Derivative Financial Instruments (Offsetting Assets) (Details) - USD ($) $ in Millions	Sep. 30, 2018	Dec. 31, 2017
Derivative assets
Gross Amount Recognized	$ 177.0	$ 173.2
Gross Amounts Not Offset, But Permitted Under Master Netting Agreements	(151.9)	(114.4)
Net Amount	25.1	58.8
Derivative liabilities
Gross Amount Recognized	173.3	137.1
Gross Amounts Not Offset Permitted Under Master Netting Agreements	(151.9)	(114.4)
Net Amount	$ 21.4	$ 22.7

Fair value of financial asset or other contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset, elected not to be offset, deducted from derivative assets.

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