Condensed Consolidated Statements of Cash Flows - USD ($) $ in Millions		3 Months Ended			6 Months Ended
		Mar. 31, 2025		Mar. 31, 2024	Jun. 30, 2024
Statement of Cash Flows [Abstract]
Net Income		$ 97.0		$ 70.2
Adjustments to Reconcile Net Income to Net Cash Provided by Operating Activities
Net Realized Investment Gains		(0.9)		(6.6)
Impairment Losses		(0.3)		1.5
Depreciation and Amortization of Property, Equipment, Software and Intangible Assets Acquired		12.5		14.6
Income on Investments in Alternative Energy Partnership		(0.6)		(6.0)
Change in Fair Value of Equity and Convertible Securities		(0.1)		(3.4)
Receivables from Policyholders		(78.5)		4.4
Reinsurance Recoverables		(0.9)		1.8
Deferred Policy Acquisition Costs		(21.2)		(4.2)
Insurance Reserves		43.1		(69.0)
Unearned Premiums		100.8		(24.1)
Income Taxes		22.7		26.9
Other		5.2		24.9
Net Cash Provided by Operating Activities		180.0		43.0
Cash Flows from Investing Activities:
Proceeds from the Sales, Calls and Maturities of Fixed Maturities		215.1		323.2
Proceeds from the Sales or Paydowns of Investments:
Equity Securities		7.3		13.4
Mortgage Loans		24.1		34.1
Other Investments		5.9		3.5
Purchases of Investments:
Fixed Maturities		(302.5)		(286.9)
Equity Securities		(20.5)		(3.1)
Real Estate Investments		(1.1)		(0.2)
Mortgage Loans		(51.7)		(27.4)
Other Investments		15.0		9.6
Net Sales of Short-term Investments		493.6		2.4
Acquisition of Software and Long-lived Assets		(7.7)		(15.3)
Settlement Proceeds from Company-Owned Life Insurance		2.9		4.9
Other		0.7		0.3
Net Cash Provided by Investing Activities		351.1		39.3
Cash Flows from Financing Activities:
Repayment of Long-term Debt		(450.0)		0.0
Proceeds from Policyholder Contract Obligations		20.0		25.5
Repayment of Policyholder Contract Obligations		(25.9)		(20.6)
Proceeds from Shares Issued under Employee Stock Purchase Plan		0.8		0.9
Common Stock Repurchases		(4.0)		0.0
Dividends Paid		(20.2)		(19.5)
Other		(1.8)		(6.0)
Net Cash Used in Financing Activities		(481.1)		(19.7)
Net increase (decrease) in cash		50.0	[1]	62.6	$ 62.6	[1]
Cash, Beginning of Year	[1]	65.4		64.1	$ 64.1
Cash, End of Period	[1]	115.4		126.7
Cash (paid) received during the year for:
Interest		(24.5)		(20.0)
Taxes		0.0		10.4
Operating Leases		(5.1)		(5.7)
Non-Cash Activities:
Right-of-Use Assets Obtained in Exchange for New Operating Lease Liabilities		$ 7.6		$ 0.9

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