Consolidated Statements of Cash Flows - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022		Dec. 31, 2021
Cash Flows from Operating Activities:
Net Loss	$ (272.3)	$ (286.6)	[1]	$ (123.7)	[1]
Adjustments to Reconcile Net Loss to Net Cash (Used in) Provided by Operating Activities:
Net Realized Gain on Sale of Investments	18.6	(4.3)	[1]	(64.8)	[1]
Impairment Losses	1.1	25.8	[1]	11.0	[1]
Depreciation and Amortization of Property, Equipment and Software	44.4	50.5	[2]	46.3	[2]
Amortization of Intangible Assets Acquired	14.2	20.4	[2]	53.5	[2]
Settlement Costs Related to Defined Benefit Pension Plan	70.2	0.0	[2]	0.0	[2]
Loss from Early Extinguishment of Debt	0.0	3.7	[2]	0.0	[1]
(Increase) Decrease in Value of Equity and Convertible Securities	(4.7)	79.9	[1]	(114.6)	[1]
Goodwill impairment	49.6	0.0	[2]	0.0	[1]
Changes in:
Receivables from Policyholders	326.4	129.4	[2]	(75.2)	[2]
Reinsurance Recoverables	12.1	(1.9)	[2]	20.6	[2]
Deferred Policy Acquisition Costs	43.9	14.2	[2]	(77.6)	[2]
Insurance Reserves	(30.8)	26.5	[2]	616.4	[2]
Unearned Premiums	(403.1)	(183.5)	[2]	105.9	[2]
Income Taxes	33.2	(83.6)	[2]	(163.9)	[2]
Other Assets and Liabilities	(33.0)	(11.2)	[2]	89.1	[2]
Net Cash (Used in) Provided by Operating Activities	(134.2)	(210.3)	[2]	350.7	[2]
Cash Flows from Investing Activities:
Proceeds from the Sales, Calls and Maturities of Fixed Maturities	673.0	1,295.5	[2]	1,388.9	[2]
Equity Securities	149.0	536.0	[2]	316.6	[2]
Real Estate Investments	0.0	0.0	[2]	8.0	[2]
Mortgage Loans	95.2	91.3	[2]	70.8	[2]
Other Investments	18.3	52.1	[2]	47.5	[2]
Fixed Maturities	(447.4)	(1,815.8)	[2]	(1,825.4)	[2]
Equity Securities	(44.4)	(58.9)	[2]	(124.3)	[2]
Real Estate Investments	(1.0)	(3.1)	[2]	(5.1)	[2]
Corporate-Owned Life Insurance	0.0	(110.0)	[2]	(100.0)	[2]
Mortgage Loans	(104.1)	(81.1)	[2]	(119.9)	[2]
Other Investments	(19.8)	(13.0)	[2]	(104.9)	[2]
Net (Purchases) Sales of Short-term Investments	(238.4)	6.1	[2]	687.2	[2]
Acquisition of Business, Net of Cash Acquired	0.0	0.0	[2]	(316.6)	[2]
Sale of Reserve National, Net of Cash Disposed	0.0	14.8	[2]	0.0	[2]
Acquisition of Software and Long-lived Assets	(53.8)	(30.8)	[2]	(57.8)	[2]
Settlement Proceeds from Company-Owned Life Insurance	102.2	0.0	[2]	0.0	[2]
Other	(20.9)	8.5	[2]	16.8	[2]
Net Cash Provided by (Used in) Investing Activities	107.9	(108.4)	[2]	(118.2)	[2]
Cash Flows from Financing Activities:
Repayments of Long-term Debt	0.0	(280.0)		(50.0)
Proceeds from Issuance of 5.875% Fixed-Rate Reset Junior Subordinated Debentures Due 2062	0.0	145.6		0.0
Proceeds from Policyholder Contract Obligations	123.3	335.5		386.8
Repayment of Policyholder Contract Obligations	(169.0)	(138.2)		(394.0)
Proceeds from Shares Issued under Employee Stock Purchase Plan	4.3	4.9		5.4
Common Stock Repurchases	0.0	0.0		(161.7)
Dividends Paid	(80.1)	(79.7)		(80.6)
Other	(0.5)	0.6		3.7
Net Cash (Used in) Provided by Financing Activities	(122.0)	382.9		(290.4)
Net (decrease) increase in cash	(148.3)	64.2		(57.9)
Cash, Beginning of Year	212.4	148.2		206.1
Cash, End of Year	64.1	212.4		148.2
Cash (paid) received during the year for:
Interest	(54.5)	(51.5)		(43.9)
Income taxes paid	106.7	(0.7)		(38.0)
Non-Cash Activities:
Operating Leases	(25.4)	(24.0)		(23.6)
Right-of-Use Assets Obtained in Exchange for New Operating Lease Liabilities	13.8	9.7		15.5
Equity Method Limited Liability Investments
Adjustments to Reconcile Net Loss to Net Cash (Used in) Provided by Operating Activities:
(Income) Loss from Change in Value of Alternative Energy Partnership Investments	(1.1)	(9.5)	[2]	(33.5)	[2]
Alternative Energy Partnership Investments
Adjustments to Reconcile Net Loss to Net Cash (Used in) Provided by Operating Activities:
(Income) Loss from Change in Value of Alternative Energy Partnership Investments	(2.9)	19.9	[2]	61.2	[2]
Senior Notes, 3.800 Percent Due February 23, 2032
Cash Flows from Financing Activities:
Proceeds from Issuance of 3.800% Senior Notes due February 23, 2032	0.0	396.3		0.0
Issue Fess	0.0	(1.2)		0.0
5.875% Fixed-Rate Reset Junior Subordinated Debentures due 2062
Cash Flows from Financing Activities:
Issue Fess	$ 0.0	$ (0.9)		$ 0.0

[1] As of January 1, 2023, the Company adopted ASU 2018-12 using the modified retrospective method applied as of the transition date of January 1, 2021. Prior period amounts in the financial statements have been recast to reflect application of the new guidance. See Note 2 to the Consolidated Financial Statements for additional information.

[2] As of January 1, 2023, the Company adopted ASU 2018-12 using the modified retrospective method applied as of the transition date of January 1, 2021. Prior period amounts in the financial statements have been recast to reflect application of the new guidance. See Note 2 to the Consolidated Financial Statements for additional information.