Investments Classified by Maturity Date (Details) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Debt Maturities, within One Year, Amortized Cost Basis, Percent of Total	12.60%
Available-for-sale Securities, Debt Maturities, within One Year, Fair Value, Percent of Total	12.60%
Available-for-sale Securities, Debt Maturities, after One Through Five Years, Amortized Cost Basis, Percent of Total	41.30%
Available-for-sale Securities, Debt Maturities, after One Through Five Years, Fair Value, Percent of Total	41.20%
Available-for-sale Securities, Debt Maturities, after Five Through Ten Years, Amortized Cost Basis, Percent of Total	33.30%
Available-for-sale Securities, Debt Maturities, after Five Through Ten Years, Fair Value, Percent of Total	33.20%
Available-for-sale Securities, Debt Maturities, after Ten Years, Amortized Cost Basis, Percent of Total	12.80%
Available-for-sale Securities, Debt Maturities, after Ten Years, Fair Value, Percent of Total	13.00%
Available-for-sale Securities, Debt Maturities, Amortized Cost Basis, Percent of Total	100.00%
Available-for-sale Securities	$ 452,714	$ 381,627
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	$ 50,080
Available-for-sale Securities, Debt Maturities, Next Twelve Months, Fair Value	50,135
Available-for-sale Securities, Debt Maturities, Year Two Through Five, Amortized Cost Basis	163,917
Available-for-sale Securities, Debt Maturities, Year Two Through Five, Fair Value	163,621
Available-for-sale Securities, Debt Maturities, Year Six Through Ten, Amortized Cost Basis	131,968
Available-for-sale Securities, Debt Maturities, Year Six Through Ten, Fair Value	131,678
Available-for-sale Securities, Debt Maturities, after Ten Years, Amortized Cost Basis	50,450
Available-for-sale Securities, Debt Maturities, after Ten Years, Fair Value	51,264
Available-for-sale Securities, Debt Maturities, Amortized Cost Basis	396,415	350,063
Available-for-sale Securities	$ 396,698	$ 352,630