Document and Entity Information Statement [Table] Statement [Line Items] Statement Entity Registrant Name Entity Central Index Key Document Type Document Period End Date Amendment Flag Current Fiscal Year End Date Entity Current Reporting Status Entity Filer Category Entity Small Business Entity Emerging Growth Company Entity Ex Transition Period Entity Common Stock, Shares Outstanding Document Fiscal Year Focus Document Fiscal Period Focus Statements of Financial Condition Assets [Abstract] Assets Cash Cash Assets Total assets Stockholders' Equity Attributable to Parent [Abstract] Stockholders' Equity Common Stock, Value, Issued Common Stock, par value $.1 per share, 1,000 shares authorized, 100 issued and outstanding Additional Paid in Capital, Common Stock Additional paid-in capital (see note 4) Stockholders' Equity Attributable to Parent Total stockholder's equity Common Stock, Par or Stated Value Per Share Par Value Common Stock, par value per share Common Stock, Shares Authorized Common Stock, shares authorized Common Stock, shares authorized Common Stock, Shares, Issued Common Stock, shares issued Common Stock, Shares, Outstanding Common Stock, shares outstanding Organization Organization, Consolidation and Presentation of Financial Statements Disclosure [Text Block] Organization Summary of Significant Accounting Policies Significant Accounting Policies [Text Block] Significant Accounting Policies Summary of Significant Accounting Policies Stockholder's Equity Stockholders' Equity Note Disclosure [Text Block] Shares Stockholder's Equity Subsequent Events Subsequent Events [Text Block] Subsequent Events Basis of Accounting, Policy [Policy Text Block] Basis of Accounting Basis of Accounting Stock Issued During Period, Shares, New Issues Amount contributed to purchase shares Shares issued Shares Issued, Price Per Share Public offering price The cash inflow associated with the amount received from the entity's first offering of stock to the public, net of offering costs. Proceeds From Issuance Initial Public Offering Net Of Offering Costs Proceeds, net of underwriting discounts and commissions Business Acquisition, Share Price Price per interest of TWM LLC acquired Stock Issued During Period, Value, New Issues Stock issued to Chief Executive Officer The number of votes per share to which each share of stock is entitled. Common Stock Voting Rights Per Share Number of votes per share to which holders are entitled Subsequent Event [Table] Subsequent Event [Line Items] Subsequent Events The existence of economic interests means the right to receive any dividends or distributions. Common Stock Economic Rights Economic interest in the Corporation The number of shares contributed by the majority owner of the acquiree in the exchange transaction. Stock Contributed During Period Acquiree Majority Owner Shares contributed by Refinitiv Owner Stock Issued During Period, Shares, Acquisitions Shares issued to acquire TWM LLC The conversion ratio used to value the conversion shares of the acquired entity with shares issued in the acquisition. Business Acquisition Conversion Ratio Acquisition conversion ratio The number of Class A shares to be issued upon conversion. ClassA Shares To Be Issued Upon Conversion Number of Class A shares to be issued upon conversion The number of Class C shares to be issued upon conversion. Class C Shares To Be Issued Upon Conversion Number of Class C shares to be issued upon conversion Number of shares of common stock canceled during the period. Common Stock, Shares, Retired Number of shares canceled The voting power threshold percentage to require conversion of shares. Voting Power Threshold Percentage To Require Conversion of Shares Voting power threshold percentage to require conversion of shares The percentage of federal, state and local income or franchise tax savings that the Corporation owes to the acquiree and its owners in specified conditions. Tax Sharing Agreement Percentage Percentage of tax savings due to TWM LLC and its continuing owners Sale of Stock, Percentage of Ownership after Transaction Corporation ownership percentage Noncontrolling Interest, Ownership Percentage by Noncontrolling Owners Ownership percentage, Continuing LLC Owners Common Stock, Dividends, Per Share, Declared Cash dividend declared Cash and Cash Equivalents, at Carrying Value Cash Cash and cash equivalents, including cash deposited with related parties of $246,416 and $283,790 at March 31, 2019 and December 31, 2018 respectively Restricted Cash Restricted cash Receivables from Brokers-Dealers and Clearing Organizations Receivable from brokers and dealers and clearing organizations including receivables from related parties of $199 and $3,332 at March 31, 2019 and December 31, 2018, respectively Deposits with Clearing Organizations and Others, Securities Deposits with clearing organizations including deposits from related parties of $500 at both March 31, 2019 and December 31, 2018 Accounts Receivable, Net Accounts receivable, net of allowance including receivables from related parties of $46,947 and $40,730 at March 31, 2019 and December 31, 2018, respectively Property, Plant and Equipment, Net Furniture, equipment, purchased software and leasehold improvements, net of accumulated depreciation and amortization Operating Lease, Right-of-Use Asset Right-to-use assets Right-of-use assets Capitalized Computer Software, Net Software development costs, net of accumulated amortization Intangible Assets, Net (Excluding Goodwill) Intangible assets, net of accumulated amortization Goodwill Due from Affiliates Receivable from affiliates Other Assets Other assets including other assets from related parties of $0 and $9 at March 31, 2019 and December 31, 2018, respectively Liabilities and Equity [Abstract] Liabilities and Members' Capital Liabilities [Abstract] Liabilities Payables to Broker-Dealers and Clearing Organizations Payable to brokers and dealers and clearing organizations including payables to related parties of $0 and $2,404 at March 31, 2019 and December 31, 2018, respectively Employee-related Liabilities Accrued compensation Contract with Customer, Liability Deferred revenue balance - end of period Deferred revenue balance - beginning of period Deferred revenue including deferred revenue from related parties of $8,556 and $9,151 at March 31, 2019 and December 31, 2018, respectively Accounts Payable and Accrued Liabilities Accounts payable, accrued expenses and other liabilities including payables to related parties of $387 and $0 at march 31, 2019 and December 31, 2018, respectively Equity compensation payable to employees. Equity Compensation Payable Employee equity compensation payable Operating Lease, Liability Lease liability Due to Affiliate Payable to affiliates Deferred Income Tax Liabilities, Net Deferred tax liability Liabilities Total liabilities Commitments and Contingencies. Commitments and contingencies (note 13) Temporary Equity [Abstract] Mezzanine Capital Temporary Equity, Carrying Amount, Attributable to Parent Class C Shares and Class P(C) Shares Members' Equity [Abstract] Members' capital Members' Capital Members' capital Accumulated Other Comprehensive Income (Loss), Net of Tax Accumulated other comprehensive income Members' Equity Members' capital end of period Members' capital beginning of period Total members' capital Liabilities and Equity Total liabilities and equity Cash deposited with related parties, included with cash and cash equivalents. Cash And Cash Equivalents Related Parties Cash deposited with related parties Cash and cash equivalents Receivables from related parties, included with receivables from brokers, dealers and clearing organizations. Receivables From Brokers Dealers And Clearing Organizations Related Parties Receivables from related parties Receivables from brokers and dealers and clearing organizations Deposits from related parties, included with deposits with clearing organizations. Deposits Related Parties Deposits from related parties Deposits with clearing organizations Accounts Receivable, Related Parties Accounts receivable Accounts receivable, net of allowance from related parties Other assets from related parties. Other Assets Related Parties Other assets from related parties Other assets Payables to related parties, included with payables to brokers, dealers and clearing organizations. Payables To Broker Dealers And Clearing Organizations Related Parties Payables to related parties, brokers, dealers and clearing organizations Payable to brokers and dealers and clearing organizations Amount of obligation to transfer good or service to related parties for which consideration has been received or is receivable. Contract with Customer, Liability, Related Parties Deferred revenues from related parties Deferred revenue Accounts Payable, Related Parties Accounts payable, accrued expenses and other liabilities Payables to related parties Income Statement [Abstract] Revenues [Abstract] Revenues Revenue from Contract with Customer, Excluding Assessed Tax Gross revenues Gross revenue Contingent consideration to related parties. Contingent Consideration Related Parties Contingent consideration to related parties Contingent consideration to related parties Revenues Net revenue Net revenue Operating Expenses [Abstract] Expenses Labor and Related Expense Employee compensation and benefits Depreciation, Depletion and Amortization, Nonproduction Depreciation and amortization Communications and Information Technology Technology and communications including from related parties of $740 in both the three months ended March 31, 2019 and 2018 Other General and Administrative Expense General and administrative including from related parties of $180 in both the three months ended March 31, 2019 and 2018 Professional Fees Professional fees Occupancy, Net Occupancy including from related parties of $155 in both the three months ended March 31, 2019 and 2018 Costs and Expenses Operating expenses Total expenses Operating Income (Loss) Operating income Operating income Investment Income, Interest Interest income including from related parties of $208 and $21 in the three months ended March 31, 2019 and 2018, respectively Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest Income before taxes Income Tax Expense (Benefit) Provision for income taxes Total Net Income (Loss) Attributable to Parent Net income Net income Net Income Per Share Net income per share Earnings Per Share, Basic Basic net income per share Basic Earnings Per Share, Diluted Diluted net income per share Diluted Weighted Average Number of Shares Outstanding Reconciliation [Abstract] Weighted average number of shares outstanding (note 14) Weighted Average Number of Shares Outstanding, Basic Basic Weighted Average Number of Shares Outstanding, Diluted Diluted weighted average shares outstanding Diluted Revenue from Related Parties Related party revenue Revenue from related parties Information technology and communication expenses from related parties. Communications And Information Technology Related Parties Technology and communications from related parties General and administrative expense from related parties. General And Administrative Expense Related Parties General and administrative from related parties Occupancy expense from related parties. Occupancy Related Parties Occupancy from related parties Interest Income, Related Party Interest income from money market funds invested and savings deposited Interest income from related parties Consolidated Statements of Comprehensive Income Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, Net of Tax, Portion Attributable to Parent Foreign currency translation adjustments Comprehensive Income (Loss), Net of Tax, Attributable to Parent Comprehensive income Increase (Decrease) in Stockholders' Equity [Roll Forward] Comprehensive Income (Loss), Net of Tax, Attributable to Parent [Abstract] Comprehensive income: Adjustments to Additional Paid in Capital, Increase in Carrying Amount of Redeemable Preferred Stock Adjustment to Class C Shares and Class P(C) Shares in mezzanine capital Limited Liability Company (LLC) Members' Equity, Unit-based Compensation Share-based compensation Distribution Made to Limited Liability Company (LLC) Member, Cash Distributions Declared Capital distributions Consolidated Statements of Cash Flows Net Cash Provided by (Used in) Operating Activities [Abstract] Cash flows from operating activities Net Income (Loss), Including Portion Attributable to Noncontrolling Interest Net income Adjustments, Noncash Items, to Reconcile Net Income (Loss) to Cash Provided by (Used in) Operating Activities [Abstract] Adjustments to reconcile net income to net cash used in operating activities: Business Combination, Contingent Consideration Arrangements, Change in Amount of Contingent Consideration, Liability Contingent consideration Share-based Compensation Share-based compensation expense Deferred Income Tax Expense (Benefit) Total deferred Deferred taxes Increase (Decrease) in Operating Assets [Abstract] (Increase) decrease in operating assets: Increase (Decrease) in Receivables from Brokers-Dealers and Clearing Organizations Receivable from brokers and dealers and clearing organizations Increase (Decrease) in Deposit Assets Deposits with clearing organizations Increase (Decrease) in Accounts Receivable Accounts receivable Increase (Decrease) Due from Affiliates Receivable from affiliates Increase (Decrease) in Other Operating Assets Other assets Increase (Decrease) in Operating Liabilities [Abstract] Increase (decrease) in operating liabilities: Increase (Decrease) in Payables to Broker-Dealers and Clearing Organizations Payable to brokers and dealers and clearing organizations Increase (Decrease) in Employee Related Liabilities Accrued compensation Increase (Decrease) in Deferred Revenue Deferred revenue Increase (Decrease) in Accounts Payable and Accrued Liabilities Accounts payable, accrued expenses and other liabilities The increase (decrease) during the period in equity compensation payable. Increase Decrease In Equity Compensation Payable Employee equity compensation payable Increase (Decrease) in Due to Affiliates Payable to affiliates Net Cash Provided by (Used in) Operating Activities Net cash used in operating activities Net Cash Provided by (Used in) Investing Activities [Abstract] Cash flows from investing activities Payments to Acquire Property, Plant, and Equipment Purchase of furniture, equipment, software and leasehold improvements Payments for Software Capitalized software development costs Net Cash Provided by (Used in) Investing Activities Net cash used in investing activities Net Cash Provided by (Used in) Financing Activities [Abstract] Cash flows from financing activities Payments of Dividends Capital distributions Net Cash Provided by (Used in) Financing Activities Net cash used in financing activities Effect of Exchange Rate on Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, Including Disposal Group and Discontinued Operations Effect of exchange rate changes on cash and cash equivalents Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, Period Increase (Decrease), Including Exchange Rate Effect Net decrease in cash and cash equivalents Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, Including Disposal Group and Discontinued Operations [Abstract] Cash and cash equivalents and restricted cash Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents End of period Beginning of period Cash and cash equivalents and restricted cash Supplemental Cash Flow Information [Abstract] Supplemental disclosure of cash flow information Income Taxes Paid Income taxes paid Proceeds from Distribution of Restricted Cash from Pollution Control Bond Restricted cash Entities [Table] Entity Information [Line Items] Organization No definition available. Pushdown Accounting The entire disclosure for reporting pushdown accounting. Pushdown Accounting [Text Block] Pushdown Accounting Leases Lessee, Operating Leases [Text Block] Leases Intangible Assets and Goodwill Goodwill and Intangible Assets Disclosure [Text Block] Intangible Assets and Goodwill Deferred Revenue The entire disclosure about the contract with customer liability. Contract With Customer Liability [Text Block] Deferred Revenue Income Taxes Income Tax Disclosure [Text Block] Income Taxes Shares Share-Based Compensation Plans Disclosure of Compensation Related Costs, Share-based Payments [Text Block] Share-Based Compensation Plans Related Party Transactions Related Party Transactions Disclosure [Text Block] Related Party Transactions Fair Value of Financial Instruments Fair Value Disclosures [Text Block] Fair Value of Financial Instruments Credit Risk Allowance for Credit Losses [Text Block] Credit Risk Commitments and Contingencies Commitments and Contingencies Disclosure [Text Block] Commitments and Contingencies Earnings Per Share [Text Block] Net Income Per Share Regulatory Capital Requirements The entire disclosure of capital requirements and required financial resources under applicable regulations. Regulatory Capital Requirements [Text Block] Regulatory Capital Requirements Employee Savings Plan Pension and Other Postretirement Benefits Disclosure [Text Block] Employee Savings Plan Business Segment and Geographic Information