Schedule of Participating Mortgage Loans by Internal Credit Rating and Loan to Value (Details) - USD ($) $ in Millions	Jun. 30, 2023	Dec. 31, 2022
Mortgage Loans on Real Estate
Mortgage Loans, Carrying Amount	$ 2,372.8	$ 2,435.4
Mortgage Loans, Percent of Total	100.00%	100.00%
Loan to Value Ratio Below or Equal to 65 Percent
Mortgage Loans on Real Estate
Mortgage Loans, Carrying Amount	$ 1,381.2	$ 1,389.6
Mortgage Loans, Percent of Total	58.20%	57.00%
Loan To Value Ratio Above 65 To 75 Percent
Mortgage Loans on Real Estate
Mortgage Loans, Carrying Amount	$ 815.2	$ 937.2
Mortgage Loans, Percent of Total	34.40%	38.50%
Loan To Value Ratio Above 75 To 85 Percent
Mortgage Loans on Real Estate
Mortgage Loans, Carrying Amount	$ 111.5	$ 75.0
Mortgage Loans, Percent of Total	4.70%	3.10%
Loan To Value Ratio Above 85 Percent
Mortgage Loans on Real Estate
Mortgage Loans, Carrying Amount	$ 64.9	$ 33.6
Mortgage Loans, Percent of Total	2.70%	1.40%
AA Credit Rating
Mortgage Loans on Real Estate
Mortgage Loans, Carrying Amount	$ 79.6	$ 92.3
Mortgage Loans, Percent of Total	3.40%	3.80%
A Credit Rating
Mortgage Loans on Real Estate
Mortgage Loans, Carrying Amount	$ 826.6	$ 843.9
Mortgage Loans, Percent of Total	34.80%	34.60%
BBB Credit Rating
Mortgage Loans on Real Estate
Mortgage Loans, Carrying Amount	$ 1,404.0	$ 1,458.0
Mortgage Loans, Percent of Total	59.20%	59.90%
BB Credit Rating
Mortgage Loans on Real Estate
Mortgage Loans, Carrying Amount	$ 62.6	$ 41.2
Mortgage Loans, Percent of Total	2.60%	1.70%