Investments - Schedule of Contract Maturities (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Cost or Amortized Cost
One year or less	$ 104,099
After one year through five years	456,660
After five years through ten years	306,679
After ten years	232,200
Residential mortgage-backed	297,932
Commercial mortgage and asset-backed	324,966
Redeemable preferred stock	2,025
Total fixed maturity securities, Cost or Amortized Cost	1,724,561	$ 1,398,533
Fair Value
One year or less	105,328
After one year through five years	483,155
After five years through ten years	330,510
After ten years	250,152
Residential mortgage-backed	306,469
Commercial mortgage and asset-backed	335,834
Redeemable preferred stock	2,023
Total investments available-for-sale, Fair Value	$ 1,813,471	$ 1,433,626