Fair Value Measurements - Financial Assets and Liabilities, Excluding Cash and Cash Equivalents, Measured on a Recurring Basis at Fair Value (Detail) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Mutual fund assets	$ 28,285	$ 28,227
Derivative assets:
Foreign currency contracts	28	981
Total assets at fair value	28,313	29,208
Derivative liabilities:
Foreign currency contracts	924	429
Level 1 [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Mutual fund assets	28,285	28,227
Derivative assets:
Total assets at fair value	28,285	28,227
Level 2 [Member]
Derivative assets:
Foreign currency contracts	28	981
Total assets at fair value	28	981
Derivative liabilities:
Foreign currency contracts	$ 924	$ 429