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, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Basic
Net income	$ 6,504	$ 8,661	$ 14,337	$ 18,330
Preferred stock dividends		164	0	328
Net income available to common shareholders	$ 6,504	$ 8,497	$ 14,337	$ 18,002
Weighted average common shares outstanding for basic earnings per common share	16,044,125	15,628,537	16,280,935	15,618,154
Basic earnings per common share	$ 0.41	$ 0.54	$ 0.88	$ 1.15
Diluted
Net income available to common shareholders—basic	$ 6,504	$ 8,497	$ 14,337	$ 18,002
Preferred stock dividends		164	0	328
Net income available to common shareholders—diluted	$ 6,504	$ 8,661	$ 14,337	$ 18,330
Weighted average common shares outstanding for basic earnings per common share	16,044,125	15,628,537	16,280,935	15,618,154
Add: Dilutive effects of convertible preferred shares		1,294,175		1,294,175
Average shares and dilutive potential common shares outstanding—diluted	16,044,125	16,922,712	16,280,935	16,912,329
Diluted earnings per common share	$ 0.41	$ 0.51	$ 0.88	$ 1.08