Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Fixed maturities, available-for-sale, amortized cost	$ 2,188.2	$ 2,173.1
Equity securities, available-for-sale, cost	364.6	318.6
Other invested assets, available-for-sale, cost	56.6	25.8
Deferred Policy Acquisitions Costs from Affiliates	48.3	57.2
Property and equipment, accumulated depreciation	7.5	7.2
Losses And Loss Expenses Payable From Affiliates	593.6	711.4
Unearned premiums, affiliates	112.4	187.9
Net Other Liabilities from Affiliates	17.7	15.5
Notes payable, affiliates	$ 15.2	$ 15.2
Common stock, no par value (usd per share)	$ 0	$ 0
Common stock, shares authorized (shares)	100,000,000.0	100,000,000.0
Common stock, shares issued (shares)	50,000,000.0	49,200,000
Common Stock, Par or Stated Value Per Share	$ 2.50	$ 2.50
Treasury Stock, Shares	6,800,000	6,800,000
Class A Preferred stock
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
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