Investments Amortized Cost and Estimated Fair Value (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Amortized Cost
Due in one year or less, Amortized Cost	$ 51,519
Due after one year through five years, Amortized Cost	295,621
Due after five years though ten years, Amortized Cost	311,755
Due after ten years through twenty years, Amortized Cost	79,555
Due after twenty years, Amortized Cost	950
Asset-backed securities, Amortized Cost	420,459
Totals, Amortized Cost	1,159,859	$ 1,192,357
Estimated Fair Value
Due in one year or less, Fair Value	51,881
Due after one year through five years, Fair Value	287,963
Due after five years through ten years, Fair Value	305,990
Due after ten years through twenty years, Fair Value	83,326
Due after twenty years, Fair Value	906
Asset-backed securities, Fair Value	435,389
Totals, Fair Value	$ 1,165,455	$ 1,228,040