Deferred Policy Acquisition Costs and Value of Business Acquired (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2013		Dec. 31, 2012		Dec. 31, 2011
Movement Analysis of Deferred Policy Acquisition Costs [Roll Forward]
Beginning balance	$ 296.5		$ 334.9		$ 307.6
Deferrals of commissions and expenses	71.3		79.1		79.8
Amortization:
Amortization	(69.7)		(72.1)		(71.5)
Interest accrued	34.0	[1]	31.1	[1]	31.9	[1]
Net amortization included in the Consolidated Statements of Operations	(35.7)		(41.0)		(39.6)
Change in unrealized capital gains/losses on available-for-sale securities	144.1		(76.5)		(12.9)
Ending balance	476.2		296.5		334.9
Movement Analysis Of Value of Business Acquired VOBA [Roll Forward]
Beginning balance	381.4		593.6		864.2
Deferrals of commissions and expenses	7.2		8.1		8.5
Amortization	(83.6)		(152.6)		(125.1)
Interest accrued	61.0	[1]	62.5	[1]	70.5	[1]
Net amortization included in the Condensed Consolidated Statements of Operations	(22.6)		(90.1)		(54.6)
Change in unrealized capital gains/losses on availabe-for-sale securities	330.6		(130.2)		(224.5)
Ending balance	696.6		381.4		593.6
Movement Analysis of Deferred Policy Acquisition Costs and Value of Business Acquired (VOBA) [Roll Forward]
Beginning balance	677.9		928.5		1,171.8
Deferrals of commissions and expenses	78.5		87.2		88.3
Amortization	(153.3)		(224.7)		(196.6)
Interest accrued	95.0	[1]	93.6	[1]	102.4	[1]
Net amortization of deferred policy acquisition costs and value of business acquired	(58.3)		(131.1)		(94.2)
Change in unrealized capital gains/losses on availabe-for-sale securities	474.7		(206.7)		(237.4)
Ending balance	1,172.8		677.9		928.5
Estimated amount of VOBA amortization expense, net of interest:
2014	62.7
2015	52.5
2016	46.8
2017	42.6
2018	$ 40.6
Minimum
Movement Analysis of Deferred Policy Acquisition Costs and Value of Business Acquired (VOBA) [Roll Forward]
Value of Business Acquired (VOBA), Interest accrued percentage	1.00%		5.00%		5.00%
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%		7.00%

[1] Interest accrued at the following rates for VOBA: 1.0% to 7.0% during 2013, 5.0% to 7.0% during 2012 and 5.0% to 7.0% during 2011.