Investments - Schedule of Amortized Cost and Fair Value of Fixed Maturity Securities (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Amortized Cost
One year or less	$ 81,705
After one year through five years	456,076
After five years through ten years	219,717
After ten years	128,177
Residential mortgage-backed	261,524
Commercial mortgage and asset-backed	249,309
Redeemable preferred stock	2,025
Cost or Amortized Cost	1,398,533	$ 1,199,409
Fair Value
One year or less	82,048
After one year through five years	466,952
After five years through ten years	228,596
After ten years	137,393
Residential mortgage-backed	264,146
Commercial mortgage and asset-backed	252,457
Redeemable preferred stock	2,034
Total, Fair Value	$ 1,433,626	$ 1,184,202