Fair Value Measurements - Financial Assets and Liabilities Measured on a Recurring Basis at Fair Value (Detail) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Mutual fund assets	$ 25,082	$ 28,270
Derivative assets:
Foreign currency contracts	185	335
Total assets at fair value	25,267	28,605
Derivative liabilities:
Foreign currency contracts	10	94
Total liabilities at fair value	10	94
Level 1 [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Mutual fund assets	25,082	28,270
Derivative assets:
Total assets at fair value	25,082	28,270
Level 2 [Member]
Derivative assets:
Foreign currency contracts	185	335
Total assets at fair value	185	335
Derivative liabilities:
Foreign currency contracts	10	94
Total liabilities at fair value	$ 10	$ 94