XML 20 R92.htm IDEA: XBRL DOCUMENT
v2.4.0.8

Discontinued Operations (Details) (USD $) In Millions, unless otherwise specified | 3 Months Ended | 6 Months Ended |  | 3 Months Ended | 6 Months Ended |  | 6 Months Ended |  | 1 Months Ended | 3 Months Ended |  |  | 3 Months Ended | 6 Months Ended
--- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | ---
Jun. 30, 2013 | Jun. 30, 2012 | Jun. 30, 2013 | Jun. 30, 2012 | Dec. 31, 2012 | Jun. 30, 2013 Segment, Discontinued Operations | Jun. 30, 2012 Segment, Discontinued Operations | Jun. 30, 2013 Segment, Discontinued Operations | Jun. 30, 2012 Segment, Discontinued Operations | Dec. 31, 2012 Segment, Discontinued Operations | Jun. 30, 2013 Segment, Discontinued Operations OneBeacon Runoff Contract | Dec. 31, 2012 Segment, Discontinued Operations OneBeacon Runoff | May 30, 2001 Segment, Discontinued Operations GRC Cover OneBeacon Runoff | Jun. 30, 2013 Segment, Discontinued Operations NICO Cover OneBeacon Runoff | May 31, 2001 Segment, Discontinued Operations General Reinsurance Corporation GRC Cover OneBeacon Runoff | Feb. 22, 2012 AutoOne Entity | Jun. 30, 2012 OneBeacon Runoff Segment, Discontinued Operations | Jun. 30, 2012 OneBeacon Runoff Segment, Discontinued Operations
Reinsurance [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Other revenue | $ 0.4 | $ (0.5) | $ 28.7 | $ 30.7 |  | $ 12.2 | $ 0 | $ 12.2 | $ 0 |  | $ 7.8 |  |  |  |  |  |  |
Number of insurance companies sold |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 2 |  |
Loss from sale of discontinued operations |  |  |  |  |  | 0 | 0 | 0 | 0 |  |  |  |  |  |  |  |  |
Net gain (loss) income from discontinued operations, net of tax | 3.9 | 0.5 | 4.4 | (8.8) |  | 3.9 | 0.5 | 4.4 | (8.8) |  |  |  |  |  |  |  |  |
Net favorable and unfavorable loss reserve development | (15.4) | (3.5) | (14.0) | (11.1) |  |  |  |  |  |  |  |  |  |  |  |  | 0.1 | 12.5
Number of contracts seller caused one beacon to purchase prior to acquisition |  |  |  |  |  |  |  |  |  |  | 2 |  |  |  |  |  |  |
Reinsurance recoverable cover under reinsurance contract |  |  |  |  |  |  |  |  |  |  |  |  | 570.0 | 2,500.0 |  |  |  |
Adverse loss reserve development on losses occurring in years 2000 and prior |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 400.0 |  |  |
Loss reserves ceded at acquisition |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 170.0 |  |  |
Reinsurance recoverables |  |  |  |  |  |  |  |  |  |  | 1,315.4 | 1,401.9 |  |  |  |  |  |
A M Best Rating System, Number of Debt Ratings |  |  |  |  |  |  |  |  |  |  | 16 |  |  |  |  |  |  |
Reinsurance recoverable on paid losses | 16.1 |  | 16.1 |  | 17.9 | 21.4 |  | 21.4 |  | 15.6 | 21.4 |  |  |  |  |  |  |
Reinsurance recoverables, gross of purchase accounting adjustments |  |  |  |  |  |  |  |  |  |  | 1,879.8 |  |  |  |  |  |  |
Purchase accounting adjustments |  |  |  |  |  |  |  |  |  |  | $ 143.5 |  |  |  |  |  |  |

X
- Definition Amount of gain (loss), after tax expense or benefit and not previously recognized, resulting from the sale of a business component. + 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 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 3: 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 Reference 4: 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. + Details
Name: | us-gaap_DiscontinuedOperationGainLossOnDisposalOfDiscontinuedOperationNetOfTax
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Amount of income (loss) from a disposal group, net of income tax before extraordinary items allocable to noncontrolling interests. Includes, net of tax, income (loss) from operations during the phase-out period, gain (loss) on disposal, provision (or any reversals of earlier provisions) for loss on disposal, and adjustments of a prior period gain (loss) on disposal. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher AICPA -Name Accounting Research Bulletin (ARB) -Number 51 -Paragraph 29 -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 205 -SubTopic 20 -Section 45 -Paragraph 3 -URI http://asc.fasb.org/extlink&oid=6892542&loc=d3e957-107759 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 144 -Paragraph 47 -Subparagraph c -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 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 5: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 205 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=6360339&loc=d3e1361-107760 Reference 6: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 225 -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-04.12) -URI http://asc.fasb.org/extlink&oid=6879464&loc=d3e573970-122913 Reference 7: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 04 -Paragraph 13 -Article 7 Reference 8: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 225 -SubTopic 10 -Section S99 -Paragraph 2 -Subparagraph (SX 210.5-03.14) -URI http://asc.fasb.org/extlink&oid=6880815&loc=d3e20235-122688 Reference 9: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 03 -Paragraph 15 -Article 5 + Details
Name: | us-gaap_IncomeLossFromDiscontinuedOperationsNetOfTax
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Amount of provision in the period for claims incurred in prior reporting periods and related claims settlement costs. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Financial Reporting Release (FRR) -Number 403 -Paragraph 04 -Subparagraph b Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 40 -Section 50 -Paragraph 3 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=6482485&loc=d3e14764-158437 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher AICPA -Name Statement of Position (SOP) -Number 94-5 -Paragraph 11 -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. + Details
Name: | us-gaap_LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseIncurredClaimsPriorYears
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Reflects the sum of all other revenue and income recognized by the entity in the period not otherwise specified in the income statement. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 225 -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-04.4) -URI http://asc.fasb.org/extlink&oid=6879464&loc=d3e573970-122913 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 04 -Paragraph 4 -Article 7 + Details
Name: | us-gaap_OtherIncome
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Receivables currently due from reinsurers for ceded claims paid. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 605 -Section 50 -Paragraph 1 -Subparagraph (a)(2) -URI http://asc.fasb.org/extlink&oid=6486672&loc=d3e27261-158547 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 03 -Paragraph 6 -Article 7 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 310 -Section 45 -Paragraph 6 -URI http://asc.fasb.org/extlink&oid=6485522&loc=d3e21412-158489 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 310 -Section 45 -Paragraph 5 -URI http://asc.fasb.org/extlink&oid=6485522&loc=d3e21409-158489 Reference 5: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-03.6) -URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910 Reference 6: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 113 -Paragraph 14, 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. + Details
Name: | us-gaap_ReinsuranceReceivablesPaidLossesRecoverable
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition The known and estimated amount recoverable as of the balance sheet date from reinsurers for claims paid or incurred by the ceding insurer and associated claims settlement expenses, including estimated amounts for claims incurred but not reported, and policy benefits, net of any related valuation allowance. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 03 -Paragraph 6 -Article 7 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 20 -Section 50 -Paragraph 5 -URI http://asc.fasb.org/extlink&oid=6480758&loc=d3e6824-158387 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-03.(a),6) -URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 113 -Paragraph 14, 16, 27, 113 -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
Name: | us-gaap_ReinsuranceRecoverables
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Represents the amount of adverse loss reserve development on losses occurring in years 2000 and prior. + References No definition available. + Details
Name: | wtm_AdverseLossReserveDevelopmentOnLossesOccurringInYears2000AndPrior
Namespace Prefix: | wtm_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition The number of ratings in the A.M. Best debt rating system. + References No definition available. + Details
Name: | wtm_AMBestRatingSystemNumberOfDebtRatings
Namespace Prefix: | wtm_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | duration

X
- Definition Represents the amount of reserves ceded as of the date of the OneBeacon acquisition. + References No definition available. + Details
Name: | wtm_LossReservesCededAtAcquisition
Namespace Prefix: | wtm_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Represents the number of reinsurance contracts the seller caused OneBeacon to purchase from subsidiaries of Berkshire Hathaway Inc. immediately prior to the entity's acquisition of OneBeacon. + References No definition available. + Details
Name: | wtm_NumberOfContractsSellerCausedOneBeaconToPurchasePriorToAcquisition
Namespace Prefix: | wtm_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | instant

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

X
- Definition Represents the cover amount under reinsurance contracts. + References No definition available. + Details
Name: | wtm_ReinsuranceRecoverableCoverUnderReinsuranceContract
Namespace Prefix: | wtm_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Reinsurance recoverables gross of purchase accounting adjustments. + References No definition available. + Details
Name: | wtm_ReinsuranceRecoverablesGrossOfPurchaseAccountingAdjustments
Namespace Prefix: | wtm_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Purchase accounting adjustments related to reinsurance recoverables. + References No definition available. + Details
Name: | wtm_ReinsuranceRecoverablesGrossPurchaseAccountingAdjustments
Namespace Prefix: | wtm_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant