Summary Of Accounting Policies And Accounting Changes - Impact on Income Statement (Details) (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Total Revenues	$ 596.6	$ 645.6	$ 608.9	$ 611.2	$ 613.3	$ 592.8	$ 647.7	$ 641.2	$ 2,462.3	$ 2,495.0	$ 2,642.5
Policyholders’ Benefits and Incurred Losses and Loss Adjustment Expenses	413.0	368.7	423.8	376.6	376.7	399.6	477.1	392.3	1,582.1	1,645.7	1,647.2
Insurance Expenses	169.5	172.7	167.7	162.4	170.1	176.8	170.6	166.1	672.3	683.6	685.9
Write-off of Goodwill and Other Intangibles Acquired					13.5	0	0	0	0	13.5	14.8
Interest and Other Expenses	20.1	22.7	20.9	21.8	21.9	21.4	20.9	19.7	85.5	83.9	68.3
Total Expenses	602.6	564.1	612.4	560.8	582.2	597.8	668.6	578.1	2,339.9	2,426.7	2,416.2
Income from Continuing Operations before Income Taxes and Equity in Net Loss of Former Investee	(6.0)	81.5	(3.5)	50.4	31.1	(5.0)	(20.9)	63.1	122.4	68.3	226.3
Income Tax Expense	4.3	(25.9)	5.1	(14.1)	(6.1)	6.1	11.5	(18.1)	(30.6)	(6.6)	(63.8)
Income from Continuing Operations before Equity in Net Loss of Former Investee									91.8	61.7	162.5
Equity in Net Loss of Former Investee									0	0	(0.1)
Income from Continuing Operations	(1.7)	55.6	1.6	36.3	25.0	1.1	(9.4)	45.0	91.8	61.7	162.4
Income from Discontinued Operations	3.6	0	0.7	7.3	(0.7)	0.9	6.1	6.5	11.6	12.8	15.5
Net Income	1.9	55.6	2.3	43.6	24.3	2.0	(3.3)	51.5	103.4	74.5	177.9
Income from Continuing Operations Per Unrestricted Share - Basic	$ (0.03)	$ 0.95	$ 0.03	$ 0.61	$ 0.41	$ 0.01	$ (0.16)	$ 0.74	$ 1.55	$ 1.02	$ 2.62
Income from Continuing Operations Per Unrestricted Share - Diluted	$ (0.03)	$ 0.95	$ 0.03	$ 0.60	$ 0.41	$ 0.01	$ (0.16)	$ 0.73	$ 1.54	$ 1.02	$ 2.62
Net Income Per Unrestricted Share - Basic	$ 0.03	$ 0.95	$ 0.04	$ 0.73	$ 0.40	$ 0.03	$ (0.06)	$ 0.85	$ 1.75	$ 1.23	$ 2.87
Net Income Per Unrestricted Share - Diluted	$ 0.03	$ 0.95	$ 0.04	$ 0.72	$ 0.40	$ 0.03	$ (0.06)	$ 0.84	$ 1.74	$ 1.23	$ 2.87
Accounting Standards Update 2010-26 [Member] | Scenario, Computed Without Change in Accounting Principle [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Total Revenues									2,462.3
Policyholders’ Benefits and Incurred Losses and Loss Adjustment Expenses									1,582.1
Insurance Expenses									662.5
Interest and Other Expenses									85.5
Total Expenses									2,330.1
Income from Continuing Operations before Income Taxes and Equity in Net Loss of Former Investee									132.2
Income Tax Expense									(34.1)
Income from Continuing Operations									98.1
Income from Discontinued Operations									11.6
Net Income									109.7
Income from Continuing Operations Per Unrestricted Share - Basic									$ 1.65
Income from Continuing Operations Per Unrestricted Share - Diluted									$ 1.65
Net Income Per Unrestricted Share - Basic									$ 1.85
Net Income Per Unrestricted Share - Diluted									$ 1.85
Accounting Standards Update 2010-26 [Member] | Scenario, Previously Reported [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Total Revenues										2,495.0	2,642.5
Policyholders’ Benefits and Incurred Losses and Loss Adjustment Expenses										1,645.7	1,647.2
Insurance Expenses										669.3	675.5
Write-off of Goodwill and Other Intangibles Acquired										13.5	14.8
Interest and Other Expenses										83.9	68.3
Total Expenses										2,412.4	2,405.8
Income from Continuing Operations before Income Taxes and Equity in Net Loss of Former Investee										82.6	236.7
Income Tax Expense										(11.7)	(67.5)
Income from Continuing Operations before Equity in Net Loss of Former Investee											169.2
Equity in Net Loss of Former Investee											(0.1)
Income from Continuing Operations										70.9	169.1
Income from Discontinued Operations										12.8	15.5
Net Income										83.7	184.6
Income from Continuing Operations Per Unrestricted Share - Basic										$ 1.17	$ 2.73
Income from Continuing Operations Per Unrestricted Share - Diluted										$ 1.17	$ 2.73
Net Income Per Unrestricted Share - Basic										$ 1.38	$ 2.98
Net Income Per Unrestricted Share - Diluted										$ 1.38	$ 2.98
Accounting Standards Update 2010-26 [Member] | Restatement Adjustment [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Total Revenues									0	0	0
Policyholders’ Benefits and Incurred Losses and Loss Adjustment Expenses									0	0	0
Insurance Expenses									9.8	14.3	10.4
Write-off of Goodwill and Other Intangibles Acquired										0	0
Interest and Other Expenses									0	0	0
Total Expenses									9.8	14.3	10.4
Income from Continuing Operations before Income Taxes and Equity in Net Loss of Former Investee									(9.8)	(14.3)	(10.4)
Income Tax Expense									3.5	5.1	3.7
Income from Continuing Operations before Equity in Net Loss of Former Investee											(6.7)
Equity in Net Loss of Former Investee											0
Income from Continuing Operations									(6.3)	(9.2)	(6.7)
Income from Discontinued Operations									0	0	0
Net Income									$ (6.3)	$ (9.2)	$ (6.7)
Income from Continuing Operations Per Unrestricted Share - Basic									$ (0.10)	$ (0.15)	$ (0.11)
Income from Continuing Operations Per Unrestricted Share - Diluted									$ (0.11)	$ (0.15)	$ (0.11)
Net Income Per Unrestricted Share - Basic									$ (0.10)	$ (0.15)	$ (0.11)
Net Income Per Unrestricted Share - Diluted									$ (0.11)	$ (0.15)	$ (0.11)