v2.4.0.6

Fair Value Measurements (Quantitative Information Used As Level 3 Inputs) (Details) (USD $) In Thousands, unless otherwise specified | 3 Months Ended |
--- | --- | ---
Mar. 31, 2013 | Mar. 31, 2012 | Dec. 31, 2012
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items] |  |  |
Net premiums written | $ 436,813 | $ 492,575 |
Reserve for claims and claim expenses | 1,755,783 |  | 1,879,377
Fair Value, Inputs, Level 3 [Member] |  |  |
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items] |  |  |
Assets, fair value | 451,601 |  |
Other assets and (liabilities). fair value | 21,328 |  |
Fair Value, Inputs, Level 3 [Member] | Corporate [Member] | Discounted Cash Flow Valuation Technique [Member] |  |  |
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items] |  |  |
Assets, fair value | 17,813 |  |
Fair Value, Inputs, Level 3 [Member] | Corporate [Member] | Discounted Cash Flow Valuation Technique [Member] | Weighted Average or Actual [Member] |  |  |
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items] |  |  |
Credit spread | 2.40% |  |
Liquidity premium | 1.00% |  |
Risk-free rate | 0.10% |  |
Dividend rate | 5.90% |  |
Fair Value, Inputs, Level 3 [Member] | Corporate [Member] | Internal Valuation Model Valuation Technique [Member] |  |  |
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items] |  |  |
Assets, fair value | 10,254 |  |
Fair Value, Inputs, Level 3 [Member] | Fixed maturity investments [Member] |  |  |
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items] |  |  |
Assets, fair value | 28,067 |  |
Fair Value, Inputs, Level 3 [Member] | Private equity partnerships [Member] | Net Asset Valuation Technique [Member] |  |  |
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items] |  |  |
Assets, fair value | 345,666 |  |
Fair Value, Inputs, Level 3 [Member] | Private equity partnerships [Member] | Net Asset Valuation Technique [Member] | Low [Member] |  |  |
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items] |  |  |
Estimated performance | (12.00%) |  |
Fair Value, Inputs, Level 3 [Member] | Private equity partnerships [Member] | Net Asset Valuation Technique [Member] | Maximum [Member] |  |  |
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items] |  |  |
Estimated performance | 120.00% |  |
Fair Value, Inputs, Level 3 [Member] | Private equity partnerships [Member] | Net Asset Valuation Technique [Member] | Weighted Average or Actual [Member] |  |  |
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items] |  |  |
Estimated performance | 4.90% |  |
Fair Value, Inputs, Level 3 [Member] | Senior secured bank loan funds [Member] | Net Asset Valuation Technique [Member] |  |  |
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items] |  |  |
Assets, fair value | 28,537 |  |
Fair Value, Inputs, Level 3 [Member] | Senior secured bank loan funds [Member] | Net Asset Valuation Technique [Member] | Low [Member] |  |  |
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items] |  |  |
Estimated performance | 0.80% |  |
Fair Value, Inputs, Level 3 [Member] | Senior secured bank loan funds [Member] | Net Asset Valuation Technique [Member] | Maximum [Member] |  |  |
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items] |  |  |
Estimated performance | 2.10% |  |
Fair Value, Inputs, Level 3 [Member] | Senior secured bank loan funds [Member] | Net Asset Valuation Technique [Member] | Weighted Average or Actual [Member] |  |  |
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items] |  |  |
Estimated performance | 1.30% |  |
Fair Value, Inputs, Level 3 [Member] | Hedge funds [Member] | Net Asset Valuation Technique [Member] |  |  |
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items] |  |  |
Assets, fair value | 5,219 |  |
Fair Value, Inputs, Level 3 [Member] | Hedge funds [Member] | Net Asset Valuation Technique [Member] | Low [Member] |  |  |
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items] |  |  |
Estimated performance | 0.00% |  |
Fair Value, Inputs, Level 3 [Member] | Hedge funds [Member] | Net Asset Valuation Technique [Member] | Maximum [Member] |  |  |
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items] |  |  |
Estimated performance | 0.00% |  |
Fair Value, Inputs, Level 3 [Member] | Hedge funds [Member] | Net Asset Valuation Technique [Member] | Weighted Average or Actual [Member] |  |  |
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items] |  |  |
Estimated performance | 0.00% |  |
Fair Value, Inputs, Level 3 [Member] | Other Investments [Member] |  |  |
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items] |  |  |
Assets, fair value | 402,206 |  |
Fair Value, Inputs, Level 3 [Member] | Assumed and ceded reinsurance contracts [Member] | Internal Valuation Model Valuation Technique [Member] |  |  |
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items] |  |  |
Other assets and (liabilities). fair value | 676 |  |
Fair Value, Inputs, Level 3 [Member] | Assumed and ceded reinsurance contracts [Member] | Internal Valuation Model Valuation Technique [Member] | Low [Member] |  |  |
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items] |  |  |
Net premiums written | 0 |  |
Contract period |  |  |
Reserve for claims and claim expenses | 0 |  |
Fair Value, Inputs, Level 3 [Member] | Assumed and ceded reinsurance contracts [Member] | Internal Valuation Model Valuation Technique [Member] | Maximum [Member] |  |  |
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items] |  |  |
Net premiums written | 0 |  |
Contract period |  |  |
Reserve for claims and claim expenses | 0 |  |
Fair Value, Inputs, Level 3 [Member] | Weather and energy related derivatives [Member] | Spread Option, Quanto, Black Scholes and Simulation Valuation Techniques [Member] |  |  |
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items] |  |  |
Other assets and (liabilities). fair value | 20,000 |  |
Fair Value, Inputs, Level 3 [Member] | Weather and energy related derivatives [Member] | Spread Option, Quanto, Black Scholes and Simulation Valuation Techniques [Member] | Low [Member] |  |  |
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items] |  |  |
Correlation | 0.00% |  |
Volatility | 4.00% |  |
Commodity curve | 3.83 |  |
Weather curve | 7 |  |
Counterparty default risk | 0.00% |  |
Fair Value, Inputs, Level 3 [Member] | Weather and energy related derivatives [Member] | Spread Option, Quanto, Black Scholes and Simulation Valuation Techniques [Member] | Maximum [Member] |  |  |
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items] |  |  |
Correlation | 100.00% |  |
Volatility | 79.00% |  |
Commodity curve | 93.26 |  |
Weather curve | 5,427 |  |
Counterparty default risk | 22.50% |  |
Fair Value, Inputs, Level 3 [Member] | Other [Member] | Internal Valuation Model Valuation Technique [Member] |  |  |
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items] |  |  |
Other assets and (liabilities). fair value | 625 |  |
Fair Value, Inputs, Level 3 [Member] | Other [Member] | Net Asset Valuation Technique [Member] |  |  |
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items] |  |  |
Assets, fair value | 22,784 |  |
Other assets and (liabilities). fair value | $ 22,784 |  |
Fair Value, Inputs, Level 3 [Member] | Other [Member] | Net Asset Valuation Technique [Member] | Weighted Average or Actual [Member] |  |  |
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items] |  |  |
Estimated performance | 0.90% |  |

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- Definition Assets (Liabilities), Fair Value Disclosure, Recurring + References No definition available. + Details
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- Definition Fair Value Inputs, Contract Period + References No definition available. + Details
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- Definition Fair Value Inputs, Correlation + References No definition available. + Details
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- Definition Fair Value Inputs, Degree Days Fahrenheit + References No definition available. + Details
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- Definition Estimated percentage return for the period on fair value at beginning of period. + References No definition available. + Details
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- Definition This element represents the aggregate of the assets reported on the balance sheet at period end measured at fair value on a recurring basis by the entity. This element is intended to be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements. + References No definition available. + Details
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- Definition Expected dividends to be paid to holders of the underlying shares or financial instruments (expressed as a percentage of the share or instrument's price). + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (e) -URI http://asc.fasb.org/extlink&oid=7578670&loc=d3e19207-110258 + Details
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- Definition Measure of dispersion, in percentage terms (for instance, the standard deviation or variance), for a given stock price. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (e) -URI http://asc.fasb.org/extlink&oid=7578670&loc=d3e19207-110258 + Details
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- Definition Risk-free interest rate assumption used in valuing an instrument. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (e) -URI http://asc.fasb.org/extlink&oid=7578670&loc=d3e19207-110258 + Details
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- Definition Risk that one party to the contract will default expressed as a percentage, used as an input to measure fair value. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (bbb) -URI http://asc.fasb.org/extlink&oid=7578670&loc=d3e19207-110258 + Details
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- Definition Adjustment to the discount rate used to measure fair value for lack of ability to convert business interests into cash quickly. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (bbb) -URI http://asc.fasb.org/extlink&oid=7578670&loc=d3e19207-110258 + Details
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- Definition Risk associated with risk of default, credit spread risk and downgrade risk, expressed as a percentage, used as an input to measure fair value. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (bbb) -URI http://asc.fasb.org/extlink&oid=7578670&loc=d3e19207-110258 + Details
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- Definition The amount needed to reflect the estimated ultimate cost of settling claims relating to insured events that have occurred on or before the balance sheet date, whether or not reported to the insurer at that date. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 40 -Section 50 -Paragraph 3 -Subparagraph (a),(b),(c) -URI http://asc.fasb.org/extlink&oid=6482485&loc=d3e14764-158437 Reference 2: 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
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- Definition Premiums written for all insurance and reinsurance contracts, after adding premiums assumed from other insurers and subtracting any amounts ceded to another insurer. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 17 -Article 12 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 113 -Paragraph 27 -Subparagraph a, 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 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 605 -Section 50 -Paragraph 1 -Subparagraph (b),(c) -URI http://asc.fasb.org/extlink&oid=6486672&loc=d3e27261-158547 + Details
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