Derivative Financial Instruments Offsetting Assets and Liabilities (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2013		Dec. 31, 2012
Offsetting Assets and liabilities [Line Items]
Asset Fair Value	$ 464.4		$ 512.3
Liability Fair Value	216.6		346.8
Counterparty netting, Assets	(201.3)	[1]	(291.4)	[1]
Counterparty netting, Liabilities	(201.3)	[1]	(291.4)	[1]
Cash collateral netting, Assets	(134.0)	[1]	(167.1)	[1]
Cash collateral netting, Liabilities	(5.4)	[1]	0	[1]
Securities collateral netting, Assets	(15.9)	[1]	(3.1)	[1]
Securities collateral netting, Liabilities	(4.8)	[1]	(35.8)	[1]
Net receivables	113.2		50.7
Net payables	5.1		19.6
Credit contracts
Offsetting Assets and liabilities [Line Items]
Notional Amount	384.0		347.5
Asset Fair Value	8.1		3.6
Liability Fair Value	0		0
Equity contract
Offsetting Assets and liabilities [Line Items]
Notional Amount	0		0
Asset Fair Value	0		0
Liability Fair Value	0		0
Foreign exchange contracts
Offsetting Assets and liabilities [Line Items]
Notional Amount	197.1		161.6
Asset Fair Value	7.7		0.4
Liability Fair Value	10.2		18.3
Interest rate contracts
Offsetting Assets and liabilities [Line Items]
Notional Amount	22,206.0		19,131.1
Asset Fair Value	448.6		508.3
Liability Fair Value	$ 206.4		$ 328.5

[1] Represents the netting of receivable balances with payable balances, net of collateral, for the same counterparty under eligible netting rules.