Investments Contractual Maturities of Available-for-Sale Fixed Maturity Securities (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Amortized Cost
Due in one year or less, Amortized Cost	$ 11,278
Due after one year through five years, Amortized Cost	124,996
Due after five years through ten years, Amortized Cost	171,090
Due after ten years, Amortized Cost	231,952
Total fixed maturities, Amortized Cost	1,074,618	$ 1,031,817
Estimated Fair Value
Due in one year or less, Estimated Fair Value	11,466
Due after one year through five years, Estimated Fair Value	131,847
Due after five years through ten years, Estimated Fair Value	177,032
Due after ten years, Estimated Fair Value	236,844
Estimated Fair Value	1,099,763	1,081,800
Asset-backed securities [Member]
Amortized Cost
Without single maturity date, Amortized Cost	255,544
Total fixed maturities, Amortized Cost	255,544	236,813
Estimated Fair Value
Without single maturity date, Estimated Fair Value	259,425
Estimated Fair Value	259,425	240,661
Commercial mortgage-backed securities
Amortized Cost
Without single maturity date, Amortized Cost	62,519
Total fixed maturities, Amortized Cost	62,519	66,110
Estimated Fair Value
Without single maturity date, Estimated Fair Value	64,826
Estimated Fair Value	64,826	70,969
Residential mortgage-backed securities [Member]
Amortized Cost
Without single maturity date, Amortized Cost	217,239
Total fixed maturities, Amortized Cost	217,239	217,859
Estimated Fair Value
Without single maturity date, Estimated Fair Value	218,323
Estimated Fair Value	$ 218,323	$ 222,656