Financial Instruments (Notional Amounts and Fair Values of Derivatives Designated as Cash Flow Hedges and Derivatives Not Designated as Cash Flow Hedges) (Details) - USD ($) $ in Millions	Jun. 30, 2017	Dec. 31, 2016
Derivatives, Fair Value [Line Items]
Fair Value of assets for derivatives not designated as cash flow hedges	$ 14.2	$ 9.3
Fair Value of liability for derivatives not designated as cash flow hedges	2.6	2.9
Commodity futures
Derivatives, Fair Value [Line Items]
Notional Amount	127.0	142.5
Fair Value of assets for derivatives not designated as cash flow hedges	12.7	9.2
Fair Value of liability for derivatives not designated as cash flow hedges	0.6	1.8
Foreign currency exchange
Derivatives, Fair Value [Line Items]
Notional Amount	119.1	30.7
Fair Value of assets for derivatives not designated as cash flow hedges	1.5	0.1
Fair Value of liability for derivatives not designated as cash flow hedges	$ 2.0	$ 1.1