Earnings per Common Share - Computation of Basic and Diluted Earnings per Common Share (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Basic
Net income	$ 3,680	$ 3,253	$ 13,586	$ 9,546
Preferred stock dividends	374	391	1,156	1,186
Net income available to common shareholders - basic	$ 3,306	$ 2,862	$ 12,430	$ 8,360
Weighted average common shares outstanding - basic	8,042,303	7,843,578	7,922,170	7,815,222
Basic earnings per common share	$ 0.41	$ 0.36	$ 1.57	$ 1.07
Diluted
Net income available to common shareholders - basic	$ 3,306	$ 2,862	$ 12,430	$ 8,360
Preferred stock dividends	374	391	1,156	1,186
Net income available to common shareholders - diluted	$ 3,680	$ 3,253	$ 13,586	$ 9,546
Weighted average common shares outstanding for basic earnings per common share basic	8,042,303	7,843,578	7,922,170	7,815,222
Add: Dilutive effects of convertible preferred shares	2,922,609	3,078,245	3,024,712	3,101,937
Average shares and dilutive potential common shares outstanding - diluted	10,964,912	10,921,823	10,946,882	10,917,159
Diluted earnings per common share	$ 0.34	$ 0.30	$ 1.24	$ 0.87