SCHEDULE I - Consolidated Summary of Investments Other Than Investments in Related Parties (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Fair Value	$ 15,711,073	[1]
Amount at which shown in the balance sheet	15,711,073	[1]
[FixedMaturitiesMember]
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost	13,653,615	[1],[2]
Fair Value	14,395,315	[1]
Amount at which shown in the balance sheet	14,395,315	[1]
[FixedMaturitiesMember] | [USTreasuryAndGovernmentMember]
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost	1,108,513	[1],[2]
Fair Value	1,130,924	[1]
Amount at which shown in the balance sheet	1,130,924	[1]
[FixedMaturitiesMember] | [USStatesAndPoliticalSubdivisionsMember]
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost	232,433	[1],[2]
Fair Value	243,386	[1]
Amount at which shown in the balance sheet	243,386	[1]
[FixedMaturitiesMember] | [NonUsSovereignGovernmentSupranationalAndGovernmentRelatedMember]
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost	2,221,272	[1],[2]
Fair Value	2,375,673	[1]
Amount at which shown in the balance sheet	2,375,673	[1]
[FixedMaturitiesMember] | [CorporateDebtSecuritiesMember]
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost	6,197,594	[1],[2]
Fair Value	6,655,838	[1]
Amount at which shown in the balance sheet	6,655,838	[1]
[FixedMaturitiesMember] | [AssetBackedSecuritiesSecuritizedLoansAndReceivablesMember]
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost	701,264	[1],[2]
Fair Value	723,470	[1]
Amount at which shown in the balance sheet	723,470	[1]
[FixedMaturitiesMember] | [ResidentialMortgageBackedSecuritiesMember]
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost	3,128,618	[1],[2]
Fair Value	3,199,924	[1]
Amount at which shown in the balance sheet	3,199,924	[1]
[FixedMaturitiesMember] | [CommercialMortgageBackedSecuritiesMember]
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost	63,921	[1],[2]
Fair Value	66,100	[1]
Amount at which shown in the balance sheet	66,100	[1]
[EquitySecuritiesMember]
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost	1,000,326	[1],[2]
Fair Value	1,094,002	[1]
Amount at which shown in the balance sheet	1,094,002	[1]
[EquitySecuritiesMember] | [BanksTrustAndInsuranceEquitiesMember]
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost	123,747	[1],[2]
Fair Value	139,537	[1]
Amount at which shown in the balance sheet	139,537	[1]
[EquitySecuritiesMember] | [PublicUtilityEquitiesMember]
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost	25,981	[1],[2]
Fair Value	28,709	[1]
Amount at which shown in the balance sheet	28,709	[1]
[EquitySecuritiesMember] | [IndustrialMiscellaneousAndAllOthersMember]
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost	850,598	[1],[2]
Fair Value	925,756	[1]
Amount at which shown in the balance sheet	925,756	[1]
[ShortTermInvestmentsMember]
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost	150,634	[1],[2]
Fair Value	150,552	[1]
Amount at which shown in the balance sheet	150,552	[1]
[OtherInvestedAssetsMember]
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Fair Value	71,204	[1],[3]
Amount at which shown in the balance sheet	$ 71,204	[1],[3]

[1] Excludes the investment portfolio underlying the funds held – directly managed account. While the net investment income and net realized and unrealized gains and losses inure to the benefit of the Company, the Company does not legally own the investments.

[2] Original cost of fixed maturities reduced by repayments and adjusted for amortization of premiums or accrual of discounts. Original cost of equity securities. For investments acquired from Paris Re, cost is based on the fair value at the date of acquisition and subsequently adjusted for amortization of fixed maturities and short-term investments.

[3] Other invested assets excludes the Company’s investments accounted for using the cost method of accounting, equity method of accounting or investment company accounting.