Business and Significant Accounting Policies	6 Months Ended
Business and Significant Accounting Policies	Jun. 30, 2022
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Business and Significant Accounting Policies	Business and Significant Accounting Policies Business The accompanying consolidated financial statements of Argo Group International Holdings, Ltd. and its subsidiaries (“Argo Group,” “we,” “us,” “our” or the “Company”) have been prepared in accordance with U.S. generally accepted accounting principles (“GAAP”) for interim financial information and with the instructions for Form 10-Q and Article 10 of Regulation S-X. Argo Group is an underwriter of specialty insurance products in the property and casualty market. The preparation of interim 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 reported amounts of revenues and expenses during the reporting period. The major estimates reflected in our consolidated financial statements include, but are not limited to, reserves for losses and loss adjustment expenses; reinsurance recoverables, including the reinsurance recoverables allowance for expected credit losses; estimates of written and earned premiums; reinsurance premium receivable; fair value of investments and assessment of potential impairment, including the allowance for credit losses on fixed maturity securities; valuation of goodwill and intangibles and our deferred tax asset valuation allowance. Actual results could materially differ from those estimates. Certain financial information that is normally included in annual financial statements, including certain financial statement footnotes, prepared in accordance with GAAP, is not required for interim reporting purposes and has been condensed or omitted. These statements should be read in conjunction with the consolidated financial statements and notes thereto included in our Annual Report on Form 10-K and Form 10-K/A for the year ended December 31, 2021 filed with the Securities and Exchange Commission ("SEC") (collectively, “2021 Form 10-K”). The interim financial information as of, and for, the three and six months ended, June 30, 2022 and 2021 is unaudited. However, in the opinion of management, the interim information includes all adjustments, consisting of normal recurring accruals, necessary for a fair presentation of the results presented for the interim periods. The operating results for the interim periods are not necessarily indicative of the results to be expected for the full year. All significant intercompany amounts have been eliminated in consolidation. Certain reclassifications have been made to financial information presented for prior years to conform to the current year’s presentation. Sale of ArgoGlobal SE On June 22, 2022, we completed the sale of our Malta operations, ArgoGlobal Holdings (Malta) Ltd. and subsidiaries (“AGSE”) to RiverStone Holdings Limited (part of the RiverStone International Group) for €4.9 million (approximately $5.2 million), subject to the terms and conditions set forth in the purchase agreement. AGSE is one of the business units within our International Operations reporting segment. As a result, we realized a loss on the sale of AGSE of $21.3 million, which is included as a component of Net realized investment and other gains (losses) in our Condensed Consolidated Statements of Income (Loss). This amount includes $4.5 million of losses from the realization of historical foreign currency translation, which was previously a component of accumulated other comprehensive income. Loss Portfolio Transfer In April 2022, Argo Managing Agency Limited, for and on behalf of Lloyd’s Syndicate 1200, reached an agreement to enter into a loss portfolio transfer of the 2018 and 2019 years of account to Riverstone Managing Agency Limited, for and on behalf of Lloyd's Syndicate 3500, retrospectively from January 1, 2022. Sale of Argo Seguros Brasil S.A. On February 15, 2022, we completed the sale of our Brazilian operations, Argo Seguros Brasil S.A. (“Argo Seguros”), to Spice Private Equity Ltd., an investment company focused on global private equity investments, for a purchase price of 160 million Brazilian Reais (approximately $30.5 million), subject to the terms and conditions set forth in the purchase agreement. Argo Seguros is one of the business units within our International Operations reporting segment. As a result, in the first quarter of 2022, we realized a loss on the sale of Argo Seguros of $28.5 million, which is included as a component of Net realized investment and other gains (losses) in our Condensed Consolidated Statements of Income (Loss). This amount includes $27.3 million of losses from the realization of historical foreign currency translation, which was previously a component of accumulated other comprehensive income We previously recognized a $6.3 million loss during 2021 as we adjusted the carrying value of Argo Seguros to its fair value. Basis of Presentation and Use of Estimates Commercial Mortgage Loans Commercial mortgages are carried at unpaid principal balances less allowance for credit losses and plus or minus adjustments for the accretion or amortization of discount or premium. Interest income on such loans is accrued as earned. Non-Operating Expenses Non-operating expenses represent costs not associated with our ongoing insurance or other operations, including severance expenses, certain legal costs, merger and acquisition and other transaction-related expenses, and certain non-recurring expenses.