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Earnings Per Share (Tables) | 3 Months Ended
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Mar. 31, 2025
Earnings Per Share [Abstract] |
Schedule of earnings per share from continuing operations | The following table presents the Company’s computation of earnings per share from continuing operations for the three months ended March 31, 2025 and 2024.
|  |  |  | Three Months Ended March 31,
|  |  |  |  |  | 2025 |  | 2024
Basic and diluted earnings per share numerators (in millions): |  |  |  |  |  |  |  |
Net income (loss) attributable to White Mountains’s common shareholders |  |  |  |  |  | $ | 33.9 |  |  | $ | 236.4 |
Allocation of (earnings) losses to participating restricted common shares (1) |  |  |  |  |  | (.3) |  |  | (2.7) |
Basic and diluted earnings (losses) per share numerators |  |  |  |  |  | $ | 33.6 |  |  | $ | 233.7 |
Basic earnings per share denominators (in thousands): |  |  |  |  |  |  |  |
Total average common shares outstanding during the period |  |  |  |  |  | 2,567.0 |  |  | 2,559.7 |
Average unvested restricted common shares (2) |  |  |  |  |  | (26.1) |  |  | (28.6) |
Basic earnings (losses) per share denominator |  |  |  |  |  | 2,540.9 |  |  | 2,531.1 |
Diluted earnings per share denominator (in thousands): |  |  |  |  |  |  |  |
Total average common shares outstanding during the period |  |  |  |  |  | 2,567.0 |  |  | 2,559.7 |
Average unvested restricted common shares (2) |  |  |  |  |  | (26.1) |  |  | (28.6) |
Diluted earnings (losses) per share denominator |  |  |  |  |  | 2,540.9 |  |  | 2,531.1 |
Basic and diluted earnings per share (in dollars): |  |  |  |  |  |  |  |
Distributed earnings - dividends declared and paid |  |  |  |  |  | $ | 1.00 |  |  | $ | 1.00 |
Undistributed earnings (losses) |  |  |  |  |  | 12.19 |  |  | 91.33 |
Basic and diluted earnings (losses) per share |  |  |  |  |  | $ | 13.19 |  |  | $ | 92.33 |
(1) Restricted shares issued by White Mountains receive dividends, and therefore, are considered participating securities. (2) Restricted shares outstanding vest upon a stated date. See Note 12 — “Employee Share-Based Incentive Compensation Plans.”
Schedule of undistributed earnings | The following table presents the undistributed net earnings (losses) for the three months ended March 31, 2025 and 2024.
|  |  |  | Three Months Ended March 31,
Millions |  |  |  |  |  | 2025 |  | 2024
Undistributed net earnings: |  |  |  |  |  |  |  |
Net income (loss) attributable to White Mountains’s common shareholders, net of restricted common share amounts |  |  |  |  |  | $ | 33.6 |  |  | $ | 233.7 |
Dividends declared, net of restricted common share amounts (1) |  |  |  |  |  | (2.5) |  |  | (2.5) |
Total undistributed net earnings (losses), net of restricted common share amounts |  |  |  |  |  | $ | 31.1 |  |  | $ | 231.2 |
(1) Restricted shares issued by White Mountains receive dividends, and therefore, are considered participating securities.

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- Definition Tabular disclosure of an entity's basic and diluted earnings per share calculations, including a reconciliation of numerators and denominators of the basic and diluted per-share computations for income from continuing operations. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 260 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 1 -Subparagraph (a) -Publisher FASB -URI https://asc.fasb.org/1943274/2147482662/260-10-50-1 + Details
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- Definition Schedule of Undistributed Earnings + References No definition available. + Details
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