Stock-Based Compensation - Summary of Stock Option Activity (Detail) - USD ($)	3 Months Ended	9 Months Ended
	Sep. 30, 2015	Sep. 30, 2015	Dec. 31, 2014	Sep. 30, 2014	Dec. 31, 2013
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Number of options, outstanding	122,000	122,000	108,400	134,000	134,000
Number of options, granted	0	15,000
Number of options, exercised		(1,400)
Number of options, exercisable	104,900	104,900
Weighted-Average Exercise Price, outstanding	$ 10.29	$ 10.29	$ 10.01	$ 10.01	$ 10.01
Weighted-Average Exercise Price, Options granted		12.50
Weighted-Average Exercise Price, Options exercised		10.00
Weighted-Average Exercise Price, Exercisable	$ 10.01	$ 10.01
Weighted-Average Remaining Contractual Term, Outstanding		3 years 6 months
Weighted-Average Remaining Contractual Term, Exercisable		3 years 3 months 18 days
Aggregate Intrinsic Value, Exercisable	$ 182,526	$ 182,526