Investments - Schedule of Contractual Maturities of Mortgage Loan Principal Balances (Details) - Commercial Mortgage Loans - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Principal Balance by Contractual Maturity, Amount
Due in one year or less	$ 4,208	$ 497
Due after one year through five years	60,826	34,306
Due after five years through ten years	154,787	142,477
Due after ten years through fifteen years	107,662	96,359
Due after fifteen years	7,977	0
Totals	$ 335,460	$ 273,639
Principal Balance by Contractual Maturity, Percentage
Due in one year or less	1.30%	0.20%
Due after one year through five years	18.10%	12.50%
Due after five years through ten years	46.10%	52.10%
Due after ten years through fifteen years	32.10%	35.20%
Due after fifteen years	2.40%	0.00%
Totals	100.00%	100.00%