Fair Value Measurements and Risk (Details) In Millions, unless otherwise specified						3 Months Ended
	Mar. 31, 2012 country	Mar. 31, 2012 Recurring basis Total USD ($)	Dec. 31, 2011 Recurring basis Total USD ($)	Mar. 31, 2012 Recurring basis Significant Other Observable Inputs (Level 2) USD ($)	Dec. 31, 2011 Recurring basis Significant Other Observable Inputs (Level 2) USD ($)	Mar. 31, 2012 Fixed-rate natural gas swaps USD ($) MMBTU	Mar. 31, 2012 Fixed-rate aluminum swaps USD ($) lb	Mar. 31, 2012 Currency forward contracts EUR (€)
Items measured at Fair Value on a Recurring Basis
Maximum period of cash flow hedging						12 months	12 months
Contract volume, or notional amount, of the commodity contracts (in MMBtu or Pounds)						3,700,000	3,000,000
Total contract value						$ 13.8	$ 3.1
Total notional amount related to the remaining outstanding currency forward contracts								245.6
Number of countries where company does business, greater than	40
Assets
Currency derivatives, assets		12.4	20.4	12.4	20.4
Total Assets		12.4	20.4	12.4	20.4
Liabilities
Currency derivatives, liabilities		0.5	0.5	0.5	0.5
Commodity derivatives, liabilities		4.5	3.8	4.5	3.8
Total Liabilities		$ 5.0	$ 4.3	$ 5.0	$ 4.3