Condensed Consolidated Balance Sheets - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2018	Dec. 31, 2017
Document Period End Date	Sep. 30, 2018
Assets
Fixed maturities, available-for-sale, at fair value (amortized cost $2,185.2 and $2,173.1, respectively)	$ 2,141.6	$ 2,192.8
Equity securities	376.3	365.3
Other invested assets	54.5	56.0
Other invested assets, at cost	5.6	5.6
Notes receivable from affiliate	70.0	70.0
Total investments	2,648.0	2,689.7
Cash and cash equivalents	49.5	91.5
Accrued investment income and other assets	39.5	36.5
Deferred policy acquisition costs (affiliated net assumed $50.1 and $57.2, respectively)	104.5	110.3
Reinsurance recoverable on losses and loss expenses payable	5.0	3.1
Prepaid reinsurance premiums	6.8	6.4
Due from Affiliates	10.6	0.0
Current federal income taxes	5.9	4.8
Net deferred federal income taxes	62.3	58.8
Property and equipment, at cost	7.1	7.3
Total assets	2,939.2	3,008.4
Liabilities and Stockholders’ Equity
Losses and loss expenses payable (affiliated net assumed $619.4 and $711.4, respectively)	1,198.7	1,255.6
Unearned premiums (affiliated net assumed $121.7 and $187.9, respectively)	595.6	611.8
Notes payable (affiliates $15.2 and $15.2, respectively)	122.0	122.1
Pension and postretirement benefits (affiliated $28.0 and $34.8, respectively)	52.1	64.5
Due to Affiliate	0.0	2.7
Other liabilities (affiliated net assumed $70.0 and $15.5, respectively)	101.4	76.7
Total liabilities	2,069.8	2,133.4
Stockholders’ equity:
Common stock, without par value. Authorized 100.0 shares; 49.8 and 49.2 shares issued, respectively, at stated value of $2.50 per share	124.5	123.0
Treasury stock, 6.8 and 6.8 shares, respectively, at cost	(117.0)	(116.8)
Additional paid-in capital	188.6	171.8
Accumulated Other Comprehensive Income (Loss), Net of Tax	(68.3)	36.7
Retained earnings	741.6	660.3
Total stockholders’ equity	869.4	875.0
Total liabilities and stockholders’ equity	2,939.2	3,008.4
Class A Preferred Stock [Member]
Stockholders’ equity:
Preferred stock value	0.0	0.0
Class B Preferred Stock [Member]
Stockholders’ equity:
Preferred stock value	$ 0.0	$ 0.0