Parent Financial Statements - Condensed Statements of Operations (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Condensed Financial Statements Captions [Line Items]
Interest income	$ 43,803	$ 33,700
Interest expense	10,225	6,001
Net interest income	33,578	27,699
Net losses on disposition of other assets	(7)	(220)
Other income	165	54
Total noninterest income	4,303	3,507
Noninterest expense	32,119	26,747
Income tax benefit	533	797
Net income (loss)	3,878	(1,272)
Parent Company
Condensed Financial Statements Captions [Line Items]
Interest income		2
Interest expense	512	481
Net interest income	(512)	(479)
Net losses on disposition of other assets	(73)
Other income	529	857
Total noninterest income	456	857
Noninterest expense	1,659	1,752
Loss before income taxes and equity in undistributed earnings (losses) of subsidiaries	(1,715)	(1,374)
Income tax benefit	(212)	(340)
Loss before equity in undistributed earnings of subsidiaries	(1,503)	(1,034)
Equity in undistributed earnings (losses) of subsidiaries	5,381	(238)
Net income (loss)	$ 3,878	$ (1,272)