Summary Of Accounting Policies And Accounting Changes - Impact on Statement of Cash Flows (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Net Income	$ 103.4	$ 74.5	$ 177.9
Increase in Deferred Policy Acquisition Costs	(9.4)	(7.8)	(4.7)
Change in Income Taxes	(14.9)	17.2	8.7
Net Cash Provided (Used) by Operating Activities	65.7	(25.0)	58.5
Accounting Standards Update 2010-26 [Member] | Scenario, Previously Reported [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Net Income		83.7	184.6
Increase in Deferred Policy Acquisition Costs		(22.1)	(15.1)
Change in Income Taxes		22.3	12.4
Net Cash Provided (Used) by Operating Activities		(25.0)	58.5
Accounting Standards Update 2010-26 [Member] | Scenario, Computed Without Change in Accounting Principle [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Net Income	109.7
Increase in Deferred Policy Acquisition Costs	(19.2)
Change in Income Taxes	(11.4)
Net Cash Provided (Used) by Operating Activities	65.7
Accounting Standards Update 2010-26 [Member] | Restatement Adjustment [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Net Income	(6.3)	(9.2)	(6.7)
Increase in Deferred Policy Acquisition Costs	9.8	14.3	10.4
Change in Income Taxes	(3.5)	(5.1)	(3.7)
Net Cash Provided (Used) by Operating Activities	$ 0	$ 0	$ 0