Derivative Financial Instruments - Summary of Interest Rate Swap Agreements (Detail) - USD ($)	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2016	Dec. 31, 2015
Derivative [Line Items]
Notional Amount		$ 100,000,000	$ 50,000,000
Interest Rate Swap [Member]
Derivative [Line Items]
Notional Amount	$ 100,000,000
Effective Date	Sep. 04, 2013
Expiration Date	Sep. 04, 2018
Fixed Rate Paid	1.371%
Interest Rate Swap [Member] | London Interbank Offered Rate (LIBOR) [Member]
Derivative [Line Items]
Floating Rate Received	1 month LIBOR