Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015
Fixed maturities, available-for-sale, amortized cost	$ 2,095.9	$ 1,972.9
Equity securities, available-for-sale, cost	323.1	265.2
Other invested assets, available-for-sale, cost	25.5	56.9
Deferred Policy Acquisitions Costs from Affiliates	50.7	49.3
Property and equipment, accumulated depreciation	6.6	6.3
Losses And Loss Expenses Payable From Affiliates	630.9	532.4
Unearned premiums, affiliates	220.9	214.2
Net Postretirement and Pension Benefits	(40.1)	(56.0)
Net Other Liabilities from Affiliates	11.0	(8.4)
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	100,000,000
Common stock, shares issued (shares)	48,600,000	48,100,000
Common Stock, Par or Stated Value Per Share	$ 2.50	$ 2.50
Net Accumulated Other Comprehensive Income	$ (53.7)	$ (56.7)
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