Deferred Policy Acquisition Costs and Value of Business Acquired (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Movement Analysis of Deferred Policy Acquisition Costs [Roll Forward]
Beginning balance			$ 296.5	$ 334.9
Deferrals of commissions and expenses			52.4	55.5
Amortization:
Amortization			(45.2)	(59.6)
Interest accrued			25.1	22.9
Net amortization included in the Consolidated Statements of Operations			(20.1)	(36.7)
Change in unrealized capital gains/losses on available-for-sale securities			136.8	(76.7)
Ending balance	465.6	277.0	465.6	277.0
Movement Analysis Of Value of Business Acquired VOBA [Roll Forward]
Beginning balance			381.4	593.6
Deferrals of commissions and expenses			5.6	6.0
Amortization			(57.2)	(128.4)
Interest accrued			45.6	46.6
Net amortization included in the Condensed Consolidated Statements of Operations			(11.6)	(81.8)
Change in unrealized capital gains/losses on availabe-for-sale securities			310.2	(153.9)
Ending balance	685.6	363.9	685.6	363.9
Movement Analysis of Deferred Policy Acquisition Costs and Value of Business Acquired (VOBA) [Roll Forward]
Beginning balance			677.9	928.5
Deferrals of commissions and expenses			58.0	61.5
Amortization			(102.4)	(188.0)
Interest accrued			70.7	69.5
Net amortization of deferred policy acquisition costs and value of business acquired	15.2	(13.5)	(31.7)	(118.5)
Change in unrealized capital gains/losses on availabe-for-sale securities			447.0	(230.6)
Ending balance	$ 1,151.2	$ 640.9	$ 1,151.2	$ 640.9
Minimum
Movement Analysis of Deferred Policy Acquisition Costs and Value of Business Acquired (VOBA) [Roll Forward]
Deferred Policy Acquisition Costs, Interest accrued percentage			0.00%	0.00%
Value of Business Acquired (VOBA), Interest accrued percentage			1.00%	5.00%
Maximum
Movement Analysis of Deferred Policy Acquisition Costs and Value of Business Acquired (VOBA) [Roll Forward]
Deferred Policy Acquisition Costs, Interest accrued percentage			7.00%	7.00%
Value of Business Acquired (VOBA), Interest accrued percentage			7.00%	7.00%