Investments (Details 3) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2013	Dec. 31, 2012
Amortized cost and fair value of fixed maturity securities investments classified by contractual maturity date
Due in 1 year or less, Available for sale, Cost or amortized cost	$ 216,068
Due after 1 year through 5 years, Available for sale, Cost or amortized cost	1,098,887
Due after 5 years through 10 years, Available for sale, Cost or amortized cost	1,470,040
Due after 10 years through 15 years, Available for sale, Cost or amortized cost	1,016,530
Due after 15 years, Available for sale, Cost or amortized cost	1,003,332
Securities with contractual maturities, Available for sale, Cost or amortized cost	4,804,857
Mortgage-backed and asset-backed securities, Available for sale, Cost or amortized cost	1,254,996
Available-for-sale fixed maturity Securities, Amortized Cost Basis	6,059,853	5,856,432
Due in 1 year or less, Available for sale, Fair value	219,092
Due after 1 year through 5 years, Available for sale, Fair value	1,139,408
Due after 5 years through 10 years, Available for sale, Fair value	1,533,694
Due after 10 years through 15 years, Available for sale, Fair value	1,036,012
Due after 15 years, Available for sale, Fair value	1,000,945
Securities with contractual maturities, Available for sale, Fair value	4,929,151
Mortgage-backed and asset-backed securities, Available for sale, Fair value	1,265,474
Available-for-sale Securities, Fixed Maturity Securities, Fair value	$ 6,194,625

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Available For Sale Securities Debt Maturities After Fifteen Years Amortized Cost.

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Available For Sale Securities Debt Maturities After Fifteen Years Fair Value.

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Available For Sale Securities Debt Maturities After Ten Through Fifteen Years Amortized Cost.

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Available For Sale Securities Debt Maturities After Ten Through Fifteen Years Fair Value.

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Available For Sale Securities With Contractual Maturities Amortized Cost.

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Available For Sale Securities With Contractual Maturities Fair Value.

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This item represents the cost of debt securities, which are categorized neither as held-to-maturity nor trading, net of adjustments including accretion, amortization, collection of cash, previous other-than-temporary impairments recognized in earnings (less any cumulative-effect adjustments recognized, as defined), and fair value hedge accounting adjustments, if any.

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Amount of investment in debt and equity securities categorized neither as held-to-maturity nor trading.

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Amount of available-for-sale debt securities at cost, net of adjustments, maturing in the sixth fiscal year through the tenth fiscal year following the latest fiscal year. Adjustments include, but are not limited to, accretion, amortization, collection of cash, previous other-than-temporary impairments (OTTI) recognized in earnings (less any cumulative-effect adjustments, as defined) and fair value hedge accounting adjustments.

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Amount of available-for-sale debt securities at fair value maturing in the sixth fiscal year through the tenth fiscal year following the latest fiscal year.

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Amount of available-for-sale debt securities at cost, net of adjustments, maturing in the second fiscal year through the fifth fiscal year following the latest fiscal year. Adjustments include, but are not limited to, accretion, amortization, collection of cash, previous other-than-temporary impairments (OTTI) recognized in earnings (less any cumulative-effect adjustments, as defined) and fair value hedge accounting adjustments.

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