0000001 - Document - Cover Page link:presentationLink link:calculationLink link:definitionLink 9952151 - Statement - CONSOLIDATED BALANCE SHEETS link:presentationLink link:calculationLink link:definitionLink 9952152 - Statement - CONSOLIDATED BALANCE SHEETS (Parenthetical) link:presentationLink link:calculationLink link:definitionLink 9952153 - Statement - CONSOLIDATED STATEMENTS OF OPERATIONS link:presentationLink link:calculationLink link:definitionLink 9952154 - Statement - CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (LOSS) link:presentationLink link:calculationLink link:definitionLink 9952155 - Statement - CONSOLIDATED STATEMENTS OF CHANGES IN EQUITY link:presentationLink link:calculationLink link:definitionLink 9952156 - Statement - CONSOLIDATED STATEMENTS OF CASH FLOWS link:presentationLink link:calculationLink link:definitionLink 9952157 - Statement - CONSOLIDATED STATEMENTS OF CASH FLOWS (Parenthetical) link:presentationLink link:calculationLink link:definitionLink 9952158 - Disclosure - Basis of Presentation and Significant Accounting Policies link:presentationLink link:calculationLink link:definitionLink 9952159 - Disclosure - Significant Transactions link:presentationLink link:calculationLink link:definitionLink 9952160 - Disclosure - Investment Securities link:presentationLink link:calculationLink link:definitionLink 9952161 - Disclosure - Goodwill and Other Intangible Assets link:presentationLink link:calculationLink link:definitionLink 9952162 - Disclosure - Loss and Loss Adjustment Expense Reserves link:presentationLink link:calculationLink link:definitionLink 9952163 - Disclosure - Third-Party Reinsurance link:presentationLink link:calculationLink link:definitionLink 9952164 - Disclosure - Debt link:presentationLink link:calculationLink link:definitionLink 9952165 - Disclosure - Income Taxes link:presentationLink link:calculationLink link:definitionLink 9952166 - Disclosure - Derivatives link:presentationLink link:calculationLink link:definitionLink 9952167 - Disclosure - Municipal Bond Guarantee Insurance link:presentationLink link:calculationLink link:definitionLink 9952168 - Disclosure - Earnings Per Share link:presentationLink link:calculationLink link:definitionLink 9952169 - Disclosure - Employee Share-Based Incentive Compensation Plans link:presentationLink link:calculationLink link:definitionLink 9952170 - Disclosure - Noncontrolling Interests link:presentationLink link:calculationLink link:definitionLink 9952171 - Disclosure - Segment Information link:presentationLink link:calculationLink link:definitionLink 9952172 - Disclosure - Variable Interest Entities link:presentationLink link:calculationLink link:definitionLink 9952173 - Disclosure - Equity Method Eligible Investments link:presentationLink link:calculationLink link:definitionLink 9952174 - Disclosure - Fair Value of Financial Instruments link:presentationLink link:calculationLink link:definitionLink 9952175 - Disclosure - Commitments and Contingencies link:presentationLink link:calculationLink link:definitionLink 9952176 - Disclosure - Held for Sale link:presentationLink link:calculationLink link:definitionLink 9955511 - Disclosure - Basis of Presentation and Significant Accounting Policies (Policies) link:presentationLink link:calculationLink link:definitionLink 9955512 - Disclosure - Significant Transactions (Tables) link:presentationLink link:calculationLink link:definitionLink 9955513 - Disclosure - Investment Securities (Tables) link:presentationLink link:calculationLink link:definitionLink 9955514 - Disclosure - Goodwill and Other Intangible Assets (Tables) link:presentationLink link:calculationLink link:definitionLink 9955515 - Disclosure - Loss and Loss Adjustment Expense Reserves (Tables) link:presentationLink link:calculationLink link:definitionLink 9955516 - Disclosure - Third-Party Reinsurance (Tables) link:presentationLink link:calculationLink link:definitionLink 9955517 - Disclosure - Debt (Tables) link:presentationLink link:calculationLink link:definitionLink 9955518 - Disclosure - Municipal Bond Guarantee Insurance (Tables) link:presentationLink link:calculationLink link:definitionLink 9955519 - Disclosure - Earnings Per Share (Tables) link:presentationLink link:calculationLink link:definitionLink 9955520 - Disclosure - Employee Share-Based Incentive Compensation Plans (Tables) link:presentationLink link:calculationLink link:definitionLink 9955521 - Disclosure - Noncontrolling Interests (Tables) link:presentationLink link:calculationLink link:definitionLink 9955522 - Disclosure - Segment Information (Tables) link:presentationLink link:calculationLink link:definitionLink 9955523 - Disclosure - Equity Method Eligible Investments (Tables) link:presentationLink link:calculationLink link:definitionLink 9955524 - Disclosure - Fair Value of Financial Instruments (Tables) link:presentationLink link:calculationLink link:definitionLink 9955525 - Disclosure - Basis of Presentation and Significant Accounting Policies (Details) link:presentationLink link:calculationLink link:definitionLink 9955526 - Disclosure - Significant Transactions - Bamboo (Details) link:presentationLink link:calculationLink link:definitionLink 9955527 - Disclosure - Significant Transactions - Distinguished Programs (Details) link:presentationLink link:calculationLink link:definitionLink 9955528 - Disclosure - Significant Transactions - Schedule of Assets Acquired and Liabilities Assumed, Bamboo (Details) link:presentationLink link:calculationLink link:definitionLink 9955529 - Disclosure - Significant Transactions - BroadStreet and Bishop Street (Details) link:presentationLink link:calculationLink link:definitionLink 9955530 - Disclosure - Significant Transactions - Enterprise Solutions (Details) link:presentationLink link:calculationLink link:definitionLink 9955531 - Disclosure - Investment Securities - Schedule of Pre-Tax Net Investment Income (Details) link:presentationLink link:calculationLink link:definitionLink 9955532 - Disclosure - Investment Securities - Net Realized and Unrealized Investment Gains (Losses) (Details) link:presentationLink link:calculationLink link:definitionLink 9955533 - Disclosure - Investment Securities - Investment Gains (Losses) for Level 3 (Details) link:presentationLink link:calculationLink link:definitionLink 9955534 - Disclosure - Investment Securities - Investment Holdings (Details) link:presentationLink link:calculationLink link:definitionLink 9955535 - Disclosure - Investment Securities - Cost and Amortized Cost Maturity Schedule (Details) link:presentationLink link:calculationLink link:definitionLink 9955536 - Disclosure - Investment Securities - Common Equity Securities and Other Long Term Investments (Details) link:presentationLink link:calculationLink link:definitionLink 9955537 - Disclosure - Investment Securities - Fair Value Measurement by Level (Details) link:presentationLink link:calculationLink link:definitionLink 9955538 - Disclosure - Investment Securities - Narrative (Details) link:presentationLink link:calculationLink link:definitionLink 9955539 - Disclosure - Investment Securities - Debt Securities Issued by Corporation (Details) link:presentationLink link:calculationLink link:definitionLink 9955540 - Disclosure - Investment Securities - Mortgage-backed Asset Securities (Details) link:presentationLink link:calculationLink link:definitionLink 9955541 - Disclosure - Investment Securities - Other Long-Term Investments (Details) link:presentationLink link:calculationLink link:definitionLink 9955542 - Disclosure - Investment Securities - Fair Value of Hedge Funds Subject to Restrictions on Redemption Frequency (Details) link:presentationLink link:calculationLink link:definitionLink 9955543 - Disclosure - Investment Securities - Investments In Private Equity Funds Subject to Lock-Up Periods (Details) link:presentationLink link:calculationLink link:definitionLink 9955544 - Disclosure - Investment Securities - Rollforward of Fair Value Measurements by Level (Details) link:presentationLink link:calculationLink link:definitionLink 9955545 - Disclosure - Investment Securities - Significant Unobservable Inputs (Details) link:presentationLink link:calculationLink link:definitionLink 9955546 - Disclosure - Goodwill and Other Intangible Assets - Summary of Goodwill and Intangible Assets (Details) link:presentationLink link:calculationLink link:definitionLink 9955547 - Disclosure - Goodwill and Other Intangible Assets - Schedule of Goodwill and Other Intangible Assets Rollforward (Details) link:presentationLink link:calculationLink link:definitionLink 9955548 - Disclosure - Loss and Loss Adjustment Expense Reserves - LAE Reserve Activity (Details) link:presentationLink link:calculationLink link:definitionLink 9955549 - Disclosure - Loss and Loss Adjustment Expense Reserves - Narrative (Details) link:presentationLink link:calculationLink link:definitionLink 9955550 - Disclosure - Third-Party Reinsurance - Effects of Reinsurance (Details) link:presentationLink link:calculationLink link:definitionLink 9955551 - Disclosure - Third-Party Reinsurance - Reinsurance Recoverables (Details) link:presentationLink link:calculationLink link:definitionLink 9955552 - Disclosure - Third-Party Reinsurance - Remaining Gross and Net Reinsurance Recoverables (Details) link:presentationLink link:calculationLink link:definitionLink 9955553 - Disclosure - Debt - Summary of Debt Outstanding (Details) link:presentationLink link:calculationLink link:definitionLink 9955554 - Disclosure - Debt - Ark Subordinated Notes (Details) link:presentationLink link:calculationLink link:definitionLink 9955555 - Disclosure - Debt - Ark Standby Letters of Credit (Details) link:presentationLink link:calculationLink link:definitionLink 9955556 - Disclosure - Debt - Kudu Credit Facility (Details) link:presentationLink link:calculationLink link:definitionLink 9955557 - Disclosure - Debt - HG Global Senior Notes (Details) link:presentationLink link:calculationLink link:definitionLink 9955558 - Disclosure - Debt - Distinguished Credit Facility (Details) link:presentationLink link:calculationLink link:definitionLink 9955559 - Disclosure - Debt - Other Operations Debt (Details) link:presentationLink link:calculationLink link:definitionLink 9955560 - Disclosure - Debt - Schedule of the Change in Debt (Details) link:presentationLink link:calculationLink link:definitionLink 9955561 - Disclosure - Income Taxes (Details) link:presentationLink link:calculationLink link:definitionLink 9955562 - Disclosure - Derivatives (Details) link:presentationLink link:calculationLink link:definitionLink 9955563 - Disclosure - Municipal Bond Guarantee Insurance - Narrative (Details) link:presentationLink link:calculationLink link:definitionLink 9955564 - Disclosure - Municipal Bond Guarantee Insurance - Schedule of Change in the Fair Value of BAM Surplus Notes (Details) link:presentationLink link:calculationLink link:definitionLink 9955565 - Disclosure - Municipal Bond Guarantee Insurance - Schedule of Municipal Bond Guarantee Insured Obligations (Details) link:presentationLink link:calculationLink link:definitionLink 9955566 - Disclosure - Municipal Bond Guarantee Insurance - Schedule of Municipal Guarantee Insurance Contracts, Premium Received Over Contract Period (Details) link:presentationLink link:calculationLink link:definitionLink 9955567 - Disclosure - Municipal Bond Guarantee Insurance - Schedule of Net Written Premiums (Details) link:presentationLink link:calculationLink link:definitionLink 9955568 - Disclosure - Earnings Per Share - Schedule of Earnings Per Share from Continuing Operations (Details) link:presentationLink link:calculationLink link:definitionLink 9955569 - Disclosure - Earnings Per Share - Schedule of Undistributed Net Earnings (Details) link:presentationLink link:calculationLink link:definitionLink 9955570 - Disclosure - Employee Share-Based Incentive Compensation Plans - Narrative (Details) link:presentationLink link:calculationLink link:definitionLink 9955571 - Disclosure - Employee Share-Based Incentive Compensation Plans - Performance Shares (Details) link:presentationLink link:calculationLink link:definitionLink 9955572 - Disclosure - Employee Share-Based Incentive Compensation Plans - Performance Shares Granted Under the WTM Incentive Plan (Details) link:presentationLink link:calculationLink link:definitionLink 9955573 - Disclosure - Employee Share-Based Incentive Compensation Plans - Restricted Shares (Details) link:presentationLink link:calculationLink link:definitionLink 9955574 - Disclosure - Noncontrolling Interest - Narrative (Details) link:presentationLink link:calculationLink link:definitionLink 9955575 - Disclosure - Noncontrolling Interests - Schedule of Noncontrolling Interest (Details) link:presentationLink link:calculationLink link:definitionLink 9955576 - Disclosure - Segment Information - Narrative (Details) link:presentationLink link:calculationLink link:definitionLink 9955577 - Disclosure - Segment Information - Financial Information for White Mountain's Segments (Details) link:presentationLink link:calculationLink link:definitionLink 9955578 - Disclosure - Segment Information - Revenues (Details) link:presentationLink link:calculationLink link:definitionLink 9955579 - Disclosure - Segment Information - Assets (Details) link:presentationLink link:calculationLink link:definitionLink 9955580 - Disclosure - Variable Interest Entities (Details) link:presentationLink link:calculationLink link:definitionLink 9955581 - Disclosure - Equity Method Eligible Investments - Carrying Value and Ownership Percentages (Details) link:presentationLink link:calculationLink link:definitionLink 9955582 - Disclosure - Equity Method Eligible Investments - Narrative (Details) link:presentationLink link:calculationLink link:definitionLink 9955583 - Disclosure - Fair Value of Financial Instruments (Details) link:presentationLink link:calculationLink link:definitionLink 9955584 - Disclosure - Held for Sale - Narrative (Details) link:presentationLink link:calculationLink link:definitionLink