CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in Millions	Mar. 31, 2020	Dec. 31, 2019
Investments
Allowance for credit losses for Fixed Maturity Securities	$ 48.0	$ 0.0
Amortized Cost of Fixed Maturity Securities	41,030.3	41,079.3
Allowance for credit losses for Mortgage Loans	11.1	0.0
Other Assets [Abstract]
Accounts Receivable, after Allowance for Credit Loss	32.6	10.3
Reinsurance Recoverable, Allowance for Credit Loss	$ 1.8	$ 0.0
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	306,201,660	305,813,326
Treasury Stock, Shares at Cost	102,876,514	102,876,514