Deferred Policy Acquisition Costs and Value of Business Acquired (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Movement Analysis of Deferred Policy Acquisition Costs [Roll Forward]
Beginning balance			$ 396.5	$ 476.2
Deferrals of commissions and expenses			36.6	32.0
Amortization:
Amortization			(50.3)	(31.8)
Interest accrued			18.1	17.9
Net amortization included in the Consolidated Statements of Operations			(32.2)	(13.9)
Change in unrealized capital gains/losses on available-for-sale securities			59.2	(94.8)
Ending balance	$ 460.1	$ 399.5	460.1	399.5
Movement Analysis Of Value of Business Acquired VOBA [Roll Forward]
Beginning balance			526.8	696.6
Deferrals of commissions and expenses			2.9	3.5
Amortization			(48.4)	(43.0)
Interest accrued			28.5	30.2
Net amortization included in the Condensed Consolidated Statements of Operations			(19.9)	(12.8)
Change in unrealized capital gains/losses on available-for-sale securities			121.0	(149.9)
Ending balance	630.8	537.4	630.8	537.4
Movement Analysis of Deferred Policy Acquisition Costs and Value of Business Acquired (VOBA) [Roll Forward]
Beginning balance			923.3	1,172.8
Deferrals of commissions and expenses			39.5	35.5
Amortization			(98.7)	(74.8)
Interest accrued			46.6	48.1
Net amortization of deferred policy acquisition costs and value of business acquired	(29.6)	(6.9)	(52.1)	(26.7)
Change in unrealized capital gains/losses on available-for-sale securities			180.2	(244.7)
Ending balance	$ 1,090.9	$ 936.9	$ 1,090.9	$ 936.9
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%