Condensed Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Millions	Mar. 31, 2020	Dec. 31, 2019
Fixed maturities, available-for-sale, amortized cost	$ 2,051.8	$ 2,080.0
Deferred policy acquisitions costs from affiliates	21.8	20.2
Losses and loss expenses payable, affiliates	457.3	500.8
Unearned premiums, affiliates	126.3	116.7
Notes payable, affiliates	15.2	15.2
Net Other Liabilities from Affiliates	$ 10.7	$ 19.5
Common stock, no par value (usd per share)	$ 0	$ 0
Common stock, shares authorized (shares)	100,000,000	100,000,000
Common stock, shares issued (shares)	50,600,000	50,400,000
Common stock, stated value per share (usd per share)	$ 2.50	$ 2.50
Treasury stock (shares)	6,900,000	6,900,000
Class A Preferred Stock [Member]
Preferred stock, no par value (usd per share)	$ 0	$ 0
Preferred stock, shares authorized (shares)	2,500,000	2,500,000
Preferred stock, shares issued (shares)	0	0
Class B Preferred Stock [Member]
Preferred stock, no par value (usd per share)	$ 0	$ 0
Preferred stock, shares authorized (shares)	2,500,000	2,500,000
Preferred stock, shares issued (shares)	0	0