Stock-Based Compensation - Summary of Stock Option Activity (Detail) - Stock Options [Member]	3 Months Ended
	Mar. 31, 2018 $ / shares shares
Summary Of Stock Option Activities [Line Items]
Options Outstanding, Beginning balance, Shares | shares	470,484
Options Outstanding, Granted | shares	2,000
Options Outstanding, Forfeited | shares	(84)
Options Outstanding, Cancelled/expired | shares	(12,400)
Options Outstanding, Ending balance, Shares | shares	460,000
Options Exercisable, Ending balance, Shares | shares	447,782
Weighted Average Exercise Price, Beginning balance | $ / shares	$ 7.24
Weighted Average Exercise Price, Options granted | $ / shares	6.98
Weighted Average Exercise Price, Options forfeited | $ / shares	7.31
Weighted Average Exercise Price, Options cancelled/expired | $ / shares	9.12
Weighted Average Exercise Price, Ending balance | $ / shares	7.19
Weighted Average Exercise Price, Exercisable | $ / shares	$ 7.23