Fair Values of Financial Instruments Carrying Amounts and Estimated Fair value of Financial Instruments Not Measured at Fair Value (Details) - USD ($) $ in Millions	Sep. 30, 2020	Dec. 31, 2019
Fair Value, Balance Sheet Grouping, Financial Statement Captions
Mortgage Loans, Carrying Amount	$ 2,406.5	$ 2,397.0
Policy Loans	3,669.1	3,779.5
Other Long-term Investments	931.0	844.2
Long-term Debt	3,378.6	2,926.9
Unfunded Commitments	1.8
Liabilities, Fair Value Disclosure	87.7	57.4
Fair Value, Nonrecurring
Fair Value, Balance Sheet Grouping, Financial Statement Captions
Mortgage Loans, Fair Value Disclosure	2,623.3	2,556.3
Mortgage Loans, Carrying Amount	2,406.5	2,397.0
Policy Loans, Fair Value Disclosure	3,819.2	3,911.4
Policy Loans	3,669.1	3,779.5
Miscellaneous Long-Term Investments, Fair Value Disclosure	58.3	76.9
Other Long-term Investments	58.3	76.9
Financial Instruments, Financial Assets Fair Value Disclosure	6,500.8	6,544.6
Total Financial Instrument Assets Not Carried at Fair Value	6,133.9	6,253.4
Long-term Debt, Fair Value Disclosure	3,764.5	3,239.0
Long-term Debt	3,378.6	2,926.9
Advances, Fair Value Disclosure	30.2
Federal Home Loan Bank Funding Agreements	30.2
Unfunded Commitments	1.8	1.9
Liabilities, Fair Value Disclosure	3,796.5	3,240.9
Total Financial Instrument Liabilities Not Carried at Fair Value	3,410.6	2,928.8
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	2,561.0	1,712.8
Advances, Fair Value Disclosure	0.0
Unfunded Commitments	0.0	0.0
Liabilities, Fair Value Disclosure	2,561.0	1,712.8
Fair Value, Inputs, Level 2 \| Fair Value, Nonrecurring
Fair Value, Balance Sheet Grouping, Financial Statement Captions
Mortgage Loans, Fair Value Disclosure	2,623.3	2,556.3
Policy Loans, Fair Value Disclosure	0.0	0.0
Miscellaneous Long-Term Investments, Fair Value Disclosure	21.7	18.5
Financial Instruments, Financial Assets Fair Value Disclosure	2,645.0	2,574.8
Long-term Debt, Fair Value Disclosure	1,203.5	1,526.2
Advances, Fair Value Disclosure	30.2
Unfunded Commitments	1.8	1.9
Liabilities, Fair Value Disclosure	1,235.5	1,528.1
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	3,819.2	3,911.4
Miscellaneous Long-Term Investments, Fair Value Disclosure	36.6	58.4
Financial Instruments, Financial Assets Fair Value Disclosure	3,855.8	3,969.8
Long-term Debt, Fair Value Disclosure	0.0	0.0
Advances, Fair Value Disclosure	0.0
Unfunded Commitments	0.0	0.0
Liabilities, Fair Value Disclosure	$ 0.0	$ 0.0

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Miscellaneous Long-Term Investments

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Total Financial Instrument Liabilities Not Carried at Fair Value

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Fair value of Federal Home Loan Bank (FHLBank) advances carried under the fair value option.

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Fair value of financial and nonfinancial obligations.

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Amount before allowance of loans made to policy and contract holders using their life insurance contracts' cash value or separate accounts as collateral. Includes deferred interest and fees, undisbursed portion of loan balance, unamortized costs and premiums over and discounts from face amounts. Excludes loans and leases covered under loss sharing agreements.

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Fair value portion of loan receivable, including, but not limited to, mortgage loans held for investment, finance receivables held for investment, policy loans on insurance contracts.

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Amount of long-term debt and lease obligation, classified as noncurrent.

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The balance represents the amount of loans that are secured by real estate mortgages, offset by the reserve to cover probable credit losses on the loan portfolio.

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Fair value portion of mortgage loans held-for-sale.

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Amount of long-term investments classified as other.

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Amount of commitment or contingent commitments to qualified affordable housing project investments.

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