Investments (Details 3) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012
Amortized cost and estimated fair value of fixed maturity securities by contractual maturity
Due in one year or less, Amortized cost	$ 40,900
Due after one year through five years, Amortized cost	97,214
Due after five years through ten years, Amortized cost	189,141
Due after ten years, Amortized cost	71,161
Mortgage and asset-backed securities, Amortized cost	366,943
Amortized cost, Total	765,359
Due in one year or less, Estimated fair value	41,544
Due after one year through five years, Estimated fair value	104,414
Due after five years through ten years, Estimated fair value	207,642
Due after ten years, Estimated fair value	89,834
Mortgage and asset-backed securities, Estimated fair value	386,143
Estimated fair value, Total	$ 829,577

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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 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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