Derivative Financial Instruments - Additional Information (Detail) - USD ($)	3 Months Ended
	Mar. 31, 2018	Dec. 31, 2017
Derivative Instruments And Hedging Activities Disclosure [Abstract]
Net gain (loss) on derivative financial instruments	$ (1,586,000)	$ (1,816,000)
Net deferred losses expected to be reclassified from AOCI over next 12 months	(200,000)
Notional value of outstanding derivative contracts	$ 199,000,000
Derivative contracts, maturity date	Jun. 30, 2020
Fair value of derivative contracts	$ 1,000,000