Accumulated Other Comprehensive Income - Changes in AOCI, including Reclassification Adjustments (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
Available-for-sale securities, Before-Tax Amount:
Net unrealized gains/losses on Other	$ 0.2		$ 0.2		$ (2.5)		$ 13.1
Other-than-temporary impairments	5.9		13.5		30.2		44.8
Adjustments for amounts recognized in Net realized capital gains (losses) in the Condensed Consolidated Statements of Operations	(2.3)		(25.6)		(36.3)		(66.6)
DAC/VOBA	203.8		173.9		(589.4)	[1]	1,618.1	[1]
Sales inducements	14.1		6.9		(16.5)		84.3
Net realized gains/losses on available-for-sale securities	(517.3)		(209.4)		1,452.9		(2,623.3)
Available-for-sale securities, Income Tax:
Net unrealized gains/losses on Other	0		0		0.9		(4.5)
Change in OTTI, Income Tax	(2.1)		(4.7)		(10.6)		(15.6)
Adjustments for amounts recognized in Net realized capital gains (losses) in the Condensed Consolidated Statements of Operations	0.8		9.0		12.7		23.2
DAC/VOBA	(71.4)		(61.2)		206.3		(562.5)
Sales inducements	(4.9)		(2.4)		5.8		(29.3)
Net realized gains/losses on available-for-sale securities	179.0		74.0		(511.3)		911.9
Available-for-sale securities, After-Tax Amount:
Net unrealized gains/losses on Other	0.2		0.2		(1.6)		8.6
Change in OTTI, After-Tax Amount	3.8		8.8		19.6		29.2
Adjustments for amounts recognized in Net realized capital gains (losses) in the Condensed Consolidated Statements of Operations	(1.5)		(16.6)		(23.6)		(43.4)
DAC/VOBA	132.4		112.7		(383.1)		1,055.6
Sales inducements	9.2		4.5		(10.7)		55.0
Net realized gains/losses on available-for-sale securities	(338.3)		(135.4)		941.6		(1,711.4)
Derivatives, Before-Tax Amount:
Net unrealized capital gains/losses arising during the period, Before-Tax Amount	14.4	[2]	0.5	[2]	60.8	[2]	(63.7)	[2]
Adjustments for amounts recognized in Net investment income in the Condensed Consolidated Statements of Operations	(2.0)		(0.8)		(5.1)		(1.6)
Net unrealized gains/losses on derivatives	12.4		(0.3)		55.7		(65.3)
Derivatives, Income Tax:
Net unrealized capital gains/losses arising during the period, Income Tax	(5.1)		(0.2)		(21.3)		22.1
Adjustments for amounts recognized in Net investment income in the Condensed Consolidated Statements of Operations	0.7		0.3		1.8		0.6
Net unrealized gains/losses on derivatives	(4.4)		0.1		(19.5)		22.7
Derivatives, After-Tax Amount:
Net unrealized capital gains/losses arising during the period, After-Tax Amount	9.3		0.3		39.5		(41.6)
Adjustments for amounts recognized in Net investment income in the Condensed Consolidated Statements of Operations	(1.3)		(0.5)		(3.3)		(1.0)
Net unrealized gains/losses on derivatives	8.0		(0.2)		36.2		(42.6)
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	(3.4)		(3.4)		(10.3)		(10.3)
Net pension and other post-employment benefit liability	(3.4)		(3.4)		(10.3)		(10.3)
Other comprehensive income (loss), before tax	(508.3)		(213.1)		1,498.3		(2,698.9)
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	1.2		1.2		3.6		3.6
Net pension and other post-employment benefit liability	1.2		1.2		3.6		3.6
Other comprehensive income (loss)	175.8		75.3		(527.2)		938.2
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	(2.2)		(2.2)		(6.7)		(6.7)
Net pension and other post-employment benefit liability	(2.2)		(2.2)		(6.7)		(6.7)
Other comprehensive income (loss), after tax	(332.5)		(137.8)		971.1		(1,760.7)
Fixed maturities
Available-for-sale securities, Before-Tax Amount:
Net unrealized gains/losses on securities	(738.9)		(379.3)		2,083.1		(4,316.0)
Available-for-sale securities, Income Tax:
Net unrealized gains/losses on securities	256.6		133.7		(730.5)		1,500.3
Available-for-sale securities, After-Tax Amount:
Net unrealized gains/losses on securities	(482.3)		(245.6)		1,352.6		(2,815.7)
Equity securities
Available-for-sale securities, Before-Tax Amount:
Net unrealized gains/losses on securities	(0.1)		1.0		(15.7)		(1.0)
Available-for-sale securities, Income Tax:
Net unrealized gains/losses on securities	0		(0.4)		4.1		0.3
Available-for-sale securities, After-Tax Amount:
Net unrealized gains/losses on securities	$ (0.1)		$ 0.6		$ (11.6)		$ (0.7)

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

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