Schedule of Participating Mortgage Loans by Internal Credit Rating and Loan to Value (Details) - USD ($) $ in Millions	Jun. 30, 2024	Dec. 31, 2023
Mortgage Loans on Real Estate
Mortgage Loans, Carrying Amount	$ 2,261.1	$ 2,318.2
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	$ 1,485.8	$ 1,409.9
Mortgage Loans, Percent of Total	65.70%	60.80%
Loan To Value Ratio Above 65 To 75 Percent
Mortgage Loans on Real Estate
Mortgage Loans, Carrying Amount	$ 588.7	$ 707.0
Mortgage Loans, Percent of Total	26.00%	30.50%
Loan To Value Ratio Above 75 To 85 Percent
Mortgage Loans on Real Estate
Mortgage Loans, Carrying Amount	$ 116.5	$ 136.5
Mortgage Loans, Percent of Total	5.20%	5.90%
Loan To Value Ratio Above 85 Percent
Mortgage Loans on Real Estate
Mortgage Loans, Carrying Amount	$ 70.1	$ 64.8
Mortgage Loans, Percent of Total	3.10%	2.80%
AA Credit Rating
Mortgage Loans on Real Estate
Mortgage Loans, Carrying Amount	$ 83.6	$ 85.2
Mortgage Loans, Percent of Total	3.70%	3.70%
A Credit Rating
Mortgage Loans on Real Estate
Mortgage Loans, Carrying Amount	$ 988.6	$ 942.5
Mortgage Loans, Percent of Total	43.80%	40.60%
BBB Credit Rating
Mortgage Loans on Real Estate
Mortgage Loans, Carrying Amount	$ 1,133.8	$ 1,249.5
Mortgage Loans, Percent of Total	50.10%	53.90%
BB Credit Rating
Mortgage Loans on Real Estate
Mortgage Loans, Carrying Amount	$ 55.1	$ 41.0
Mortgage Loans, Percent of Total	2.40%	1.80%