XML 154 R102.htm IDEA: XBRL DOCUMENT
v2.4.0.8

Income Taxes (Net Operating and Capital Loss Carryforwards) (Details) (USD $) | 12 Months Ended |  | 3 Months Ended |
--- | --- | --- | --- | ---
Dec. 31, 2013 | Dec. 31, 2012 | Dec. 31, 2011 | Dec. 31, 2013 UNITED STATES | Dec. 31, 2012 Sirius Re Holdings Inc. | Dec. 31, 2013 Sirius Re Holdings Inc. | Dec. 31, 2013 Expected to be utilized [Member] Luxembourg | Dec. 31, 2013 Subject to annual limitations [Member] UNITED STATES | Dec. 31, 2013 Operating and Capital Loss Carryforward | Dec. 31, 2013 Operating and Capital Loss Carryforward UNITED STATES | Dec. 31, 2013 Operating and Capital Loss Carryforward Luxembourg | Dec. 31, 2013 Operating and Capital Loss Carryforward SWEDEN | Dec. 31, 2013 Operating and Capital Loss Carryforward UNITED KINGDOM | Dec. 31, 2013 Operating and Capital Loss Carryforward NETHERLANDS | Dec. 31, 2013 Operating and Capital Loss Carryforward 2013 [Member] | Dec. 31, 2013 Operating and Capital Loss Carryforward 2013 [Member] UNITED STATES | Dec. 31, 2013 Operating and Capital Loss Carryforward 2013 [Member] Luxembourg | Dec. 31, 2013 Operating and Capital Loss Carryforward 2013 [Member] SWEDEN | Dec. 31, 2013 Operating and Capital Loss Carryforward 2013 [Member] UNITED KINGDOM | Dec. 31, 2013 Operating and Capital Loss Carryforward 2013 [Member] NETHERLANDS | Dec. 31, 2013 Operating and Capital Loss Carryforward 2014-2018 [Member] | Dec. 31, 2013 Operating and Capital Loss Carryforward 2014-2018 [Member] UNITED STATES | Dec. 31, 2013 Operating and Capital Loss Carryforward 2014-2018 [Member] Luxembourg | Dec. 31, 2013 Operating and Capital Loss Carryforward 2014-2018 [Member] SWEDEN | Dec. 31, 2013 Operating and Capital Loss Carryforward 2014-2018 [Member] UNITED KINGDOM | Dec. 31, 2013 Operating and Capital Loss Carryforward 2014-2018 [Member] NETHERLANDS | Dec. 31, 2013 Operating and Capital Loss Carryforward 2019-2013 [Member] | Dec. 31, 2013 Operating and Capital Loss Carryforward 2019-2013 [Member] UNITED STATES | Dec. 31, 2013 Operating and Capital Loss Carryforward 2019-2013 [Member] Luxembourg | Dec. 31, 2013 Operating and Capital Loss Carryforward 2019-2013 [Member] SWEDEN | Dec. 31, 2013 Operating and Capital Loss Carryforward 2019-2013 [Member] UNITED KINGDOM | Dec. 31, 2013 Operating and Capital Loss Carryforward 2019-2013 [Member] NETHERLANDS | Dec. 31, 2013 Operating and Capital Loss Carryforward 2024-2033 [Member] | Dec. 31, 2013 Operating and Capital Loss Carryforward 2024-2033 [Member] UNITED STATES | Dec. 31, 2013 Operating and Capital Loss Carryforward 2024-2033 [Member] Luxembourg | Dec. 31, 2013 Operating and Capital Loss Carryforward 2024-2033 [Member] SWEDEN | Dec. 31, 2013 Operating and Capital Loss Carryforward 2024-2033 [Member] UNITED KINGDOM | Dec. 31, 2013 Operating and Capital Loss Carryforward 2024-2033 [Member] NETHERLANDS | Dec. 31, 2013 Operating and Capital Loss Carryforward No expiration date [Member] | Dec. 31, 2013 Operating and Capital Loss Carryforward No expiration date [Member] UNITED STATES | Dec. 31, 2013 Operating and Capital Loss Carryforward No expiration date [Member] Luxembourg | Dec. 31, 2013 Operating and Capital Loss Carryforward No expiration date [Member] SWEDEN | Dec. 31, 2013 Operating and Capital Loss Carryforward No expiration date [Member] UNITED KINGDOM | Dec. 31, 2013 Operating and Capital Loss Carryforward No expiration date [Member] NETHERLANDS
Summary of net operating loss and capital loss carryforwards, the expiration dates and the deferred tax assets thereon |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Operating Loss Carryforwards |  |  |  |  |  |  | $ 1,284,100,000 | $ 18,200,000 | $ 2,270,000,000 | $ 441,000,000 | $ 1,750,000,000 | $ 62,300,000 | $ 15,600,000 | $ 1,100,000 | $ 0 | $ 0 | $ 0 | $ 0 | $ 0 | $ 0 | $ 500,000 | $ 0 | $ 0 | $ 0 | $ 0 | $ 500,000 | $ 11,800,000 | $ 11,200,000 | $ 0 | $ 0 | $ 0 | $ 600,000 | $ 429,800,000 | $ 429,800,000 | $ 0 | $ 0 | $ 0 | $ 0 | $ 1,827,900,000 | $ 0 | $ 1,750,000,000 | $ 62,300,000 | $ 15,600,000 | $ 0
Net deferred tax assets |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Gross deferred tax asset |  |  |  |  |  |  |  |  | 669,200,000 | 148,600,000 | 511,300,000 | 5,800,000 | 3,200,000 | 300,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Valuation allowance |  |  |  |  |  |  |  |  | (254,300,000) | (58,300,000) | (195,700,000) | 0 | 0 | (300,000) |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Total net deferred income tax assets | 617,600,000 | 697,100,000 |  |  |  |  |  |  | 414,900,000 | 90,300,000 | 315,600,000 | 5,800,000 | 3,200,000 | 0 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Foreign tax credit carryforwards, subject to expiration |  |  |  | 11,600,000 |  | 5,200,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Valuation allowance | 33,600,000 | 14,100,000 | (128,200,000) |  | 3,900,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Alternative minimum tax credit carryforwards, not subject to expiration | $ 11,500,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |

X
- Definition Amount after allocation of valuation allowances of deferred tax asset attributable to deductible temporary differences and carryforwards. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (b),(c) -URI http://asc.fasb.org/extlink&oid=6907707&loc=d3e32537-109319 + Details
Name: | us-gaap_DeferredTaxAssetsNet
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amount before allocation of valuation allowances of deferred tax asset attributable to deductible operating loss carryforwards. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 50 -Paragraph 6 -URI http://asc.fasb.org/extlink&oid=6907707&loc=d3e32621-109319 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 50 -Paragraph 8 -URI http://asc.fasb.org/extlink&oid=6907707&loc=d3e32632-109319 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 25 -Paragraph 20 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=29652012&loc=d3e28680-109314 + Details
Name: | us-gaap_DeferredTaxAssetsOperatingLossCarryforwards
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amount before allocation of valuation allowances of deferred tax asset attributable to deductible alternative minimum tax credit carryforwards. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 50 -Paragraph 6 -URI http://asc.fasb.org/extlink&oid=6907707&loc=d3e32621-109319 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 50 -Paragraph 8 -URI http://asc.fasb.org/extlink&oid=6907707&loc=d3e32632-109319 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 50 -Paragraph 3 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=6907707&loc=d3e32559-109319 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Glossary Alternative Minimum Tax -URI http://asc.fasb.org/extlink&oid=6504908 + Details
Name: | us-gaap_DeferredTaxAssetsTaxCreditCarryforwardsAlternativeMinimumTax
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amount before allocation of valuation allowances of deferred tax asset attributable to deductible foreign tax credit carryforwards. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 50 -Paragraph 6 -URI http://asc.fasb.org/extlink&oid=6907707&loc=d3e32621-109319 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 50 -Paragraph 8 -URI http://asc.fasb.org/extlink&oid=6907707&loc=d3e32632-109319 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 50 -Paragraph 3 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=6907707&loc=d3e32559-109319 + Details
Name: | us-gaap_DeferredTaxAssetsTaxCreditCarryforwardsForeign
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amount of the difference between reported income tax expense (benefit) and expected income tax expense (benefit) computed by applying the domestic federal statutory income tax rates to pretax income (loss) from continuing operations attributable to increase (decrease) in the valuation allowance for deferred tax assets. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 50 -Paragraph 12 -URI http://asc.fasb.org/extlink&oid=6907707&loc=d3e32687-109319 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 50 -Paragraph 13 -URI http://asc.fasb.org/extlink&oid=6907707&loc=d3e32698-109319 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 45 -Paragraph 20 -URI http://asc.fasb.org/extlink&oid=21917399&loc=d3e32123-109318 + Details
Name: | us-gaap_IncomeTaxReconciliationChangeInDeferredTaxAssetsValuationAllowance
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Amount of operating loss carryforward, before tax effects, available to reduce future taxable income under enacted tax laws. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 50 -Paragraph 3 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=6907707&loc=d3e32559-109319 + Details
Name: | us-gaap_OperatingLossCarryforwards
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition The portion of the valuation allowance pertaining to the deferred tax asset representing potential future taxable deductions from net operating loss carryforwards for which it is more likely than not that a tax benefit will not be realized. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=6907707&loc=d3e32537-109319 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 50 -Paragraph 3 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=6907707&loc=d3e32559-109319 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 30 -Paragraph 5 -Subparagraph (e) -URI http://asc.fasb.org/extlink&oid=6907311&loc=d3e30536-109315 + Details
Name: | us-gaap_OperatingLossCarryforwardsValuationAllowance
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

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

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