XML 53 R71.htm IDEA: XBRL DOCUMENT
v2.4.0.8

Third Party Reinsurance (Sirius Group) (Details) |  |  |  |  | 12 Months Ended |  |  |  |  | 12 Months Ended | 2 Months Ended | 12 Months Ended
--- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | ---
Dec. 31, 2013 USD ($) | Dec. 31, 2012 USD ($) | Dec. 31, 2011 USD ($) | Dec. 31, 2010 USD ($) | Dec. 31, 2013 Sirius Group USD ($) | Dec. 31, 2012 Sirius Group USD ($) | Dec. 31, 2013 OneBeacon USD ($) | Dec. 31, 2012 OneBeacon USD ($) | Dec. 31, 2013 AAA Sirius Group USD ($) | Dec. 31, 2013 AA Sirius Group USD ($) | Dec. 31, 2013 AA OneBeacon USD ($) | Dec. 31, 2013 A Sirius Group USD ($) | Dec. 31, 2013 A OneBeacon USD ($) | Dec. 31, 2013 BBB Sirius Group USD ($) | Dec. 31, 2013 BBB OneBeacon USD ($) | Dec. 31, 2013 BBB or lower Sirius Group USD ($) | Dec. 31, 2013 Not Rated [Member] Sirius Group USD ($) | Dec. 31, 2013 Faculative and Direct Property Portfolios Sirius Group USD ($) | Dec. 31, 2013 Faculative and Direct Property Portfolios Lloyds Syndicate 1945 [Member] USD ($) | Dec. 31, 2013 Faculative and Direct U.S. Catastophe Exposed Business Lloyds Syndicate 1945 [Member] USD ($) | Dec. 31, 2013 Non U.S and Non Japan Earthquake Related Exposure Sirius Group USD ($) | Dec. 31, 2013 Non U.S and Non Japan Earth Quake Related Exposure Partial Coverage Sirius Group USD ($) | Dec. 31, 2013 ILW Sirius Group USD ($) | Dec. 31, 2013 ILW Sirius Group EUR (€) | Dec. 31, 2013 Aviation Reinsurance Sirius Group USD ($) | Dec. 31, 2013 Aviation Reinsurance Minimum Sirius Group USD ($) | Dec. 31, 2013 Aviation Reinsurance Maximum Sirius Group USD ($) | Dec. 31, 2013 Marine Yacht Portfolio, London Branch and Syndicate 1945 Sirius Group USD ($) | Dec. 31, 2013 Accident and Health Sirius Group USD ($) | Dec. 31, 2013 Accident and Health Sirius Group EUR (€) | Feb. 28, 2014 Subsequent Event Faculative and Direct Property Portfolios Lloyds Syndicate 1945 [Member] USD ($) | Feb. 28, 2014 Subsequent Event ILW Sirius Group USD ($) | Dec. 31, 2013 Hamburg and Stockholm [Member] Faculative and Direct Property Portfolios Lloyds Syndicate 1945 [Member] USD ($)
Reinsurance Retention Policy [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Reinsurance retention policy, amount retained |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 5,000,000 | $ 5,000,000 | $ 5,000,000 | $ 35,000,000 | $ 75,000,000 | $ 7,500,000 |  |  | $ 150,000,000 | $ 2,250,000,000 | $ 300,000 | $ 6,900,000 | € 5,000,000 | $ 2,500,000 |  | $ 20,000,000
Reinsurance retention level, event policy |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 6,900,000,000 | 5,000,000,000 |  |  |  |  |  |  |  | 7,500,000,000 |
Percentage of quota share reinsurance agreement |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 15.00% |  |  |  |  |  |  |  |
Percentage of trade credit business ceded under quota share retrocession |  |  |  |  | 20.00% |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Percentage of bond business ceded under renewed quota share retrocession |  |  |  |  | 50.00% |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Aviation reinsurance program cover in first event industry loss warranties |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 350,000,000 | 1,000,000,000 |  |  |  |  |  |
Reinsurance retention policy, excess retention, amount reinsured |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 15,000,000 | 10,000,000 | 5,000,000 | 40,000,000 | 15,800,000 |  |  | 30,500,000 |  |  | 9,800,000 | 13,800,000 | 10,000,000 | 2,500,000 | 10,000,000 | 15,000,000
Direct contingency business ceded |  |  |  |  | 30.00% |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Percentage of property catastrophe reinsurance treaty reinstatement premiums |  |  |  |  | 100.00% |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Reinsurance recoverable on paid losses |  |  |  |  | 15,700,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Reinsurance recoverable on unpaid losses | 428,100,000 | 429,100,000 | 2,507,300,000 | 2,344,000,000 | 347,900,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Reinsurance recoverables, gross | 453,500,000 | 447,000,000 |  |  | 363,600,000 | [1] | 336,300,000 | 89,900,000 |  | 110,700,000 | 62,900,000 | [1] | 60,600,000 | [1] |  |  | 127,500,000 | [1] |  |  | 21,000,000 | [1] |  |  | 16,600,000 | [1] | 75,000,000 | [1] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Reinsurance Recoverables, Collateral |  |  |  |  | 37,600,000 | [1] |  |  |  |  | 0 | [1] | 4,500,000 | [1] |  |  | 1,600,000 | [1] |  |  | 0 | [1] |  |  | 0 | [1] | 31,500,000 | [1] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Reinsurance recoverable on paid and unpaid losses |  |  |  |  | $ 326,000,000 | [1] |  | $ 89,900,000 | [2] |  | $ 62,900,000 | [1] | $ 56,100,000 | [1] | $ 26,400,000 | [2] | $ 125,900,000 | [1] | $ 56,100,000 | [2] | $ 21,000,000 | [1] | $ 7,400,000 | [2] | $ 16,600,000 | [1] | $ 43,500,000 | [1] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Reinsurance recoverables, percentage of total |  |  |  |  | 100.00% | [1] |  | 100.00% | [2] |  | 19.00% | [1] | 17.00% | [1] | 30.00% | [2] | 39.00% | [1] | 62.00% | [2] | 7.00% | [1] | 8.00% | [2] | 5.00% | [1] | 13.00% | [1] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
[1] | Standard & Poor’s ratings as detailed above are: “AAA” (Extremely strong), “AA” (Very strong), “A” (Strong), and “BBB+” and “BBB” (Adequate).
[2] | Standard & Poor’s ratings as detailed above are: “AA” (Very strong), “A” (Strong) and “BBB+” (Adequate).

X
- Definition Estimated amount after valuation allowance of reinsurance recoverables, due from reinsurers for incurred claims not yet reported, and claims settlement expenses. + References Reference 1: 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 2: 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 3: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 03 -Paragraph 6 -Article 7 + Details
Name: | us-gaap_ReinsuranceReceivablesIncurredButNotReportedClaims
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amount after valuation allowance currently billed or billable under reinsurance contracts. + References Reference 1: 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 2: 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 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-03.6) -URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 03 -Paragraph 6 -Article 7 Reference 5: 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 + Details
Name: | us-gaap_ReinsuranceReceivablesPaidLossesRecoverable
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amount after valuation allowance recoverable including premium paid under reinsurance contracts. Examples include, but are not limited to, settled and unsettled claims, incurred but not reported losses, loss adjustment expense, premium paid, policy benefits and policy reserves. + 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 + Details
Name: | us-gaap_ReinsuranceRecoverables
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amount of valuation allowance for reinsurance recoverables. Examples include, but are not limited to, settled and unsettled claims, incurred but not reported losses, loss adjustment expense, premium paid, policy benefits and policy reserves. + References No definition available. + Details
Name: | us-gaap_ReinsuranceRecoverablesAllowance
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Amount before valuation allowance recoverable under reinsurance contracts. Examples include, but are not limited to, settled and unsettled claims, incurred but not reported losses, loss adjustment expense, premium paid, policy benefits and policy reserves. + References No definition available. + Details
Name: | us-gaap_ReinsuranceRecoverablesGross
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Percentage of total reinsurance recoverables. + References No definition available. + Details
Name: | us-gaap_ReinsuranceRecoverablesPercentageOfTotal
Namespace Prefix: | us-gaap_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition Stated amount that is the upper retention limit per entity policy. + References No definition available. + Details
Name: | us-gaap_ReinsuranceRetentionPolicyAmountRetained
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Amount of risk reinsured in excess of stated retention per company policy. + References No definition available. + Details
Name: | us-gaap_ReinsuranceRetentionPolicyExcessRetentionAmountReinsured
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Details
Name: | us-gaap_ReinsuranceRetentionPolicyLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Represents the cover which the entity has purchased in case of first event industry loss warranties under the aviation reinsurance program. + References No definition available. + Details
Name: | wtm_AviationReinsuranceProgramCoverInFirstEventIndustryLossWarranties
Namespace Prefix: | wtm_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Direct Contingency Business Ceded + References No definition available. + Details
Name: | wtm_DirectContingencyBusinessCeded
Namespace Prefix: | wtm_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Represents the percentage of ceded bond business under a renewed quota share retrocession. + References No definition available. + Details
Name: | wtm_PercentageOfBondBusinessCededUnderRenewedQuotaShareRetrocession
Namespace Prefix: | wtm_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Percentage of Property Catastrophe Reinsurance Treaty Reinstatement Premiums + References No definition available. + Details
Name: | wtm_PercentageOfPropertyCatastropheReinsuranceTreatyReinstatementPremiums
Namespace Prefix: | wtm_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Represents the percentage ceded under quota share reinsurance agreement. + References No definition available. + Details
Name: | wtm_PercentageOfQuotaShareReinsuranceAgreement
Namespace Prefix: | wtm_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Represents the percentage of ceded trade credit business under a quota share retrocession. + References No definition available. + Details
Name: | wtm_PercentageOfTradeCreditBusinessCededUnderQuotaShareRetrocession
Namespace Prefix: | wtm_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Reinsurance Trigger Level, Event Policy + References No definition available. + Details
Name: | wtm_ReinsuranceTriggerLevelEventPolicy
Namespace Prefix: | wtm_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration