Derivative Instruments and Hedging Activities (Details) $ in Millions	6 Months Ended
	Jun. 30, 2015 USD ($)	Jun. 30, 2015 EUR (€) MMBTU T MW t lb	Dec. 31, 2014 EUR (€) MMBTU T MW t lb
Natural Gas [Member]
Derivative [Line Items]
Beginning Settlement Date	Jul. 01, 2015
Ending Settlement Date	Dec. 31, 2016
Gains (losses) expected to be reclassified into cost of products sold within the next twelve months	$ (10.3)
Zinc [Member]
Derivative [Line Items]
Beginning Settlement Date	Jul. 01, 2015
Ending Settlement Date	Dec. 31, 2016
Gains (losses) expected to be reclassified into cost of products sold within the next twelve months	$ (4.7)
Iron Ore [Member]
Derivative [Line Items]
Beginning Settlement Date	Jul. 01, 2015
Ending Settlement Date	Feb. 28, 2017
Gains (losses) expected to be reclassified into cost of products sold within the next twelve months	$ (16.2)
Electricity [Member]
Derivative [Line Items]
Beginning Settlement Date	Jul. 01, 2015
Ending Settlement Date	Dec. 31, 2016
Gains (losses) expected to be reclassified into cost of products sold within the next twelve months	$ (1.2)
Commodity Contract [Member] | Nickel [Member]
Derivative [Line Items]
Nonmonetary Notional Amount of Derivatives | lb		314,500	259,300
Commodity Contract [Member] | Natural Gas [Member]
Derivative [Line Items]
Nonmonetary Notional Amount of Derivatives | MMBTU		28,285,000	33,992,500
Commodity Contract [Member] | Zinc [Member]
Derivative [Line Items]
Nonmonetary Notional Amount of Derivatives | lb		55,496,200	61,800,000
Commodity Contract [Member] | Iron Ore [Member]
Derivative [Line Items]
Nonmonetary Notional Amount of Derivatives | t		2,475,000	2,335,000
Commodity Contract [Member] | Electricity [Member]
Derivative [Line Items]
Nonmonetary Notional Amount of Derivatives | MW		1,298,500	1,182,800
Commodity Contract [Member] | Hot Roll Carbon Steel Coils [Member]
Derivative [Line Items]
Nonmonetary Notional Amount of Derivatives | T		6,000	15,000
Foreign Exchange Contract [Member]
Derivative [Line Items]
Derivative, Notional Amount | €		€ 39,575,000	€ 23,675,000