CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Cash Flows from Operating Activities
Net Income	$ 738.5	$ 1,779.1	$ 1,283.8
Adjustments to Reconcile Net Income to Net Cash Provided by Operating Activities
Change in Receivables	529.4	623.9	602.7
Change in Deferred Acquisition Costs	(170.0)	(130.5)	(150.8)
Change in Insurance Liabilities	437.3	(780.9)	(313.2)
Change in Income Taxes	(22.6)	97.6	(84.3)
Change in Other Accrued Liabilities	(112.4)	(32.3)	(74.8)
Non-cash Components of Net Investment Income	(223.0)	(248.9)	(240.3)
Net Investment Loss	106.6	34.6	36.0
Depreciation	123.0	116.1	108.8
Cash Related to Reinsurance Transaction	945.3	0.0	0.0
Settlement Loss on the U.S. Pension Plan Annuity Purchase	103.8	0.0	0.0
Amortization of Deferred Gain on Reinsurance	(9.0)	0.0	0.0
Other, Net	14.7	13.1	(9.2)
Net Cash Provided by Operating Activities	687.7	1,513.2	1,202.8
Cash Flows from Investing Activities
Proceeds from Sales of Fixed Maturity Securities	822.7	877.3	1,062.7
Proceeds from Maturities of Fixed Maturity Securities	2,131.7	1,483.0	1,578.1
Proceeds from Sales and Maturities of Other Investments	506.4	332.1	360.0
Purchase of Fixed Maturity Securities	(2,393.6)	(2,001.7)	(2,991.4)
Purchase of Other Investments	(361.2)	(319.1)	(361.2)
Net Purchases of Short-term Investments	(355.7)	(842.1)	(141.0)
Net Increase (Decrease) in Payables for Collateral on Investments	330.9	251.8	(98.3)
Net Purchases of Property and Equipment	(132.3)	(125.7)	(134.8)
Net Cash Used by Investing Activities	548.9	(344.4)	(725.9)
Cash Flows from Financing Activities
Short-term Debt Repayment	(275.0)	0.0	(2.0)
Issuance of Long-term Debt	296.0	391.6	0.0
Long-term Debt Repayment	0.0	(350.0)	0.0
Issuance of Common Stock	5.1	6.0	5.2
Repurchase of Common Stock	(1,010.3)	(972.9)	(250.1)
Dividends Paid to Stockholders	(306.2)	(296.5)	(277.1)
Proceeds from Policyholder Account Deposits	124.1	133.2	143.4
Payments for Policyholder Account Withdrawals	(88.5)	(82.7)	(87.0)
Cash Received Related to Active Life Volatility Cover Agreement	17.4	26.7	18.6
Other, Net	(3.8)	(7.4)	(1.1)
Net Cash Used by Financing Activities	(1,241.2)	(1,152.0)	(450.1)
Net Increase (Decrease) in Cash and Bank Deposits	(4.6)	16.8	26.8
Cash and Bank Deposits at Beginning of Year	162.8	146.0	119.2
Cash and Bank Deposits at End of Year	158.2	162.8	146.0
Amortization of Deferred Loss on Reinsurance	$ 116.7	$ 41.4	$ 44.1