Share-based Compensation - Summary of Stock Option Activity (Detail) - USD ($)		12 Months Ended
		Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Options outstanding, beginning		251,026	218,300
Options exercisable, beginning		251,026	218,300
Granted, shares		17,500	86,790
Forfeited, shares		(6,805)	(1,195)
Exercised, shares		(25,491)	(43,244)
Expired, shares		(9,459)	(9,625)
Options outstanding, ending		226,771	251,026	218,300
Options exercisable, ending		214,271	251,026	218,300
Options outstanding, ending, Weighted Average Exercise Price		$ 7.43	$ 6.35
Options exercisable, ending, Weighted Average Exercise Price		7.43	6.35
Granted, Weighted Average Exercise Price		9.97	10.08
Forfeited, Weighted Average Exercise Price		10.37	8.43
Exercised, Weighted Average Exercise Price		5.84	5.85
Expired, Weighted Average Exercise Price		11.20	13.76
Options outstanding, ending, Weighted Average Exercise Price		7.56	7.43	$ 6.35
Options exercisable, ending, Weighted Average Exercise Price		$ 7.42	$ 7.43	$ 6.35
Options outstanding, ending, Weighted Average Remaining Contractual Life		6 years 5 months 4 days	6 years 8 months 23 days	6 years
Options exercisable, ending, Weighted Average Remaining Contractual Life		6 years 5 months 4 days	6 years 8 months 23 days	6 years
Options outstanding, ending, Aggregate Intrinsic Value	[1]	$ 223,478	$ 753,229	$ 378,288
Options exercisable, ending, Aggregate Intrinsic Value	[1]		$ 753,229	$ 378,288

[1] The aggregate intrinsic value of a stock option in the table above represents the total pre-tax intrinsic value (the amount by which the current market value of the underlying stock exceeds the exercise price of the option) that would have been received by the option holders had all option holders exercised their options as of the respective years ended. This amount changes based on changes in the market value of the Company’s common stock.