Fair Value Measurements - Valuation of Company's Assets and Liabilities Measured at Fair Value (Detail) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Assets
Money market funds	$ 4,454	$ 20,856
Total assets	42,034	48,967
Liabilities
Contingent consideration payable	41,084	15,026
Total liabilities		15,831
U.S. Treasuries [Member]
Assets
Trading securities	24,964
Corporate Debt [Member]
Assets
Trading securities		19,222
Mutual Funds Held In Rabbi Trust [Member]
Assets
Trading securities	10,803	8,889
Foreign Currency Forward Position [Member]
Assets
Foreign currency forward position	1,813
Liabilities
Foreign currency forward position		805
Level 1 [Member]
Assets
Money market funds	4,454	20,856
Total assets	4,454	20,856
Level 2 [Member]
Assets
Total assets	37,580	28,111
Liabilities
Total liabilities		805
Level 2 [Member] \| U.S. Treasuries [Member]
Assets
Trading securities	24,964
Level 2 [Member] \| Corporate Debt [Member]
Assets
Trading securities		19,222
Level 2 [Member] \| Mutual Funds Held In Rabbi Trust [Member]
Assets
Trading securities	10,803	8,889
Level 2 [Member] \| Foreign Currency Forward Position [Member]
Assets
Foreign currency forward position	1,813
Liabilities
Foreign currency forward position		805
Level 3 [Member]
Liabilities
Contingent consideration payable	$ 41,084	15,026
Total liabilities		$ 15,026

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

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Amount of liability recognized arising from contingent consideration in a business combination.

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Amount of investment in debt security measured at fair value with change in fair value recognized in net income (trading).

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