Investments Maturity Distribution of Debt Securities (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)
Available-for-sale Securities, Debt Maturities, Amortized Cost Basis, Fiscal Year Maturity [Abstract]
Available-for-sale Securities, Debt Maturities, within One Year, Amortized Cost Basis	$ 46,129
Available-for-sale Securities, Debt Maturities, after One through Five Years, Amortized Cost Basis	103,680
Available-for-sale Securities, Debt Maturities, after Five through Ten years, Amortized Cost Basis	120,915
Available-for-sale Securities, Debt Maturities, after Ten Years, Amortized Cost Basis	589,749
Available-for-sale Debt Securities, Amortized Cost Basis	860,473	$ 714,137
Available-for-sale Securities, Debt Maturities, Fair Value, Fiscal Year Maturity [Abstract]
Available-for-sale Securities, Debt Maturities, within One Year, Fair Value	46,698
Available-for-sale Securities, Debt Maturities, after One through Five Years, Fair Value	106,407
Available-for-sale Securities, Debt Maturities, after Five through Ten Years, Fair Value	127,697
Available-for-sale Securities, Debt Maturities, after Ten Years, Fair Value	600,866
Available for Sale Securities, Total	881,668	735,648
Held-to-maturity Securities, Debt Maturities, Net Carrying Amount [Abstract]
Held-to-maturity Securities, Debt Maturities, within One Year, Net Carrying Amount	2,972
Held-to-maturity Securities, Debt Maturities, after One through Five Years, Net Carrying Amount	58,138
Held-to-maturity Securities, Debt Maturities, after Five through Ten Years, Net Carrying Amount	43,320
Held-to-maturity Securities, Debt Maturities, after Ten Years, Net Carrying Amount	142,574
Fixed maturities held-to-maturity, at amortized cost	247,004	259,953
Held-to-maturity Securities, Debt Maturities, Fair Value, Fiscal Year Maturity [Abstract]
Held-to-maturity Securities, Debt Maturities, within One Year, Fair Value	2,991
Held-to-maturity Securities, Debt Maturities, after One through Five Years, Fair Value	59,873
Held-to-maturity Securities, Debt Maturities, after Five through Ten Years, Fair Value	44,568
Held-to-maturity Securities, Debt Maturities, after Ten Years, Fair Value	145,113
Held-to-maturity Securities, Fair Value	252,545	$ 264,966
Total Fixed maturity securities, Amortized Cost	1,107,477
Total Fixed Maturity Securities, Fair Value	$ 1,134,213
Number of investments exceeding 10% of stocksholder's equity	0
Number of Non-Income Producing Fixed Maturity Securities	0