Deferred Policy Acquisition Costs ("DAC") and Value of Business Acquired ("VOBA") - Deferred Policy Acquisition Costs (Details) (USD $) In Millions, unless otherwise specified	6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011
Movement Analysis of Deferred Policy Acquisition Costs [Roll Forward]
Balance at January 1	$ 335.0	$ 452.3
Deferrals of commission and expenses	36.7	38.7
Amortization:
Amortization	(42.6)	(44.7)
Interest accrued at 4% to 7%	15.4	16.2
Net amortization included in Condensed Consolidated Statement of Operations	(27.2)	(28.5)
Change in unrealized capital gains/losses on availabe-for-sale securities	(29.0)	(29.6)
Balance at June 30	$ 315.5	$ 432.9
Minimum
Amortization:
Deferred Policy Acquisition Costs, Interest Accrued Percentage	4.00%
Maximum
Amortization:
Deferred Policy Acquisition Costs, Interest Accrued Percentage	7.00%