Revenue from Contracts with Customers - Schedule of Revenue from Contracts (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Disaggregation of Revenue [Line Items]
Total net interest income	$ 27,331	$ 23,770	$ 78,350	$ 70,458
Noninterest income:
Service charges on deposit accounts	2,239	2,310	6,558	6,801
Lockbox fees	996	937	2,850	3,018
Net gains on sales of securities		53	13	61
Gains on sales of mortgage loans				154
Other income	934	986	3,112	3,676
Total noninterest income	4,169	4,286	12,520	13,710
ASU 2014-09 [Member]
Disaggregation of Revenue [Line Items]
Total net interest income	27,331	23,770	78,350	70,458
Noninterest income:
Service charges on deposit accounts	2,239	2,310	6,558	6,801
Lockbox fees	996	937	2,850	3,018
Net gains on sales of securities		53		61
Gains on sales of mortgage loans		0		154
Other income	934	986	3,112	3,676
Total noninterest income	4,169	4,286	12,520	13,710
Total revenues	31,500	28,056	90,870	84,168
ASU 2014-09 [Member] | Revenue Guidance Contracts in Scope of Topic 606 [Member]
Noninterest income:
Service charges on deposit accounts	2,239	2,310	6,558	6,801
Lockbox fees	996	937	2,850	3,018
Other income	580	728	1,738	2,338
Total noninterest income	3,815	3,975	11,146	12,157
Total revenues	$ 3,815	$ 3,975	$ 11,146	$ 12,157