Derivatives (Outstanding Commodity Futures Contracts) (Details) - lb lb in Millions	Dec. 31, 2017	Dec. 31, 2016
Copper [Member] | Not Designated as Hedging Instrument [Member]
Derivative [Line Items]
Notional Amounts	1.8	2.4
Copper [Member] | Cash Flow Hedging [Member]
Derivative [Line Items]
Notional Amounts	20.6	30.4
Aluminum [Member] | Not Designated as Hedging Instrument [Member]
Derivative [Line Items]
Notional Amounts	1.8	2.6