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Significant Transactions Formation of HG and BAM (Details) (USD $) In Millions, except Share data, unless otherwise specified | 9 Months Ended
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Sep. 30, 2012
Significant Transactions |
Shares remaining under share repurchase authorization | 970,496
Percentage of par value of policy reinsured | 15.00%
White Mountains [Member] |
Significant Transactions |
Funds to Capitalized HG Global | $ 594.5
HG Global [Member] |
Significant Transactions |
Interest income, surplus notes | 8.3
Income (Loss) from Continuing Operations before Income Taxes, Foreign | 4.8
Surplus Notes | 503.0
HG Global [Member] | Common Stock |
Significant Transactions |
Ownership interest (as a percent) | 89.00%
Percentage of par value of policy reinsured | 15.00%
HG Global [Member] | Preferred Stock |
Significant Transactions |
Ownership interest (as a percent) | 97.00%
Build America Mutual [Member] |
Significant Transactions |
Interest income, surplus notes | (8.3)
Income (Loss) from Continuing Operations before Income Taxes, Foreign | $ 18.0

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- Definition The percentage of ownership of common stock or equity participation in the investee accounted for under the equity method of accounting. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 159 -Paragraph 18 -Subparagraph f -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy. Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 323 -SubTopic 10 -Section 50 -Paragraph 3 -Subparagraph (a)(1) -URI http://asc.fasb.org/extlink&oid=6382943&loc=d3e33918-111571 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher AICPA -Name Accounting Principles Board Opinion (APB) -Number 18 -Paragraph 20 -Subparagraph a (1) -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy. + Details
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- Definition The portion of earnings or loss from continuing operations before income taxes that is attributable to foreign operations, which is defined as Income or Loss generated from operations located outside the entity's country of domicile. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 235 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.4-08.(h)(1)(i)) -URI http://asc.fasb.org/extlink&oid=6881521&loc=d3e23780-122690 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 08 -Paragraph h -Subparagraph 1(i) -Article 4 + Details
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- Definition The remaining number of shares authorized to be repurchased by an entity's Board of Directors under a stock repurchase plan. + References No definition available. + Details
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