Fair Value Measurements - Financial Assets and Liabilities Measured at Fair Value Based on Three-Tier Fair Value Hierarchy (Detail) - USD ($) $ in Thousands		Sep. 30, 2016	Dec. 31, 2015
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Liabilities, Fair Value Disclosure, Nonrecurring		$ 0
Assets, Fair Value Disclosure, Nonrecurring		0
Time deposit pledged for credit card facility	[1]	1,341	$ 1,093
Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets measured and recorded at fair value		15,549	107,569
Total liabilities measured and recorded at fair value		17	371
Fair Value, Measurements, Recurring [Member] | Cost-method Investments [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets measured and recorded at fair value		530	1,840
Bank Time Deposits [Member] | Fair Value, Measurements, Recurring [Member] | Prepaids and other current assets [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Time deposit pledged for credit card facility		580	580
Money market funds [Member] | Fair Value, Measurements, Recurring [Member] | Cash equivalents [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets measured and recorded at fair value		6,276	53,434
US Treasury Bill Securities [Member] | Fair Value, Measurements, Recurring [Member] | Cash equivalents [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets measured and recorded at fair value			24,998
Corporate bonds [Member] | Fair Value, Measurements, Recurring [Member] | Short-term Investments [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets measured and recorded at fair value		7,931	25,505
Foreign exchange forward contracts [Member] | Fair Value, Measurements, Recurring [Member] | Prepaids and other current assets [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets measured and recorded at fair value		232	113
Foreign exchange forward contracts [Member] | Fair Value, Measurements, Recurring [Member] | Accrued Liabilities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total liabilities measured and recorded at fair value		17	371
Commercial Paper [Member] | Fair Value, Measurements, Recurring [Member] | Short-term Investments [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets measured and recorded at fair value			1,099
Level 1 [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets measured and recorded at fair value		6,806	80,272
Total liabilities measured and recorded at fair value		0	0
Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Cost-method Investments [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets measured and recorded at fair value		530	1,840
Level 1 [Member] | Bank Time Deposits [Member] | Fair Value, Measurements, Recurring [Member] | Prepaids and other current assets [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Time deposit pledged for credit card facility		0
Level 1 [Member] | Money market funds [Member] | Fair Value, Measurements, Recurring [Member] | Cash equivalents [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets measured and recorded at fair value		6,276	53,434
Level 1 [Member] | US Treasury Bill Securities [Member] | Fair Value, Measurements, Recurring [Member] | Cash equivalents [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets measured and recorded at fair value			24,998
Level 1 [Member] | Corporate bonds [Member] | Fair Value, Measurements, Recurring [Member] | Short-term Investments [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets measured and recorded at fair value		0	0
Level 1 [Member] | Foreign exchange forward contracts [Member] | Fair Value, Measurements, Recurring [Member] | Prepaids and other current assets [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets measured and recorded at fair value		0	0
Level 1 [Member] | Foreign exchange forward contracts [Member] | Fair Value, Measurements, Recurring [Member] | Accrued Liabilities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total liabilities measured and recorded at fair value		0	0
Level 1 [Member] | Commercial Paper [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets measured and recorded at fair value			0
Level 2 [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets measured and recorded at fair value		8,743	27,297
Total liabilities measured and recorded at fair value		17	371
Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Cost-method Investments [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets measured and recorded at fair value		0	0
Level 2 [Member] | Bank Time Deposits [Member] | Fair Value, Measurements, Recurring [Member] | Prepaids and other current assets [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Time deposit pledged for credit card facility		580	580
Level 2 [Member] | Money market funds [Member] | Fair Value, Measurements, Recurring [Member] | Cash equivalents [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets measured and recorded at fair value		0	0
Level 2 [Member] | US Treasury Bill Securities [Member] | Fair Value, Measurements, Recurring [Member] | Cash equivalents [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets measured and recorded at fair value			0
Level 2 [Member] | Corporate bonds [Member] | Fair Value, Measurements, Recurring [Member] | Short-term Investments [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets measured and recorded at fair value		7,931	25,505
Level 2 [Member] | Foreign exchange forward contracts [Member] | Fair Value, Measurements, Recurring [Member] | Prepaids and other current assets [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets measured and recorded at fair value		232	113
Level 2 [Member] | Foreign exchange forward contracts [Member] | Fair Value, Measurements, Recurring [Member] | Accrued Liabilities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total liabilities measured and recorded at fair value		17	371
Level 2 [Member] | Commercial Paper [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets measured and recorded at fair value			1,099
Level 3 [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets measured and recorded at fair value		0	0
Total liabilities measured and recorded at fair value		0	0
Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Cost-method Investments [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets measured and recorded at fair value		0	0
Level 3 [Member] | Bank Time Deposits [Member] | Fair Value, Measurements, Recurring [Member] | Prepaids and other current assets [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Time deposit pledged for credit card facility		0
Level 3 [Member] | Money market funds [Member] | Fair Value, Measurements, Recurring [Member] | Cash equivalents [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets measured and recorded at fair value		0	0
Level 3 [Member] | US Treasury Bill Securities [Member] | Fair Value, Measurements, Recurring [Member] | Cash equivalents [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets measured and recorded at fair value			0
Level 3 [Member] | Corporate bonds [Member] | Fair Value, Measurements, Recurring [Member] | Short-term Investments [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets measured and recorded at fair value		0	0
Level 3 [Member] | Foreign exchange forward contracts [Member] | Fair Value, Measurements, Recurring [Member] | Prepaids and other current assets [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets measured and recorded at fair value		0	0
Level 3 [Member] | Foreign exchange forward contracts [Member] | Fair Value, Measurements, Recurring [Member] | Accrued Liabilities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total liabilities measured and recorded at fair value		$ 0	0
Level 3 [Member] | Commercial Paper [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets measured and recorded at fair value			$ 0

[1] The restricted cash balances are primarily held as cash collateral security for certain bank guarantees. These restricted funds are invested in bank deposits and cannot be withdrawn from the Company’s accounts without the prior written consent of the applicable secured party. Additionally, as of September 30, 2016, the Company recorded approximately $1.1 million of restricted cash for the bank guarantee associated with the TVN French Subsidiary’s office building lease. This amount is reported under “Other Long-term Assets” on the Company’s Condensed Consolidated Balance Sheets.