DESCRIPTION OF BUSINESS AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Policies)	9 Months Ended
	Sep. 30, 2022
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation The accompanying unaudited condensed consolidated financial statements have been prepared in accordance with generally accepted accounting principles in the United States (“GAAP”) and pursuant to the rules and regulations of the SEC for interim financial reporting. The condensed consolidated financial statements are unaudited, and in management’s opinion, include all adjustments, including normal recurring adjustments and accruals necessary for a fair presentation of the results for the interim periods presented. Operating results for the periods presented are not necessarily indicative of the results that may be expected for the full fiscal year ending December 31, 2022 or any future period. These unaudited condensed consolidated financial statements should be read in conjunction with the audited annual consolidated financial statements and notes included in our Annual Report on Form 10-K for the year ended December 31, 2021 (“2021 Form 10-K”). There have been no material changes in our significant accounting policies as described in our consolidated financial statements included in our audited annual consolidated financial statements for the year ended December 31, 2021, other than recently adopted accounting pronouncements as described in Note 2. The unaudited condensed consolidated financial statements include the accounts of RHM and its wholly-owned subsidiaries. All intercompany balances and transactions have been eliminated. Certain prior-period amounts have been reclassified to conform to the current period’s presentation. The impact of these reclassifications is immaterial to the presentation of the unaudited condensed consolidated financial statements.
Use of Estimates	Use of Estimates In accordance with GAAP, management is required to make estimates and assumptions that affect the reported amounts of assets, liabilities, revenue, and expenses, as well as related disclosures, on the unaudited condensed consolidated financial statements. We base our estimates on current and historical experience and other assumptions we believe to be reasonable under the circumstances. Assumptions and estimates used in preparing our unaudited condensed consolidated financial statements include those related to revenue recognition, the determination of allowances for credit losses, the capitalization and estimated useful life of internally developed software, investment valuation, valuation of user cryptocurrencies safeguarding obligation and the corresponding asset, contingent liabilities, useful lives of property and equipment, the incremental borrowing rate used to determine the present value of lease payments, the valuation and recognition of share-based compensation, the valuation of the convertible notes and warrant liability, the valuation and estimated useful lives of acquired intangible assets, uncertain tax positions, accrued liabilities, and the recognition and measurement of current and deferred income tax assets and liabilities. Actual results could differ from these estimates and could have a material adverse effect on our operating results.
Concentrations of Credit	Concentrations of Credit We are engaged in various trading and brokerage activities in which the counterparties primarily include broker-dealers, banks, and other financial institutions. In the event our counterparties do not fulfill their obligations, we may be exposed to risk. The risk of default depends on the creditworthiness of the counterparty. Default of a counterparty in equities and options trades, which are facilitated through clearinghouses, would generally be spread among the clearinghouse's members rather than falling entirely on us. It is our policy to review, as necessary, the credit standing of each counterparty.
Cryptocurrencies	Cryptocurrencies We act as an agent in the cryptocurrency transactions that users initiate on our platform (i.e., in their RHC accounts). We have determined we are an agent, for accounting purposes, because we do not control the cryptocurrency before delivery to the user, we are not primarily responsible for the delivery of cryptocurrency to our users, we are not exposed to risks arising from fluctuations of the market price of cryptocurrency before delivery to the user, and we do not set the prices charged to users. After purchasing cryptocurrency on the platform, users are the legal owners of cryptocurrency held under custody by us and users have all the rights and benefits of ownership, including the rights to appreciation and depreciation of the cryptocurrency. We do not allow users to purchase cryptocurrency on margin and cryptocurrency does not serve as collateral for margin loans. We hold cryptocurrency in custody for users in one or more omnibus cryptocurrency wallets; we do not utilize third-party custodians. We hold cryptographic key information and maintain internal record keeping for the cryptocurrencies we hold in custody for users, and we are obligated to secure such assets from loss or theft. Based on the terms of our user agreement and applicable law, we believe the cryptocurrency we hold in custody for users of our platform should be respected as users’ property (and should not be available to satisfy the claims of our general creditors) in the event we were to enter bankruptcy. For additional information relating to platform bankruptcy generally, see Item 2, Part II of this Quarterly Report on Form 10-Q, “Risk Factors—Risks Related to Cryptocurrency Products and Services—Cryptocurrency laws, regulations, and accounting standards are often difficult to interpret and are rapidly evolving in ways that are difficult to predict. Changes in these laws and regulations, or our failure to comply with them, could negatively impact cryptocurrency trading on our platform.”
Securities Borrowing and Lending	Securities Borrowing and Lending We operate a securities lending program under which shares that users have pledged to us to collateralize their margin borrowing are lent by us to third parties (“Margin Securities Lending”) and a securities lending program under which we borrow fully-paid shares from participating users and lend them to third parties (“Fully-Paid Securities Lending”). We also occasionally borrow securities from third parties for operational purposes, and we occasionally lend to third parties securities that we hold for our own account (such as our holdings to support fractional share operations). When we lend securities to third parties, the borrower provides cash as collateral. We earn interest revenue on cash collateral deposited by borrowers, and we can also earn additional revenue for lending certain securities based on demand for those securities. For our Fully-Paid Securities Lending, portions of such revenues are paid to participating users, and those payments are recorded as interest expense. For the three and nine months ended September 30, 2022, interest revenue earned and interest expenses incurred related to the Fully-Paid Securities Lending program were not material. When we borrow securities from users participating in the Fully-Paid Securities Lending program (or from third parties), we provide cash as collateral and we record a receivable representing our right to the return of that collateral. Commencing in the quarter ended September 30, 2022, the amount of that receivable is presented in "securities borrowed" on our consolidated balance sheets. Prior period amounts (which were not material) have been reclassified to conform to the current presentation. In the case of our Fully-Paid Securities Lending program, the cash collateral is held by a third-party bank in a deposit account pledged to the user, which we administer as the user’s agent. Users are not entitled to interest on such account, and any interest earned is for our benefit. Our authorization from users to lend shares that collateralize their margin borrowing is found in our margin account agreement, our borrowing of fully-paid shares from users is conducted under the terms of our Fully-Paid Securities Lending program to which users consent when they enroll in that program, and substantially all of our securities lending and borrowing transactions with third parties are conducted under the terms of an industry-standard master securities loan agreement (“MSLA”), which has an open contractual term and may be terminated upon notice by either party.
Variable Interest Entities	Variable Interest EntitiesWe evaluate our ownership, contractual and other interests in entities to determine if we have a variable interest in an entity. These evaluations are complex, involve judgment, and the use of estimates and assumptions based on available historical and prospective information, among other factors. If we determine that an entity for which we hold a contractual or ownership interest in is a variable interest entity (“VIE”) and that we are the primary beneficiary, we consolidate such entity in the consolidated financial statements. The primary beneficiary of a VIE is the party that meets both of the following criteria: (1) has the power to make decisions that most significantly affect the economic performance of the VIE; and (2) has the obligation to absorb losses or the right to receive benefits that in either case could potentially be significant to the VIE. Periodically, we determine whether any changes in the interest or relationship with the entity impacts the determination of whether we are still the primary beneficiary. If we are not deemed to be the primary beneficiary in a VIE, we account for the investment or other variable interests in a VIE in accordance with applicable GAAP.
Non-Marketable Equity Securities	Non-Marketable Equity Securities Investments in equity securities without readily determinable fair values are initially recorded at cost and are subsequently adjusted to fair value for impairments and price changes from observable transactions in the same or a similar security from the same issuer. Non-marketable equity securities were not material for the periods presented and were included in other non-current assets on the unaudited condensed consolidated balance sheets.
Recently Adopted Accounting Pronouncements/Recently Issued Accounting Pronouncements Not Yet Adopted	Recently Adopted Accounting Pronouncements In March 2022, the staff of the SEC issued SAB 121, which provides guidance to entities that have obligations to safeguard crypto-assets held in custody on behalf of their platform users. SAB 121 states that the entity should recognize a liability representing its obligation to safeguard such crypto-assets accompanied by a corresponding asset on its balance sheet representing the platform users’ crypto-assets held in custody measured at fair value initially and at each subsequent reporting period. SAB 121 also states that accompanying disclosures should be considered regarding the entity’s obligation to safeguard crypto-assets for platform users. We adopted SAB 121 as part of the financial statements covering the interim period ended June 30, 2022, with retrospective application as of the beginning of fiscal year 2022. As a result of (and solely by virtue of) our adoption of SAB 121, we recognized an asset captioned “Asset related to user cryptocurrencies safeguarding obligation” and a liability captioned “User cryptocurrencies safeguarding obligation” on our unaudited condensed consolidated balance sheets. As of September 30, 2022, the carrying value of each was $9.4 billion. We also added disclosures to Note 1 - Description of business and summary of significant accounting policies and Note 7 - Investments and fair value measurement. Recently Issued Accounting Pronouncements Not Yet Adopted In October 2021, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update 2021-08, “Business Combinations (Topic 805): Accounting for Contract Assets and Contract Liabilities from Contracts with Customers.” This guidance requires contract assets and contract liabilities from contracts with customers that are acquired in a business combination to be recognized and measured as if the acquirer had originated the original contract. The guidance is effective for fiscal years beginning after December 15, 2022 on a prospective basis, including interim periods within those fiscal years. Early adoption is permitted. As of September 30, 2022, the planned adoption of this guidance is not expected to have any impact on our financial statements.