Summary of Significant Accounting Policies - Summary of Financial Assets at Fair Value (Detail) $ in Thousands	Sep. 30, 2017 USD ($)
Assets measured at fair value on a recurring basis:
Derivative financial instruments	$ 3,203
Fair Value, Measurements, Recurring
Assets measured at fair value on a recurring basis:
Cash and cash equivalents held in bank accounts	25,392
Derivative financial instruments	3,203
Total assets	28,595
Fair Value, Measurements, Recurring | Level 1
Assets measured at fair value on a recurring basis:
Cash and cash equivalents held in bank accounts	25,392
Total assets	25,392
Fair Value, Measurements, Recurring | Level 2
Assets measured at fair value on a recurring basis:
Derivative financial instruments	3,203
Total assets	$ 3,203