Fair Value Measurements - Schedule of Fair Value of Assets and Liabilities Measured on Recurring Basis (Detail) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivatives - currency forward contracts	$ 487	$ 1,486
Derivatives - currency forward contracts	2,193	263
Short-term investments	308,768	430,663
Available-for-sale investments	308,768	430,663
Other current assets	487	1,486
Other current liabilities	2,193	263
Fair Value Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivatives - currency forward contracts	487	1,486
Total assets	552,415	538,589
Derivatives - currency forward contracts	2,193	263
Cash and cash equivalents	243,160	106,440
Short-term investments	308,768	430,663
Other current assets	487	1,486
Total current assets	552,415	538,589
Other current liabilities	2,193	263
Money Market Funds [Member] \| Fair Value Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents	197,650	106,099
Bankers' Acceptance Drafts [Member] \| Fair Value Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents	15	11
Available-for-sale investments	1,646	728
Time Deposits and Certificates of Deposit [Member] \| Fair Value Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale investments	23,005	11,892
Asset-Backed Securities [Member] \| Fair Value Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale investments	74,057	124,997
U.S. Treasury Obligations [Member] \| Fair Value Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents	35,496
Available-for-sale investments	4,360
U.S. Agency Obligations [Member] \| Fair Value Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale investments	110,233	119,582
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] \| Fair Value Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	197,650	106,099
Cash and cash equivalents	197,650	106,099
Total current assets	197,650	106,099
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] \| Money Market Funds [Member] \| Fair Value Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents	197,650	106,099
Significant Other Observable Inputs (Level 2) [Member] \| Fair Value Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivatives - currency forward contracts	487	1,486
Total assets	354,765	432,490
Derivatives - currency forward contracts	2,193	263
Cash and cash equivalents	45,510	341
Short-term investments	308,768	430,663
Other current assets	487	1,486
Total current assets	354,765	432,490
Other current liabilities	2,193	263
Significant Other Observable Inputs (Level 2) [Member] \| Bankers' Acceptance Drafts [Member] \| Fair Value Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents	15	11
Available-for-sale investments	1,646	728
Significant Other Observable Inputs (Level 2) [Member] \| Time Deposits and Certificates of Deposit [Member] \| Fair Value Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale investments	23,005	11,892
Significant Other Observable Inputs (Level 2) [Member] \| Asset-Backed Securities [Member] \| Fair Value Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale investments	74,057	124,997
Significant Other Observable Inputs (Level 2) [Member] \| U.S. Treasury Obligations [Member] \| Fair Value Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents	35,496
Available-for-sale investments	4,360
Significant Other Observable Inputs (Level 2) [Member] \| U.S. Agency Obligations [Member] \| Fair Value Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale investments	110,233	119,582
Commercial Paper [Member] \| Fair Value Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents	9,999
Commercial Paper [Member] \| Significant Other Observable Inputs (Level 2) [Member] \| Fair Value Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents	9,999
Corporate Obligations [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale investments	90,856	165,109
Corporate Obligations [Member] \| Fair Value Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents		330
Available-for-sale investments	90,856	165,109
Corporate Obligations [Member] \| Significant Other Observable Inputs (Level 2) [Member] \| Fair Value Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents		330
Available-for-sale investments	90,856	165,109
Municipal Bonds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale investments	4,611	8,355
Municipal Bonds [Member] \| Fair Value Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale investments	4,611	8,355
Municipal Bonds [Member] \| Significant Other Observable Inputs (Level 2) [Member] \| Fair Value Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale investments	$ 4,611	$ 8,355

Current assets fair value disclosure.

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- Definition

Fair value portion of probable future economic benefits obtained or controlled by an entity as a result of past transactions or events.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
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Amount of investment in debt and equity securities categorized neither as held-to-maturity nor trading.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 25
-Paragraph 1
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Fair value portion of currency on hand as well as demand deposits with banks or financial institutions. Includes other kinds of accounts that have the general characteristics of demand deposits. Also includes short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Cash
-URI http://asc.fasb.org/extlink&oid=6506951

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-Name Accounting Standards Codification
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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

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- Definition

Fair value as of the balance sheet date of all foreign currency derivative assets designated as cash flow hedging instruments.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4B
-Subparagraph (c)(1)
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Fair value as of the balance sheet date of all foreign currency derivative liabilities designated as cash flow hedging instruments.

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- Definition

Investments which are intended to be sold in the short term (usually less than one year or the normal operating cycle, whichever is longer) including trading securities, available-for-sale securities, held-to-maturity securities, and other short-term investments not otherwise listed in the existing taxonomy.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
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-Name Regulation S-X (SX)
-Number 210
-Section 03
-Paragraph 1
-Subparagraph g
-Article 7

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