Fair Value Measurement Available-For-Sale Investments Measured at Fair Value on Recurring Basis (Detail) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2013	Dec. 31, 2012
Schedule of Available-for-sale Securities and Liabilities that are Measured at Fair Value [Line Items]
Amortized Cost	$ 588,462	$ 387,196
Available-for-sale securities measured at fair value on recurring basis	588,462	387,196
Money market funds [Member]
Schedule of Available-for-sale Securities and Liabilities that are Measured at Fair Value [Line Items]
Amortized Cost		43,648
Available-for-sale securities measured at fair value on recurring basis		43,648
Time deposits [Member]
Schedule of Available-for-sale Securities and Liabilities that are Measured at Fair Value [Line Items]
Amortized Cost	292,492
Available-for-sale securities measured at fair value on recurring basis	292,492
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Fair Value, Measurements, Recurring [Member]
Schedule of Available-for-sale Securities and Liabilities that are Measured at Fair Value [Line Items]
Amortized Cost	0	43,648
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Fair Value, Measurements, Recurring [Member] | Money market funds [Member]
Schedule of Available-for-sale Securities and Liabilities that are Measured at Fair Value [Line Items]
Amortized Cost	0	43,648
Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member]
Schedule of Available-for-sale Securities and Liabilities that are Measured at Fair Value [Line Items]
Amortized Cost	292,492
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]
Amortized Cost	292,492
Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Contingent consideration [Member]
Schedule of Available-for-sale Securities and Liabilities that are Measured at Fair Value [Line Items]
Contingent consideration	47,700	34,800
Estimate of Fair Value, Fair Value Disclosure [Member] | Fair Value, Measurements, Recurring [Member]
Schedule of Available-for-sale Securities and Liabilities that are Measured at Fair Value [Line Items]
Available-for-sale securities measured at fair value on recurring basis	292,492	43,648
Contingent consideration	47,700	34,800
Estimate of Fair Value, Fair Value Disclosure [Member] | Fair Value, Measurements, Recurring [Member] | Money market funds [Member]
Schedule of Available-for-sale Securities and Liabilities that are Measured at Fair Value [Line Items]
Available-for-sale securities measured at fair value on recurring basis	0	43,648
Estimate of Fair Value, Fair Value Disclosure [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]
Available-for-sale securities measured at fair value on recurring basis	$ 292,492