Financial Assets Measured at Fair Value on Recurring Basis (Detail) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Foreign exchange forward contracts asset	$ 36	$ 4,784
Total assets measured and recorded at fair value	36	4,784
Fair Value, Inputs, Level 1
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Foreign exchange forward contracts asset	0	0
Total assets measured and recorded at fair value	0	0
Fair Value, Inputs, Level 2
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Foreign exchange forward contracts asset	36	4,784
Total assets measured and recorded at fair value	36	4,784
Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Foreign exchange forward contracts asset	0	0
Total assets measured and recorded at fair value	$ 0	$ 0