Condensed Consolidated Balance Sheets (Parenthetical) - USD ($) shares in Millions, $ in Millions	Sep. 30, 2020	Dec. 31, 2019
Fixed maturities, available-for-sale, amortized cost	$ 2,047.1	$ 2,080.0
Deferred policy acquisitions costs from affiliates	27.6	20.2
Losses and loss expenses payable, affiliates	450.9	500.8
Unearned premiums, affiliates	450.8	415.8
Notes payable, affiliates	15.2	15.2
Net Other Liabilities from Affiliates	$ 18.5	$ 19.5
Common stock, shares authorized (shares)	100.0	100.0
Common stock, shares issued (shares)	50.7	50.4
Common stock, stated value per share (usd per share)	$ 2.50	$ 2.50
Treasury stock (shares)	6.9	6.9
Class A Preferred Stock [Member]
Preferred stock, shares authorized (shares)	2.5	2.5
Class B Preferred Stock [Member]
Preferred stock, shares authorized (shares)	2.5	2.5