Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Fixed maturity securities, allowances for credit losses	$ 0.0	$ (1.2)
Fixed maturity securities available for sale, amortized cost	6,903.9
Commercial mortgage loans on real estate, allowance for credit losses	1.1	1.6
Other investments, allowance for credit losses	0.0	1.4
Premiums and accounts receivable, allowance for credit losses	9.4	13.3
Reinsurance recoverable, allowance for credit losses	5.0	24.6
Other assets, allowance for credit losses	$ 2.5	$ 1.8
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized (in shares)	800,000,000	800,000,000
Common stock shares issued (in shares)	58,050,202	62,967,808
Common stock, shares outstanding (in shares)	55,754,113	57,967,808
Treasury stock, at cost (in shares)	2,296,089	5,000,000
Series D Preferred Stock
Preferred stock, dividend rate	6.50%	6.50%
Preferred stock, par value (in dollars per share)	$ 1.00	$ 1.00
Preferred stock, shares authorized (in shares)	0	2,875,000
Preferred stock, shares issued (in shares)	0	2,875,000
Preferred stock, shares outstanding (in shares)	0	2,875,000
Fixed Maturities
Fixed maturity securities, allowances for credit losses	$ 0.0	$ (1.2)
Fixed maturity securities available for sale, amortized cost	$ 6,903.9	$ 6,245.8