Summary of Significant Accounting Policies	9 Months Ended
Sep. 30, 2012
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	Summary of Significant Accounting Policies Basis of Presentation These interim consolidated financial statements include the accounts of White Mountains Insurance Group, Ltd. (the “Company” or the “Registrant”) and its subsidiaries (collectively, with the Company, “White Mountains”) and have been prepared in accordance with generally accepted accounting principles in the United States (“GAAP”). The Company is an exempted Bermuda limited liability company whose principal businesses are conducted through its property and casualty insurance and reinsurance subsidiaries and affiliates. The Company’s headquarters is located at 14 Wesley Street, Hamilton, Bermuda HM 11, its principal executive office is located at 80 South Main Street, Hanover, New Hampshire 03755-2053 and its registered office is located at Clarendon House, 2 Church Street, Hamilton, Bermuda HM 11. White Mountains’ reportable segments are OneBeacon, Sirius Group and Other Operations. As discussed further in Note 2, on October 7, 2011, White Mountains completed its sale of Esurance Holdings, Inc. and its subsidiaries (“Esurance Insurance”) and Answer Financial Inc. and its subsidiaries (“AFI”) (collectively, “Esurance”). Esurance has been presented as discontinued operations. (See Note 14 for discontinued operations). The OneBeacon segment consists of OneBeacon Insurance Group, Ltd. (“OneBeacon Ltd.”), an exempted Bermuda limited liability company that owns a family of U.S.-based property and casualty insurance companies (collectively “OneBeacon”), most of which operate in a multi-company pool. OneBeacon is a specialty property and casualty insurance writer that offers a wide range of insurance products through independent agencies, regional and national brokers, wholesalers and managing general agencies. As of September 30, 2012 and December 31, 2011, White Mountains owned 75.2% and 75.5% of OneBeacon Ltd.’s outstanding common shares. As discussed further in Note 2, OneBeacon entered into a definitive agreement to sell its runoff business in October 2012 and sold its AutoOne Insurance business (“AutoOne”) in February 2012. The runoff business and AutoOne are presented as discontinued operations. Assets and liabilities associated with the runoff business as of September 30, 2012 and AutoOne as of December 31, 2011 have been presented as held for sale in the financial statements. Prior year income statement and cash flow amounts have been reclassified to conform to the current year’s presentation. (See Note 14 for discontinued operations). The Sirius Group segment consists of Sirius International Insurance Group, Ltd., an exempted Bermuda limited liability company, and its subsidiaries (collectively, “Sirius Group”). Sirius Group provides insurance and reinsurance products for property, accident and health, aviation and space, trade credit, marine, agriculture and certain other exposures on a worldwide basis through its subsidiaries, Sirius International Insurance Corporation (“Sirius International”), Sirius America Insurance Company (“Sirius America”) and Lloyds Syndicate 1945 (“Syndicate 1945”). Sirius Group also specializes in the acquisition and management of runoff insurance and reinsurance companies both in the United States and internationally through its White Mountains Solutions division. On December 31, 2011, Sirius Group completed a transaction led by White Mountains Solutions to acquire the runoff loss reserve portfolio of Old Lyme Insurance Company Ltd. (“Old Lyme”). Sirius Group also includes Scandinavian Reinsurance Company, Ltd. (“Scandinavian Re”) and Central National Insurance Company of Omaha (“Central National”), which are both in runoff. White Mountains’ Other Operations segment consists of the Company and its intermediate holding companies, its wholly-owned investment management subsidiary, White Mountains Advisors LLC (“WM Advisors”), White Mountains’ variable annuity reinsurance business, White Mountains Life Reinsurance (Bermuda) Ltd. (“WM Life Re”), which is in runoff, as well as various other entities not included in other segments. For 2011, the Other Operations segment also included the consolidated results of the Tuckerman Capital, LP fund (“Tuckerman Fund I”). On December 31, 2011, Tuckerman Fund I liquidated and distributed all of its assets, which consisted of shares of two small manufacturing companies, Hamer, LLC (“Hamer”) and Bri-Mar Manufacturing, LLC (“Bri-Mar”), to its partners, including White Mountains. Commencing on January 1, 2012, the consolidated results of Hamer and Bri-Mar are included in the Other Operations segment. In July 2012, White Mountains capitalized HG Global Ltd. ("HG Global") to fund Build America Mutual Assurance Company ("BAM"), a newly formed mutual municipal bond insurer, and HG Re, Ltd. ("HG Re"), a wholly-owned subsidiary of HG Global. As of September 30, 2012, White Mountains owned 97% of HG Global's preferred equity and 89% of its common equity. HG Global provided the initial capitalization of BAM through the purchase of surplus notes. Through HG Re, HG Global provides first loss reinsurance protection for policies underwritten by BAM of 15% of par outstanding, on a per policy basis. HG Re's obligations to BAM are collateralized in trusts, and there is an aggregate loss limit that is equal to the total assets in the collateral trusts at any point in time. HG Global and BAM are both included in the Other Operations segment. U.S. GAAP requires White Mountains to consolidate the results of BAM. However, BAM is a mutual insurance company owned by its members and its equity and results of operations are included in noncontrolling interests. White Mountains’ discontinued operations consist of Esurance Insurance, AFI, OneBeacon's runoff business and AutoOne. Esurance Insurance wrote personal auto insurance directly to customers in 30 states through its website and over the phone and also sold other lines of personal insurance for unaffiliated insurance companies. Esurance Insurance also wrote personal auto policies through select online agents and provided other insurance products through partnerships with industry leading online providers. Esurance Insurance earned commissions and fees by referring to unaffiliated insurance companies those shoppers that it could not underwrite because of pricing or underwriting eligibility. AFI sold insurance online and through call centers for both Esurance Insurance and unaffiliated companies utilizing a comparison quoting platform. AutoOne was formed by OneBeacon in 2001 to provide products and services to automobile assigned risk markets primarily in New York and New Jersey. All significant intercompany transactions have been eliminated in consolidation. These interim financial statements include all adjustments considered necessary by management to fairly present the financial position, results of operations and cash flows of White Mountains. These interim financial statements may not be indicative of financial results for the full year and should be read in conjunction with the Company’s 2011 Annual Report on Form 10-K. The preparation of 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 as of the date of the financial statements and the reported amounts of revenues and expenses during the reporting period. Actual results could differ from those estimates. Refer to the Company’s 2011 Annual Report on Form 10-K for a complete discussion regarding White Mountains’ significant accounting policies. Noncontrolling Interests Noncontrolling interests consist of the ownership interests of noncontrolling parties in consolidated entities and are presented separately as a component of equity on the balance sheet. The percentage of the noncontrolling equity interests in OneBeacon Ltd. at September 30, 2012 and December 31, 2011 was 24.8% and 24.5%. In July 2012, HG Global was capitalized with $594.5 million from White Mountains and $14.5 million from certain management members of BAM, the latter of which is included in noncontrolling interest. Upon closing, certain BAM management members also received additional common and preferred shares of HG Global that resulted in a $2.2 million allocation of the carrying value of White Mountains' investment in HG Global to the noncontrolling interest, which was recorded as an adjustment to paid-in surplus in White Mountains' consolidated statement of changes in equity. White Mountains is required to consolidate BAM in its GAAP financial statements. However, since BAM is a mutual insurance company that is owned by its members and not White Mountains, BAM's results do not affect White Mountains' common shareholders' equity as they are attributable to noncontrolling interests. For the third quarter of 2012, BAM reported $18 million in pre-tax losses that have been allocated to noncontrolling interest. In May 2007, Sirius International Group, Ltd. (“SIG”), an intermediate holding company of Sirius Group, issued $250 million non-cumulative perpetual preference shares with a $1,000 per share liquidation preference (the “SIG Preference Shares”). Proceeds of $245.7 million, net of $4.3 million of issuance costs and commissions, were received from the issuance. The SIG Preference Shares are included in noncontrolling interests on the balance sheet. At September 30, 2012 and December 31, 2011, the noncontrolling equity interest in limited partnerships that are consolidated with White Mountains (the Prospector Offshore Fund, the Prospector Turtle Fund and Tuckerman Fund I prior to December 31, 2011) was $52.8 million and $54.2 million. On December 31, 2011, Tuckerman Fund I was dissolved and all of the net assets of the fund, which consisted of common stock of Hamer and Bri-Mar, were distributed. At September 30, 2012, the noncontrolling equity interest in Hamer and Bri-Mar was $4.5 million. At September 30, 2012 and December 31, 2011, the noncontrolling equity interest in A.W.G. Dewar Inc, a subsidiary of OneBeacon, was $3.2 million and $2.3 million. At September 30, 2012 and December 31, 2011, the noncontrolling equity interest in Passage2Health Limited, a subsidiary of Sirius Group, was $0.3 million and $0.6 million. Recently Adopted Changes in Accounting Principles Policy Acquisition Costs On January 1, 2012, White Mountains adopted ASU 2010-26, Accounting for Costs Associated with Acquiring or Renewing Insurance Contracts (ASC 944). The new standard changes the types of policy acquisition costs that are eligible for deferral. Specifically, the new guidance limits deferrable costs to those that are incremental direct costs of contract acquisition and certain costs related to acquisition activities performed by the insurer, such as underwriting, policy issuance and processing, medical and inspection costs and sales force contract selling. The ASU defines incremental direct costs as those costs that result directly from and were essential to the contract acquisition and would not have been incurred absent the acquisition. Accordingly, under the new guidance, deferrable acquisition costs are limited to costs related to successful contract acquisitions. Acquisition costs that are not eligible for deferral are to be charged to expense in the period incurred. White Mountains adopted ASU 2010-26 prospectively. Upon adoption, certain acquisition costs, primarily a portion of the profit sharing commissions associated with OneBeacon’s collector car and boats business, no longer meet the criteria for deferral. Deferred acquisition costs of $5.6 million at January 1, 2012 that no longer meet the criteria for deferral under ASU 2010-26 will be recognized in expense over the original amortization periods. For the three and nine months ended September 30, 2012, White Mountains recognized $0.9 million and $5.3 million of expense related to such previously deferrable acquisition costs. If White Mountains had adopted ASU 2010-26 retrospectively, $1.4 million and $5.7 million of acquisition costs that were deferred would have been recognized in expense for the three and nine months ended September 30, 2011. Fair Value Measurements On January 1, 2012, White Mountains adopted ASU 2011-04, Amendments to Achieve Common Fair Value Measurement and Disclosure Requirements in U.S. GAAP and IFRS. The ASU clarifies existing guidance with respect to the concepts of highest and best use and valuation premise and measuring instruments classified within a reporting entity’s shareholders’ equity. The ASU also clarifies disclosure requirements, requiring disclosure of quantitative information about unobservable inputs used in Level 3 fair value measurements. The ASU also amends existing guidance. In circumstances where a reporting entity manages a portfolio of financial assets and liabilities based on the net market and counterparty credit risk exposures, the ASU permits determination of the fair value of those instruments to be based on the net risk exposure. In addition, the ASU permits the application of premiums or discounts to be applied in a fair value measurement to the extent that market participants would consider them in valuing the financial instruments. The ASU also expands the required disclosures for Level 3 measurements, requiring that reporting entities provide a narrative description of the sensitivity of Level 3 fair value measurements to changes in unobservable inputs and the interrelationships between those inputs, if any. As a result of adopting ASU 2011-04, White Mountains expanded its fair value disclosures. (See Note 5). Comprehensive Income For fiscal periods beginning after December 15, 2011, ASU 2011-05, Comprehensive Income, became effective, which requires all components of comprehensive income to be reported in a continuous financial statement or in consecutive statements displaying the components of net income and the components of other comprehensive income. Since White Mountains previously presented comprehensive income in a continuous financial statement, adoption of ASU 2011-05 had no effect on White Mountains’ financial statement presentation. Recently Issued Accounting Pronouncements Offsetting Assets and Liabilities On December 16, 2011, the FASB issued ASU 2011-11, Disclosures about Offsetting Assets and Liabilities (ASC 210). The new standard expands the required disclosures in circumstances where either balances have been offset or the right of offset exists. The required disclosures are intended to provide information to enable financial statement users to evaluate the effect or potential effect of netting arrangements on a reporting entity’s financial position. Disclosures required under the new standard include the gross amount of assets and liabilities recognized; the amounts that have been offset to arrive at the amounts presented in the statement of financial position; and for any amounts subject to an enforceable master netting arrangement, whether such amounts have been offset. In addition, a description of the rights of offset should be disclosed. ASU 2011-11 is effective for periods beginning on or after January 1, 2013. White Mountains is party to master netting arrangements in connection with the derivative instruments held by WM Life Re and is currently evaluating the effect of adoption will have on its disclosures, but does not expect adoption to have a material effect on its financial position, results of operations or cash flows.

Summary of Significant Accounting Policies

Basis of Presentation

These interim consolidated financial statements include the accounts of White Mountains Insurance Group, Ltd. (the “Company” or the “Registrant”) and its subsidiaries (collectively, with the Company, “White Mountains”) and have been prepared in accordance with generally accepted accounting principles in the United States (“GAAP”). The Company is an exempted Bermuda limited liability company whose principal businesses are conducted through its property and casualty insurance and reinsurance subsidiaries and affiliates. The Company’s headquarters is located at 14 Wesley Street, Hamilton, Bermuda HM 11, its principal executive office is located at 80 South Main Street, Hanover, New Hampshire 03755-2053 and its registered office is located at Clarendon House, 2 Church Street, Hamilton, Bermuda HM 11. White Mountains’ reportable segments are OneBeacon, Sirius Group and Other Operations. As discussed further in Note 2, on October 7, 2011, White Mountains completed its sale of Esurance Holdings, Inc. and its subsidiaries (“Esurance Insurance”) and Answer Financial Inc. and its subsidiaries (“AFI”) (collectively, “Esurance”). Esurance has been presented as discontinued operations. (See Note 14 for discontinued operations).

The OneBeacon segment consists of OneBeacon Insurance Group, Ltd. (“OneBeacon Ltd.”), an exempted Bermuda limited liability company that owns a family of U.S.-based property and casualty insurance companies (collectively “OneBeacon”), most of which operate in a multi-company pool. OneBeacon is a specialty property and casualty insurance writer that offers a wide range of insurance products through independent agencies, regional and national brokers, wholesalers and managing general agencies. As of September 30, 2012 and December 31, 2011, White Mountains owned 75.2% and 75.5% of OneBeacon Ltd.’s outstanding common shares.

As discussed further in Note 2, OneBeacon entered into a definitive agreement to sell its runoff business in October 2012 and sold its AutoOne Insurance business (“AutoOne”) in February 2012. The runoff business and AutoOne are presented as discontinued operations. Assets and liabilities associated with the runoff business as of September 30, 2012 and AutoOne as of December 31, 2011 have been presented as held for sale in the financial statements. Prior year income statement and cash flow amounts have been reclassified to conform to the current year’s presentation. (See Note 14 for discontinued operations).

The Sirius Group segment consists of Sirius International Insurance Group, Ltd., an exempted Bermuda limited liability company, and its subsidiaries (collectively, “Sirius Group”). Sirius Group provides insurance and reinsurance products for property, accident and health, aviation and space, trade credit, marine, agriculture and certain other exposures on a worldwide basis through its subsidiaries, Sirius International Insurance Corporation (“Sirius International”), Sirius America Insurance Company (“Sirius America”) and Lloyds Syndicate 1945 (“Syndicate 1945”). Sirius Group also specializes in the acquisition and management of runoff insurance and reinsurance companies both in the United States and internationally through its White Mountains Solutions division. On December 31, 2011, Sirius Group completed a transaction led by White Mountains Solutions to acquire the runoff loss reserve portfolio of Old Lyme Insurance Company Ltd. (“Old Lyme”). Sirius Group also includes Scandinavian Reinsurance Company, Ltd. (“Scandinavian Re”) and Central National Insurance Company of Omaha (“Central National”), which are both in runoff.

White Mountains’ Other Operations segment consists of the Company and its intermediate holding companies, its wholly-owned investment management subsidiary, White Mountains Advisors LLC (“WM Advisors”), White Mountains’ variable annuity reinsurance business, White Mountains Life Reinsurance (Bermuda) Ltd. (“WM Life Re”), which is in runoff, as well as various other entities not included in other segments. For 2011, the Other Operations segment also included the consolidated results of the Tuckerman Capital, LP fund (“Tuckerman Fund I”). On December 31, 2011, Tuckerman Fund I liquidated and distributed all of its assets, which consisted of shares of two small manufacturing companies, Hamer, LLC (“Hamer”) and Bri-Mar Manufacturing, LLC (“Bri-Mar”), to its partners, including White Mountains. Commencing on January 1, 2012, the consolidated results of Hamer and Bri-Mar are included in the Other Operations segment.

In July 2012, White Mountains capitalized HG Global Ltd. ("HG Global") to fund Build America Mutual Assurance Company ("BAM"), a newly formed mutual municipal bond insurer, and HG Re, Ltd. ("HG Re"), a wholly-owned subsidiary of HG Global. As of September 30, 2012, White Mountains owned 97% of HG Global's preferred equity and 89% of its common equity. HG Global provided the initial capitalization of BAM through the purchase of surplus notes. Through HG Re, HG Global provides first loss reinsurance protection for policies underwritten by BAM of 15% of par outstanding, on a per policy basis. HG Re's obligations to BAM are collateralized in trusts, and there is an aggregate loss limit that is equal to the total assets in the collateral trusts at any point in time. HG Global and BAM are both included in the Other Operations segment. U.S. GAAP requires White Mountains to consolidate the results of BAM. However, BAM is a mutual insurance company owned by its members and its equity and results of operations are included in noncontrolling interests.

White Mountains’ discontinued operations consist of Esurance Insurance, AFI, OneBeacon's runoff business and AutoOne. Esurance Insurance wrote personal auto insurance directly to customers in 30 states through its website and over the phone and also sold other lines of personal insurance for unaffiliated insurance companies. Esurance Insurance also wrote personal auto policies through select online agents and provided other insurance products through partnerships with industry leading online providers. Esurance Insurance earned commissions and fees by referring to unaffiliated insurance companies those shoppers that it could not underwrite because of pricing or underwriting eligibility. AFI sold insurance online and through call centers for both Esurance Insurance and unaffiliated companies utilizing a comparison quoting platform. AutoOne was formed by OneBeacon in 2001 to provide products and services to automobile assigned risk markets primarily in New York and New Jersey.

All significant intercompany transactions have been eliminated in consolidation. These interim financial statements include all adjustments considered necessary by management to fairly present the financial position, results of operations and cash flows of White Mountains. These interim financial statements may not be indicative of financial results for the full year and should be read in conjunction with the Company’s 2011 Annual Report on Form 10-K.

The preparation of 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 as of the date of the financial statements and the reported amounts of revenues and expenses during the reporting period. Actual results could differ from those estimates. Refer to the Company’s 2011 Annual Report on Form 10-K for a complete discussion regarding White Mountains’ significant accounting policies.

Noncontrolling Interests

Noncontrolling interests consist of the ownership interests of noncontrolling parties in consolidated entities and are presented separately as a component of equity on the balance sheet.

The percentage of the noncontrolling equity interests in OneBeacon Ltd. at September 30, 2012 and December 31, 2011 was 24.8% and 24.5%.

In July 2012, HG Global was capitalized with $594.5 million from White Mountains and $14.5 million from certain management members of BAM, the latter of which is included in noncontrolling interest. Upon closing, certain BAM management members also received additional common and preferred shares of HG Global that resulted in a $2.2 million allocation of the carrying value of White Mountains' investment in HG Global to the noncontrolling interest, which was recorded as an adjustment to paid-in surplus in White Mountains' consolidated statement of changes in equity.

White Mountains is required to consolidate BAM in its GAAP financial statements. However, since BAM is a mutual insurance company that is owned by its members and not White Mountains, BAM's results do not affect White Mountains' common shareholders' equity as they are attributable to noncontrolling interests. For the third quarter of 2012, BAM reported $18 million in pre-tax losses that have been allocated to noncontrolling interest.

In May 2007, Sirius International Group, Ltd. (“SIG”), an intermediate holding company of Sirius Group, issued $250 million non-cumulative perpetual preference shares with a $1,000 per share liquidation preference (the “SIG Preference Shares”). Proceeds of $245.7 million, net of $4.3 million of issuance costs and commissions, were received from the issuance. The SIG Preference Shares are included in noncontrolling interests on the balance sheet.

At September 30, 2012 and December 31, 2011, the noncontrolling equity interest in limited partnerships that are consolidated with White Mountains (the Prospector Offshore Fund, the Prospector Turtle Fund and Tuckerman Fund I prior to December 31, 2011) was $52.8 million and $54.2 million. On December 31, 2011, Tuckerman Fund I was dissolved and all of the net assets of the fund, which consisted of common stock of Hamer and Bri-Mar, were distributed. At September 30, 2012, the noncontrolling equity interest in Hamer and Bri-Mar was $4.5 million. At September 30, 2012 and December 31, 2011, the noncontrolling equity interest in A.W.G. Dewar Inc, a subsidiary of OneBeacon, was $3.2 million and $2.3 million. At September 30, 2012 and December 31, 2011, the noncontrolling equity interest in Passage2Health Limited, a subsidiary of Sirius Group, was $0.3 million and $0.6 million.

Recently Adopted Changes in Accounting Principles

Policy Acquisition Costs

On January 1, 2012, White Mountains adopted ASU 2010-26, Accounting for Costs Associated with Acquiring or Renewing Insurance Contracts (ASC 944). The new standard changes the types of policy acquisition costs that are eligible for deferral. Specifically, the new guidance limits deferrable costs to those that are incremental direct costs of contract acquisition and certain costs related to acquisition activities performed by the insurer, such as underwriting, policy issuance and processing, medical and inspection costs and sales force contract selling. The ASU defines incremental direct costs as those costs that result directly from and were essential to the contract acquisition and would not have been incurred absent the acquisition. Accordingly, under the new guidance, deferrable acquisition costs are limited to costs related to successful contract acquisitions. Acquisition costs that are not eligible for deferral are to be charged to expense in the period incurred.

White Mountains adopted ASU 2010-26 prospectively. Upon adoption, certain acquisition costs, primarily a portion of the profit sharing commissions associated with OneBeacon’s collector car and boats business, no longer meet the criteria for deferral. Deferred acquisition costs of $5.6 million at January 1, 2012 that no longer meet the criteria for deferral under ASU 2010-26 will be recognized in expense over the original amortization periods. For the three and nine months ended September 30, 2012, White Mountains recognized $0.9 million and $5.3 million of expense related to such previously deferrable acquisition costs. If White Mountains had adopted ASU 2010-26 retrospectively, $1.4 million and $5.7 million of acquisition costs that were deferred would have been recognized in expense for the three and nine months ended September 30, 2011.

Fair Value Measurements

On January 1, 2012, White Mountains adopted ASU 2011-04, Amendments to Achieve Common Fair Value Measurement and Disclosure Requirements in U.S. GAAP and IFRS. The ASU clarifies existing guidance with respect to the concepts of highest and best use and valuation premise and measuring instruments classified within a reporting entity’s shareholders’ equity. The ASU also clarifies disclosure requirements, requiring disclosure of quantitative information about unobservable inputs used in Level 3 fair value measurements. The ASU also amends existing guidance. In circumstances where a reporting entity manages a portfolio of financial assets and liabilities based on the net market and counterparty credit risk exposures, the ASU permits determination of the fair value of those instruments to be based on the net risk exposure. In addition, the ASU permits the application of premiums or discounts to be applied in a fair value measurement to the extent that market participants would consider them in valuing the financial instruments. The ASU also expands the required disclosures for Level 3 measurements, requiring that reporting entities provide a narrative description of the sensitivity of Level 3 fair value measurements to changes in unobservable inputs and the interrelationships between those inputs, if any. As a result of adopting ASU 2011-04, White Mountains expanded its fair value disclosures. (See Note 5).

Comprehensive Income

For fiscal periods beginning after December 15, 2011, ASU 2011-05, Comprehensive Income, became effective, which requires all components of comprehensive income to be reported in a continuous financial statement or in consecutive statements displaying the components of net income and the components of other comprehensive income. Since White Mountains previously presented comprehensive income in a continuous financial statement, adoption of ASU 2011-05 had no effect on White Mountains’ financial statement presentation.

Recently Issued Accounting Pronouncements

Offsetting Assets and Liabilities

On December 16, 2011, the FASB issued ASU 2011-11, Disclosures about Offsetting Assets and Liabilities (ASC 210). The new standard expands the required disclosures in circumstances where either balances have been offset or the right of offset exists. The required disclosures are intended to provide information to enable financial statement users to evaluate the effect or potential effect of netting arrangements on a reporting entity’s financial position. Disclosures required under the new standard include the gross amount of assets and liabilities recognized; the amounts that have been offset to arrive at the amounts presented in the statement of financial position; and for any amounts subject to an enforceable master netting arrangement, whether such amounts have been offset. In addition, a description of the rights of offset should be disclosed. ASU 2011-11 is effective for periods beginning on or after January 1, 2013. White Mountains is party to master netting arrangements in connection with the derivative instruments held by WM Life Re and is currently evaluating the effect of adoption will have on its disclosures, but does not expect adoption to have a material effect on its financial position, results of operations or cash flows.