Investments Classified by Maturity Date (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Debt Maturities, within One Year, Amortized Cost Basis, Percent of Total	54.50%
Available-for-sale Securities, Debt Maturities, within One Year, Fair Value, Percent of Total	53.00%
Available-for-sale Securities, Debt Maturities, after One Through Five Years, Amortized Cost Basis, Percent of Total	9.20%
Available-for-sale Securities, Debt Maturities, after One Through Five Years, Fair Value, Percent of Total	9.20%
Available-for-sale Securities, Debt Maturities, after Five Through Ten Years, Amortized Cost Basis, Percent of Total	16.80%
Available-for-sale Securities, Debt Maturities, after Five Through Ten Years, Fair Value, Percent of Total	17.90%
Available-for-sale Securities, Debt Maturities, after Ten Years, Amortized Cost Basis, Percent of Total	19.50%
Available-for-sale Securities, Debt Maturities, after Ten Years, Fair Value, Percent of Total	19.90%
Available-for-sale Securities, Debt Maturities, Amortized Cost Basis, Percent of Total	100.00%
Available-for-sale Securities, Fair Value Disclosure	$ 152,180	$ 124,259
Available-for-sale Securities, Fair Value Disclosure, Percent of Total	100.00%
Fixed Maturities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Debt Maturities, Next Twelve Months, Amortized Cost Basis	79,118
Available-for-sale Securities, Debt Maturities, Next Twelve Months, Fair Value	79,021
Available-for-sale Securities, Debt Maturities, Year Two Through Five, Amortized Cost Basis	13,412
Available-for-sale Securities, Debt Maturities, Year Two Through Five, Fair Value	13,754
Available-for-sale Securities, Debt Maturities, Year Six Through Ten, Amortized Cost Basis	24,292
Available-for-sale Securities, Debt Maturities, Year Six Through Ten, Fair Value	26,663
Available-for-sale Securities, Debt Maturities, after Ten Years, Amortized Cost Basis	28,267
Available-for-sale Securities, Debt Maturities, after Ten Years, Fair Value	29,719
Available-for-sale Securities, Debt Maturities, Amortized Cost Basis	145,089
Available-for-sale Securities, Fair Value Disclosure	$ 149,157	$ 120,378