SCHEDULE I - Consolidated Summary of Investments Other Than Investments in Related Parties (Details) (USD $)	Dec. 31, 2013
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Fair Value	$ 14,963,041,000	[1]
Amount at which shown in the balance sheet	14,963,041,000	[1]
Fixed maturities [Member]
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost	13,376,455,000	[1],[2]
Fair Value	13,593,303,000	[1]
Amount at which shown in the balance sheet	13,593,303,000	[1]
Fixed maturities [Member] | US Government and government sponsored enterpises [Member]
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost	1,635,578,000	[1],[2]
Fair Value	1,623,859,000	[1]
Amount at which shown in the balance sheet	1,623,859,000	[1]
Fixed maturities [Member] | US states, territories and municipalities [Member]
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost	121,697,000	[1],[2]
Fair Value	124,587,000	[1]
Amount at which shown in the balance sheet	124,587,000	[1]
Fixed maturities [Member] | Non US sovereign government supranational and government related [Member]
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost	2,295,608,000	[1],[2]
Fair Value	2,353,699,000	[1]
Amount at which shown in the balance sheet	2,353,699,000	[1]
Fixed maturities [Member] | Corporate [Member]
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost	5,866,991,000	[1],[2]
Fair Value	6,048,663,000	[1]
Amount at which shown in the balance sheet	6,048,663,000	[1]
Fixed maturities [Member] | Asset-backed securities [Member]
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost	1,126,812,000	[1],[2]
Fair Value	1,138,231,000	[1]
Amount at which shown in the balance sheet	1,138,231,000	[1]
Fixed maturities [Member] | Residential mortgage-backed securities [Member]
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost	2,294,870,000	[1],[2]
Fair Value	2,268,517,000	[1]
Amount at which shown in the balance sheet	2,268,517,000	[1]
Fixed maturities [Member] | Other mortgage-backed securities [Member]
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost	34,899,000	[1],[2]
Fair Value	35,747,000	[1]
Amount at which shown in the balance sheet	35,747,000	[1]
Equity securities [Member]
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost	1,009,286,000	[1],[2]
Fair Value	1,221,053,000	[1]
Amount at which shown in the balance sheet	1,221,053,000	[1]
Equity securities [Member] | Banks, trust and insurance companies [Member]
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost	170,367,000	[1],[2]
Fair Value	282,727,000	[1]
Amount at which shown in the balance sheet	282,727,000	[1]
Equity securities [Member] | Public utilities [Member]
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost	35,562,000	[1],[2]
Fair Value	37,151,000	[1]
Amount at which shown in the balance sheet	37,151,000	[1]
Equity securities [Member] | Industrial, miscellaneous and all others [Member]
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost	803,357,000	[1],[2]
Fair Value	901,175,000	[1]
Amount at which shown in the balance sheet	901,175,000	[1]
Short-term investments [Member]
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost	13,543,000	[1],[2]
Fair Value	13,546,000	[1]
Amount at which shown in the balance sheet	13,546,000	[1]
Other invested assets [Member]
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Fair Value	135,139,000	[1],[3]
Amount at which shown in the balance sheet	135,139,000	[1],[3]
Investments Not Carried At Fair Value	$ 186,000,000

[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.

[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 of $186 million.