Deferred Policy Acquisition Costs and Value of Business Acquired (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014		Sep. 30, 2013
Movement Analysis of Deferred Policy Acquisition Costs [Roll Forward]
Beginning balance			$ 4,316.1		$ 3,221.6
Deferrals of commissions and expenses			280.5		300.0
Amortization:
Amortization			(385.1)		(507.6)
Interest accrued			174.9	[1]	173.6	[1]
Net amortization included in the Consolidated Statements of Operations			(210.2)		(334.0)
Change in unrealized capital gains/losses on available-for-sale securities			(373.2)		1,061.5
Ending balance	4,013.2	4,249.1	4,013.2		4,249.1
Movement Analysis Of Value of Business Acquired VOBA [Roll Forward]
Beginning balance			1,035.5		434.7
Deferrals of commissions and expenses			9.6		10.2
Amortization:
Amortization			(128.7)		(53.2)
Interest accrued			66.5	[1]	67.6	[1]
Net amortization included in Condensed Consolidated Statements of Operations			(62.2)		14.4
Change in unrealized capital gains/losses on available-for-sale securities			(216.2)		556.6
Ending balance	766.7	1,015.9	766.7		1,015.9
Movement Analysis of Deferred Policy Acquisition Costs and Value of Business Acquired (VOBA) [Roll Forward]
Beginning balance			5,351.6		3,656.3
Deferrals of commissions and expenses			290.1		310.2
Amortization:
Amortization			(513.8)		(560.8)
Interest accrued			241.4		241.2
Net amortization included in Condensed Consolidated Statements of Operations	(30.6)	(64.6)	(272.4)		(319.6)
Change in unrealized capital gains/losses on available-for-sale securities			(589.4)		1,618.1
Ending balance	$ 4,779.9	$ 5,265.0	$ 4,779.9		$ 5,265.0
Minimum
Amortization:
Deferred Policy Acquisition Costs, Interest accrued percentage			0.60%		1.00%
Value of Business Acquired (VOBA), Interest accrued percentage			3.10%		3.00%
Maximum
Amortization:
Deferred Policy Acquisition Costs, Interest accrued percentage			7.40%		7.40%
Value of Business Acquired (VOBA), Interest accrued percentage			7.50%		7.50%

[1] Interest accrued at the following rates for DAC: 0.6% to 7.4% during 2014 and 1.0% to 7.4% during 2013. Interest accrued at the following rates for VOBA: 3.1% to 7.5% during 2014 and 3.0% to 7.5% during 2013.