Derivative Instruments - Schedule of Derivative Instruments in Statement of Financial Position, Fair Value (Detail) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Derivatives, Fair Value [Line Items]
Derivative asset	$ 21	$ 16
Derivative liability	91	13
Not Designated as Hedging Instrument | Prepaid Expenses and Other Current Assets
Derivatives, Fair Value [Line Items]
Derivative asset	21	16
Not Designated as Hedging Instrument | Accrued Expenses
Derivatives, Fair Value [Line Items]
Derivative liability	$ 91	$ 13