Earnings Per Share - Summary of Components Comprising Basic and Diluted Earnings Per Share (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Basic EPS Computation:
Numerator – Earnings available to common stockholders	$ 5,643	$ 5,616
Denominator – Weighted average number of common shares outstanding	10,238,798	10,129,861
Basic earnings per common share (in dollars per share)	$ 0.55	$ 0.55
Diluted EPS Computation:
Numerator – Earnings available to common stockholders	$ 5,643	$ 5,616
Denominator – Weighted average number of common shares outstanding	10,238,798	10,129,861
Dilutive effect of stock options (in shares)	4,228	4,513
Weighted average number of shares outstanding-diluted	10,243,026	10,134,374
Diluted earnings per common share (in dollars per share)	$ 0.55	$ 0.55