DAC and VOBA Value of Business Acquired (Details) (USD $) In Millions, unless otherwise specified	9 Months Ended
	Sep. 30, 2012		Sep. 30, 2011
Movement Analysis Of Value of Business Acquired VOBA [Roll Forward]
Beginning balance	$ 46.2		$ 66.6
Amortization
Amortization	(18.5)		(6.8)
Interest accrued	2.3	[1]	2.7	[1]
Net amortization included in the Condensed Statements of Operations	(16.2)		(4.1)
Change in unrealized capital gains/losses on available-for-sale securities	1.0		(15.7)
Ending balance	$ 31.0		$ 46.8
Minimum
Amortization
Value of Business Acquired VOBA Amortization Expense Interest Accrued Percentage	4.00%
Maximum
Amortization
Value of Business Acquired VOBA Amortization Expense Interest Accrued Percentage			8.00%

[1] Interest accrued at 4% to 8% during 2012 and 2011.