Derivative Instruments and Hedging Activities (Schedule of Derivative Instruments in Statement of Financial Position, Fair Value) (Details) (USD $) In Millions	Jun. 30, 2011	Dec. 31, 2010
Derivatives designated as hedging instruments under ASC 815	$ 8.9	$ 2.8
Derivatives not designated as hedging instruments under ASC 815	115.4	81.8
Total derivatives	124.3	84.6
Derivative Assets (Current) [Member] | Foreign Exchange Contract [Member]
Derivatives designated as hedging instruments under ASC 815	8.9	2.8
Derivatives not designated as hedging instruments under ASC 815	21.5	34.2
Derivative Assets (Current) [Member] | Provisional Pricing Arrangements [Member]
Derivatives not designated as hedging instruments under ASC 815	15.8
Derivative Assets (Current) [Member] | Customer Supply Agreements [Member]
Derivatives not designated as hedging instruments under ASC 815	64.0	45.6
Foreign Exchange Contract [Member] | Deposits and Miscellaneous [Member]
Derivatives not designated as hedging instruments under ASC 815		2.0
Accounts Receivable [Member]
Total derivatives	14.1
Accounts Receivable [Member] | Provisional Pricing Arrangements [Member]
Derivatives not designated as hedging instruments under ASC 815	$ 14.1