Consolidated Statements of Income (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Revenues:
Earned Premiums	$ 451.5	$ 462.8	$ 470.3	$ 477.6	$ 495.6	$ 507.5	$ 512.8	$ 509.9	$ 1,862.2	$ 2,025.8	$ 2,107.1
Net Investment Income	93.1	72.3	72.6	71.1	76.9	82.4	74.6	80.8	309.1	314.7	295.9
Other Income	0.6	0.5	0.2	0.1	0.3	0.1	0.2	0.2	1.4	0.8	0.8
Net Realized Gains on Sales of Investments	21.0	8.0	3.5	6.6	20.8	49.1	2.3	26.9	39.1	99.1	65.4
Other-than-temporary Impairment Losses:
Total Other-than-temporary Impairment Losses	(6.5)	(3.8)	(4.1)	(0.8)	(7.6)	(3.5)	(2.3)	(2.4)	(15.2)	(15.8)	(7.2)
Portion of Losses Recognized in Other Comprehensive Income	0	0	0	0	0	0.1	1.3	0.5	0	1.9	0.3
Net Impairment Losses Recognized in Earnings	(6.5)	(3.8)	(4.1)	(0.8)	(7.6)	(3.4)	(1.0)	(1.9)	(15.2)	(13.9)	(6.9)
Total Revenues	559.7	539.8	542.5	554.6	586.0	635.7	588.9	615.9	2,196.6	2,426.5	2,462.3
Expenses:
Policyholders’ Benefits and Incurred Losses and Loss Adjustment Expenses	285.8	300.5	347.5	327.9	315.5	338.3	354.2	349.2	1,261.7	1,357.2	1,582.1
Insurance Expenses	156.4	158.6	161.3	152.1	162.9	170.1	163.1	158.3	628.4	654.4	672.3
Write-off of Long-lived Asset	0	54.6	0	0					54.6	0	0
Interest and Other Expenses	24.4	22.1	22.5	22.7	26.2	25.3	25.2	23.8	91.7	100.5	85.5
Total Expenses	466.6	535.8	531.3	502.7	504.6	533.7	542.5	531.3	2,036.4	2,112.1	2,339.9
Income from Continuing Operations before Income Taxes	93.1	4.0	11.2	51.9	81.4	102.0	46.4	84.6	160.2	314.4	122.4
Income Tax Expense	(29.8)	0.8	(1.9)	(16.7)	(26.6)	(33.4)	(13.9)	(26.0)	(47.6)	(99.9)	(30.6)
Income from Continuing Operations	63.3	4.8	9.3	35.2	54.8	68.6	32.5	58.6	112.6	214.5	91.8
Discontinued Operations:
Income from Discontinued Operations	2.1	(0.1)	0	(0.1)	0.4	1.5	1.5	(0.2)	1.9	3.2	11.6
Net Income	$ 65.4	$ 4.7	$ 9.3	$ 35.1	$ 55.2	$ 70.1	$ 34.0	$ 58.4	$ 114.5	$ 217.7	$ 103.4
Income from Continuing Operations Per Unrestricted Share:
Income from Continuing Operations Per Unrestricted Share - Basic	$ 1.20	$ 0.09	$ 0.17	$ 0.63	$ 0.98	$ 1.21	$ 0.56	$ 1.00	$ 2.08	$ 3.75	$ 1.55
Income from Continuing Operations Per Unrestricted Share - Diluted	$ 1.20	$ 0.09	$ 0.17	$ 0.63	$ 0.98	$ 1.21	$ 0.56	$ 1.00	$ 2.08	$ 3.74	$ 1.54
Net Income Per Unrestricted Share:
Net Income Per Unrestricted Share - Basic	$ 1.24	$ 0.09	$ 0.17	$ 0.63	$ 0.99	$ 1.24	$ 0.59	$ 1.00	$ 2.12	$ 3.81	$ 1.75
Net Income Per Unrestricted Share - Diluted	$ 1.24	$ 0.09	$ 0.17	$ 0.63	$ 0.99	$ 1.23	$ 0.59	$ 1.00	$ 2.12	$ 3.80	$ 1.74
Dividends Paid to Shareholders Per Share	$ 0.24	$ 0.24	$ 0.24	$ 0.24	$ 0.24	$ 0.24	$ 0.24	$ 0.24	$ 0.96	$ 0.96	$ 0.96