Quarterly Financial Data (unaudited) - Schedule of Quarterly Financial Data (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020		Dec. 31, 2019		Dec. 31, 2018
Quarterly Financial Information Disclosure [Abstract]
Interest income	$ 51,334	$ 50,612	$ 49,980	$ 52,019	$ 53,369	$ 54,300	$ 54,060	$ 52,364	$ 203,945		$ 214,093		$ 190,488
Interest expense	6,813	6,758	6,462	9,551	10,940	11,655	11,425	10,841	29,584		44,861		32,426
Net interest income	44,521	43,854	43,518	42,468	42,429	42,645	42,635	41,523	174,361	[1]	169,232	[1]	158,062	[1]
(Reversal of provision) provision for credit losses	(8,721)	3,935	23,737	21,843	2,225	1,533	2,073	2,680	39,439		8,518		20,310
Net interest income after provision for credit losses	53,242	39,919	19,781	20,625	40,204	41,112	40,562	38,843	133,567		160,721		137,752
Noninterest income	20,139	21,805	18,000	18,384	16,170	16,599	16,356	16,297	78,328		65,422		60,173
Total noninterest expense	41,734	38,527	35,960	38,777	37,480	36,267	36,781	35,562	154,998		146,090		137,239
Income before income taxes	31,647	23,197	1,821	232	18,894	21,444	20,137	19,578	56,897		80,053		60,686
Income tax expense	5,773	5,078	(264)	(606)	3,384	3,782	3,669	3,499	9,981		14,334		10,143
Net income	$ 25,874	$ 18,119	$ 2,085	$ 838	$ 15,510	$ 17,662	$ 16,468	$ 16,079	$ 46,916		$ 65,719		$ 50,543
Weighted average shares outstanding - basic earnings per share	29,237	29,189	29,149	29,218	29,232	29,211	29,181	29,146	29,198		29,193		29,177
Weighted average shares outstanding - diluted earnings per share	29,309	29,217	29,164	29,283	29,313	29,285	29,243	29,205	29,268		29,261		29,259
Net income per share:
Basic (in dollars per share)	$ 0.88	$ 0.62	$ 0.07	$ 0.03	$ 0.53	$ 0.60	$ 0.56	$ 0.55	$ 1.60		$ 2.24		$ 1.72
Diluted (in dollars per share)	0.88	0.62	0.07	0.03	0.53	0.60	0.56	0.55	1.60		2.24		1.72
Dividends declared per share	$ 0	$ 0.20	$ 0.20	$ 0.20	$ 0.20	$ 0.20	$ 0.20	$ 0.20	$ 0.60		$ 0.80		$ 0.80

[1] Net interest income as well as many other revenues for financial assets and liabilities including loans, leases, securities, and derivatives are excluded from the scope of FASB ASC 606 "Revenue from Contracts with Customers" (FASB ASC 606). Noninterest income streams that are out of scope of FASB ASC 606 include bank owned life insurance income, sales of investment securities and mortgage banking activities.