Schedule of Tax Effects Allocated to Each Component of Other Comprehensive Income (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Components Of Other Comprehensive Income Loss [Line Items]
Foreign currency translation adjustment	$ (5,046)	$ 5,770	$ (11,691)	$ 7,925
Unrealized gain (loss) on cash flow hedging instruments	520	304	727	(119)
Income tax (expense) benefit	(140)	(82)	(196)	32
Unrealized gain (loss) on cash flow hedging instruments, net of tax	380	222	531	(87)
Reclassification of loss (gain) on cash flow hedging instruments into earnings	144	(937)	1,175	(1,180)
Income tax (benefit) expense	(39)	254	(317)	319
Reclassification of loss (gain) on cash flow hedging instruments into earnings, net of tax	105	(683)	858	(861)
Unrealized (loss) gain on equity securities		(8)		5
Income tax benefit (expense)		3		(2)
Unrealized (loss) gain on equity securities, net of tax		(5)		3
Other comprehensive (loss) income	$ (4,561)	$ 5,304	$ (10,302)	$ 6,980