DAC and VOBA Deferred Policy Acquisition Costs (Details) (USD $) In Millions, unless otherwise specified	9 Months Ended
	Sep. 30, 2012		Sep. 30, 2011
Movement Analysis of Deferred Policy Acquisition Costs [Roll Forward]
Beginning balance	$ 3,326.4		$ 2,758.9
Deferrals of commissions and expenses	82.6		100.1
Amortization:
Amortization	(432.3)		453.8
Interest accrued	163.9	[1]	116.9	[1]
Net amortization included in the Condensed Statements of Operations	(268.4)		570.7
Change in unrealized capital gains/losses on available-for-sale securities	(179.8)		(305.0)
Ending balance	$ 2,960.8		$ 3,124.7
Minimum
Amortization:
Deferred Policy Acquisition Costs Amortization Expense Interest Accrued Percentage	3.00%
Maximum
Amortization:
Deferred Policy Acquisition Costs Amortization Expense Interest Accrued Percentage			6.00%

[1] Interest accrued at 3% to 6% during 2012 and 2011.