Investments - Investments Classified by Contractual Maturity Date (Details) - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
Fair Value
Total	$ 1,015,291	$ 884,861
Fixed Maturities
Cost or Amortized Cost
Due in one year or less	92,581
Due after one year through five years	270,443
Due after five years through ten years	253,982
Due after ten years	13,505
Asset and mortgage backed securities	345,286
Cost or adjusted/amortized cost	$ 975,797	869,598
Percent of Total
Due in one year or less	9.50%
Due after one year through five years	27.70%
Due after five years through ten years	26.00%
Due after ten years	1.40%
Asset and mortgage backed securities	35.40%
Total	100.00%
Fair Value
Due in one year or less	$ 93,257
Due after one year through five years	281,671
Due after five years through ten years	268,862
Due after ten years	14,086
Asset and mortgage backed securities	357,415
Total	$ 1,015,291	$ 884,861
Percent of Total
Due in one year or less	9.20%
Due after one year through five years	27.70%
Due after five years through ten years	26.50%
Due after ten years	1.40%
Asset and mortgage backed securities	35.20%
Total	100.00%