Dividend Restrictions	12 Months Ended
Dec. 31, 2025
Disclosure of Restrictions on Dividends, Loans and Advances Disclosure [Abstract]
Dividend Restrictions	11. DIVIDEND RESTRICTIONS INSURANCE SUBSIDIARIES The individual law of all states, including New Hampshire and Michigan, where Hanover Insurance and Citizens are domiciled, respectively, restrict the payment of dividends to stockholders by insurers. These laws affect the dividend paying ability of Hanover Insurance and Citizens. Pursuant to New Hampshire’s statute, the maximum dividends and other distributions that an insurer may pay in any twelve-month period, without prior approval of the New Hampshire Insurance Commissioner, is limited to the lesser of: (a) 10% of such insurer’s statutory policyholder surplus as of the preceding December 31, or (b) statutory net income less net realized gains, and including undistributed net income from the previous two calendar years. Hanover Insurance declared and paid dividends to its parent totaling $295.0 million in 2025, and $100.0 million in 2024 and 2023. At January 1, 2026, the maximum dividend payable without prior approval was $37.8 million. In May 2026, the maximum dividend declared payable without prior approval will increase by $150.0 million to a total amount of $187.8 million, and further increase in November 2026 by $145.0 million to a total amount of $332.8 million. Pursuant to Michigan’s statute, the maximum dividends and other distributions that an insurer may pay in any twelve-month period, without prior approval of the Michigan Insurance Commissioner, is limited to the greater of: (a) 10% of policyholders’ surplus as of December 31 of the immediately preceding year or (b) the statutory net income less net realized gains for the immediately preceding calendar year. Citizens declared and paid dividends to its parent, Hanover Insurance, totaling $91.0 million in 2025, $59.0 million in 2024, and $10.0 million in 2023. At January 1, 2026, the maximum dividend payable without prior approval was $51.9 million. In November 2026, the maximum dividend declared payable without prior approval will increase by $91.0 million to a total amount of $142.9 million. The statutes in both New Hampshire and Michigan require that prior notice to the respective Insurance Commissioner of any proposed dividend be provided and such Commissioner may, in certain circumstances, prohibit the payment of the proposed dividend.

Dividend Restrictions

12 Months Ended

Dec. 31, 2025

Disclosure of Restrictions on Dividends, Loans and Advances Disclosure [Abstract]

11. DIVIDEND RESTRICTIONS

INSURANCE SUBSIDIARIES

The individual law of all states, including New Hampshire and Michigan, where Hanover Insurance and Citizens are domiciled, respectively, restrict the payment of dividends to stockholders by insurers. These laws affect the dividend paying ability of Hanover Insurance and Citizens.

Pursuant to New Hampshire’s statute, the maximum dividends and other distributions that an insurer may pay in any twelve-month period, without prior approval of the New Hampshire Insurance Commissioner, is limited to the lesser of: (a) 10% of such insurer’s statutory policyholder surplus as of the preceding December 31, or (b) statutory net income less net realized gains, and including undistributed net income from the previous two calendar years. Hanover Insurance declared and paid dividends to its parent totaling $295.0 million in 2025, and $100.0 million in 2024 and 2023. At January 1, 2026, the maximum dividend payable without prior approval was $37.8 million. In May 2026, the maximum dividend declared payable without prior approval will increase by $150.0 million to a total amount of $187.8 million, and further increase in November 2026 by $145.0 million to a total amount of $332.8 million.

Pursuant to Michigan’s statute, the maximum dividends and other distributions that an insurer may pay in any twelve-month period, without prior approval of the Michigan Insurance Commissioner, is limited to the greater of: (a) 10% of policyholders’ surplus as of December 31 of the immediately preceding year or (b) the statutory net income less net realized gains for the immediately preceding calendar year. Citizens declared and paid dividends to its parent, Hanover Insurance, totaling $91.0 million in 2025, $59.0 million in 2024, and $10.0 million in 2023. At January 1, 2026, the maximum dividend payable without prior approval was $51.9 million. In November 2026, the maximum dividend declared payable without prior approval will increase by $91.0 million to a total amount of $142.9 million.

The statutes in both New Hampshire and Michigan require that prior notice to the respective Insurance Commissioner of any proposed dividend be provided and such Commissioner may, in certain circumstances, prohibit the payment of the proposed dividend.