Earnings per Common Share - Computation of Basic and Diluted Earnings per Common Share (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Basic
Net income	$ 5,181	$ 3,122	$ 9,906	$ 6,292
Preferred stock dividends	391	391	782	795
Net income available to common shareholders - basic	$ 4,790	$ 2,731	$ 9,124	$ 5,497
Weighted average common shares outstanding - basic	7,877,119	7,842,159	7,861,444	7,800,808
Basic earnings per common share	$ 0.61	$ 0.35	$ 1.16	$ 0.70
Diluted
Net income available to common shareholders - basic	$ 4,790	$ 2,731	$ 9,124	$ 5,497
Preferred stock dividends	391	391	782	795
Net income available to common shareholders - diluted	$ 5,181	$ 3,122	$ 9,906	$ 6,292
Weighted average common shares outstanding for basic earnings per common share basic	7,877,119	7,842,159	7,861,444	7,800,808
Add: Dilutive effects of convertible preferred shares	3,074,402	3,079,665	3,076,323	3,113,980
Average shares and dilutive potential common shares outstanding - diluted	10,951,521	10,921,824	10,937,767	10,914,788
Diluted earnings per common share	$ 0.47	$ 0.29	$ 0.91	$ 0.58