Fair Values of Financial Instruments Carrying Amounts and Estimated Fair value of Financial Instruments Not Measured at Fair Value (Details) - USD ($) $ in Millions		Dec. 31, 2025	Dec. 31, 2024
Fair Value, Balance Sheet Grouping, Financial Statement Captions
Mortgage Loans	[1]	$ 2,109.5	$ 2,224.5
Policy Loans		3,668.1	3,617.2
Long-term Debt		3,767.6	3,465.2
Liabilities, Fair Value Disclosure		269.7	255.7
Fair Value, Nonrecurring
Fair Value, Balance Sheet Grouping, Financial Statement Captions
Mortgage Loans, Fair Value Disclosure		1,965.1	1,975.4
Mortgage Loans		2,109.5	2,224.5
Policy Loans, Fair Value Disclosure		3,739.5	3,672.9
Policy Loans		3,668.1	3,617.2
Miscellaneous Long-Term Investments, Fair Value Disclosure		40.9	26.9
Miscellaneous Long-Term Investments		40.9	26.9
Financial Instruments, Financial Assets Fair Value Disclosure		5,745.5	5,675.2
Total Financial Instrument Assets Not Carried at Fair Value		5,818.5	5,868.6
Long-term Debt, Fair Value Disclosure		3,641.4	3,289.3
Long-term Debt		3,767.6	3,465.2
Unfunded Commitments		0.2	0.2
Federal Home Loan Bank Funding Agreements, Fair Value Disclosure		643.8	324.2
Payables for Collateral on Investments		643.8	324.2
Liabilities, Fair Value Disclosure		4,285.4	3,613.7
Total Financial Instrument Liabilities Not Carried at Fair Value		4,411.6	3,789.6
Fair Value, Inputs, Level 1 | Fair Value, Nonrecurring
Fair Value, Balance Sheet Grouping, Financial Statement Captions
Mortgage Loans, Fair Value Disclosure		0.0	0.0
Policy Loans, Fair Value Disclosure		0.0	0.0
Miscellaneous Long-Term Investments, Fair Value Disclosure		0.0	0.0
Financial Instruments, Financial Assets Fair Value Disclosure		0.0	0.0
Long-term Debt, Fair Value Disclosure		2,548.2	3,246.1
Unfunded Commitments		0.0	0.0
Federal Home Loan Bank Funding Agreements, Fair Value Disclosure		0.0	0.0
Liabilities, Fair Value Disclosure		2,548.2	3,246.1
Fair Value, Inputs, Level 2 | Fair Value, Nonrecurring
Fair Value, Balance Sheet Grouping, Financial Statement Captions
Mortgage Loans, Fair Value Disclosure		1,965.1	1,975.4
Policy Loans, Fair Value Disclosure		0.0	0.0
Miscellaneous Long-Term Investments, Fair Value Disclosure		40.7	26.7
Financial Instruments, Financial Assets Fair Value Disclosure		2,005.8	2,002.1
Long-term Debt, Fair Value Disclosure		1,093.2	43.2
Unfunded Commitments		0.2	0.2
Federal Home Loan Bank Funding Agreements, Fair Value Disclosure		643.8	324.2
Liabilities, Fair Value Disclosure		1,737.2	367.6
Fair Value, Inputs, Level 3 | Fair Value, Nonrecurring
Fair Value, Balance Sheet Grouping, Financial Statement Captions
Mortgage Loans, Fair Value Disclosure		0.0	0.0
Policy Loans, Fair Value Disclosure		3,739.5	3,672.9
Miscellaneous Long-Term Investments, Fair Value Disclosure		0.2	0.2
Financial Instruments, Financial Assets Fair Value Disclosure		3,739.7	3,673.1
Long-term Debt, Fair Value Disclosure		0.0	0.0
Unfunded Commitments		0.0	0.0
Federal Home Loan Bank Funding Agreements, Fair Value Disclosure		0.0	0.0
Liabilities, Fair Value Disclosure		$ 0.0	$ 0.0

[1] Loan-to-Value Ratio utilizes the most recent internal valuation of the property