XML 16 R46.htm IDEA: XBRL DOCUMENT
v2.4.0.6

Investment Securities (Details 6) (USD $) In Millions, unless otherwise specified | Mar. 31, 2012 | Dec. 31, 2011 | Mar. 31, 2011 | Dec. 31, 2010
--- | --- | --- | --- | ---
Fair Value Measurements by Level |  |  |  |
Fair value, investment-related liabilities | $ 75.5 | $ 68.1 |  |
Investment securities |  |  |  |
Carrying value | 5,411.3 | 6,221.9 |  |
Total fixed maturity investments including assets held for sale |  | 6,333.7 |  |
Fair Value |  |  |  |
Investment securities |  |  |  |
Fair value investments | 7,583.8 | 8,346.8 | 7,784.8 | 7,901.6
Level 1 Inputs |  |  |  |
Investment securities |  |  |  |
Fair value investments | 1,983.3 | 1,879.1 | 1,826.0 | 1,894.4
Level 2 Inputs |  |  |  |
Investment securities |  |  |  |
Fair value investments | 5,115.0 | 6,088.2 | 5,498.5 | 5,477.4
Fixed maturity investments. | Level 3 Inputs |  |  |  |
Investment securities |  |  |  |
Fair value investments | 179.1 | 78.9 | 84.3 | 128.4
U.S. Government and agency obligations |  |  |  |
Investment securities |  |  |  |
Carrying value | 266.9 | 305.0 |  |
Debt securities issued by corporations |  |  |  |
Investment securities |  |  |  |
Fair value investments | 2,332.4 | 2,135.1 |  |
Carrying value | 2,332.4 | 2,135.1 |  |
Municipal obligations |  |  |  |
Investment securities |  |  |  |
Carrying value | 2.7 | 2.7 |  |
Mortgage-backed and asset-backed securities |  |  |  |
Investment securities |  |  |  |
Carrying value | 2,151.2 | 3,222.9 |  |
Mortgage-backed and asset-backed securities | Fair Value |  |  |  |
Investment securities |  |  |  |
Fair value investments | 2,151.2 | 3,222.9 |  |
Mortgage-backed and asset-backed securities | Level 2 Inputs |  |  |  |
Investment securities |  |  |  |
Fair value investments | 2,062.9 | 3,207.8 |  |
Mortgage-backed and asset-backed securities | Level 3 Inputs |  |  |  |
Investment securities |  |  |  |
Fair value investments | 88.3 | 15.1 |  |
Non-cumulative perpetual preference shares |  |  |  |
Investment securities |  |  |  |
Carrying value | 86.5 | 78.8 |  |
Common equity securities | Level 3 Inputs |  |  |  |
Investment securities |  |  |  |
Fair value investments | 32.9 | 32.3 | 74.2 | 71.2
Other long-term investments | Level 3 Inputs |  |  |  |
Investment securities |  |  |  |
Fair value investments | 273.5 | 268.3 | 301.8 | 330.2
Carrying value of investment accounted for using the equity method | 33.2 | 33.0 | 37.5 | 41.9
Fair value measured on a recurring basis | Fair Value |  |  |  |
Investment securities |  |  |  |
Fair value investments | 7,583.8 | 8,346.8 |  |
Fair value measured on a recurring basis | Level 1 Inputs |  |  |  |
Investment securities |  |  |  |
Fair value investments | 1,983.3 | 1,879.1 |  |
Fair value measured on a recurring basis | Level 2 Inputs |  |  |  |
Investment securities |  |  |  |
Fair value investments | 5,115.0 | 6,088.2 |  |
Fair value measured on a recurring basis | Level 3 Inputs |  |  |  |
Investment securities |  |  |  |
Fair value investments | 485.5 | 379.5 |  |
Fair value measured on a recurring basis | Fixed maturity investments. | Fair Value |  |  |  |
Investment securities |  |  |  |
Fair value investments | 5,411.3 | 6,333.7 |  |
Fair value measured on a recurring basis | Fixed maturity investments. | Fair Value | AutoOne |  |  |  |
Investment securities |  |  |  |
Fair value investments |  | 111.8 |  |
Fair value measured on a recurring basis | Fixed maturity investments. | Level 1 Inputs |  |  |  |
Investment securities |  |  |  |
Fair value investments | 328.6 | 365.7 |  |
Fair value measured on a recurring basis | Fixed maturity investments. | Level 2 Inputs |  |  |  |
Investment securities |  |  |  |
Fair value investments | 4,903.6 | 5,889.1 |  |
Fair value measured on a recurring basis | Fixed maturity investments. | Level 3 Inputs |  |  |  |
Investment securities |  |  |  |
Fair value investments | 179.1 | 78.9 |  |
Fair value measured on a recurring basis | U.S. Government and agency obligations | Fair Value |  |  |  |
Investment securities |  |  |  |
Fair value investments | 266.9 | 305.0 |  |
Fair value measured on a recurring basis | U.S. Government and agency obligations | Level 1 Inputs |  |  |  |
Investment securities |  |  |  |
Fair value investments | 259.9 | 296.2 |  |
Fair value measured on a recurring basis | U.S. Government and agency obligations | Level 2 Inputs |  |  |  |
Investment securities |  |  |  |
Fair value investments | 7.0 | 8.8 |  |
Fair value measured on a recurring basis | Debt securities issued by corporations | Fair Value |  |  |  |
Investment securities |  |  |  |
Fair value investments | 2,332.4 | 2,135.1 |  |
Fair value measured on a recurring basis | Debt securities issued by corporations | Level 1 Inputs |  |  |  |
Investment securities |  |  |  |
Fair value investments | 3.1 | 3.8 |  |
Fair value measured on a recurring basis | Debt securities issued by corporations | Level 2 Inputs |  |  |  |
Investment securities |  |  |  |
Fair value investments | 2,308.3 | 2,131.3 |  |
Fair value measured on a recurring basis | Debt securities issued by corporations | Level 3 Inputs |  |  |  |
Investment securities |  |  |  |
Fair value investments | 21.0 |  |  |
Fair value measured on a recurring basis | Debt securities issued by corporations | Consumer | Fair Value |  |  |  |
Investment securities |  |  |  |
Fair value investments | 746.6 | 790.7 |  |
Fair value measured on a recurring basis | Debt securities issued by corporations | Consumer | Level 2 Inputs |  |  |  |
Investment securities |  |  |  |
Fair value investments | 725.6 | 790.7 |  |
Fair value measured on a recurring basis | Debt securities issued by corporations | Consumer | Level 3 Inputs |  |  |  |
Investment securities |  |  |  |
Fair value investments | 21.0 |  |  |
Fair value measured on a recurring basis | Debt securities issued by corporations | Industrial | Fair Value |  |  |  |
Investment securities |  |  |  |
Fair value investments | 436.8 | 359.4 |  |
Fair value measured on a recurring basis | Debt securities issued by corporations | Industrial | Level 2 Inputs |  |  |  |
Investment securities |  |  |  |
Fair value investments | 436.8 | 359.4 |  |
Fair value measured on a recurring basis | Debt securities issued by corporations | Financials | Fair Value |  |  |  |
Investment securities |  |  |  |
Fair value investments | 315.2 | 239.6 |  |
Fair value measured on a recurring basis | Debt securities issued by corporations | Financials | Level 1 Inputs |  |  |  |
Investment securities |  |  |  |
Fair value investments | 3.1 | 3.8 |  |
Fair value measured on a recurring basis | Debt securities issued by corporations | Financials | Level 2 Inputs |  |  |  |
Investment securities |  |  |  |
Fair value investments | 312.1 | 235.8 |  |
Fair value measured on a recurring basis | Debt securities issued by corporations | Communications | Fair Value |  |  |  |
Investment securities |  |  |  |
Fair value investments | 262.7 | 225.8 |  |
Fair value measured on a recurring basis | Debt securities issued by corporations | Communications | Level 2 Inputs |  |  |  |
Investment securities |  |  |  |
Fair value investments | 262.7 | 225.8 |  |
Fair value measured on a recurring basis | Debt securities issued by corporations | Energy | Fair Value |  |  |  |
Investment securities |  |  |  |
Fair value investments | 193.1 | 155.8 |  |
Fair value measured on a recurring basis | Debt securities issued by corporations | Energy | Level 2 Inputs |  |  |  |
Investment securities |  |  |  |
Fair value investments | 193.1 | 155.8 |  |
Fair value measured on a recurring basis | Debt securities issued by corporations | Basic materials | Fair Value |  |  |  |
Investment securities |  |  |  |
Fair value investments | 183.3 | 195.7 |  |
Fair value measured on a recurring basis | Debt securities issued by corporations | Basic materials | Level 2 Inputs |  |  |  |
Investment securities |  |  |  |
Fair value investments | 183.3 | 195.7 |  |
Fair value measured on a recurring basis | Debt securities issued by corporations | Utilities | Fair Value |  |  |  |
Investment securities |  |  |  |
Fair value investments | 165.9 | 140.1 |  |
Fair value measured on a recurring basis | Debt securities issued by corporations | Utilities | Level 2 Inputs |  |  |  |
Investment securities |  |  |  |
Fair value investments | 165.9 | 140.1 |  |
Fair value measured on a recurring basis | Debt securities issued by corporations | Technology | Fair Value |  |  |  |
Investment securities |  |  |  |
Fair value investments | 25.1 | 24.5 |  |
Fair value measured on a recurring basis | Debt securities issued by corporations | Technology | Level 2 Inputs |  |  |  |
Investment securities |  |  |  |
Fair value investments | 25.1 | 24.5 |  |
Fair value measured on a recurring basis | Debt securities issued by corporations | Diversified | Fair Value |  |  |  |
Investment securities |  |  |  |
Fair value investments | 3.7 | 3.5 |  |
Fair value measured on a recurring basis | Debt securities issued by corporations | Diversified | Level 2 Inputs |  |  |  |
Investment securities |  |  |  |
Fair value investments | 3.7 | 3.5 |  |
Fair value measured on a recurring basis | Municipal obligations | Fair Value |  |  |  |
Investment securities |  |  |  |
Fair value investments | 2.7 | 2.7 |  |
Fair value measured on a recurring basis | Municipal obligations | Level 2 Inputs |  |  |  |
Investment securities |  |  |  |
Fair value investments | 2.7 | 2.7 |  |
Fair value measured on a recurring basis | Mortgage-backed and asset-backed securities | Fair Value |  |  |  |
Investment securities |  |  |  |
Fair value investments | 2,151.2 | 3,222.9 |  |
Fair value measured on a recurring basis | Mortgage-backed and asset-backed securities | Level 2 Inputs |  |  |  |
Investment securities |  |  |  |
Fair value investments | 2,062.9 | 3,207.8 |  |
Fair value measured on a recurring basis | Mortgage-backed and asset-backed securities | Level 3 Inputs |  |  |  |
Investment securities |  |  |  |
Fair value investments | 88.3 | 15.1 |  |
Fair value measured on a recurring basis | Foreign government, agency and provincial obligations | Fair Value |  |  |  |
Investment securities |  |  |  |
Fair value investments | 571.6 | 589.2 |  |
Fair value measured on a recurring basis | Foreign government, agency and provincial obligations | Level 1 Inputs |  |  |  |
Investment securities |  |  |  |
Fair value investments | 65.6 | 65.7 |  |
Fair value measured on a recurring basis | Foreign government, agency and provincial obligations | Level 2 Inputs |  |  |  |
Investment securities |  |  |  |
Fair value investments | 506.0 | 523.5 |  |
Fair value measured on a recurring basis | Non-cumulative perpetual preference shares | Fair Value |  |  |  |
Investment securities |  |  |  |
Fair value investments | 86.5 | 78.8 |  |
Fair value measured on a recurring basis | Non-cumulative perpetual preference shares | Level 2 Inputs |  |  |  |
Investment securities |  |  |  |
Fair value investments | 16.7 | 15.0 |  |
Fair value measured on a recurring basis | Non-cumulative perpetual preference shares | Level 3 Inputs |  |  |  |
Investment securities |  |  |  |
Fair value investments | 69.8 | 63.8 |  |
Fair value measured on a recurring basis | Common equity securities | Fair Value |  |  |  |
Investment securities |  |  |  |
Fair value investments | 868.7 | 755.0 |  |
Fair value measured on a recurring basis | Common equity securities | Level 1 Inputs |  |  |  |
Investment securities |  |  |  |
Fair value investments | 777.2 | 667.4 |  |
Fair value measured on a recurring basis | Common equity securities | Level 2 Inputs |  |  |  |
Investment securities |  |  |  |
Fair value investments | 58.6 | 55.3 |  |
Fair value measured on a recurring basis | Common equity securities | Level 3 Inputs |  |  |  |
Investment securities |  |  |  |
Fair value investments | 32.9 | 32.3 |  |
Fair value measured on a recurring basis | Common equity securities | Consumer | Fair Value |  |  |  |
Investment securities |  |  |  |
Fair value investments | 197.5 | 188.8 |  |
Fair value measured on a recurring basis | Common equity securities | Consumer | Level 1 Inputs |  |  |  |
Investment securities |  |  |  |
Fair value investments | 197.1 | 188.5 |  |
Fair value measured on a recurring basis | Common equity securities | Consumer | Level 2 Inputs |  |  |  |
Investment securities |  |  |  |
Fair value investments | 0.4 | 0.3 |  |
Fair value measured on a recurring basis | Common equity securities | Financials | Fair Value |  |  |  |
Investment securities |  |  |  |
Fair value investments | 296.0 | 219.2 |  |
Fair value measured on a recurring basis | Common equity securities | Financials | Level 1 Inputs |  |  |  |
Investment securities |  |  |  |
Fair value investments | 261.9 | 185.8 |  |
Fair value measured on a recurring basis | Common equity securities | Financials | Level 2 Inputs |  |  |  |
Investment securities |  |  |  |
Fair value investments | 1.2 | 1.5 |  |
Fair value measured on a recurring basis | Common equity securities | Financials | Level 3 Inputs |  |  |  |
Investment securities |  |  |  |
Fair value investments | 32.9 | 31.9 |  |
Fair value measured on a recurring basis | Common equity securities | Energy | Fair Value |  |  |  |
Investment securities |  |  |  |
Fair value investments | 80.1 | 72.6 |  |
Fair value measured on a recurring basis | Common equity securities | Energy | Level 1 Inputs |  |  |  |
Investment securities |  |  |  |
Fair value investments | 80.1 | 72.6 |  |
Fair value measured on a recurring basis | Common equity securities | Basic materials | Fair Value |  |  |  |
Investment securities |  |  |  |
Fair value investments | 123.4 | 121.0 |  |
Fair value measured on a recurring basis | Common equity securities | Basic materials | Level 1 Inputs |  |  |  |
Investment securities |  |  |  |
Fair value investments | 122.2 | 119.9 |  |
Fair value measured on a recurring basis | Common equity securities | Basic materials | Level 2 Inputs |  |  |  |
Investment securities |  |  |  |
Fair value investments | 1.2 | 1.1 |  |
Fair value measured on a recurring basis | Common equity securities | Utilities | Fair Value |  |  |  |
Investment securities |  |  |  |
Fair value investments | 44.0 | 42.0 |  |
Fair value measured on a recurring basis | Common equity securities | Utilities | Level 1 Inputs |  |  |  |
Investment securities |  |  |  |
Fair value investments | 43.8 | 41.8 |  |
Fair value measured on a recurring basis | Common equity securities | Utilities | Level 2 Inputs |  |  |  |
Investment securities |  |  |  |
Fair value investments | 0.2 | 0.2 |  |
Fair value measured on a recurring basis | Common equity securities | Technology | Fair Value |  |  |  |
Investment securities |  |  |  |
Fair value investments | 29.5 | 25.8 |  |
Fair value measured on a recurring basis | Common equity securities | Technology | Level 1 Inputs |  |  |  |
Investment securities |  |  |  |
Fair value investments | 29.5 | 25.8 |  |
Fair value measured on a recurring basis | Common equity securities | Other: | Fair Value |  |  |  |
Investment securities |  |  |  |
Fair value investments | 98.2 | 85.6 |  |
Fair value measured on a recurring basis | Common equity securities | Other: | Level 1 Inputs |  |  |  |
Investment securities |  |  |  |
Fair value investments | 42.6 | 33.0 |  |
Fair value measured on a recurring basis | Common equity securities | Other: | Level 2 Inputs |  |  |  |
Investment securities |  |  |  |
Fair value investments | 55.6 | 52.2 |  |
Fair value measured on a recurring basis | Common equity securities | Other: | Level 3 Inputs |  |  |  |
Investment securities |  |  |  |
Fair value investments |  | 0.4 |  |
Fair value measured on a recurring basis | Short-term investments | Fair Value |  |  |  |
Investment securities |  |  |  |
Fair value investments | 877.5 | 846.0 |  |
Fair value measured on a recurring basis | Short-term investments | Level 1 Inputs |  |  |  |
Investment securities |  |  |  |
Fair value investments | 877.5 | 846.0 |  |
Fair value measured on a recurring basis | Convertible fixed maturities | Fair Value |  |  |  |
Investment securities |  |  |  |
Fair value investments | 152.8 | 143.8 |  |
Fair value measured on a recurring basis | Convertible fixed maturities | Level 2 Inputs |  |  |  |
Investment securities |  |  |  |
Fair value investments | 152.8 | 143.8 |  |
Fair value measured on a recurring basis | Other long-term investments |  |  |  |
Investment securities |  |  |  |
Carrying value of investment accounted for using the equity method | 33.2 |  |  |
Fair value measured on a recurring basis | Other long-term investments | Fair Value |  |  |  |
Investment securities |  |  |  |
Fair value investments | 273.5 | 268.3 |  |
Fair value measured on a recurring basis | Other long-term investments | Level 3 Inputs |  |  |  |
Investment securities |  |  |  |
Fair value investments | 273.5 | 268.3 |  |
Carrying value of investment accounted for using the equity method |  | $ 111.8 |  |

X
- Definition This element represents the portion of the balance sheet assertion valued at fair value by the entity whether such amount is presented as a separate caption or as a parenthetical disclosure. Additionally, this element may be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements. The element may be used in both the balance sheet and disclosure in the same submission. This item represents investments accounted for under the equity method of accounting as of the balance sheet date. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher AICPA -Name Accounting Principles Board Opinion (APB) -Number 18 -Paragraph 6 -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 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 323 -SubTopic 10 -Section 25 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=6903542&loc=d3e32014-111567 + Details
Name: | us-gaap_EquityMethodInvestmentsFairValueDisclosure
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Carrying value as of the balance sheet date of obligations incurred from short sales. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher AICPA -Name Audit and Accounting Guide (AAG) -Number AAG-BRD -Chapter 7 -Paragraph 40 -IssueDate 2006-05-01 -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 940 -SubTopic 320 -Section 35 -Paragraph 1 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=6475908&loc=d3e42429-110968 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher AICPA -Name Audit and Accounting Guide (AAG) -Number AAG-BRD -Chapter 4 -Paragraph 38 -IssueDate 2006-05-01 -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 AICPA -Name Audit and Accounting Guide (AAG) -Number AAG-BRD -Chapter 7 -Paragraph 19 -IssueDate 2006-05-01 -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 AICPA -Name Audit and Accounting Guide (AAG) -Number AAG-BRD -Chapter 7 -Paragraph 2 -IssueDate 2006-05-01 -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_FinancialInstrumentsSoldNotYetPurchasedAtFairValue
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition This element represents the portion of the balance sheet assertion valued at fair value by the entity whether such amount is presented as a separate caption or as a parenthetical disclosure. Additionally, this element may be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements. The element may be used in both the balance sheet and disclosure in the same submission. This item represents investment securities as of the balance sheet date which may include marketable securities, derivative financial instruments, and investments accounted for under the equity method. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Glossary Available-for-Sale Securities -URI http://asc.fasb.org/extlink&oid=6505594 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 25 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=6379932&loc=d3e22054-111558 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 115 -Paragraph 13 -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 -Glossary Trading Securities -URI http://asc.fasb.org/extlink&oid=6526789 Reference 5: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 115 -Paragraph 12 -Subparagraph a -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 SEC -Name Regulation S-X (SX) -Number 210 -Article 7 -Section 03 -Paragraph 1 -Subparagraph a, f, g Reference 7: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 35 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=6956420&loc=d3e24584-111560 + Details
Name: | us-gaap_InvestmentsFairValueDisclosure
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

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

X
- Definition Debt securities that are bought and held principally for the purpose of selling them in the near term (thus held for only a short period of time) or for debt securities formerly categorized as available-for-sale or held-to-maturity which the entity held as of the date it opted to account for such securities at fair value. An enterprise may also categorize such a security as trading without the intent to sell it in the near term assuming the decision to categorize the security as trading occurred at acquisition. + References Reference 1: 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 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 115 -Paragraph 12 -Subparagraph a -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 159 -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 4: 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),1) -URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910 Reference 5: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 115 -Paragraph 13 -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 942 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-03.4) -URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878 Reference 7: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 45 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=6871852&loc=d3e26626-111562 Reference 8: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Implementation Guide (Q and A) -Number FAS115 -Paragraph 35 -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 9: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 45 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=6871852&loc=d3e26610-111562 + Details
Name: | us-gaap_TradingSecuritiesDebt
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

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

X
- Definition Represents the fair value of trading debt securities including assets classified as held for sale. + References No definition available. + Details
Name: | wtm_TradingSecuritiesDebtIncludingAssetsHeldForSale
Namespace Prefix: | wtm_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant