Condensed Consolidated Statements of Cash Flows - USD ($) $ in Millions	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022	Dec. 31, 2022
Net Loss	$ (146.4)	$ (74.8)	$ (323.6)	$ (233.3)
Adjustments to Reconcile Net Income (Loss) to Cash Provided by (Used in) Operating Activities [Abstract]
Net Realized Investment Losses (Gains)			38.3	(0.4)
Impairment Gains (Losses)	1.1	8.3	(0.1)	22.1
Depreciation and Amortization of Property, Equipment and Software			39.1	38.9
Amortization of Intangibles Assets Acquired			11.0	16.0
Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Gain (Loss) Due to Settlement and Curtailment			70.2	0.0
Loss from Early Extinguishment of Debt	0.0	0.0	0.0	3.7
Income (Loss) from Equity Method Investments, Net of Dividends or Distributions			(2.9)	(13.7)
(Increase) Decrease in Value of Equity and Convertible Securities	(2.8)	11.2	(6.9)	79.9
Goodwill Impairment			49.6	0.0
Receivables from Policyholders			184.0	69.6
Reinsurance Recoverables			11.6	(1.8)
Deferred Policy Acquisition Costs			13.4	4.2
Insurance Reserves			7.9	(25.0)
Unearned Premiums			(219.3)	(93.4)
Income Taxes			27.5	(62.9)
Other Assets and Liabilities			(2.0)	4.8
Net Cash Provided by (Used in) Operating Activities, Total			(104.5)	(170.1)
Cash Flows from Investing Activities:
Proceeds from Sales, Calls and Maturities of Fixed Maturities			529.8	1,019.4
Proceeds from the Sales or Paydowns of Investments:
Equity Securities			73.9	458.3
Mortgage Loans			68.9	69.9
Other Investments			11.2	41.9
Payments to Acquire Investments [Abstract]
Payments to Acquire Debt Securities, Available-for-Sale			(362.7)	(1,386.7)
Payments to Acquire Equity Securities, FV-NI			(40.1)	(55.3)
Payments to Acquire Real Estate Held-for-investment			(0.8)	(2.9)
Payment to Acquire Life Insurance Policy, Investing Activities			0.0	(110.0)
Payments to Acquire Mortgage Notes Receivable			(76.6)	(67.3)
Payments to Acquire Interest in Subsidiaries and Affiliates			15.9	9.7
Net Purchases of Short-term Investments			(136.5)	(73.6)
Proceeds from Sale of Other Assets, Investing Activities			0.0	4.9
Acquisition of Software and Long-lived Assets			(39.1)	(27.1)
Settlement Proceeds from Company-Owned Life Insurance			102.2	0.0
Other			(9.1)	8.6
Net Cash Provided by (Used in) Investing Activities, Total			105.2	(129.6)
Cash Flows from Financing Activities:
Repayment of Long-term Debt			0.0	(280.0)
Proceeds from Issuance of Senior Long-term Debt			0.0	396.3
Proceeds from Issuance of Subordinated Long-term Debt			0.0	145.6
Proceeds from Policyholder Contract Obligations			123.3	319.9
Repayment of Policyholder Contract Obligations			(168.4)	(120.1)
Proceeds from Shares Issued under Employee Stock Purchase Plan			3.3	3.8
Dividends Paid			(59.8)	(59.9)
Other			0.9	0.3
Net Cash Provided by (Used in) Financing Activities, Total			(100.7)	403.8
Net increase (decrease) in cash, Including Held-for-Sale			(100.0)	104.1
Cash at end of period, Including Held-for-Sale	112.4	252.3	112.4	252.3	$ 212.4
Net increase (decrease) in cash, Held-for-Sale			0.0	3.1
Cash at beginning of year, Held-for-Sale			0.0	0.0	0.0
Cash at end of period, Held-for-Sale	0.0	3.1	0.0	3.1	0.0
Net (decrease) increase in cash			(100.0)		101.0
Cash, Beginning of Year			212.4	148.2	148.2
Cash, End of Period	$ 112.4	$ 249.2	112.4	249.2	$ 212.4
Senior Notes, 3.800 Percent Due February 23, 2033
Cash Flows from Financing Activities:
Payments of Debt Issuance Costs			0.0	(1.2)
5.875% Fixed-Rate Reset Junior Subordinated Debentures due 2062
Cash Flows from Financing Activities:
Payments of Debt Issuance Costs			0.0	(0.9)
Alternative Energy Partnership Investments
Adjustments to Reconcile Net Income (Loss) to Cash Provided by (Used in) Operating Activities [Abstract]
Income (Loss) from Equity Method Investments			$ 2.3	$ (21.2)