Financial Assets and Liabilities Measured at Fair Value on Recurring Basis (Detail) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2013	Dec. 31, 2012
Foreign Exchange Forward Contracts
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Foreign currency forward contracts, liabilities	$ 2,365	$ 3,290
Recurring Basis
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	962,678	1,547,472
Recurring Basis | Foreign Exchange Forward Contracts
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Foreign currency forward contracts, liabilities	2,365	3,290
Recurring Basis | Money Market Funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	343,199	677,523
Recurring Basis | Time Deposits
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	64,709	89,084
Restricted cash	10,031	9,855
Investments	332,499	525,533
Recurring Basis | Corporate Debt Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	212,240	245,477
Fair Value, Inputs, Level 1 | Recurring Basis
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	343,199	677,523
Fair Value, Inputs, Level 1 | Recurring Basis | Money Market Funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	343,199	677,523
Fair Value, Inputs, Level 2 | Recurring Basis
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	619,479	869,949
Fair Value, Inputs, Level 2 | Recurring Basis | Foreign Exchange Forward Contracts
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Foreign currency forward contracts, liabilities	2,365	3,290
Fair Value, Inputs, Level 2 | Recurring Basis | Time Deposits
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	64,709	89,084
Restricted cash	10,031	9,855
Investments	332,499	525,533
Fair Value, Inputs, Level 2 | Recurring Basis | Corporate Debt Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	$ 212,240	$ 245,477