Investments Contractual Maturities of Available-for-Sale Fixed Maturity Securities (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Amortized Cost
Due in one year or less, Amortized Cost	$ 12,905
Due after one year through five years, Amortized Cost	110,503
Due after five years through ten years, Amortized Cost	78,077
Due after ten years, Amortized Cost	122,386
Total fixed maturities, Amortized Cost	699,641	$ 514,237
Estimated Fair Value
Due in one year or less, Estimated Fair Value	12,990
Due after one year through five years, Estimated Fair Value	113,402
Due after five years through ten years, Estimated Fair Value	81,102
Due after ten years, Estimated Fair Value	128,617
Estimated Fair Value	716,639	510,251
Commercial mortgage and asset-backed securities [Member]
Amortized Cost
Without single maturity date, Amortized Cost	190,472
Total fixed maturities, Amortized Cost	190,472	151,137
Estimated Fair Value
Without single maturity date, Estimated Fair Value	193,906
Estimated Fair Value	193,906	149,867
Residential mortgage-backed securities [Member]
Amortized Cost
Without single maturity date, Amortized Cost	185,298
Total fixed maturities, Amortized Cost	185,298	110,717
Estimated Fair Value
Without single maturity date, Estimated Fair Value	186,622
Estimated Fair Value	$ 186,622	$ 108,421