Condensed Consolidated Statements of Cash Flows - USD ($) $ in Millions		3 Months Ended		9 Months Ended		12 Months Ended
		Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023	Dec. 31, 2023
Net Income (Loss)		$ 72.2	$ (146.4)	$ 216.8	$ (323.6)
Adjustments to Reconcile Net Income (Loss) to Net Cash Provided by (Used in) Operating Activities
Net Realized Investment (Gains) Losses				(9.2)	38.3
Impairment Losses		2.2	1.1	3.8	(0.1)
Depreciation and Amortization of Property, Equipment and Software				33.3	39.1
Amortization of Intangibles Assets Acquired				7.5	11.0
Settlement Related to Defined Benefit Pension Plan				(2.6)	70.2
Change in Fair Value of Equity and Convertible Securities		2.3	(2.8)	0.1	(6.9)
Goodwill Impairment				0.0	49.6
Receivables from Policyholders				(28.4)	184.0
Reinsurance Recoverables				4.6	11.6
Deferred Policy Acquisition Costs				(30.3)	13.4
Insurance Reserves				(43.1)	7.9
Unearned Premiums				(2.9)	(219.3)
Income Taxes				42.5	27.5
Other Assets and Liabilities				(7.5)	(2.0)
Net Cash Provided by (Used in) Operating Activities				207.8	(104.5)
Cash Flows from Investing Activities:
Proceeds from the Sales, Calls and Maturities of Fixed Maturities				929.2	529.8
Proceeds from the Sales or Paydowns of Investments:
Equity Securities				15.8	73.9
Mortgage Loans				96.5	68.9
Other Investments				10.9	11.2
Purchases of Investments:
Fixed Maturities				(792.2)	(362.7)
Equity Securities				(12.1)	(40.1)
Real Estate Investments				(0.9)	(0.8)
Mortgage Loans				(87.8)	(76.6)
Other Investments				40.7	15.9
Net Purchases of Short-term Investments				(184.1)	(136.5)
Acquisition of Software and Long-lived Assets				(43.5)	(39.1)
Settlement Proceeds from Company-Owned Life Insurance				6.2	102.2
Other				13.1	(9.1)
Net Cash (Used in) Provided by Investing Activities				(89.6)	105.2
Cash Flows from Financing Activities:
Proceeds from Policyholder Contract Obligations				62.8	123.3
Repayment of Policyholder Contract Obligations				(100.6)	(168.4)
Proceeds from Shares Issued under Employee Stock Purchase Plan				2.9	3.3
Common Stock Repurchases				(25.0)	0.0
Dividends Paid				(60.1)	(59.8)
Other				(5.4)	0.9
Net Cash Used in Financing Activities				(125.4)	(100.7)
Net increase (decrease) in cash	[1]			(7.2)		$ (100.0)
Cash, Beginning of Year	[1]			64.1	212.4	212.4
Cash, End of Period	[1]	$ 56.9	$ 112.4	56.9	112.4	$ 64.1
Cash (paid) received during the year for:
Interest				(52.0)	(47.2)
Taxes				(10.5)	113.5
Operating Leases				(16.4)	(19.6)
Non-Cash Activities:
Right-of-Use Assets Obtained in Exchange for New Operating Lease Liabilities				8.5	6.6
Equity Method Limited Liability Investments
Adjustments to Reconcile Net Income (Loss) to Net Cash Provided by (Used in) Operating Activities
Income (Loss) from Equity Method Investments				(24.7)	2.9
Alternative Energy Partnership Investments
Adjustments to Reconcile Net Income (Loss) to Net Cash Provided by (Used in) Operating Activities
Income (Loss) from Equity Method Investments				$ 1.5	$ 2.3

[1] 1Includes amounts attributable to Kemper Reciprocal reported as non-controlling interest.