Derivatives and Hedging Transactions (Details 2) (USD $) In Millions, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014
Asset Derivatives
Gross value of derivatives	$ 163.3	$ 75.5
Gross amounts offset in the Consolidated Balance Sheet	(26.3)	(18.1)
Net value of derivatives presented in the Consolidated Balance Sheet	137.0us-gaap_DerivativeAssets	57.4us-gaap_DerivativeAssets
Liability Derivatives
Gross value of derivatives	58.2	52.1
Gross amounts offset in the Consolidated Balance Sheet	(26.3)	(18.1)
Net value of derivatives presented in the Consolidated Balance Sheet	$ 31.9us-gaap_DerivativeLiabilities	$ 34.0us-gaap_DerivativeLiabilities

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