Organization	6 Months Ended
Jun. 30, 2026
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Organization	Organization Hamilton Insurance Group, Ltd. ("Hamilton Group", the "Group", the "Company", "we", "us" or "our"), the ultimate group holding company, was incorporated on September 4, 2013, under the laws of Bermuda. On November 14, 2023, the Company consummated an initial public offering ("IPO") of its Class B common shares, which are listed on the New York Stock Exchange ("NYSE"). Our Bermuda operations are led by Hamilton Re, Ltd. ("Hamilton Re"), a registered Class 4 insurer incorporated in Bermuda. Hamilton Re writes property, casualty and specialty insurance and reinsurance on a global basis. Hamilton Re US is a tax partnership that was formed pursuant to an arrangement between Hamilton Re and its Bermuda-incorporated affiliate, Hamilton ILS Holdings Limited. The tax partnership is treated as a U.S. corporation for U.S. tax purposes and is registered with the U.S. Internal Revenue Service, such that underwriting and investment income derived from capital allocated to Hamilton Re US are subject to U.S. taxation. Ada Capital Management Limited ("ACML"), a wholly owned insurance agent incorporated and regulated in Bermuda, is authorized to underwrite on behalf of Ada Re, Ltd. ("Ada Re"). Our London operations are comprised of Hamilton Managing Agency Limited ("HMA"), a Lloyd’s managing agency, which manages our wholly aligned Syndicate 4000. Syndicate 4000 operates in the Lloyd’s market and underwrites property, casualty and specialty insurance and reinsurance business on a subscription basis. Our Dublin operations are comprised of Hamilton Insurance Designated Activity Company ("HIDAC"), a Dublin-based insurer with a U.K. branch and extensive licensing in the United States, including excess and surplus lines and reinsurance in all 50 states. Hamilton Managing General Agency Americas LLC ("HMGA Americas") is licensed throughout the United States and underwrites on behalf of the Group's London, Dublin and Bermuda operations solely in respect of Hamilton Re US, providing access from the U.S. to the Lloyd's market, the Group's rated Irish carrier and the Group's Bermuda balance sheet, respectively. Hamilton Select Insurance Inc. ("Hamilton Select") is a U.S. domestic excess and surplus lines carrier incorporated in Delaware and authorized to write excess and surplus business in all 50 states. Two Sigma Hamilton Fund, LLC ("TS Hamilton Fund"), is a Delaware limited liability company. In 2013, Hamilton Re entered into a limited liability company agreement with TS Hamilton Fund and Two Sigma Principals, LLC (the "Managing Member"), a related party Delaware limited liability company which serves as the managing member of TS Hamilton Fund. The Managing Member, on behalf of TS Hamilton Fund, has engaged Two Sigma Investments, LP ("Two Sigma"), a related party Delaware limited partnership, to serve as the fund’s investment manager. Two Sigma is an investment adviser registered with the U.S. Securities and Exchange Commission, specializing in quantitative analysis. On April 1, 2026, the Company, Hamilton Re, TS Hamilton Fund, the Managing Member and Two Sigma entered into an investment agreement (the "Original Investment Agreement") relating to Hamilton Re’s investment in TS Hamilton Fund. The Original Investment Agreement replaced and superseded the commitment agreement, dated July 1, 2023, as amended on January 1, 2025 (the "Prior Commitment Agreement"), which previously governed such investment. On June 1, 2026, the parties entered into an amended and restated investment agreement (the “Investment Agreement”), which amended and restated, and superseded in its entirety, the Original Investment Agreement. The principal effect of the June 1, 2026 amendment and restatement was to relocate the provisions governing withdrawals from the Investment Agreement to the Sixth Amended and Restated Limited Liability Company Agreement of the TS Hamilton Fund dated May 21, 2026 (the “LLCA”). The terms governing withdrawals were not substantively changed in connection with such amendment and restatement, and, other than the relocation of such provisions, no other material terms were modified. Unconsolidated Related Parties Ada Re is a special purpose insurer funded by investors and formed to provide fully collateralized reinsurance and retrocession to both Hamilton Group and third party cedants. Easton Re has issued an industry loss index-triggered catastrophe bond that provides the Company's operating platforms with multi-year risk transfer capacity to protect against named storm risk in the United States and earthquake risk in the United States and Canada. See Note 6, Reinsurance for further details.

Hamilton Insurance Group, Ltd. ("Hamilton Group", the "Group", the "Company", "we", "us" or "our"), the ultimate group holding company, was incorporated on September 4, 2013, under the laws of Bermuda. On November 14, 2023, the Company consummated an initial public offering ("IPO") of its Class B common shares, which are listed on the New York Stock Exchange ("NYSE").

Hamilton Re US is a tax partnership that was formed pursuant to an arrangement between Hamilton Re and its Bermuda-incorporated affiliate, Hamilton ILS Holdings Limited. The tax partnership is treated as a U.S. corporation for U.S. tax purposes and is registered with the U.S. Internal Revenue Service, such that underwriting and investment income derived from capital allocated to Hamilton Re US are subject to U.S. taxation.

Our London operations are comprised of Hamilton Managing Agency Limited ("HMA"), a Lloyd’s managing agency, which manages our wholly aligned Syndicate 4000. Syndicate 4000 operates in the Lloyd’s market and underwrites property, casualty and specialty insurance and reinsurance business on a subscription basis.

Our Dublin operations are comprised of Hamilton Insurance Designated Activity Company ("HIDAC"), a Dublin-based insurer with a U.K. branch and extensive licensing in the United States, including excess and surplus lines and reinsurance in all 50 states.

Hamilton Managing General Agency Americas LLC ("HMGA Americas") is licensed throughout the United States and underwrites on behalf of the Group's London, Dublin and Bermuda operations solely in respect of Hamilton Re US, providing access from the U.S. to the Lloyd's market, the Group's rated Irish carrier and the Group's Bermuda balance sheet, respectively.

Two Sigma Hamilton Fund, LLC ("TS Hamilton Fund"), is a Delaware limited liability company. In 2013, Hamilton Re entered into a limited liability company agreement with TS Hamilton Fund and Two Sigma Principals, LLC (the "Managing Member"), a related party Delaware limited liability company which serves as the managing member of TS Hamilton Fund. The Managing Member, on behalf of TS Hamilton Fund, has engaged Two Sigma Investments, LP ("Two Sigma"), a related party Delaware limited partnership, to serve as the fund’s investment manager. Two Sigma is an investment adviser registered with the U.S. Securities and Exchange Commission, specializing in quantitative analysis.

On April 1, 2026, the Company, Hamilton Re, TS Hamilton Fund, the Managing Member and Two Sigma entered into an investment agreement (the "Original Investment Agreement") relating to Hamilton Re’s investment in TS Hamilton Fund. The Original Investment Agreement replaced and superseded the commitment agreement, dated July 1, 2023, as amended on January 1, 2025 (the "Prior Commitment Agreement"), which previously governed such investment. On June 1, 2026, the parties entered into an amended and restated investment agreement (the “Investment Agreement”), which amended and restated, and superseded in its entirety, the Original Investment Agreement. The principal effect of the June 1, 2026 amendment and restatement was to relocate the provisions governing withdrawals from the Investment Agreement to the Sixth Amended and Restated Limited Liability Company Agreement of the TS Hamilton Fund dated May 21, 2026 (the “LLCA”). The terms governing withdrawals were not substantively changed in connection with such amendment and restatement, and, other than the relocation of such provisions, no other material terms were modified.

Easton Re has issued an industry loss index-triggered catastrophe bond that provides the Company's operating platforms with multi-year risk transfer capacity to protect against named storm risk in the United States and earthquake risk in the United States and Canada. See Note 6, Reinsurance for further details.