Derivative Instruments - Additional Information (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Derivative Instruments, Gain (Loss) [Line Items]
Interest expense	$ 16,709	$ 15,469	$ 13,047
Reclassification out of Accumulated Other Comprehensive Income
Derivative Instruments, Gain (Loss) [Line Items]
Interest expense	$ 2,500
Interest Rate Swap Agreements
Derivative Instruments, Gain (Loss) [Line Items]
Interest rate swap agreement beginning date	Dec. 31, 2015
Interest rate swap terminated date	Nov. 28, 2017
Fair value of the interest rate swap liability		$ 4,800