Summary of Significant Accounting Policies	9 Months Ended
Summary of Significant Accounting Policies	Sep. 30, 2021
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	Summary of Significant Accounting Policies Definitions – The following defines certain of the commonly used terms in these financial statements: “RMBS” refers to residential mortgage-backed securities backed by adjustable-rate, hybrid adjustable-rate, or fixed-rate residential loans; “Agency RMBS” refers to RMBS representing interests in or obligations backed by pools of residential loans guaranteed by a government sponsored enterprise (“GSE”), such as the Federal National Mortgage Association (“Fannie Mae”) or the Federal Home Loan Mortgage Corporation (“Freddie Mac”), or an agency of the U.S. government, such as the Government National Mortgage Association (“Ginnie Mae”); “non-Agency RMBS” refers to RMBS that are not guaranteed by any agency of the U.S. Government or GSE; “IOs” refers collectively to interest only and inverse interest only mortgage-backed securities that represent the right to the interest component of the cash flow from a pool of mortgage loans; “POs” refers to mortgage-backed securities that represent the right to the principal component of the cash flow from a pool of mortgage loans; “ARMs” refers to adjustable-rate residential loans; “Agency ARMs” refers to Agency RMBS comprised of adjustable-rate and hybrid adjustable-rate RMBS; “Agency fixed-rate RMBS” refers to Agency RMBS comprised of fixed-rate RMBS; “ABS” refers to debt and/or equity tranches of securitizations backed by various asset classes including, but not limited to, automobiles, aircraft, credit cards, equipment, franchises, recreational vehicles and student loans; “CMBS” refers to commercial mortgage-backed securities comprised of commercial mortgage pass-through securities issued by a GSE, as well as PO, IO or mezzanine securities that represent the right to a specific component of the cash flow from a pool of commercial mortgage loans; “Agency CMBS” refers to CMBS representing interests or obligations backed by pools of mortgage loans guaranteed by a GSE, such as Fannie Mae or Freddie Mac; “multi-family CMBS” refers to CMBS backed by commercial mortgage loans on multi-family properties; “CDO” refers to collateralized debt obligation and includes debt that permanently finances the residential loans held in Consolidated SLST, multi-family loans held in the Consolidated K-Series and the Company's residential loans held in securitization trusts and non-Agency RMBS re-securitization that we consolidate, or consolidated, in our financial statements in accordance with GAAP; “business purpose loans” refers to short-term loans collateralized by residential properties made to investors who intend to rehabilitate and sell the residential property for a profit; “Consolidated SLST” refers to a Freddie Mac-sponsored residential loan securitization, comprised of seasoned re-performing and non-performing residential loans, of which we own or owned the first loss subordinated securities and certain IOs and senior securities that we consolidate in our financial statements in accordance with GAAP; “Consolidated K-Series” refers to Freddie Mac-sponsored multi-family loan K-Series securitizations, of which we, or one of our “special purpose entities,” or “SPEs,” owned the first loss POs, certain IOs and certain senior or mezzanine securities that we consolidated in our financial statements in accordance with GAAP prior to disposition; and “SOFR” refers to Secured Overnight Funding Rate. Basis of Presentation – The accompanying condensed consolidated balance sheet as of December 31, 2020 has been derived from audited financial statements. The accompanying condensed consolidated balance sheet as of September 30, 2021, the accompanying condensed consolidated statements of operations for the three and nine months ended September 30, 2021 and 2020, the accompanying condensed consolidated statements of comprehensive income for the three and nine months ended September 30, 2021 and 2020, the accompanying condensed consolidated statements of changes in stockholders’ equity for the three and nine months ended September 30, 2021 and 2020 and the accompanying condensed consolidated statements of cash flows for the nine months ended September 30, 2021 and 2020 are unaudited. In our opinion, all adjustments (which include only normal recurring adjustments) necessary to present fairly the Company’s financial position, results of operations and cash flows have been made. Certain information and footnote disclosures normally included in financial statements prepared in accordance with GAAP have been condensed or omitted in accordance with Article 10 of Regulation S-X and the instructions to Form 10-Q. These condensed consolidated financial statements should be read in conjunction with the audited consolidated financial statements and notes thereto included in our Annual Report on Form 10-K for the year ended December 31, 2020, as filed with the U.S. Securities and Exchange Commission (“SEC”). Accordingly, significant accounting policies and other disclosures have been omitted since such items are disclosed in Note 2 in the audited consolidated financial statements and notes thereto included in our Annual Report on Form 10-K for the year ended December 31, 2020. Provided in this section is a summary of additional accounting policies that are significant to, or newly adopted by, the Company for the three and nine months ended September 30, 2021. 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. The accompanying condensed consolidated financial statements have been prepared on the accrual basis of accounting in accordance with GAAP. 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 and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenues and expenses during the reporting period. Management has made significant estimates in several areas, including fair valuation of its residential loans, multi-family loans, certain equity investments and Consolidated SLST CDOs. Although the Company’s estimates contemplate current conditions and how it expects those conditions to change in the future, it is reasonably possible that actual conditions could be different than anticipated in those estimates, which could materially impact the Company’s results of operations and its financial condition. The COVID-19 pandemic and resulting emergency measures have led (and may continue to lead) to significant disruptions in the global supply chain, global capital markets, the economy of the U.S. and the economies of other countries impacted by COVID-19. The fluidity of this situation precludes any prediction as to the ultimate adverse impact of COVID-19 on economic and market conditions. The Company believes the estimates and assumptions underlying our condensed consolidated financial statements are reasonable and supportable based on the information available as of September 30, 2021; however, uncertainty over the ultimate impact COVID-19 will have on the global economy generally, and our business in particular, makes any estimates and assumptions as of September 30, 2021 inherently less certain than they would be absent the current and potential impacts of COVID-19. Accordingly, it is reasonably possible that actual conditions could be different than anticipated in those estimates, which could materially impact the Company’s results of operations and its financial condition. Reclassifications – Certain prior period amounts have been reclassified in the accompanying condensed consolidated financial statements to conform to current period presentation. Principles of Consolidation and Variable Interest Entities – The accompanying condensed consolidated financial statements of the Company include the accounts of all its subsidiaries which are majority-owned, controlled by the Company or a variable interest entity (“VIE”) where the Company is the primary beneficiary. All significant intercompany accounts and transactions have been eliminated in consolidation. A VIE is an entity that lacks one or more of the characteristics of a voting interest entity. A VIE is defined as an entity in which equity investors do not have 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. The Company consolidates a VIE when it is the primary beneficiary of such VIE, herein referred to as a "Consolidated VIE". As primary beneficiary, the Company has both the power to direct the activities that most significantly impact the economic performance of the VIE and a right to receive benefits or absorb losses of the entity that could be potentially significant to the VIE. The Company is required to reconsider its evaluation of whether to consolidate a VIE each reporting period, based upon changes in the facts and circumstances pertaining to the VIE. Goodwill – Goodwill is not amortized but is evaluated for impairment on an annual basis, or more frequently if the Company believes indicators of impairment exist, by initially performing a qualitative screen and, if necessary, then comparing fair value of the reporting unit to its carrying value, including goodwill. If the fair value of the reporting unit is less than the carrying value, an impairment charge for the amount by which the carrying amount exceeds the reporting unit’s fair value (in an amount not to exceed the total amount of goodwill allocated to the reporting unit) is recognized. In the first quarter of 2020, financial, credit and mortgage-related asset markets experienced significant volatility as a result of the spread of COVID-19, which in turn put significant pressure on the mortgage REIT industry, including financing operations, mortgage asset pricing and liquidity demands. In response to these conditions and the Company's intention to improve its liquidity, in March 2020, the Company sold, among other things, its entire portfolio of first loss POs issued by the Consolidated K-Series, certain senior and mezzanine securities issued by the Consolidated K-Series, Agency CMBS and CMBS that were held by its multi-family investment reporting unit. As a result of the sales, the Company re-evaluated its goodwill balance associated with the multi-family investment reporting unit for impairment. The Company considered qualitative indicators such as macroeconomic conditions, disruptions in equity and credit markets, REIT-specific market considerations, and changes in the net assets in the multi-family investment reporting unit to determine that a quantitative assessment of the fair value of the reporting unit was necessary. The Company performed its quantitative analysis by updating its discounted cash flow projection for the multi-family investment reporting unit for the reduced investment portfolio. This analysis yielded an impairment of the entire goodwill balance related to the Company's multi-family investment reporting unit reported as a $25.2 million impairment of goodwill on the accompanying condensed consolidated statements of operations for the nine months ended September 30, 2020. Other Assets – Other assets as of September 30, 2021 and December 31, 2020 include restricted cash held by third parties, including cash held by the Company's securitization trusts, of $21.9 million and $11.3 million, respectively. Other assets includes collections receivable from loan servicers, recoverable advances and interest receivable on residential loans totaling $54.4 million and $63.6 million as of September 30, 2021 and December 31, 2020, respectively. Also included in other assets are operating lease right of use assets of $9.3 million and $10.1 million as of September 30, 2021 and December 31, 2020, respectively (with corresponding operating lease liabilities of $9.9 million and $10.6 million as of September 30, 2021 and December 31, 2020, respectively, included in other liabilities in the accompanying condensed consolidated balance sheets). Net lease intangibles, escrow balances, prepaid expenses and receivables in Consolidated VIEs and a wholly-owned subsidiary that owns a multi-family apartment community totaling $19.6 million and $3.0 million as of September 30, 2021 and December 31, 2020, respectively, are also included in other assets. Summary of Recent Accounting Pronouncements In March 2020, the FASB issued ASU 2020-04, Reference Rate Reform (Topic 848): Facilitation of the Effects of Reference Rate Reform on Financial Reporting ("ASU 2020-04"). ASU 2020-04 provides optional expedients and exceptions to GAAP requirements for modifications to debt agreements, leases, derivatives and other contracts, related to the expected market transition from LIBOR, and certain other floating rate benchmark indices, or collectively, IBORs, to alternative reference rates. ASU 2020-04 generally considers contract modifications related to reference rate reform to be an event that does not require contract remeasurement at the modification date nor a reassessment of a previous accounting determination. In January 2021, the FASB issued ASU 2021-01, Reference Rate Reform (Topic 848): Scope ("ASU 2021-01"). ASU 2021-01 clarifies that certain optional expedients and exceptions in Topic 848 for contract modifications and hedge accounting apply to derivatives that are affected by the "discounting transition" (i.e., changes in the interest rates used for margining, discounting, or contract price alignment for derivative instruments that are being implemented as part of the market-wide transition to new reference rates). The guidance in ASU 2020-04 is optional and may be elected over time, through December 31, 2022, as reference rate reform activities occur. Once ASU 2020-04 is elected, the guidance must be applied prospectively for all eligible contract modifications. The amendments in ASU 2021-01 are effective immediately and may be applied on a full retrospective basis as of any date from the beginning of an interim period that includes or is subsequent to March 12, 2020 or on a prospective basis for eligible contract modifications through December 31, 2022. The Company continues to evaluate the impact of ASU 2020-04 and ASU 2021-01 and may apply elections, as applicable, as the expected market transition from IBORs to alternative reference rates continues to develop. In August 2020, the FASB issued 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): Accounting for Convertible Instruments and Contracts in an Entity's Own Equity ("ASU 2020-06"). ASU 2020-06 simplifies an issuer's accounting for convertible instruments, enhances disclosure requirements for convertible instruments and modifies how particular convertible instruments and certain instruments that may be settled in cash or shares impact the diluted earnings per share computation. Entities may adopt the guidance through either a modified retrospective method of transition or a fully retrospective method of transition. The amendments are effective for public entities for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2021. Early adoption is permitted, but no earlier than fiscal years, and interim periods within those fiscal years, beginning after December 15, 2020. The Company does not anticipate that the implementation of ASU 2020-06 will have a material impact on its consolidated financial statements or notes thereto.