Business and Significant Accounting Policies	3 Months Ended
Mar. 31, 2025
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Business and Significant Accounting Policies	Business and Significant Accounting Policies The accompanying Condensed Consolidated Financial Statements of Argo Group International Holdings, Inc. 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. On November 16, 2023, we merged with Brookfield Wealth Solutions Ltd. (formerly known as Brookfield Reinsurance Ltd.), which resulted in a change to the Company’s ownership (the “Merger”). As a result of the Merger, and overall strategic shift, the Company changed its internal segments in a manner that caused the composition of its reporting segments to change in the fourth quarter of 2024. The Company’s reporting segments were realigned to three reportable segments—Casualty Lines, Specialty Lines, and Run-off Lines. Previously, the Company reported its operations under U.S Operations, International Operations and Run-off Lines, which primarily consisted of other liability policies that were issued in the 1960s, 1970s and into the 1980s, as well as the former risk-management business. For additional segment information, refer to Note 13, “Segment Information.” The Company has recast all applicable periods for comparability. 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 Condensed 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; fair value of investments and assessment of potential impairment, including the allowance for credit losses on fixed maturity securities; valuation of intangibles, including those identified as part of purchase accounting related to the Merger, and our deferred tax asset valuation allowance. Actual results could materially differ from those estimates. Certain financial information that is normally included in annual Condensed Consolidated 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 Condensed Consolidated Financial Statements and notes thereto included in our Annual Report on Form 10-K for the year ended December 31, 2024 filed with the Securities and Exchange Commission ("SEC") (the “2024 Form 10-K”). The interim financial information as of, and for the three months ended, March 31, 2025 and 2024 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 material 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. Argo Pro In January 2025 certain subsidiaries of the Company entered into a Business Transfer Agreement, as amended and restated, with Core Specialty Insurance Holdings, Inc. (“Core”) and a Renewal Rights Agreement with Westfield Insurance Company, Westfield National Insurance Company, Westfield Select Insurance Company and Westfield Specialty Insurance Company (collectively, “Westfield”, and together with Core, collectively, the “Purchasers”), whereby the Purchasers purchased the renewal rights and related unearned premium reserves of the Company’s professional lines businesses. The Company entered into the transaction to align with strategic goals and continue to serve our broker partners through growth across other lines of business.

The accompanying Condensed Consolidated Financial Statements of Argo Group International Holdings, Inc. 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.

On November 16, 2023, we merged with Brookfield Wealth Solutions Ltd. (formerly known as Brookfield Reinsurance Ltd.), which resulted in a change to the Company’s ownership (the “Merger”). As a result of the Merger, and overall strategic shift, the Company changed its internal segments in a manner that caused the composition of its reporting segments to change in the fourth quarter of 2024. The Company’s reporting segments were realigned to three reportable segments—Casualty Lines, Specialty Lines, and Run-off Lines. Previously, the Company reported its operations under U.S Operations, International Operations and Run-off Lines, which primarily consisted of other liability policies that were issued in the 1960s, 1970s and into the 1980s, as well as the former risk-management business. For additional segment information, refer to Note 13, “Segment Information.” The Company has recast all applicable periods for comparability.

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 Condensed 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; fair value of investments and assessment of potential impairment, including the allowance for credit losses on fixed maturity securities; valuation of intangibles, including those identified as part of purchase accounting related to the Merger, and our deferred tax asset valuation allowance. Actual results could materially differ from those estimates. Certain financial information that is normally included in annual Condensed Consolidated 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 Condensed Consolidated Financial Statements and notes thereto included in our Annual Report on Form 10-K for the year ended December 31, 2024 filed with the Securities and Exchange Commission ("SEC") (the “2024 Form 10-K”).

The interim financial information as of, and for the three months ended, March 31, 2025 and 2024 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 material 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.

In January 2025 certain subsidiaries of the Company entered into a Business Transfer Agreement, as amended and restated, with Core Specialty Insurance Holdings, Inc. (“Core”) and a Renewal Rights Agreement with Westfield Insurance Company, Westfield National Insurance Company, Westfield Select Insurance Company and Westfield Specialty Insurance Company (collectively, “Westfield”, and together with Core, collectively, the “Purchasers”), whereby the Purchasers purchased the renewal rights and related unearned premium reserves of the Company’s professional lines businesses. The Company entered into the transaction to align with strategic goals and continue to serve our broker partners through growth across other lines of business.