Fair Value Measurements - Summary of Fair Value of Financial Instruments (Detail) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Short-term investments:
Short-term investments	$ 88,496	$ 86,529
U.S. Government Securities [Member]
Short-term investments:
Short-term investments	28,496	15,965
Asset Backed Securities [Member]
Short-term investments:
Short-term investments	8,807	8,588
Corporate Securities [Member]
Short-term investments:
Short-term investments	31,811	19,954
Commercial Paper [Member]
Short-term investments:
Short-term investments	19,382	42,022
Fair Value, Measurements, Recurring [Member] \| Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] \| Repurchase Agreements [Member]
Cash equivalents:
Cash equivalents	8,000
Fair Value, Measurements, Recurring [Member] \| Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] \| U.S. Treasury Money Market Funds [Member]
Cash equivalents:
Cash equivalents	5,109	14,710
Fair Value, Measurements, Recurring [Member] \| Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] \| U.S. Government Securities [Member]
Short-term investments:
Short-term investments	28,496	15,965
Fair Value, Measurements, Recurring [Member] \| Significant Other Observable Inputs (Level 2) [Member]
Liabilities:
Foreign exchange derivatives not designated as hedging instruments	136	26
Fair Value, Measurements, Recurring [Member] \| Significant Other Observable Inputs (Level 2) [Member] \| Asset Backed Securities [Member]
Short-term investments:
Short-term investments	8,807	8,588
Fair Value, Measurements, Recurring [Member] \| Significant Other Observable Inputs (Level 2) [Member] \| Corporate Securities [Member]
Cash equivalents:
Cash equivalents		2,371
Short-term investments:
Short-term investments	31,811	19,954
Fair Value, Measurements, Recurring [Member] \| Significant Other Observable Inputs (Level 2) [Member] \| Commercial Paper [Member]
Cash equivalents:
Cash equivalents		4,411
Short-term investments:
Short-term investments	$ 19,382	42,022
Fair Value, Measurements, Recurring [Member] \| Significant Unobservable Inputs (Level 3) [Member]
Liabilities:
Contingent consideration		$ 12,214

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Cash and cash equivalents fair value disclosure settled and (unsettled) amount.

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Short-term investments fair value disclosure.

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Amount of investment in debt and equity securities categorized neither as held-to-maturity nor trading.

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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.

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Fair value of contingent consideration in a business combination that is classified in shareholders' equity.

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Fair value as of the balance sheet date of all foreign currency derivative liabilities not designated as hedging instruments.

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