Schedule 2 - Parent Company Financial Statements - Statements of Income (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Condensed Financial Statements, Captions [Line Items]
Net Investment Income	$ 76.9	$ 82.4	$ 74.6	$ 80.8	$ 72.9	$ 70.4	$ 75.2	$ 77.4	$ 314.7	$ 295.9	$ 298.0
Net Realized Gains (Losses) on Sales of Investments	20.8	49.1	2.3	26.9	5.5	50.9	4.1	4.9	99.1	65.4	33.7
Total Revenues	586.0	635.7	588.9	615.9	596.6	645.6	608.9	611.2	2,426.5	2,462.3	2,495.0
Total Expenses	504.6	533.7	542.5	531.3	602.6	564.1	612.4	560.8	2,112.1	2,339.9	2,426.7
Loss before Income Taxes and Equity in Net Income of Subsidiaries					(6.0)	81.5	(3.5)	50.4		122.4
Income Tax Benefit	(26.6)	(33.4)	(13.9)	(26.0)	4.3	(25.9)	5.1	(14.1)	(99.9)	(30.6)	(6.6)
Net Income	55.2	70.1	34.0	58.4	1.9	55.6	2.3	43.6	217.7	103.4	74.5
Parent Company [Member]
Condensed Financial Statements, Captions [Line Items]
Net Investment Income									0.2	0.2	0.4
Net Realized Gains (Losses) on Sales of Investments									0.6	0.3	(0.2)
Total Revenues									0.8	0.5	0.2
Interest Expense									39.0	39.5	39.4
Other Operating Expenses									21.6	13.6	10.3
Total Expenses									60.6	53.1	49.7
Loss before Income Taxes and Equity in Net Income of Subsidiaries									(59.8)	(52.6)	(49.5)
Income Tax Benefit									20.8	18.2	18.6
Loss before Equity in Net Income of Subsidiaries									(39.0)	(34.4)	(30.9)
Equity in Net Income of Subsidiaries									256.7	137.8	105.4
Net Income									$ 217.7	$ 103.4	$ 74.5