Schedule of Participating Mortgage Loans by Internal Credit Rating and Loan to Value (Details) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022
Mortgage Loans on Real Estate
Mortgage Loans	$ 2,318.2	$ 2,435.4
Percent of Total	100.00%	100.00%
Loan to Value Ratio Below or Equal to 65 Percent
Mortgage Loans on Real Estate
Mortgage Loans	$ 1,409.9	$ 1,389.6
Percent of Total	60.80%	57.00%
Loan To Value Ratio Above 65 To 75 Percent
Mortgage Loans on Real Estate
Mortgage Loans	$ 707.0	$ 937.2
Percent of Total	30.50%	38.50%
Loan To Value Ratio Above 75 To 85 Percent
Mortgage Loans on Real Estate
Mortgage Loans	$ 136.5	$ 75.0
Percent of Total	5.90%	3.10%
Loan To Value Ratio Above 85 Percent
Mortgage Loans on Real Estate
Mortgage Loans	$ 64.8	$ 33.6
Percent of Total	2.80%	1.40%
AA Credit Rating
Mortgage Loans on Real Estate
Mortgage Loans	$ 85.2	$ 92.3
Percent of Total	3.70%	3.80%
A Credit Rating
Mortgage Loans on Real Estate
Mortgage Loans	$ 942.5	$ 843.9
Percent of Total	40.60%	34.60%
BBB Credit Rating
Mortgage Loans on Real Estate
Mortgage Loans	$ 1,249.5	$ 1,458.0
Percent of Total	53.90%	59.90%
BB Credit Rating
Mortgage Loans on Real Estate
Mortgage Loans	$ 41.0	$ 41.2
Percent of Total	1.80%	1.70%