CONSOLIDATED STATEMENTS OF CASH FLOWS (UNAUDITED) - USD ($) $ in Millions	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2026	Jun. 30, 2025	Jun. 30, 2026	Jun. 30, 2025	Dec. 31, 2025
Cash Flows from Operating Activities
Net Income	$ 256.9	$ 335.6	$ 488.9	$ 524.7
Adjustments to Reconcile Net Income to Net Cash Provided by Operating Activities
Change in Receivables			151.8	360.2
Deferred Policy Acquisition Cost			(108.4)	(89.9)
Change in Insurance Liabilities			195.4	55.0
Change in Income Taxes			91.2	10.3
Change in Other Accrued Liabilities			(49.1)	(266.3)
Non-cash Components of Net Investment Income			(177.1)	(176.8)
Gain (Loss) on Investments	(5.2)	(17.7)	(10.2)	(224.5)
Depreciation			82.4	60.2
Amortization of Deferred Loss on Reinsurance			91.5	19.3
Other, Net			67.5	(19.6)
Net Cash Provided by Operating Activities			844.3	701.6
Cash Flows from Investing Activities
Proceeds from Sale of Debt Securities, Available-for-sale			176.4	470.9
Proceeds from Maturities of Fixed Maturity Securities			1,310.5	923.3
Proceeds from Sales and Maturities of Other Investments			418.5	246.9
Payments to Acquire Debt Securities, Available-for-sale			(2,748.4)	(904.3)
Purchases of Other Investments			(352.8)	(202.6)
Net Sales and Maturities of Short-term Investments			1,172.9	328.1
Net Increase (Decrease) in Payables for Collateral on Investments			(325.0)	162.1
Net Purchases of Property and Equipment			(68.8)	(63.7)
Net Cash Provided (Used) by Investing Activities			(416.7)	960.7
Cash Flows from Financing Activities
Repayments of Long-term Debt			7.2	0.0
Issuance of Common Stock			3.0	2.8
Repurchase of Common Stock			(608.7)	(500.9)
Dividends Paid to Stockholders			(151.8)	(150.5)
Proceeds from Policyholder Account Deposits			654.0	63.3
Payments for Policyholder Account Withdrawals			(264.0)	(43.2)
Other, Net			(11.9)	(1.8)
Net Cash Used by Financing Activities			(386.6)	(630.3)
Net Increase (Decrease) in Cash and Bank Deposits			41.0	1,032.0
Cash and Bank Deposits at Beginning of Year			158.2	162.8	$ 162.8
Cash and Bank Deposits at End of Period	$ 199.2	$ 1,194.8	$ 199.2	$ 1,194.8	$ 158.2