XML 138 R58.htm IDEA: XBRL DOCUMENT
v2.4.0.6

Significant Transactions (Details 2) (USD $) In Millions, unless otherwise specified | 12 Months Ended | 1 Months Ended | 12 Months Ended | 1 Months Ended | 3 Months Ended | 12 Months Ended | 1 Months Ended | 12 Months Ended
--- | --- | --- | --- | --- | --- | --- | --- | ---
Dec. 31, 2011 | Dec. 31, 2010 | Dec. 31, 2009 | Oct. 31, 2011 Esurance | Dec. 31, 2011 AutoOne | Jul. 31, 2010 One Beacon Personal Lines entity Y | Jun. 30, 2011 One Beacon Personal Lines | Dec. 31, 2010 One Beacon Personal Lines | Dec. 31, 2009 One Beacon Personal Lines | Dec. 31, 2009 OneBeacon Commercial Lines | Dec. 31, 2011 OneBeacon Commercial Lines | Dec. 31, 2010 OneBeacon Commercial Lines
Significant Transactions |  |  |  |  |  |  |  |  |  |  |  |
Consideration in excess of tangible book value |  |  |  | $ 700 |  |  |  |  |  |  |  |
Consideration from sale of business | 1,010.6 | 188.3 |  |  |  | 166.6 |  |  |  | 23.2 | 0.8 | 10.2
Number of insurance companies sold |  |  |  |  |  | 2 |  |  |  |  |  |
Ceded share of traditional personal lines business (as a percent) |  |  |  |  |  | 100.00% |  |  |  |  |  |
Assumed risk, certain specialty lines business written by York (as a percent) |  |  |  |  |  | 100.00% |  |  |  |  |  |
Number of attorneys-in-fact sold |  |  |  |  |  | 2 |  |  |  |  |  |
Transition Service Agreement period (in years) |  |  |  |  |  | 3 |  |  |  |  |  |
Gain on sale of business in discontinued operations | 677.5 |  |  | 677.5 |  |  |  |  |  |  |  |
Loss on sale of business in discontinued operations | 19.2 |  |  |  | 19.2 |  |  |  |  |  |  |
Gain (loss) from sale of business, net of tax |  |  |  |  |  |  |  | 24.6 |  |  |  |
Gain (loss) on disposal of business before tax |  |  |  |  |  |  |  | 8.5 |  |  |  |
Tax benefit from disposal of business |  |  |  |  | 10.4 |  | 5.6 | 16.1 |  |  |  |
Written premiums for business sold, net | 1,978.6 | 2,024.8 | 2,624.6 |  |  |  |  |  | 420.0 |  |  |
Value of renewal rights sold in premiums |  |  |  |  |  |  |  |  |  | $ 490 |  | $ 200
Discount rate utilized for the revaluation of the plan obligations (as a percent) | 4.38% | 4.94% |  |  |  |  |  |  |  |  |  |

X
- Definition The interest rate used to adjust for the time value of money for the plan. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 132R -Paragraph 5 -Subparagraph j -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.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 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (k)(1) -URI http://asc.fasb.org/extlink&oid=6962843&loc=d3e1928-114920 + Details
Name: | us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingBenefitObligationDiscountRate
Namespace Prefix: | us-gaap_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition Tax expense or benefit on the gain (loss), not previously recognized and resulting from the sale of a business component, which is recognized at the date of sale. A gain (loss) reflects the amount by which the consideration received exceeds (is exceeded by) the net carrying amount (reflecting previous provisions for loss on disposal, if any) of the disposal group. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 205 -SubTopic 20 -Section 45 -Paragraph 3 -URI http://asc.fasb.org/extlink&oid=6892542&loc=d3e957-107759 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 20 -Section 45 -Paragraph 2 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=6909487&loc=d3e38679-109324 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 144 -Paragraph 43 -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 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 50 -Paragraph 10 -URI http://asc.fasb.org/extlink&oid=6907707&loc=d3e32672-109319 Reference 5: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 144 -Paragraph 47 -Subparagraph b -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 6: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 205 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=6360339&loc=d3e1361-107760 + Details
Name: | us-gaap_DiscontinuedOperationTaxEffectOfIncomeLossFromDisposalOfDiscontinuedOperation
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition The gain (loss) resulting from the sale of a disposal group that is not a discontinued operation. It is included in income from continuing operations before income taxes in the income statement. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 360 -SubTopic 10 -Section 45 -Paragraph 5 -URI http://asc.fasb.org/extlink&oid=6390789&loc=d3e2443-110228 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 144 -Paragraph 47 -Subparagraph b -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 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 144 -Paragraph 37, 45 -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 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 205 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=6360339&loc=d3e1361-107760 + Details
Name: | us-gaap_DisposalGroupNotDiscontinuedOperationGainLossOnDisposal
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Premiums written for all insurance and reinsurance contracts, after adding premiums assumed from other insurers and subtracting any amounts ceded to another insurer. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 17 -Article 12 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 113 -Paragraph 27 -Subparagraph a, b -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 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 605 -Section 50 -Paragraph 1 -Subparagraph (b),(c) -URI http://asc.fasb.org/extlink&oid=6486672&loc=d3e27261-158547 + Details
Name: | us-gaap_PremiumsWrittenNet
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition The cash inflow associated with the deconsolidation of a previously consolidated subsidiary or sale of an entity that is related to it but not strictly controlled. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 12 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=6943989&loc=d3e3179-108585 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher AICPA -Number 51 -Name Accounting Research Bulletin (ARB) -Paragraph 39 -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 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 95 -Paragraph 15 -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 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 95 -Paragraph 16 -Subparagraph b -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 5: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Glossary Investing Activities -URI http://asc.fasb.org/extlink&oid=6516133 + Details
Name: | us-gaap_ProceedsFromDivestitureOfInterestInSubsidiariesAndAffiliates
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition The percentage of the non-traditional personal lines business written directly by York which the entity has assumed on a quota share basis. + References No definition available. + Details
Name: | wtm_AssumedRiskNontraditionalPersonalLinesBusinessWrittenByYorkPercentage
Namespace Prefix: | wtm_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition The percentage of the traditional personal lines business written by the entity which is ceded on a quota share basis. + References No definition available. + Details
Name: | wtm_CededShareTraditionalPersonalLinesBusinessWrittenPercentage
Namespace Prefix: | wtm_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition Consideration in excess of tangible book value for the sale of a business + References No definition available. + Details
Name: | wtm_ConsiderationInExcessOfTangibleBookValueForTheSaleOfABusiness
Namespace Prefix: | wtm_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Represents the after-tax gain for the sale of a business. + References No definition available. + Details
Name: | wtm_DiscontinuedOperationGainOnDisposalOfDiscontinuedOperationNetOfTax
Namespace Prefix: | wtm_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Represents the after-tax loss on the sale of a business. + References No definition available. + Details
Name: | wtm_DiscontinuedOperationLossOnDisposalOfDiscontinuedOperationNetOfTax
Namespace Prefix: | wtm_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition The after-tax gain (loss) resulting from the sale of a disposal group that is not a discontinued operation. + References No definition available. + Details
Name: | wtm_DisposalGroupNotDiscontinuedOperationGainLossIncludingTaxBenefitOnDisposal
Namespace Prefix: | wtm_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Represents the number of attorneys-in-fact managing reciprocal insurance exchanges sold in a transaction. + References No definition available. + Details
Name: | wtm_NumberOfAttorneysInFact
Namespace Prefix: | wtm_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | duration

X
- Definition Represents the number of insurance companies sold in a transaction. + References No definition available. + Details
Name: | wtm_NumberOfInsuranceCompaniesSold
Namespace Prefix: | wtm_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | instant

X
- Definition Represents the period over which certain services will be provided to the acquirer under a Transition Services Agreement. + References No definition available. + Details
Name: | wtm_PeriodToProvideCertainServices
Namespace Prefix: | wtm_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | wtm_SignificantTransactionsLineItems
Namespace Prefix: | wtm_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Represents the value of premium renewal rights that were sold. + References No definition available. + Details
Name: | wtm_ValueOfRenewalRightsInPremiums
Namespace Prefix: | wtm_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration