XML 20 R46.htm IDEA: XBRL DOCUMENT
v2.4.0.8

Investment Securities (Net Realized Investment Gains (Losses)) (Details) (USD $) In Millions, unless otherwise specified | 3 Months Ended | 9 Months Ended
--- | --- | ---
Sep. 30, 2014 | Sep. 30, 2013 | Sep. 30, 2014 | Sep. 30, 2013
Schedule of Trading Securities and Other Trading Assets [Line Items] |  |  |  |
Trading Securities, Realized Gain (Loss) | $ 67.8 | $ 12.6 | $ 120.3 | $ 77.6
Trading securities, tax on realized holding gain (loss) on investments | (9.6) | (0.4) | (19.6) | (17.8)
Trading securities realized holding gain (loss) on investments after tax | 58.2 | 12.2 | 100.7 | 59.8
Foreign Currency Transaction Gain (Loss), Realized | 8.2 | (0.9) | 8.0 | (17.4)
Trading securities, realized foreign currency transaction gain (loss) t | (2.0) | 0.4 | (2.1) | 5.1
Trading securities, realized foreign currency gain (loss) net of tax | 6.2 | (0.5) | 5.9 | (12.3)
Trading Securities, Realized Gain (Loss), Total | 76.0 | 11.7 | 128.3 | 60.2
Tax on Net Realized Gain (Loss) and Foreign Currency Gain (Loss) on Trading Securities | (11.6) | 0 | (21.7) | (12.7)
Net Realized Gain (Loss) and Foreign Currency Gain (Loss) on Trading Securities Net of Tax | 64.4 | 11.7 | 106.6 | 47.5
Fixed maturity investments. |  |  |  |
Schedule of Trading Securities and Other Trading Assets [Line Items] |  |  |  |
Trading Securities, Realized Gain (Loss) | 6.9 | (9.1) | 17.1 | 12.9
Foreign Currency Transaction Gain (Loss), Realized | 7.6 | (0.3) | 7.1 | (14.4)
Trading Securities, Realized Gain (Loss), Total | 14.5 | (9.4) | 24.2 | (1.5)
Short-term investments |  |  |  |
Schedule of Trading Securities and Other Trading Assets [Line Items] |  |  |  |
Trading Securities, Realized Gain (Loss) | 0 | 0 | 0 | 0.2
Foreign Currency Transaction Gain (Loss), Realized | 1.1 | (0.6) | 1.1 | 0
Trading Securities, Realized Gain (Loss), Total | 1.1 | (0.6) | 1.1 | 0.2
Common equity securities |  |  |  |
Schedule of Trading Securities and Other Trading Assets [Line Items] |  |  |  |
Trading Securities, Realized Gain (Loss) | 54.6 | 23.5 | 92.9 | 60.7
Foreign Currency Transaction Gain (Loss), Realized | 0.1 | (3.0) | 0 | (3.0)
Trading Securities, Realized Gain (Loss), Total | 54.7 | 20.5 | 92.9 | 57.7
Convertible fixed maturity investments |  |  |  |
Schedule of Trading Securities and Other Trading Assets [Line Items] |  |  |  |
Trading Securities, Realized Gain (Loss) | 2.1 | (0.2) | 5.9 | (0.7)
Foreign Currency Transaction Gain (Loss), Realized | 0 | 0 | 0 | 0
Trading Securities, Realized Gain (Loss), Total | 2.1 | (0.2) | 5.9 | (0.7)
Other long-term investments |  |  |  |
Schedule of Trading Securities and Other Trading Assets [Line Items] |  |  |  |
Trading Securities, Realized Gain (Loss) | 3.9 | (1.1) | 4.2 | 4.8
Foreign Currency Transaction Gain (Loss), Realized | (0.6) | 3.0 | (0.2) | 0
Trading Securities, Realized Gain (Loss), Total | 3.3 | 1.9 | 4.0 | 4.8
Forward Contracts |  |  |  |
Schedule of Trading Securities and Other Trading Assets [Line Items] |  |  |  |
Trading Securities, Realized Gain (Loss) | 0.3 | (0.5) | 0.2 | (0.3)
Foreign Currency Transaction Gain (Loss), Realized | 0 | 0 | 0 | 0
Trading Securities, Realized Gain (Loss), Total | $ 0.3 | $ (0.5) | $ 0.2 | $ (0.3)

X
- Definition Amount before tax of foreign currency transaction realized gain (loss) recognized in the income statement. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 830 -SubTopic 20 -Section 45 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=6450189&loc=d3e30690-110894 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 830 -SubTopic 20 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=6450222&loc=d3e30840-110895 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 830 -SubTopic 20 -Section 45 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=6450189&loc=d3e30700-110894 + Details
Name: | us-gaap_ForeignCurrencyTransactionGainLossRealized
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

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

X
- Definition This item represents the gain (loss) realized during the period from the sale of trading securities. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 03 -Paragraph 7 -Subparagraph c -Article 5 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 225 -SubTopic 10 -Section S99 -Paragraph 2 -Subparagraph (SX 210.5-03.7(c)) -URI http://asc.fasb.org/extlink&oid=26872669&loc=d3e20235-122688 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Glossary Trading Securities -URI http://asc.fasb.org/extlink&oid=6526789 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 9 -Subparagraph (e) -URI http://asc.fasb.org/extlink&oid=27724398&loc=d3e27357-111563 + Details
Name: | us-gaap_TradingSecuritiesRealizedGainLoss
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Net Realized Gain (Loss) and Foreign Currency Gain (Loss) on Trading Securities Net of Tax + References No definition available. + Details
Name: | wtm_NetRealizedGainLossandForeignCurrencyGainLossonTradingSecuritiesNetofTax
Namespace Prefix: | wtm_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Tax on Net Realized Gain (Loss) and Foreign Currency Gain (Loss) on Trading Securities + References No definition available. + Details
Name: | wtm_TaxonNetRealizedGainLossandForeignCurrencyGainLossonTradingSecurities
Namespace Prefix: | wtm_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Trading Securities, Realized Foreign Currency Gain (Loss) Net of Tax + References No definition available. + Details
Name: | wtm_TradingSecuritiesRealizedForeignCurrencyGainLossNetofTax
Namespace Prefix: | wtm_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Trading Securities, Realized Gain (Loss), Total + References No definition available. + Details
Name: | wtm_TradingSecuritiesRealizedGainLossTotal
Namespace Prefix: | wtm_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Trading Securities Realized Holding Gain (Loss) on Investments after Tax + References No definition available. + Details
Name: | wtm_TradingSecuritiesRealizedHoldingGainLossonInvestmentsafterTax
Namespace Prefix: | wtm_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Trading Securities, Tax on Realized Foreign Currency Transaction Gain (Loss) Tax + References No definition available. + Details
Name: | wtm_TradingSecuritiesTaxonRealizedForeignCurrencyTransactionGainLossTax
Namespace Prefix: | wtm_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Trading securities, Tax on Realized Holding Gain (Loss) on Investments + References No definition available. + Details
Name: | wtm_TradingsecuritiesTaxonRealizedHoldingGainLossonInvestments
Namespace Prefix: | wtm_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration