Accumulated Other Comprehensive Income - Changes in AOCI, including Reclassification Adjustments (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013		Jun. 30, 2012
Available-for-sale securities, Before-Tax Amount:
Net unrealized gains/losses on Other			$ 0		$ 0
Adjustments for amounts recognized in Net realized capital gains (losses) in the Condensed Consolidated Statements of Operations			2.2		(55.8)
DAC/VOBA and sales inducements			412.4	[1]	(73.0)	[1]
Premium deficiency reserve adjustment			58.2		(31.2)
Net realized gains/losses on available-for-sale securities			(742.9)		165.2
Available-for-sale securities, Income Tax:
Net unrealized gains/losses on Other			0		0
Adjustments for amounts recognized in Net realized capital gains (losses) in the Condensed Consolidated Statements of Operations			(0.8)		18.9
DAC/VOBA and sales inducements			(144.3)		25.6
Premium deficiency reserve adjustment			(20.4)		10.9
Net realized gains/losses on available-for-sale securities			258.2		(45.8)
Available-for-sale securities, After-Tax Amount:
Net unrealized gains/losses on Other			0		0
Adjustments for amounts recognized in Net realized capital gains (losses) in the Condensed Consolidated Statements of Operations			1.4		(36.9)
DAC/VOBA and sales inducements			268.1		(47.4)
Premium deficiency reserve adjustment			37.8		(20.3)
Net realized gains/losses on available-for-sale securities			(484.7)		119.4
Derivatives, Before-Tax Amount:
Net unrealized capital gains/losses arising during the period, Before-Tax Amount			(64.3)	[2]	39.9	[2]
Adjustments for amounts recognized in Net investment income in the Condensed Consolidated Statements of Operations			(0.8)		0
Net unrealized gains/losses on derivatives			(65.1)		39.9
Derivatives, Income Tax:
Net unrealized capital gains/losses arising during the period, Income Tax			22.5		(14.0)
Adjustments for amounts recognized in Net investment income in the Condensed Consolidated Statements of Operations			0.3		0
Net unrealized gains/losses on derivatives			22.8		(14.0)
Derivatives, After-Tax Amount:
Net unrealized capital gains/losses arising during the period, After-Tax Amount			(41.8)		25.9
Adjustments for amounts recognized in Net investment income in the Condensed Consolidated Statements of Operations			(0.5)		0
Net unrealized gains/losses on derivatives			(42.3)		25.9
OTTI:
Other-than-temporary impairments	0.5	2.0	1.4		3.6
Change in OTTI, Income Tax			(0.5)		(1.3)
Change in OTTI, After-Tax Amount			0.9		2.3
Pension and other post-employment benefit liability, Before-Tax Amount:
Amortization of prior service cost recognized in Operating expenses in the Condensed Consolidated Statements of Operations			(1.0)	[3]	(1.1)	[3]
Net pension and other post-employment benefit liability	(0.4)	(0.5)	(1.0)		(1.1)
Other comprehensive income (loss), before tax	(639.8)	275.4	(809.0)		204.0
Pension and other post-employment benefit liability, Income Tax:
Amortization of prior service cost recognized in Operating expenses in the Condensed Consolidated Statements of Operations			0		0.4
Net pension and other post-employment benefit liability			0		0.4
Other comprehensive income (loss)	(222.8)	90.5	(281.0)		59.4
Pension and other post-employment benefit liability, After-Tax Amount:
Amortization of prior service cost recognized in Operating expenses in the Condensed Consolidated Statements of Operations			(1.0)		(0.7)
Net pension and other post-employment benefit liability			1.0		0.7
Other comprehensive income (loss), after tax	(417.0)	184.9	(528.0)		144.6
Fixed maturities
Available-for-sale securities, Before-Tax Amount:
Net unrealized gains/losses on securities			(1,220.1)		321.2
Available-for-sale securities, Income Tax:
Net unrealized gains/losses on securities			425.3		(99.8)	[4]
Available-for-sale securities, After-Tax Amount:
Net unrealized gains/losses on securities			(794.8)		221.4
Fixed maturities | Deferred Tax Asset Valuation Allowance
Available-for-sale securities, Income Tax:
Net unrealized gains/losses on securities			(1.9)		(10.0)
Equity securities
Available-for-sale securities, Before-Tax Amount:
Net unrealized gains/losses on securities			3.0		0.4
Available-for-sale securities, Income Tax:
Net unrealized gains/losses on securities			(1.1)		(0.1)
Available-for-sale securities, After-Tax Amount:
Net unrealized gains/losses on securities			$ 1.9		$ 0.3

[1] See Deferred Policy Acquisition Costs and Value of Business Acquired Note to these Condensed Consolidated Financial Statements for additional information.

[2] See Derivative Financial Instruments Note to these Condensed Consolidated Financial Statements for additional information.

[3] Amount reported in Net periodic pension cost which is reported in Operating expenses.See Benefit Plans Note in the Company's 2012 Annual Report on Form 10-K for additional information.

[4] Amount included $10.0 valuation allowance. See Income Taxes Note to these Condensed Financial Statements for additional information.