CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (Parenthetical) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Change in Net Unrealized Gain on Securities Before Adjustment, Tax (Benefit)	$ (159.4)	$ (110.5)
Change in Adjustment to Deferred Acquisition Costs and Reserves for Future Policy and Contract Benefits, Net of Reinsurance, Tax Expense	108.6	97.2
Change in Net Gain on Cash Flow Hedges, Tax (Benefit)	(0.2)	(5.9)
Change in Unrecognized Pension and Postretirement Benefit Costs, Tax Expense	$ 5.5	$ 3.5