| Summary of Significant Accounting Policies | Basis of Presentation — The accompanying unaudited condensed consolidated financial statements and related notes of KREF are prepared in accordance with accounting principles generally accepted in the United States of America (" GAAP ") for interim financial information and instructions to Form 10-Q. The condensed consolidated financial statements, including these notes, are unaudited and exclude some of the disclosures required in annual financial statements. Accordingly, certain information and footnote disclosures normally included in the consolidated financial statements have been condensed or omitted. The condensed consolidated financial statements include the accounts of KREF and its consolidated subsidiaries, and all intercompany transactions and balances have been eliminated. In the opinion of management, all adjustments considered necessary for a fair presentation of KREF ’s financial position, results of operations and cash flows have been included and are of a normal and recurring nature. The operating results presented for interim periods are not necessarily indicative of the results that may be expected for any other interim period or for the entire year. These condensed consolidated financial statements should be read in conjunction with KREF Consolidation — KREF consolidates those entities for which (i) it controls significant operating, financial and investing decisions of the entity or (ii) management determines that KREF is the primary beneficiary of entities deemed to be variable interest entities (" VIE s"). Variable Interest Entities — VIE s are defined as entities in which equity investors do not have an interest with the characteristics of a controlling financial interest or do not have sufficient equity at risk for the entity to finance its activities without additional subordinated financial support from other parties. A VIE is required to be consolidated only by its primary beneficiary, which is defined as the party that has the power to direct the activities of the VIE that most significantly impact its economic performance and that has the obligation to absorb losses of, or the right to receive benefits from, the VIE that could be potentially significant to the VIE (Note 7 ). To assess whether KREF has the power to direct the activities of a VIE that most significantly impact the VIE ’s economic performance, KREF considers all the facts and circumstances, including its role in establishing the VIE and its ongoing rights and responsibilities. This assessment includes, first, identifying the activities that most significantly impact the VIE ’s economic performance; and second, identifying which party, if any, has power to direct those activities. To assess whether KREF has the obligation to absorb losses of, or the right to receive benefits from, the VIE that could potentially be significant to the VIE , KREF considers all of its economic interests and applies judgment in determining whether these interests, in the aggregate, are considered potentially significant to the VIE . CMBS — KREF consolidates those trusts that issue beneficial ownership interests in mortgage loans secured by commercial real estate (commonly known as CMBS ) when KREF holds a variable interest in, and management considers KREF to be the primary beneficiary of, those trusts. Management believes the performance of the assets that underlie CMBS issuances most significantly impacts the economic performance of the trust, and the primary beneficiary is generally the entity that conducts activities that most significantly impact the performance of the underlying assets. In particular, the most subordinate tranches of CMBS expose the holder to the greater variability of economic performance when compared to more senior tranches since the subordinate tranches absorb a disproportionately higher amount of the credit risk related to the underlying assets. Generally, a trust designates the most junior subordinate tranche outstanding as the controlling class, which entitles the holder of the controlling class to unilaterally appoint and remove the special servicer for the trust. The special servicer is responsible for the servicing and administration of delinquent and nonperforming loans as well as real estate owned (" REO ") properties held as collateral delivered on foreclosed loans. While the special servicer cannot prevent losses, its services to the trust are designed to mitigate credit losses to holders of the CMBS . For the trusts that KREF consolidates, KREF holds non-investment grade rated and unrated tranches that represent the most subordinated tranches of the CMBS issued by those trusts, which include the controlling class. As the holder of the most subordinate tranche, KREF is in a first loss position and has the right to receive benefits. As the holder of the controlling class, KREF has the ability to unilaterally appoint and remove the special servicer for the trust. In these cases, management considers KREF to be the primary beneficiary and consolidates the CMBS trusts. For VIE s in which management determines KREF is the primary beneficiary, all of the underlying assets, liabilities and equity of the trusts are recorded on KREF 's books, and the initial investment, along with any associated unrealized holding gains and losses, are eliminated in consolidation. Similarly, the interest income earned from these trusts is eliminated in consolidation. Management elected the fair value option for KREF 's initial and subsequent recognition of the assets and liabilities of KREF 's consolidated CMBS VIE s in order to provide users of the financial statements with better information regarding the effects of credit risk and other market factors on the CMBS beneficially held by KREF 's stockholders. Since the changes in fair value include the interest income and interest expense associated with these CMBS VIE s, management does not consider the separate presentation of the components of fair value changes to be relevant. Management has elected to present these items in aggregate as " Other Income — Change in net assets related to consolidated variable interest entities " in the accompanying Condensed Consolidated Statements of Income; the residual difference between the fair value of the trusts' assets and liabilities represents KREF 's beneficial interest in the CMBS VIE s. Management separately presents the assets and liabilities of KREF 's consolidated VIE s as individual line items on KREF 's Condensed Consolidated Balance Sheets for entities in which the VIE s assets can only be used to settle the VIE ’s obligations. The liabilities of KREF 's consolidated VIE s consist solely of obligations to the CMBS holders of the consolidated trusts, excluding CMBS held by KREF as such interests are eliminated in consolidation, and the interest accrued thereon, presented as "Liabilities — Variable interest entity liabilities, at fair value ." The assets of KREF 's consolidated VIEs consist principally of commercial mortgage loans and the interest accrued thereon, and are likewise presented as a single line item entitled " Assets — Commercial mortgage loans held in variable interest entities, at fair value ." Assets of a CMBS trust, as a whole, can only be used to settle the obligations of the consolidated CMBS VIE . The assets of KREF 's CMBS VIE s are not individually accessible by, and obligations of the CMBS VIE s are not recourse to, the bondholders. REO assets generally represent a small percentage of the overall asset pool of a CMBS trust. In a new issue CMBS trust there are no REO assets, and no REO existed in KREF 's consolidated VIE assets as of September 30, 2018 . KREF derives the fair value of its Level 3 CMBS VIE assets from its Level 3 CMBS VIE liabilities, which management considers to possess more observable market value data than the CMBS VIE assets. See "— Fair Value — Valuation of Consolidated VIEs " for additional discussion regarding management's valuation of consolidated CMBS VIE s. Commercial Mezzanine Loan Joint Venture - KREF consolidated a joint venture that held a portion of KREF 's investments in commercial mezzanine loans (“Mezzanine JV”), and in which a third-party owned a 5.0% redeemable noncontrolling interest ("Mezzanine JV Redeemable Noncontrolling Interest”) (Note 7 ). Management determined the joint venture to be a VIE as the owners of the redeemable noncontrolling interest did not have substantive participating or kick-out rights. KREF owned 95.0% of the equity interests in the joint venture and participated in the profits and losses. Management considered KREF to be the primary beneficiary of the joint venture as KREF held decision-making power over the activities that most significantly impact the economic performance of the joint venture. In June 2018, KREF acquired the 5.0% Mezzanine JV Redeemable Noncontrolling Interest for its carrying value of $1.3 million . Noncontrolling Interests — Noncontrolling interests represent the ownership interests in certain consolidated subsidiaries held by entities or persons other than KREF . Those noncontrolling interests that allow the holder to redeem before liquidation or termination of the entity that issued those interests are considered redeemable noncontrolling interests. The redeemable noncontrolling interests issued by subsidiaries of KREF are subject to certain restrictions and require KREF to transfer assets or issue equity to satisfy the redemption. As KREF does not control the circumstances under which the noncontrolling interests may redeem their interests, management considers these redeemable noncontrolling interests as temporary equity, presented as " Temporary Equity — Redeemable noncontrolling interests in equity of consolidated joint venture " in the accompanying Condensed Consolidated Balance Sheets and their share of " Net Income (Loss) " as " Redeemable Noncontrolling Interests in Income (Loss) of Consolidated Joint Venture " in the Condensed Consolidated Statements of Income. KREF recorded the redeemable noncontrolling interests at fair value upon issuance by subsidiaries of KREF , and adjusts the carrying value of such interests to equal their respective redemption values at each subsequent reporting period date if KREF determines the noncontrolling interests are redeemable or probable to become redeemable. As noted above, in June 2018, KREF acquired the 5.0% Mezzanine JV Redeemable Noncontrolling Interest for its carrying value of $1.3 million . KREF determined that the Special Non-Voting Preferred Stock (“SNVPS”) became redeemable during the second quarter of 2018; accordingly, KREF adjusted the carrying value of the SNVPS to its redemption value of $0.4 million as of the balance sheet date. Equity method investments, at fair value — Investments are accounted for under the equity method when KREF has significant influence over the operations of an investee, but KREF does not consolidate that investment. Equity method investments, for which management has not elected a fair value option, are initially recorded at cost and subsequently adjusted for KREF 's share of net income or loss and cash contributions and distributions each period. Management determined that KREF 's investment in the Manager is an interest in a VIE as KREF did not have substantive participating or kick-out rights. KREF does not have the power to direct activities and the obligation to absorb losses of the Manager that could be significant to the Manager . KREF accounts for its investment in the Manager using the equity method since KREF is not the primary beneficiary of the Manager (Note 7 ). Management determined that its investment in an aggregator vehicle alongside KKR Real Estate Credit Opportunity Partners L.P. (" RECOP ") is an interest in a VIE , however KREF is not the primary beneficiary and does not have substantive participating or kick-out rights. Management elected the fair value option for KREF 's investment in RECOP . KREF records its share of net asset value in RECOP as “ Equity method investments, at fair value ” in its Condensed Consolidated Balance Sheets and its share of unrealized gains or losses in " Income from equity method investments " in its Condensed Consolidated Statements of Income (Note 7 ). Use of Estimates — The preparation of condensed consolidated financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, the disclosure of contingent assets and liabilities at the date of the condensed consolidated financial statements and the reported amounts of revenue and expenses during the reporting period. Management makes subjective estimates to project cash flows KREF expects to receive on its investments in loans and securities as well as the related market discount rates, which significantly impacts the interest income, impairments, allowance for loan loss and fair values recorded or disclosed. Actual results could differ from those estimates. Fair Value — GAAP requires the categorization of the fair value of financial instruments into three broad levels that form a hierarchy based on the transparency of inputs to the valuation. Level 1 - Inputs are unadjusted, quoted prices in active markets for identical assets or liabilities at the measurement date. Level 2 - Inputs are other than quoted prices that are observable for the asset or liability, either directly or indirectly. Level 2 inputs include quoted prices for similar instruments in active markets, and inputs other than quoted prices that are observable for the asset or liability. Level 3 - Inputs are unobservable for the asset or liability, and include situations where there is little, if any, market activity for the asset or liability. KREF follows this hierarchy for its financial instruments. The classifications are based on the lowest level of input that is significant to the fair value measurement. Estimates of fair value for cash and cash equivalents, restricted cash, and convertible notes are measured using observable, quoted market prices, or Level 1 inputs. Valuation Process — The Manager reviews the valuation of Level 3 financial instruments as part of KKR 's quarterly process. As of September 30, 2018 , KKR’s valuation process for Level 3 measurements, as described below, subjected valuations to the review and oversight of various committees. KKR has a global valuation committee assisted by the asset class-specific valuation committees, including a real estate valuation committee that reviews and approves all preliminary Level 3 valuations for real estate assets, including the financial instruments held by KREF . The global valuation committee is responsible for coordinating and implementing KKR ’s valuation process to ensure consistency in the application of valuation principles across portfolio investments and between periods. All Level 3 valuations are also subject to approval by the global valuation committee. Valuation of Consolidated VIEs — Management categorizes the financial assets and liabilities of the CMBS trusts that KREF consolidates as Level 3 assets and liabilities in the fair value hierarchy and has elected the fair value option for financial assets and liabilities of each CMBS trust. Management has adopted the measurement alternative included in Accounting Standards Update (" ASU ") No. 2014-13, Measuring the Financial Assets and the Financial Liabilities of a Consolidated Collateralized Financing Entity (" ASU 2014-13"). Pursuant to ASU 2014-13, management measures both the financial assets and financial liabilities of the CMBS trusts consolidated by KREF using the fair value of the financial liabilities, which management considers more observable than the fair value of the financial assets. As a result, KREF presents the CMBS issued by the consolidated trust, but not beneficially owned by KREF 's stockholders, as financial liabilities in KREF 's condensed consolidated financial statements, measured at their estimated fair value; KREF measures the financial assets as the total estimated fair value of the CMBS issued by the consolidated trust, regardless of whether such CMBS represent interests beneficially owned by KREF 's stockholders. Under the measurement alternative prescribed by ASU 2014-13, KREF 's " Net Income (Loss) " reflects the economic interests in the consolidated CMBS beneficially owned by KREF 's stockholders, presented as " Change in net assets related to consolidated variable interest entities " in the Condensed Consolidated Statements of Income, which includes applicable (i) changes in the fair value of CMBS beneficially owned by KREF , (ii) interest and servicing fees earned from the CMBS trust and (iii) other residual returns or losses of the CMBS trust, if any (Note 7 ). Management categorizes the commercial mezzanine loans held by separate joint ventures, VIE s consolidated by KREF as primary beneficiary, as Level 3 assets in the fair value hierarchy as such assets are illiquid, structured instruments that are specific to the properties and their corresponding operating performance (Note 12 ). Other Valuation Matters — For Level 3 financial assets originated, or otherwise acquired, and financial liabilities assumed during the calendar month immediately preceding a quarter end that were conducted in an orderly transaction with an unrelated party, management generally believes that the transaction price provides the most observable indication of fair value given the illiquid nature of these financial instruments, unless management is aware of any circumstances that may cause a material change in the fair value through the remainder of the reporting period. For instance, significant changes to the underlying property or its planned operations may cause material changes in the fair value of commercial mortgage loans acquired, or originated, by KREF . KREF ’s determination of fair value is based upon the best information available for a given circumstance and may incorporate assumptions that are management’s best estimates after consideration of a variety of internal and external factors. When an independent valuation firm expresses an opinion on the fair value of a financial instrument in the form of a range, management selects a value within the range provided by the independent valuation firm, generally the midpoint, to assess the reasonableness of management’s estimated fair value for that financial instrument. See Note 12 for additional information regarding the valuation of KREF 's financial assets and liabilities. Sales of Financial Assets and Financing Agreements — KREF will, from time to time, sell loans, securities and other assets as well as finance assets in the form of secured borrowings. In each case, management evaluates whether the transaction constitutes a sale through legal isolation of the transferred financial asset from KREF , the ability of the transferee to pledge or exchange the transferred asset without constraint and the transfer of control of the transferred asset. For transfers that constitute sales, KREF (i) recognizes the financial assets it retains and liabilities it has incurred, if any, (ii) derecognizes the financial assets it has sold, and derecognizes liabilities when extinguished and (iii) recognizes a realized gain, or loss, based upon the excess, or deficient, proceeds received over the carrying value of the transferred asset. KREF does not recognize a gain, or loss, on interests retained, if any, where management elected the fair value option prior to sale. Balance Sheet Measurement Cash, Cash Equivalents and Restricted Cash and Cash Equivalents — KREF considers cash equivalents as highly liquid short-term investments with maturities of 90 days or less when purchased. Substantially all amounts on deposit with major financial institutions exceed insured limits. KREF must also maintain sufficient cash and cash equivalents to satisfy liquidity covenants related to its secured financing agreements. However, such amounts are not restricted from use in KREF 's current operations, and KREF does not present these cash and cash equivalents as restricted. As of September 30, 2018 and December 31, 2017 , KREF was required to maintain unrestricted cash and cash equivalents of at least $19.3 million and $12.1 million , respectively, to satisfy its liquidity covenants (Note 4 ). Commercial Mortgage Loans Held‑For‑Investment and Provision for Loan Losses — KREF recognizes its investments in commercial mortgage loans based on management's intent, and KREF 's ability, to hold those investments through their contractual maturity. Management classifies those loans that management does not intend to sell in the foreseeable future, and KREF is able to hold until maturity, as held-for-investment. Loans that are held‑for‑investment are carried at their aggregate outstanding face amount, net of applicable (i) unamortized origination or acquisition premiums and discounts, (ii) unamortized deferred nonrefundable fees and other direct loan origination costs, (iii) allowance for loan losses and (iv) charge-offs or write-downs of impaired loans. If a loan is determined to be impaired, management writes down the loan through a charge to the provision for loan losses. See "— Expense Recognition — Loan Impairment — Commercial Mortgage Loans, Held-For-Investment " for additional discussion regarding management’s determination for loan losses. KREF applies the interest method to amortize origination or acquisition premiums and discounts and deferred nonrefundable fees or other direct loan origination costs, or on a straight line basis when it approximates the interest method. Loans for which management elects the fair value option at the time of origination, or acquisition, are carried at fair value on a recurring basis (Note 3 ). Commercial Mortgage Loans Held‑For‑Sale — Loans that KREF originates, or acquires, which KREF is unable to hold, or management intends to sell or otherwise dispose of, in the foreseeable future are classified as held‑for‑sale and are carried at the lower of amortized cost or fair value. Secured Financing Agreements — KREF 's secured financing agreements, including Term Loan Financings, are treated as collateralized financing transactions and consist of floating rate, uncommitted repurchase facilities and Term Loan Financing arrangements carried at their contractual amounts, net of unamortized debt issuance costs (Note 4 ). Convertible Notes, Net — KREF accounts for its convertible debt with a cash conversion feature in accordance with ASC 470-20 “Debt with Conversion and Other Options” which requires the liability and equity components of convertible debt instruments that may be settled in cash upon conversion, including partial cash settlement, to be separately accounted for in a manner that reflects the issuer’s nonconvertible debt borrowing rate. The initial proceeds from the sale of convertible notes are allocated between a liability component and an equity component in a manner that reflects interest expense at the rate of similar nonconvertible debt that could have been issued at such time. The equity component represents the excess initial proceeds received over the fair value of the liability component of the notes as of the date of issuance. KREF measured the estimated fair value of the debt component of the convertible notes due May 15, 2023 (“Convertible Notes”) as of the issuance date based on KREF ’s nonconvertible debt borrowing rate. The equity component of the Convertible Notes is reflected within additional paid-in capital on our condensed consolidated balance sheet, and the resulting debt discount is amortized over the period during which such Convertible Notes are expected to be outstanding (through the maturity date) as additional non-cash interest expense using the interest method, or on a straight line basis when it approximates the interest method. The additional non-cash interest expense attributable to such convertible notes will increase in subsequent periods through the maturity date as the notes accrete to their par value over the same period (Note 5 ). Loan Participations Sold, Net — In connection with its investments in senior loans, KREF finances certain investments through the syndication of non-recourse, or limited-recourse, loan participation to unaffiliated third parties. KREF ’s presentation of the senior loan and related financing involved in the syndication depends upon whether GAAP recognized the transaction as a sale, though such differences in presentation do not generally impact KREF ’s net stockholders’ equity or net income aside from timing differences in the recognition of certain transaction costs. To the extent that GAAP recognizes a sale resulting from the syndication, KREF derecognizes the participation in the senior loan that KREF sold and continue to carry the retained portion of the loan as an investment. While KREF does not generally expect to recognize a material gain or loss on these sales, KREF would realize a gain or loss in an amount equal to the difference between the net proceeds received from the third party purchaser and its carrying value of the loan participation that KREF sold at time of sale. Furthermore, KREF recognizes interest income only on the portion of the senior loan that it retains as a result of the sale. To the extent that GAAP does not recognize a sale resulting from the syndication, KREF does not derecognize the participation in the senior loan that it sold. Instead, KREF recognizes a loan participation sold liability in an amount equal to the principal of the loan participation syndicated less any unamortized discounts or financing costs resulting from the syndication. KREF continues to recognize interest income on the entire senior loan, including the interest attributable to the loan participation sold, as well as interest expense on the loan participation sold liability (Note 6 ). Other Assets and Accounts Payable, Accrued Expenses and Other Liabilities — As of September 30, 2018 , other assets included a $16.5 million loan principal payment receivable from a third-party servicer and $2.4 million of deferred debt issuance costs related to credit facilities, net of $0.8 million accumulated amortization. As of December 31, 2017 , other assets included a $4.6 million loan principal payment receivable from a third-party servicer and $2.1 million of deferred debt issuance costs related to credit facilities, net of $0.5 million accumulated amortization. Special Non-Voting Preferred Stock (" SNVPS ") — Equity instruments that are redeemable for cash or other assets are classified as temporary equity if the instrument is redeemable, at the option of the holder, at a fixed or determinable price on a fixed or determinable date or upon the occurrence of an event that is not solely within the control of the issuer. Redeemable equity instruments are initially carried at the fair value of the equity instrument at the issuance date, which is subsequently adjusted at each balance sheet date if the instrument is currently redeemable or probable of becoming redeemable. The fair value of the instrument is adjusted to reflect the instrument’s redemption amount at each balance sheet date if KREF determines the SNVPS is redeemable or it is probable that the SNVPS will become redeemable. KREF accounted for the SNVPS as redeemable preferred stock since a third party holds a redemption option, exercisable after May 5, 2018, and such redemption is not solely within KREF’s control. Accordingly, the Company adjusted the carrying value of the SNVPS to its redemption value of $0.4 million as of September 30, 2018 . KREF presents the SNVPS as “ Temporary Equity — Redeemable preferred stock ” in the accompanying Condensed Consolidated Balance Sheets (Note 8 ). Income Recognition Interest Income — Loans where management expects to collect all contractually required principal and interest payments are considered performing loans. KREF accrues interest income on performing loans based on the outstanding principal amount and contractual terms of the loan. Interest income also includes origination fees and direct loan origination costs for loans that KREF originates, but where management did not elect the fair value option, as a yield adjustment using the interest method over the loan term, or on a straight line basis when it approximates the interest method. KREF expenses origination fees and direct loan origination costs for loans acquired, but not originated, by KREF as well as loans for which management elected the fair value option, as incurred. Realized Gain (Loss) on Sale of Investments — KREF recognizes the excess, or deficiency, of net proceeds received, less the net carrying value of such investments, as realized gains or losses, respectively. KREF reverses cumulative, unrealized gains or losses previously reported in its Condensed Consolidated Statements of Income with respect to the investment sold at the time of sale. Expense Recognition Loan Impairment — KREF holds commercial mortgage loans for both investment and sale, which management periodically evaluates for impairment. Commercial Mortgage Loans, Held-For-Investment — For each loan in KREF 's portfolio, management performs a quarterly evaluation of impairment indicators of loans classified as held‑for‑investment using applicable loan, property, market and sponsor information obtained from borrowers, loan servicers and local market participants. Such indicators may include the net present value of the underlying collateral, property operating cash flows, the sponsor’s financial wherewithal and competency in managing the property, macroeconomic trends, and property submarket-specific economic factors. The evaluation of these indicators of impairment requires significant judgment by management to determine whether failure to collect contractual amounts is probable. If management deems that it is probable that KREF will be unable to collect all amounts owed according to the contractual terms of a loan, impairment of that loan is indicated. If management considers a loan to be impaired, management establishes an allowance for loan losses, through a valuation provision in earnings, which reduces the carrying value of the loan to the present value of expected future cash flows discounted at the loan’s contractual effective rate or the fair value of the collateral, if repayment is expected solely from the collateral. Significant judgment is required in determining impairment and in estimating the resulting loss allowance, and actual losses, if any, could materially differ from those estimates. Management considers loans to be past due when a monthly payment is due and unpaid for 60 days or more. Loans are placed on nonaccrual status and considered non-performing when full payment of principal and interest is in doubt, which generally occurs when principal or interest is 120 days or more past due unless the loan is both well secured and in the process of collection. Management may return a loan to accrual status when repayment of principal and interest is reasonably assured under the terms of the restructured loan. As of September 30, 2018 , KREF did not hold any loans that management placed on nonaccrual status or otherwise considered past due. In addition to reviewing commercial mortgage loans held-for-investment for impairment, the Manager evaluates KREF 's commercial mortgage loans to determine if an allowance for loan loss should be established. In conjunction with this review, the Manager assesses the risk factors of each loan, and assigns a risk rating based on a variety of factors, including, without limitation, underlying real estate performance and asset value, values of comparable properties, durability and quality of property cash flows, sponsor experience and financial wherewithal, and the existence of a risk-mitigating loan structure. Additional key considerations include loan-to-value ratios, debt service coverage ratios, loan structure, real estate and credit market dynamics, and risk of default or principal loss. Based on a five-point scale, KREF 's loans are rated "1" through "5," from less risk to greater risk, which ratings are defined as follows: 1—Very Low Risk—The underlying property performance has surpassed underwritten expectations, and the sponsor’s business plan is generally complete. The property demonstrates stabilized occupancy and/or rental rates resulting in strong current cash flow and/or a very low loan-to-value ratio (<65%). At the level of performance, it is very likely that th |
