Derivative Financial Instruments Notional and Fair Values (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2013		Dec. 31, 2012
Derivatives, Fair Value [Line Items]
Asset Fair Value	$ 493.4		$ 566.4
Liability Fair Value	185.7		469.2
Fixed maturities
Derivatives, Fair Value [Line Items]
Asset Fair Value	29.0		53.7
Liability Fair Value	0		0
Fixed indexed annuities (FIA)
Derivatives, Fair Value [Line Items]
Asset Fair Value	0		0
Liability Fair Value	23.1		122.4
Reinsurance Agreements
Derivatives, Fair Value [Line Items]
Asset Fair Value	0		0
Liability Fair Value	(54.0)		0
Interest rate contracts
Derivatives, Fair Value [Line Items]
Notional Amount	22,206.0		19,131.1
Foreign exchange contracts
Derivatives, Fair Value [Line Items]
Notional Amount	197.1		161.6
Equity contract
Derivatives, Fair Value [Line Items]
Notional Amount	0		0
Credit contracts
Derivatives, Fair Value [Line Items]
Notional Amount	384.0		347.5
Designated as Hedging Instrument | Cash flow hedges | Interest rate contracts
Derivatives, Fair Value [Line Items]
Notional Amount	763.3	[1]	1,000.0	[1]
Designated as Hedging Instrument | Cash flow hedges | Foreign exchange contracts
Derivatives, Fair Value [Line Items]
Notional Amount	51.2	[1]	0	[1]
Not Designated as Hedging Instrument | Interest rate contracts
Derivatives, Fair Value [Line Items]
Notional Amount	21,442.7	[1],[2]	18,131.1	[1],[2]
Not Designated as Hedging Instrument | Foreign exchange contracts
Derivatives, Fair Value [Line Items]
Notional Amount	145.9	[1]	161.6	[1]
Not Designated as Hedging Instrument | Equity contract
Derivatives, Fair Value [Line Items]
Notional Amount	9.1	[1]	14.5	[1]
Not Designated as Hedging Instrument | Credit contracts
Derivatives, Fair Value [Line Items]
Notional Amount	384.0	[1]	347.5	[1]
Maximum potential future net exposure on sale of credit default swaps	384.0		329.0
Not Designated as Hedging Instrument | Interest rate caps
Derivatives, Fair Value [Line Items]
Notional Amount	11,800.0		4,500.0
Derivatives | Designated as Hedging Instrument | Cash flow hedges | Interest rate contracts
Derivatives, Fair Value [Line Items]
Asset Fair Value	81.0	[1]	215.4	[1]
Liability Fair Value	0.2	[1]	0	[1]
Derivatives | Designated as Hedging Instrument | Cash flow hedges | Foreign exchange contracts
Derivatives, Fair Value [Line Items]
Asset Fair Value	2.2	[1]	0	[1]
Liability Fair Value	0.6	[1]	0	[1]
Derivatives | Not Designated as Hedging Instrument | Interest rate contracts
Derivatives, Fair Value [Line Items]
Asset Fair Value	367.6	[1],[2]	292.9	[1],[2]
Liability Fair Value	206.2	[1],[2]	328.5	[1],[2]
Derivatives | Not Designated as Hedging Instrument | Foreign exchange contracts
Derivatives, Fair Value [Line Items]
Asset Fair Value	5.5	[1]	0.4	[1]
Liability Fair Value	9.6	[1]	18.3	[1]
Derivatives | Not Designated as Hedging Instrument | Equity contract
Derivatives, Fair Value [Line Items]
Asset Fair Value	0	[1],[3]	0.4	[1]
Liability Fair Value	0	[1]	0	[1]
Derivatives | Not Designated as Hedging Instrument | Credit contracts
Derivatives, Fair Value [Line Items]
Asset Fair Value	8.1	[1]	3.6	[1]
Liability Fair Value	0	[1]	0	[1]
Derivatives | Not Designated as Hedging Instrument | Managed custody guarantees
Derivatives, Fair Value [Line Items]
Asset Fair Value	0	[1]	0	[1]
Liability Fair Value	0	[1]	0	[1]
Derivatives | Not Designated as Hedging Instrument | Interest rate caps
Derivatives, Fair Value [Line Items]
Asset Fair Value	162.5		17.7
Liability Fair Value	$ 29.7		$ 0.6

[1] Open derivative contracts are reported as Derivatives assets or liabilities on the Consolidated Balance Sheets at fair value

[2] As of December 31, 2013, includes a notional amount, asset fair value and liability fair value for interest rate caps of $11.8 billion, $162.5 and $29.7, respectively. As of December 31, 2012, includes a notional amount, asset fair value and liability fair value for interest rate caps of $4.5 billion, $17.7 and $0.6, respectively.

[3] Less than $0.1.