Fair Values of Financial Instruments Fair Value, by Balance Sheet Groupings (Details) - USD ($) $ in Millions	Mar. 31, 2019	Dec. 31, 2018
Financial Instruments, Financial Assets, Balance Sheet Groupings [Abstract]
Mortgage Loans, Fair Value	$ 2,273.2	$ 2,317.4
Mortgage Loans, Carrying Value	2,206.6	2,295.0
Policy Loans, Fair Value	3,780.5	3,831.1
Policy Loans, Carrying Value	3,673.3	3,729.9
Other Long-term Investments
Miscellaneous Long-Term Investments, Fair Value	101.8	115.6
Miscellaneous Long-Term Investments, Carrying Value	101.8	115.6
Total Financial Instruments Assets Not Carried at Fair Value	6,155.5	6,264.1
Financial Instruments, Financial Assets Fair Value Disclosure, Carrying Value	5,981.7	6,140.5
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Long-term Debt, Fair Value	3,164.7	3,069.2
Long-term Debt, Carrying Value	2,958.7	2,971.3
Collateralized Financings [Abstract]
Federal Home Loan Bank (FHLB) Funding Agreements, Fair Value		104.0
Federal Home Loan Bank (FHLB) Funding Agreements, Carrying Value		104.0
Other Liabilities, Unfunded Commitments	2.3	2.3
Total Financial Liabilities, Fair Value	3,167.0	3,175.5
Total Financial Liabilities, Carrying Value	2,961.0	3,077.6
Fair Value, Inputs, Level 1
Financial Instruments, Financial Assets, Balance Sheet Groupings [Abstract]
Mortgage Loans, Fair Value	0.0	0.0
Policy Loans, Fair Value	0.0	0.0
Other Long-term Investments
Miscellaneous Long-Term Investments, Fair Value	0.0	0.0
Total Financial Instruments Assets Not Carried at Fair Value	0.0	0.0
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Long-term Debt, Fair Value	2,847.6	1,429.8
Collateralized Financings [Abstract]
Federal Home Loan Bank (FHLB) Funding Agreements, Fair Value		0.0
Other Liabilities, Unfunded Commitments	0.0	0.0
Total Financial Liabilities, Fair Value	2,847.6	1,429.8
Fair Value, Inputs, Level 2
Financial Instruments, Financial Assets, Balance Sheet Groupings [Abstract]
Mortgage Loans, Fair Value	2,273.2	2,317.4
Policy Loans, Fair Value	0.0	0.0
Other Long-term Investments
Miscellaneous Long-Term Investments, Fair Value	19.1	24.1
Total Financial Instruments Assets Not Carried at Fair Value	2,292.3	2,341.5
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Long-term Debt, Fair Value	317.1	1,639.4
Collateralized Financings [Abstract]
Federal Home Loan Bank (FHLB) Funding Agreements, Fair Value		104.0
Other Liabilities, Unfunded Commitments	2.3	2.3
Total Financial Liabilities, Fair Value	319.4	1,745.7
Fair Value, Inputs, Level 3
Financial Instruments, Financial Assets, Balance Sheet Groupings [Abstract]
Mortgage Loans, Fair Value	0.0	0.0
Policy Loans, Fair Value	3,780.5	3,831.1
Other Long-term Investments
Miscellaneous Long-Term Investments, Fair Value	82.7	91.5
Total Financial Instruments Assets Not Carried at Fair Value	3,863.2	3,922.6
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Long-term Debt, Fair Value	0.0	0.0
Collateralized Financings [Abstract]
Federal Home Loan Bank (FHLB) Funding Agreements, Fair Value		0.0
Other Liabilities, Unfunded Commitments	0.0	0.0
Total Financial Liabilities, Fair Value	$ 0.0	$ 0.0

Financial Instruments, Financial Assets Fair Value Disclosure, Carrying Value

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Financial Instruments, Financial Assets Fair Value Disclosure, Total

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Miscellaneous Long-Term Investments

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Amount of Federal Home Loan Bank (FHLBank) advances to member financial institutions.

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Fair value portion of borrowing from Federal Home Loan Bank (FHLBank).

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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 capital lease obligation due after one year or beyond the normal operating cycle, if longer.

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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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Fair value portion of notes payable.

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

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