Fair Value Measurements (Term Deposits With Various Banks Outstanding) (Details) (USD $) In Millions, unless otherwise specified	Mar. 31, 2012	Dec. 31, 2011
Schedule of Fair Value of Separate Accounts by Major Category of Investment [Line Items]
Term deposits outstanding	$ 260.6	$ 234.6
Cash & Cash Equivalents [Member]
Schedule of Fair Value of Separate Accounts by Major Category of Investment [Line Items]
Term deposits outstanding	36.3	43.7
Short Term Investments [Member]
Schedule of Fair Value of Separate Accounts by Major Category of Investment [Line Items]
Term deposits outstanding	224.2	190.8
Non Current Assets [Member]
Schedule of Fair Value of Separate Accounts by Major Category of Investment [Line Items]
Term deposits outstanding	$ 0.1	$ 0.1