CONSOLIDATED STATEMENTS OF CASH FLOWS (UNAUDITED) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Cash Flows from Operating Activities
Net Income	$ 395.2	$ 358.3
Adjustments to Reconcile Net Income to Net Cash Provided (Used) by Operating Activities
Change in Receivables	103.5	89.9
Change in Deferred Acquisition Costs	(40.7)	(41.8)
Change in Insurance Reserves and Liabilities	(112.3)	(119.6)
Change in Income Taxes	107.2	76.2
Change in Other Accrued Liabilities	(144.8)	(175.1)
Non-cash Components of Net Investment Income	(76.6)	(64.4)
Net Investment (Gain) Loss	1.2	(0.1)
Depreciation	30.1	26.8
Amortization of the Cost of Reinsurance	10.4	11.0
Other, Net	25.1	(10.6)
Net Cash Provided (Used) by Operating Activities	298.3	150.6
Cash Flows from Investing Activities
Proceeds from Sales of Fixed Maturity Securities	190.1	55.1
Proceeds from Maturities of Fixed Maturity Securities	396.7	387.4
Proceeds from Sales and Maturities of Other Investments	48.5	91.6
Purchases of Fixed Maturity Securities	(575.0)	(589.1)
Purchases of Other Investments	(59.6)	(79.9)
Net Sales and Maturities of Short-term Investments	25.7	183.8
Net Increase (Decrease) in Payables for Collateral on Investments	19.6	(60.3)
Net Purchases of Property and Equipment	(28.3)	(29.1)
Net Cash Provided (Used) by Investing Activities	17.7	(40.5)
Cash Flows from Financing Activities
Issuance of Common Stock	1.3	1.2
Repurchase of Common Stock	(121.9)	(51.2)
Dividends Paid to Stockholders	(72.5)	(69.2)
Proceeds from Policyholder Account Deposits	34.5	37.7
Payments for Policyholder Account Withdrawals	(23.9)	(24.4)
Other, Net	(0.4)	(0.3)
Net Cash Used by Financing Activities	(182.9)	(106.2)
Net Increase in Cash and Bank Deposits	133.1	3.9
Cash and Bank Deposits at Beginning of Year	146.0	119.2
Cash and Bank Deposits at End of Period	$ 279.1	$ 123.1