Derivatives And Risk Management (Commodity Contract Commitments) (Details)	May 31, 2013 t
Aluminum [Member] | Long [Member]
Derivative [Line Items]
Commodity Contract Commitments	4,052
Aluminum [Member] | Short [Member]
Derivative [Line Items]
Commodity Contract Commitments	375
Copper [Member] | Long [Member]
Derivative [Line Items]
Commodity Contract Commitments	986
Copper [Member] | Short [Member]
Derivative [Line Items]
Commodity Contract Commitments	5,024
Zinc [Member] | Long [Member]
Derivative [Line Items]
Commodity Contract Commitments	22