Fair Value Measurement Available-For-Sale Investments Measured at Fair Value on Recurring Basis (Detail) - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014
Schedule of Available-for-sale Securities and Liabilities that are Measured at Fair Value [Line Items]
Estimated Fair Value	$ 921,643	$ 684,042
Time deposits [Member]
Schedule of Available-for-sale Securities and Liabilities that are Measured at Fair Value [Line Items]
Estimated Fair Value	677,679	345,780
Fair Value, Measurements, Recurring [Member] | Time deposits [Member] | Estimate of Fair Value, Fair Value Disclosure [Member]
Schedule of Available-for-sale Securities and Liabilities that are Measured at Fair Value [Line Items]
Estimated Fair Value	677,679	345,780
Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Time deposits [Member]
Schedule of Available-for-sale Securities and Liabilities that are Measured at Fair Value [Line Items]
Estimated Fair Value	$ 677,679	$ 345,780