Fair Value Measurements - Financial Assets and Liabilities Measured and Reported at Fair Value on Recurring Basis (Detail) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Assets:
Foreign currency forward exchange contracts		$ 7,804
Fair Value, Measurements, Recurring
Assets:
Foreign currency forward exchange contracts	$ 16,092	7,804
Available-for-sale security	5,243	8,991
Assets, fair value disclosure	21,335	16,795
Liabilities:
Foreign currency forward exchange contracts	2,910	19,320
Fair Value, Measurements, Recurring | Level 1
Assets:
Foreign currency forward exchange contracts	0	0
Available-for-sale security	5,243	8,991
Assets, fair value disclosure	5,243	8,991
Liabilities:
Foreign currency forward exchange contracts	0	0
Fair Value, Measurements, Recurring | Level 2
Assets:
Foreign currency forward exchange contracts	16,092
Available-for-sale security	0	0
Assets, fair value disclosure	16,092	7,804
Liabilities:
Foreign currency forward exchange contracts	2,910	19,320
Fair Value, Measurements, Recurring | Level 3
Assets:
Foreign currency forward exchange contracts	0	0
Available-for-sale security	0	0
Assets, fair value disclosure	0	0
Liabilities:
Foreign currency forward exchange contracts	$ 0	$ 0