Deferred Policy Acquisition Costs and Value of Business Acquired (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014		Jun. 30, 2013
Movement Analysis of Deferred Policy Acquisition Costs [Roll Forward]
Beginning balance			$ 476.2		$ 296.5
Deferrals of commissions and expenses			32.0		36.4
Amortization:
Amortization			(31.8)		(41.9)
Interest accrued			17.9	[1]	16.6	[1]
Net amortization included in the Consolidated Statements of Operations			(13.9)		(25.3)
Change in unrealized capital gains/losses on available-for-sale securities			(94.8)		125.8
Ending balance	399.5	433.4	399.5		433.4
Movement Analysis Of Value of Business Acquired VOBA [Roll Forward]
Beginning balance			696.6		381.4
Deferrals of commissions and expenses			3.5		3.8
Amortization			(43.0)		(52.0)
Interest accrued			30.2	[1]	30.4	[1]
Net amortization included in the Condensed Consolidated Statements of Operations			(12.8)		(21.6)
Change in unrealized capital gains/losses on available-for-sale securities			(149.9)		286.0
Ending balance	537.4	649.6	537.4		649.6
Movement Analysis of Deferred Policy Acquisition Costs and Value of Business Acquired (VOBA) [Roll Forward]
Beginning balance			1,172.8		677.9
Deferrals of commissions and expenses			35.5		40.2
Amortization			(74.8)		(93.9)
Interest accrued			48.1	[1]	47.0	[1]
Net amortization of deferred policy acquisition costs and value of business acquired	(6.9)	(28.3)	(26.7)		(46.9)
Change in unrealized capital gains/losses on available-for-sale securities			(244.7)		411.8
Ending balance	$ 936.9	$ 1,083.0	$ 936.9		$ 1,083.0
Minimum
Movement Analysis of Deferred Policy Acquisition Costs and Value of Business Acquired (VOBA) [Roll Forward]
Value of Business Acquired (VOBA), Interest accrued percentage			5.50%		5.50%
Maximum
Movement Analysis of Deferred Policy Acquisition Costs and Value of Business Acquired (VOBA) [Roll Forward]
Value of Business Acquired (VOBA), Interest accrued percentage			7.00%		7.00%

[1] Interest accrued at the following rates for VOBA: 5.5% to 7.0% during 2014 and 5.5% to 7.0% during 2013.