Financial Assets Measured at Fair Value on Recurring Basis (Detail) - USD ($) $ in Millions	Sep. 30, 2015	Dec. 31, 2014
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short Term Investments- Available for Sale Securities	$ 94.5	$ 186.8
Term Deposits	409.2	466.7
Total Assets Measured at Fair Value	503.7	653.5
Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short Term Investments- Available for Sale Securities	94.5	186.8
Total Assets Measured at Fair Value	94.5	186.8
Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Term Deposits	409.2	466.7
Total Assets Measured at Fair Value	$ 409.2	$ 466.7