Quarterly Financial Results (Unaudited) - Summary of Selected Consolidated Quarterly Financial Data (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Income Statement Data ($):
Interest income	$ 43,185	$ 46,531	$ 47,453	$ 47,523	$ 46,045	$ 43,717	$ 42,136	$ 38,047	$ 184,692	$ 169,945	$ 132,453
Interest expense	15,072	18,269	20,088	20,103	19,125	17,155	15,231	12,931	73,532	64,442	35,407
Net interest income	28,113	28,262	27,365	27,420	26,920	26,562	26,905	25,116	111,160	105,503	97,046
Provision for loan losses	18,961	1,000	7,031	5,055	975	136	570	573	32,047	2,254	4,313
Noninterest income	4,573	4,793	4,923	3,486	(383)	3,442	4,147	3,456	17,775	10,662	14,721
Noninterest expense	21,279	18,614	19,370	22,616	21,689	18,251	18,050	15,488	81,879	73,478	60,824
Net (loss) income before taxes	(7,554)	13,441	5,887	3,235	3,873	11,617	12,432	12,511	15,009	40,433	46,630
Income tax expense	(2,970)	2,117	706	334	122	1,068	2,263	2,459	187	5,912	18,531
Net income	(4,584)	11,324	5,181	2,901	3,751	10,549	10,169	10,052	14,822	34,521	28,099
Net Income (Loss) Available to Common Stockholders, Basic	$ (4,592)	$ 11,324	$ 5,173	$ 2,901	$ 3,743	$ 10,549	$ 10,161	$ 10,052	$ 14,806	$ 34,505	$ 28,083
Earnings per share, basic (in dollars per share)	$ (0.31)	$ 0.77	$ 0.35	$ 0.20	$ 0.26	$ 0.73	$ 0.71	$ 0.76	$ 1.01	$ 2.44	$ 2.14
Earnings per share, diluted (in dollars per share)	$ (0.31)	$ 0.75	$ 0.34	$ 0.19	$ 0.25	$ 0.70	$ 0.68	$ 0.73	$ 0.98	$ 2.34	$ 2.04