sep. 30, 2017
Accounting Policies [Abstract]
Use of Estimates	Use of Estimates The preparation of condensed consolidated financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the condensed consolidated financial statements and the reported amounts of income and expenses during the period. Actual results could differ from these estimates.
Restricted Cash and Cash Equivalents	Restricted Cash and Cash Equivalents The Company is required to maintain certain cash in segregated accounts with prime brokers and derivative counterparties. The amount of restricted cash held by prime brokers is primarily used to support the liability created from securities sold, not yet purchased and derivatives. Additionally, restricted cash and cash equivalent balances are held to collateralize regulatory trusts and letters of credit issued to cedents (see Notes 4 and 9). The amount of cash encumbered varies depending on the market value of the securities sold, not yet purchased, and the collateral required by the cedents in the form of trust accounts and letters of credit. In addition, derivative counterparties require cash collateral to support the current value of any amounts that may be due to the counterparty based on the value of the underlying financial instrument.
Premium Revenue Recognition	Premium Revenue Recognition The Company accounts for reinsurance contracts in accordance with U.S. GAAP. In the event that a reinsurance contract does not transfer sufficient risk, deposit accounting is used and the contract is reported as a deposit liability. Similarly for ceded contracts that do not transfer sufficient risk, deposit accounting is used and the contract is reported as a deposit asset. The Company writes excess of loss contracts as well as quota share contracts. The Company estimates the ultimate premiums for the entire contract period. These estimates are based on information received from the ceding companies and estimates from actuarial pricing models used by the Company. For excess of loss contracts, the total ultimate estimated premiums are recorded as premiums written at the inception of the contract. For quota share contracts, the premiums are recorded as written based on cession statements from cedents which typically are received monthly or quarterly depending on the terms specified in each contract. For any reporting lag, premiums written are estimated based on the portion of the ultimate estimated premiums relating to the risks underwritten during the lag period. Premium estimates are reviewed by management at least quarterly. Such review includes a comparison of actual reported premiums to expected ultimate premiums along with a review of the aging and collection of premium estimates. Based on management’s review, the appropriateness of the premium estimates is evaluated, and any adjustments to these estimates are recorded in the period in which they are determined. Changes in premium estimates, including premium receivable on both excess of loss and quota share contracts, are expected and may result in significant adjustments in any period. A significant portion of amounts included in reinsurance balances receivable represent estimated premiums written, net of commissions and brokerage, and are not currently due based on the terms of the underlying contracts. Certain contracts allow for reinstatement premiums in the event of a loss prior to the expiry of a contract. A reinstatement premium is not due until there is a loss event and therefore, in accordance with U.S. GAAP, the Company records a reinstatement premium as written only in the event that a client incurs a loss on the contract and the contract allows for a reinstatement of coverage upon payment of an additional premium. For catastrophe contracts which contractually require the payment of a reinstatement premium upon the occurrence of a loss, the reinstatement premiums are earned over the original contract period. Reinstatement premiums that are contractually calculated on a pro-rata basis of the original contract period, are earned over the remaining coverage period. For additional premiums which are due on a contract that has no remaining coverage period, the additional premiums are earned in full when due. Certain contracts may provide for a penalty to be paid if the contract is terminated and canceled prior to its expiration term. Cancellation penalties are recognized in the period the notice of cancellation is received and are recorded in the consolidated statements of income under “other income (expense), net”. Premiums written are generally recognized as earned over the contract period in proportion to the period of risk covered. Unearned premiums consist of the unexpired portion of reinsurance provided.
Deferred Acquisition Costs	Deferred Acquisition Costs Policy acquisition costs, such as commission and brokerage costs, relate directly to, and vary with, the writing of reinsurance contracts. Acquisition costs relating solely to bound contracts are deferred subject to ultimate recoverability and are amortized over the related contract term. The Company evaluates the recoverability of deferred acquisition costs by determining if the sum of future earned premiums and anticipated investment income is greater than the expected future claims and expenses. If a loss is probable on the unexpired portion of policies in force, a premium deficiency loss is recognized. At September 30, 2017 and December 31, 2016, the deferred acquisition costs were considered fully recoverable and no premium deficiency loss was recorded. Acquisition costs also include profit commissions which are expensed when incurred. Profit commissions are calculated and accrued based on the expected loss experience for contracts and recorded when the current loss estimate indicates that a profit commission is probable under the contract terms.
Loss and Loss Adjustment Expense Reserves and Recoverable	Loss and Loss Adjustment Expense Reserves and Recoverable The Company establishes reserves for contracts based on estimates of the ultimate cost of all losses including losses incurred but not reported (“IBNR”). These estimated ultimate reserves are based on the Company’s own actuarial estimates derived from reports received from ceding companies, industry data and historical experience. These estimates are reviewed by the Company periodically on a contract by contract basis and adjusted as necessary. Since reserves are estimates, the final settlement of losses may vary from the reserves established and any adjustments to the estimates, which may be material, are recorded in the period they are determined. Loss and loss adjustment expenses recoverable include the amounts due from retrocessionaires for unpaid loss and loss adjustment expenses on retrocession agreements. Ceded losses incurred but not reported are estimated based on the Company’s actuarial estimates. These estimates are reviewed periodically and adjusted when deemed necessary. The Company may not be able to ultimately recover the loss and loss adjustment expense recoverable amounts due to the retrocessionaires’ inability to pay. The Company regularly evaluates the financial condition of its retrocessionaires and records provisions for uncollectible reinsurance expenses recoverable when recovery is no longer probable. Consideration paid by the Company for retroactive reinsurance that meets the conditions for reinsurance accounting (e.g. loss portfolio transfers) are reported as loss and loss adjustment expenses recoverable to the extent those amounts do not exceed the associated liabilities. If the amounts paid for retroactive reinsurance exceed the liabilities, the Company increases the related liabilities, at the time the reinsurance contract is effective, and the excess is charged to net income as losses incurred. If the liabilities exceed the amounts paid, the recoverable balance is increased to reflect the difference, and the resulting gain is deferred and amortized over the estimated loss payout period. Changes in the estimated amount of liabilities relating to the underlying reinsured contracts are recognized in net income in the period of the change.
Notes Receivable	Notes Receivable Notes receivable include promissory notes receivable from third party entities. These notes are recorded at cost along with accrued interest, if any, which approximates the fair value. Interest income and realized gains or losses on sale of notes receivable are included under net investment income (loss) in the condensed consolidated statements of income. The Company regularly reviews all notes receivable individually for impairment and records valuation allowance provisions for uncollectible and non-performing notes. The Company places notes on non-accrual status when the recorded value of the note is not considered impaired but there is uncertainty as to the collection of interest in accordance with the terms of the note. For notes receivable placed on non-accrual status, the notes are recorded excluding any accrued interest amount. The Company resumes accrual of interest on a note when none of the principal or interest remains past due, and the Company expects to collect the remaining contractual principal and interest. Interest collected on notes that are placed on non-accrual status is treated on a cash-basis and recorded as interest income when collected, provided that the recorded value of the note is deemed to be fully collectible. Where doubt exists as to the collectability of the remaining recorded value of the notes placed on non-accrual status, any payments received are applied to reduce the recorded value of the notes.
Financial Instruments	Financial Instruments Investments in Securities and Investments in Securities Sold, Not Yet Purchased The Company’s investments in debt instruments and equity securities that are classified as “trading securities” are carried at fair value. The fair values of the listed equity investments are derived based on quoted prices (unadjusted) in active markets for identical assets (Level 1 inputs). The fair values of listed equities that have restrictions on sale or transfer which expire within one year, are determined by adjusting the observed market price of the equity using a liquidity discount based on observable market inputs. The fair values of debt instruments are derived based on inputs that are observable, either directly or indirectly, such as market maker or broker quotes reflecting recent transactions (Level 2 inputs), and are generally derived based on the average of multiple market maker or broker quotes which are considered to be binding. Where quotes are not available, debt instruments are valued using cash flow models using assumptions and estimates that may be subjective and non-observable (Level 3 inputs). The Company’s “other investments” may include investments in private and unlisted equity securities, limited partnerships and commodities, which are all carried at fair value. The fair values of commodities are determined based on quoted prices in active markets for identical assets (Level 1). The Company maximizes the use of observable direct or indirect inputs (Level 2 inputs) when deriving the fair values for “other investments”. For limited partnerships and private and unlisted equity securities, where observable inputs are not available, the fair values are derived based on unobservable inputs (Level 3 inputs) such as management’s assumptions developed from available information using the services of the investment advisor, including the most recent net asset values obtained from the managers of those underlying investments. For certain private equity fund investments, the Company has elected to measure the fair value using the net asset value practical expedient allowed under U.S. GAAP, and accordingly these investments are not classified as Level 1, 2 or 3 in the fair value hierarchy. For securities classified as “trading securities” and “other investments”, any realized and unrealized gains or losses are determined on the basis of the specific identification method (by reference to cost or amortized cost, as appropriate) and included in net investment income (loss) in the condensed consolidated statements of income. Dividend income and expense are recorded on the ex-dividend date. The ex-dividend date is the date as of when the underlying security must have been traded to be eligible for the dividend declared. Interest income and interest expense are recorded on an accrual basis.
Derivative Financial Instruments	Derivative Financial Instruments U.S. GAAP requires that an entity recognize all derivatives in the balance sheet at fair value. It also requires that unrealized gains and losses resulting from changes in fair value be included in income or comprehensive income, depending on whether the instrument qualifies as a hedge transaction, and if so, the type of hedge transaction. The Company’s derivative financial instrument assets are included in financial contracts receivable. Derivative financial instrument liabilities are included in financial contracts payable. The Company’s derivatives generally do not qualify as hedges for financial reporting purposes and are recorded in the condensed consolidated balance sheets on a gross basis and not offset against any collateral pledged or received. Pursuant to the International Swaps and Derivatives Association (“ISDA”) master agreements, securities lending agreements and other agreements, the Company and its counterparties typically have the ability to net certain payments owed to each other in specified circumstances. In addition, in the event a party to one of the ISDA master agreements, securities lending agreements or other agreements defaults, or a transaction is otherwise subject to termination, the non-defaulting party generally has the right to set off outstanding balances due from the defaulting party against payments owed to the defaulting party or collateral held by the non-defaulting party. The Company may from time to time enter into underwriting contracts such as industry loss warranty contracts (“ILW”) that are treated as derivatives for U.S GAAP purposes. Financial Contracts The Company enters into financial contracts with counterparties as part of its investment strategy. Financial contracts, which include total return swaps, credit default swaps (“CDS”), futures, options, currency forwards and other derivative instruments, are recorded at their fair value with any unrealized gains and losses included in net investment income (loss) in the condensed consolidated statements of income. Financial contracts receivable represents derivative contracts whereby, based upon the contract’s current fair value, the Company will be entitled to receive payments upon settlement of the contract. Financial contracts payable represents derivative contracts whereby, based upon each contract’s current fair value, the Company will be obligated to make payments upon settlement of the contract. Total return swap agreements, included on the condensed consolidated balance sheets as financial contracts receivable and financial contracts payable, are derivative financial instruments whereby the Company is either entitled to receive or obligated to pay the product of a notional amount multiplied by the movement in an underlying security, which the Company may not own, over a specified time frame. In addition, the Company may also be obligated to pay or receive other payments based on interest rates, dividend payments and receipts, or foreign exchange movements during a specified period. The Company measures its rights or obligations to the counterparty based on the fair value movements of the underlying security together with any other payments due. These contracts are carried at fair value, based on observable inputs (Level 2 inputs) with the resultant unrealized gains and losses reflected in net investment income (loss) in the condensed consolidated statements of income. Additionally, any changes in the value of amounts received or paid on swap contracts are reported as a gain or loss in net investment income (loss) in the condensed consolidated statements of income. Financial contracts may also include exchange traded futures or options contracts that are based on the movement of a particular index, equity security, commodity, currency or interest rate. Where such contracts are traded in an active market, the Company’s obligations or rights on these contracts are recorded at fair value based on the observable quoted prices of the same or similar financial contracts in an active market (Level 1) or on broker quotes which reflect market information based on actual transactions (Level 2). Amounts invested in exchange traded options and over the counter (“OTC”) options are recorded either as an asset or liability at inception. Subsequent to initial recognition, unexpired exchange traded option contracts are recorded at fair value based on quoted prices in active markets (Level 1). For OTC options or exchange traded options where a quoted price in an active market is not available, fair values are derived based upon observable inputs (Level 2) such as multiple quotes from brokers and market makers, which are considered to be binding. The Company may purchase and sell CDS for strategic investment purposes. A CDS is a derivative instrument that provides protection against an investment loss due to specified credit or default events of a reference entity. The seller of a CDS guarantees to pay the buyer a specified amount if the reference entity defaults on its obligations or fails to perform. The buyer of a CDS pays a premium over time to the seller in exchange for obtaining this protection. A CDS trading in an active market is valued at fair value based on broker or market maker quotes for identical instruments in an active market (Level 2) or based on the current credit spreads on identical contracts (Level 2).
Comprehensive Income (Loss)	Comprehensive Income (Loss) The Company has no comprehensive income or loss, other than the net income or loss disclosed in the condensed consolidated statements of income.
Earnings (Loss) Per Share	Earnings (Loss) Per Share Basic earnings per share are based on the weighted average number of common shares and participating securities outstanding during the period. Diluted earnings per share includes the dilutive effect of restricted stock units (“RSU”) and additional potential common shares issuable when stock options are exercised and are determined using the treasury stock method. The Company treats its unvested restricted stock as participating securities in accordance with U.S. GAAP, which requires that unvested stock awards which contain non-forfeitable rights to dividends or dividend equivalents, whether paid or unpaid (referred to as “participating securities”), be included in the number of shares outstanding for both basic and diluted earnings per share calculations. In the event of a net loss, all RSUs, stock options outstanding and participating securities are excluded from the calculation of both basic and diluted loss per share since their inclusion would be anti-dilutive.
Taxation	Taxation Under current Cayman Islands law, no corporate entity, including GLRE and Greenlight Re, is obligated to pay taxes in the Cayman Islands on either income or capital gains. The Company has an undertaking from the Governor-in-Cabinet of the Cayman Islands, pursuant to the provisions of the Tax Concessions Law, as amended, that, in the event that the Cayman Islands enacts any legislation that imposes tax on profits, income, gains or appreciations, or any tax in the nature of estate duty or inheritance tax, such tax will not be applicable to GLRE, Greenlight Re nor their respective operations, or to the Class A or Class B ordinary shares or related obligations, until February 1, 2025. Verdant is incorporated in Delaware and therefore is subject to taxes in accordance with the U.S. federal rates and regulations prescribed by the U.S. Internal Revenue Service (“IRS”). Verdant’s taxable income is generally expected to be taxed at a rate of 35%. GRIL is incorporated in Ireland and therefore is subject to the Irish corporation tax rate of 12.5% on its trading income, and 25% on its non-trading income, if any. Any deferred tax asset is evaluated for recovery and a valuation allowance is recorded when it is more likely than not that the deferred tax asset will not be realized in the future. The Company has not taken any income tax positions that are subject to significant uncertainty or that are reasonably likely to have a material impact on the Company.
Recent Accounting Pronouncements	Recent Accounting Pronouncements In January 2016, the FASB issued ASU 2016-01, “Financial Instruments – Overall (Subtopic 825-10): Recognition and Measurement of Financial Assets and Financial Liabilities” (“ASU 2016-01”). The new guidance is intended to improve the recognition and measurement of financial instruments. ASU 2016-01, among other things, requires equity investments to be measured at fair value with changes in fair value recognized in net income or loss, requires public business entities to use the exit price notion when measuring the fair value of financial instruments for disclosure purposes and requires separate presentation of financial assets and financial liabilities by measurement category and form of financial asset. ASU 2016-01 affects public and private companies, not-for-profit organizations, and employee benefit plans that hold financial assets or owe financial liabilities. The new guidance is effective for public companies for fiscal years beginning after December 15, 2017, including interim periods within those fiscal years. The Company is in the process of evaluating the impact of adopting ASU 2016-01 on the Company’s consolidated financial statements. However, the adoption of this guidance is not expected to have a significant impact on the Company’s net income or loss or retained earnings since the Company’s investments are currently classified as “trading” and the unrealized gains and losses are already recognized in net income or loss. In February 2016, the FASB issued ASU 2016-02, “Leases (Topic 842)” (“ASU 2016-02”). Under the new guidance, lessees will be required to recognize the following for all leases (with the exception of short-term leases) at the commencement date: a lease liability, which is a lessee’s obligation to make lease payments arising from a lease, measured on a discounted basis; and a right-of-use asset, which is an asset that represents the lessee’s right to use, or control the use of, a specified asset for the lease term. ASU 2016-02 is effective for public companies for fiscal years beginning after December 15, 2018, including interim periods within those fiscal years. Early adoption is permitted for any organization in any interim or annual period. The Company currently has two operating leases for its office spaces as disclosed in Note 9 of the condensed consolidated financial statements. The Company is in the process of evaluating the impact of adopting ASU 2016-02 on the Company’s consolidated financial statements and anticipates implementing ASU 2016-02 during the first quarter of fiscal year 2019. In June 2016, the FASB issued ASU 2016-13, “Financial Instruments - Credit Losses (Topic 326): Measurements of Credit Losses on Financial Instruments” (“ASU 2016-13”). ASU 2016-13 amends the guidance on reporting credits losses and affects loans, debt securities, trade receivables, reinsurance recoverables and other financial assets that have the contractual right to receive cash. The amendments are effective for annual periods beginning after December 15, 2019, and interim periods within those annual periods. Early adoption is permitted for any organization for annual periods beginning after December 15, 2018 and interim periods within those annual periods. The Company is in the process of evaluating the impact of the requirements of ASU 2016-13 on the Company’s consolidated financial statements and anticipates implementing ASU 2016-13 during the first quarter of fiscal year 2020. In November 2016, the FASB issued ASU 2016-18, “Statements of Cash Flows - Restricted Cash (Topic 230)” (“ASU 2016-18”). ASU 2016-18 requires restricted cash and cash equivalents to be included with cash and cash equivalents in the statement of cash flows and disclose the nature of the restrictions on cash and cash equivalents. ASU 2016-18 is effective for annual periods beginning after December 15, 2017, and interim periods within those fiscal years. Early adoption is permitted. The Company currently presents changes in restricted cash and cash equivalents under investing activities in the condensed consolidated statements of cash flows. Upon adoption of ASU 2016-18, the Company will amend the presentation in the statement of cash flows to include the restricted cash and cash equivalents with cash and cash equivalents in the condensed consolidated statements of cash flows and will retrospectively reclassify all periods presented. In May 2017, the FASB issued ASU 2017-09, “Compensation - Stock Compensation - Scope of Modification Accounting (Topic 718) (“ASU 2017-09”). ASU 2017-09 provides guidance on determining which changes to the terms and conditions of share-based payment awards require an entity to apply modification accounting under Topic 718. ASU 2017-09 is effective for annual periods beginning after December 15, 2017, and interim periods within those fiscal years. Early adoption is permitted. ASU 2017-09 will impact the Company to the extent that there are changes to terms and conditions of the Company’s share-based payment awards after the adoption date. The Company does not anticipate modifications to its share-based payment awards. The FASB has issued ASU No. 2014-09, “Revenue from Contracts with Customers”, and related amendments, ASU 2015-14, ASU 2016-10, ASU 2016-12, ASU 2016-20, ASU 2017-05 and ASU 2017-13, (collectively, “Topic 606”). Topic 606 creates a new comprehensive revenue recognition standard that will serve as a single source of revenue guidance for all companies that either enter into contracts with customers to transfer goods or services or enter into contracts for the transfer of non-financial assets, unless those contracts are within the scope of other standards, such as insurance contracts. Topic 606 becomes effective for annual periods beginning after December 15, 2017, and interim periods within those fiscal years. The Company will adopt Topic 606 on the effective date and since all of the Company’s revenues relate to reinsurance contracts and investment income, the adoption of Topic 606 is not expected to have a material impact on the Company’s revenues.