Summary Of Significant Accounting Policies (Policy)	3 Months Ended
Summary Of Significant Accounting Policies (Policy)	Mar. 31, 2020
Summary Of Significant Accounting Policies [Abstract]
Adoption Of New Accounting Standards	A. Adoption of New Accounting Standards In February 2016, the FASB issued ASU 2016-02, Leases (Topic 842). Under the new guidance (subsequently updated with ASU 2018-01, ASU 2018-10, ASU 2018-11, ASU 2018-20, and ASU 2019-01), lessees will be required to recognize the following for all leases with the exception of short-term leases: (i) a lease liability, which is a lessee’s obligation to make lease payments arising from a lease, measured on a discounted basis, and (ii) 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. Lessor accounting is largely unchanged. The Company adopted the provisions of the new guidance effective January 1, 2019. The Company recorded the following: (a) a right of use asset of $8,416, (b) a lease commitment liability of $8,860, (c) a reduction in retained earnings from cumulative effect of adoption of $20, (d) an increase in other receivables of $18, and (e) a reduction in other liabilities of $406. See note 13. In June 2016, the FASB issued ASU 2016-13, Financial Instruments—Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments. Under this guidance (subsequently updated with ASU 2018-19, ASU 2019-05, ASU 2019-11 and ASU 2020-02), the measurement of all expected credit losses for financial assets held at the reporting date is to be based on historical experience, current conditions, and reasonable and supportable forecasts. Financial institutions and other organizations will now use forward-looking information to better inform their credit loss estimates. Many of the loss estimation techniques applied today will still be permitted, although the inputs to those techniques will change to reflect the full amount of expected credit losses. In addition, the ASU amends the accounting for credit losses on available-for-sale debt securities and purchased financial assets with credit deterioration. The Company’s adoption of the provisions of ASU 2016-13, effective January 1, 2020 did not have a material effect on the Company’s consolidated financial statements. In January 2017, the FASB issued ASU 2017-04, Intangibles – Goodwill and Other (Topic 350): Simplifying the Test for Goodwill Impairment. The amendments in this ASU eliminate Step 2 from the goodwill impairment test. The annual or interim goodwill impairment test is performed by comparing the fair value of a reporting unit with its carrying amount. An impairment charge should be recognized for the amount by which the carrying amount exceeds the reporting unit’s fair value; however, the loss recognized should not exceed the total amount of goodwill allocated to that reporting unit. The Company adopted the provisions of ASU 2017-04, effective January 1, 2020. The Company recorded an impairment of goodwill for the three months ended March 31, 2020. See note 12. This impairment charge was not the result of the adoption of ASU 2017-04. In June 2018, the FASB issued ASU 2018-07, Compensation – Stock Compensation (Topic 718): Improvements to Nonemployee Share-Based Payment Accounting. The amendments in this ASU expand the scope of Topic 718, which previously only included share-based payments to employees, to include share-based payments issued to nonemployees for goods or services. Consequently, the accounting for share-based payments to nonemployees and employees will be substantially aligned. The Company’s adoption of the provisions of ASU 2018-07, effective January 1, 2019 did not have an effect on the Company’s consolidated financial statements. In March 2017, the FASB issued ASU 2017-08, Receivables – Nonrefundable Fees and Other Costs, Premium Amortization on Purchased Callable Debt Securities (Sub-Topic 310-20). The amendments in this ASU shorten the amortization period for certain callable debt securities held at a premium. Specifically, the amendments require the premium to be amortized to the earliest call date. The amendments do not require an accounting change for securities held at a discount; the discount continues to be amortized to maturity. The Company’s adoption of the provisions of ASU 2017-08, effective January 1, 2019 did not have an effect on the Company’s consolidated financial statements. In August 2017, the FASB issued ASU 2017-12, Derivative and Hedging – Targeted Improvements to Accounting for Hedging Activities (Topic 815). The amendments in this ASU refine and expand hedge accounting for both financial and commodity risks and contain provisions to create more transparency and clarify how economic results are presented. The Company’s adoption of the provisions of ASU 2017-12, effective January 1, 2019 did not have an effect on the Company’s consolidated financial statements. In February 2018, the FASB issued ASU 2018-02, Income Statement – Reporting Comprehensive Income (Topic 220): Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income. The amendments in this ASU provide the option to reclassify stranded tax effects within accumulated other comprehensive income (“AOCI”) to retained earnings in each period in which the effect of the change in the U.S. federal corporate income tax rate in the Tax Act (or portion thereof) is recorded. The Company’s adoption of the provisions of ASU 2018-02, effective January 1, 2019 did not have an effect on the Company’s consolidated financial statements. In August 2018, the FASB issued ASU 2018-13, Fair Value Measurement (Topic 820): Disclosure Framework – Changes to the Disclosure Requirements for Fair Value Measurement. The ASU modifies the disclosure requirements in Topic 820, by removing certain disclosure requirements related to the valuation hierarchy, modifying existing disclosure requirements related to measurement uncertainty and adding new disclosure requirements such as disclosing the changes in unrealized gains and losses for the period included in other comprehensive income for recurring level 3 fair value measurements held at the end of the reporting period and disclosing the range and weighted average of significant unobservable inputs used to develop level 3 fair value measurements. This ASU is effective for public companies for annual reporting periods and interim periods within those annual periods beginning after December 15, 2019. The Company’s adoption of the provisions of ASU 2018-13, effective January 1, 2020 did not have an effect on the Company’s consolidated financial statements. In October 2018, the FASB issued ASU 2018-17, Consolidation (Topic 810): Target Improvements to Related Party Guidance for Variable Interest Entities. The ASU made targeted changes to the related party consolidation guidance. The new guidance changes how entities evaluate decision-making fees under the variable interest entity guidance. To determine whether decision-making fees represent a variable interest, an entity will need to consider indirect interests held through related parties under common control on a proportionate basis under the new guidance, rather than in their entirety, as has been the case under current guidance. The guidance is effective in annual periods beginning after December 15, 2019 and interim periods within those fiscal years. The Company’s adoption of the provisions of ASU 2018-17, effective January 1, 2020 did not have an effect on the Company’s consolidated financial statements. In November 2018, the FASB issued ASU 2018-18, Collaborative Arrangements (Topic 808): Clarifying the Interaction Between Topic 808 and Topic 606. The ASU provides more comparability in the presentation of revenue for certain transactions between collaborative arrangement participants. It accomplishes this by allowing organizations to only present units of account in collaborative arrangements that are within the scope of the revenue recognition standard together with revenue accounted for under the revenue recognition standard. The parts of the collaborative arrangement that are not in the scope of the revenue recognition standard should be presented separately from revenue accounted for under the revenue recognition. The Company’s adoption of the provisions of ASU 2018-18, effective January 1, 2020 did not have an effect on the Company’s consolidated financial statements. In November 2019, the FASB issued ASU 2019-08, Compensation – Stock Compensation (Topic (718) and Revenue from Contracts with Customers (Topic 606): Codification Improvements– Share-Based Consideration Payable to a Customer. This ASU requires companies to measure and classify (on the balance sheet) share-based payments to customers by applying the guidance in Topic 718, Compensation—Stock Compensation. As a result, the amount recorded as a reduction in revenue would be measured based on the grant-date fair value of the share-based payment. The Company’s adoption of the provisions of ASU 2018-18, effective January 1, 2020 did not have an effect on the Company’s consolidated financial statements. 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. This ASU provides temporary optional guidance to ease the burden in accounting for reference rate reform by providing optional expedients and exceptions for applying generally accepted accounting principles to contract modifications and hedging relationships, subject to meeting certain criteria, that reference LIBOR or another reference rate expected to be discontinued. The ASU is intended to help stakeholders during the global market wide reference rate transition period and will be in effect for a limited time through December 31, 2022. The Company’s adoption of the provisions of ASU 2020-04, effective March 12, 2020 did not have an effect on the Company’s consolidated financial statements.
Recent Accounting Developments	B. Recent Accounting Developments In December 2019, the FASB issued ASU 2019-12, Income Taxes (Topic 740): Simplifying the Accounting for Income Taxes. This ASU is intended to simplify accounting for income taxes. It removes specific exceptions to the general principles in Topic 740 and amends existing guidance to improve consistent application. This ASU is effective for fiscal years beginning after December 15, 2020 and interim period with those fiscal years The Company is currently evaluating the new guidance to determine the impact it may have on its consolidated financial statements. In January 2020, the FASB issued ASU 2020-01, Investments—Equity Securities (Topic 321), Investments—Equity Method and Joint Ventures (Topic 323), and Derivatives and Hedging (Topic 815)—Clarifying the Interactions between Topic 321, Topic 323, and Topic 815. This ASU clarifies certain accounting certain topics impacted by Topic 321 Investments-Equity Securities. These topics include measuring equity securities using the measurement alternative, how the measurement alternative should be applied to equity method accounting, and certain forward contracts and purchased options which would be accounted for under the equity method of accounting upon settlement or exercise. This ASU is effective for public business entities for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2020. The Company is currently evaluating the new guidance to determine the impact it may have on its consolidated financial statements.
Fair Value Of Financial Instruments	B. Recent Accounting Developments In December 2019, the FASB issued ASU 2019-12, Income Taxes (Topic 740): Simplifying the Accounting for Income Taxes. This ASU is intended to simplify accounting for income taxes. It removes specific exceptions to the general principles in Topic 740 and amends existing guidance to improve consistent application. This ASU is effective for fiscal years beginning after December 15, 2020 and interim period with those fiscal years The Company is currently evaluating the new guidance to determine the impact it may have on its consolidated financial statements. In January 2020, the FASB issued ASU 2020-01, Investments—Equity Securities (Topic 321), Investments—Equity Method and Joint Ventures (Topic 323), and Derivatives and Hedging (Topic 815)—Clarifying the Interactions between Topic 321, Topic 323, and Topic 815. This ASU clarifies certain accounting certain topics impacted by Topic 321 Investments-Equity Securities. These topics include measuring equity securities using the measurement alternative, how the measurement alternative should be applied to equity method accounting, and certain forward contracts and purchased options which would be accounted for under the equity method of accounting upon settlement or exercise. This ASU is effective for public business entities for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2020. The Company is currently evaluating the new guidance to determine the impact it may have on its consolidated financial statements. C. Fair Value of Financial Instruments The following methods and assumptions were used by the Company in estimating the fair value of its financial instruments. These determinations were based on available market information and appropriate valuation methodologies. Considerable judgment is required to interpret market data to develop the estimates and, therefore, these estimates may not necessarily be indicative of the amount the Company could realize in a current market exchange. The use of different market assumptions and/or estimation methodologies may have a material effect on the estimated fair value amounts. Refer to note 8 for a discussion of the valuation hierarchy with respect to investments-trading; other investments, at fair value; and derivatives held by the Company. Cash equivalents: Cash equivalents are carried at historical cost, which is assumed to approximate fair value. The estimated fair value measurement of cash equivalents is classified within level 1 of the valuation hierarchy. Investments-trading: These amounts are carried at fair value. The fair value is based on either quoted market prices of an active exchange, independent broker market quotations, market price quotations from third- party pricing services, or valuation models when quotations are not available. Other investments, at fair value: These amounts are carried at fair value. The fair value is based on quoted market prices of an active exchange, independent broker market quotations, or valuation models when quotations are not available. In the case of investments in alternative investment funds, fair value is generally based on the reported net asset value of the underlying fund. Receivables under resale agreements: Receivables under resale agreements are carried at their contracted resale price, have short-term maturities, and are repriced frequently or bear market interest rates and, accordingly, these contracts are at amounts that approximate fair value. The estimated fair value measurements of receivables under resale agreements are based on observations of actual market activity and are generally classified within level 2 of the valuation hierarchy. Trading securities sold, not yet purchased: These amounts are carried at fair value. The fair value is based on quoted market prices of an active exchange, independent market quotations, market price quotations from third party pricing services, or valuation models when quotations are not available. Securities sold under agreements to repurchase: The liabilities for securities sold under agreements to repurchase are carried at their contracted repurchase price, have short-term maturities, and are repriced frequently or bear market interest rates and accordingly, these contracts are carried at amounts that approximate fair value. The estimated fair value measurements of securities sold under agreements to repurchase are based on observations of actual market activity and are generally classified within level 2 of the valuation hierarchy. Redeemable financial instruments: The liabilities for redeemable financial instruments are carried at their redemption value, which approximates fair value. The estimated fair value measurement of the redeemable financial instruments is classified within level 3 of the valuation hierarchy. Debt: These amounts are carried at outstanding principal less unamortized discount and deferred financing costs. However, a substantial portion of the debt was assumed in the Merger and recorded at fair value as of that date. As of March 31, 2020, and December 31, 2019, the fair value of the Company’s debt was estimated to be $61,501 and $58,635, respectively. The estimated fair value measurements of the debt are generally based on discounted cash flow models prepared by the Company’s management primarily using discount rates for similar instruments issued to companies with similar credit risks to the Company and are generally classified within level 3 of the value hierarchy. Derivatives: These amounts are carried at fair value. Derivatives may be included as a component of investments-trading; trading securities sold, not yet purchased; and other investments, at fair value. See notes 8 and 9. The fair value is generally based on quoted market prices on an exchange that is deemed to be active for derivative instruments such as foreign currency forward contracts and Eurodollar futures. For derivative instruments, such as TBAs and other extended settlement trades, the fair value is generally based on market price quotations from third party pricing services.