Investments (Details 3) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
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	$ 168,246
Due after 1 year through 5 years, Available for sale, Cost or amortized cost	1,150,042
Due after 5 years through 10 years, Available for sale, Cost or amortized cost	1,392,501
Due after 10 years through 15 years, Available for sale, Cost or amortized cost	875,679
Due after 15 years, Available for sale, Cost or amortized cost	997,752
Securities with contractual maturities, Available for sale, Cost or amortized cost	4,584,220
Mortgage-backed and asset-backed securities, Available for sale, Cost or amortized cost	1,768,517
Available-for-sale fixed maturity Securities, Amortized Cost Basis	6,352,737	5,921,487
Due in 1 year or less, Available for sale, Fair value	171,070
Due after 1 year through 5 years, Available for sale, Fair value	1,177,120
Due after 5 years through 10 years, Available for sale, Fair value	1,470,264
Due after 10 years through 15 years, Available for sale, Fair value	934,490
Due after 15 years, Available for sale, Fair value	1,057,272
Securities with contractual maturities, Available for sale, Fair value	4,810,216
Mortgage-backed and asset-backed securities, Available for sale, Fair value	1,800,152
Available-for-sale Securities, Fixed Maturity Securities, Fair value	$ 6,610,368	$ 6,022,473

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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 Fair Value.

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Available For Sale Securities With Contractual Maturities Amortized Cost.

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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 after adjustments of available-for-sale debt securities at cost, 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 cumulative-effect adjustments, and fair value hedge accounting adjustments. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

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Fair value of available-for-sale debt securities maturing in the sixth fiscal year through the tenth fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

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Amount after adjustments of available-for-sale debt securities at cost, 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 cumulative-effect adjustments, and fair value hedge accounting adjustments. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

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Amount after adjustments of available-for-sale debt securities at cost, maturing in the next 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 cumulative-effect adjustments, and fair value hedge accounting adjustments. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

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Amount of available-for-sale debt securities at cost, net of adjustments, that do not have a single maturity date and which the entity has decided to disclose separately rather than allocating the cost over several maturity groupings. 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 that do not have a single maturity date and which the entity has decided to disclose separately rather than allocating the fair value over several maturity groupings.

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Amount of debt securities categorized neither as held-to-maturity nor trading.

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