CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in Millions	Sep. 30, 2023	Dec. 31, 2022
Investments
Amortized Cost of Fixed Maturity Securities	$ 38,224.3	$ 37,825.2
Debt Securities, Available-for-sale, Allowance for credit losses for Fixed Maturity Securities	0.0	0.0
Other Assets
Accounts and Premiums Receivable (net of allowance for credit losses of $29.7; $32.5)	1,507.7	1,482.1
Premium Receivable, Allowance for Credit Loss	29.7	32.5
Reinsurance Recoverable, Allowance for Credit Loss	$ 1.8	$ 1.7
Stockholders' Equity
Common Stock, Par Value (in dollars per share)	$ 0.10	$ 0.10
Common Stock, Shares Authorized	725,000,000	725,000,000
Common Stock, Shares Issued	309,486,850	308,306,490
Treasury Stock, Common, Shares	114,469,894	110,551,977