Financial Assets and Liabilities Measured at Fair Value on Recurring Basis (Detail) (Recurring Basis, USD $) In Thousands, unless otherwise specified	Jun. 30, 2014	Dec. 31, 2013
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	$ 1,434,811	$ 846,385
Foreign Exchange Forward Contracts
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Foreign currency forward contracts, Liabilities	11,719
Foreign currency forward contracts, Assets		2,225
Money Market Funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	279,805	229,425
Time Deposits
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	77,236	138,956
Restricted cash	16,635	17,085
Investments	911,390	258,308
Corporate Debt Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	149,745	200,386
Fair Value, Inputs, Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	279,805	229,425
Fair Value, Inputs, Level 1 | Money Market Funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	279,805	229,425
Fair Value, Inputs, Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	1,155,006	616,960
Fair Value, Inputs, Level 2 | Foreign Exchange Forward Contracts
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Foreign currency forward contracts, Liabilities	11,719
Foreign currency forward contracts, Assets		2,225
Fair Value, Inputs, Level 2 | Time Deposits
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	77,236	138,956
Restricted cash	16,635	17,085
Investments	911,390	258,308
Fair Value, Inputs, Level 2 | Corporate Debt Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	$ 149,745	$ 200,386