Loans Held for Investment and Allowance for Loan Losses - Schedule of How Loans Were Modified as Troubled Debt Restructured Loans (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Financing Receivable, Modifications [Line Items]
Troubled Debt Restructured Loans	$ 335	$ 105	$ 335	$ 2,255
Commercial [Member]
Financing Receivable, Modifications [Line Items]
Troubled Debt Restructured Loans	205		205	361
Commercial [Member] | C&I [Member]
Financing Receivable, Modifications [Line Items]
Troubled Debt Restructured Loans	205		205	361
Agriculture [Member]
Financing Receivable, Modifications [Line Items]
Troubled Debt Restructured Loans				68
Real Estate [Member]
Financing Receivable, Modifications [Line Items]
Troubled Debt Restructured Loans	130	77	130	1,766
Real Estate [Member] | Construction & Development [Member]
Financing Receivable, Modifications [Line Items]
Troubled Debt Restructured Loans				200
Real Estate [Member] | Owner Occupied CRE [Member]
Financing Receivable, Modifications [Line Items]
Troubled Debt Restructured Loans				1,047
Real Estate [Member] | Residential [Member]
Financing Receivable, Modifications [Line Items]
Troubled Debt Restructured Loans	130	77	130	519
Consumer [Member]
Financing Receivable, Modifications [Line Items]
Troubled Debt Restructured Loans	335	28	335	60
Consumer [Member] | Auto [Member]
Financing Receivable, Modifications [Line Items]
Troubled Debt Restructured Loans		19		51
Consumer [Member] | Non Auto [Member]
Financing Receivable, Modifications [Line Items]
Troubled Debt Restructured Loans		9		9
Maturity Extended [Member]
Financing Receivable, Modifications [Line Items]
Troubled Debt Restructured Loans		18		743
Maturity Extended [Member] | Commercial [Member]
Financing Receivable, Modifications [Line Items]
Troubled Debt Restructured Loans				212
Maturity Extended [Member] | Commercial [Member] | C&I [Member]
Financing Receivable, Modifications [Line Items]
Troubled Debt Restructured Loans				212
Maturity Extended [Member] | Agriculture [Member]
Financing Receivable, Modifications [Line Items]
Troubled Debt Restructured Loans				68
Maturity Extended [Member] | Real Estate [Member]
Financing Receivable, Modifications [Line Items]
Troubled Debt Restructured Loans		18		463
Maturity Extended [Member] | Real Estate [Member] | Construction & Development [Member]
Financing Receivable, Modifications [Line Items]
Troubled Debt Restructured Loans				200
Maturity Extended [Member] | Real Estate [Member] | Residential [Member]
Financing Receivable, Modifications [Line Items]
Troubled Debt Restructured Loans		18		263
Combined Rate and Maturity [Member]
Financing Receivable, Modifications [Line Items]
Troubled Debt Restructured Loans	205	87	205	1,512
Combined Rate and Maturity [Member] | C&I [Member]
Financing Receivable, Modifications [Line Items]
Troubled Debt Restructured Loans	205		205
Combined Rate and Maturity [Member] | Residential [Member]
Financing Receivable, Modifications [Line Items]
Troubled Debt Restructured Loans		59
Combined Rate and Maturity [Member] | Non Auto [Member]
Financing Receivable, Modifications [Line Items]
Troubled Debt Restructured Loans		9		9
Combined Rate and Maturity [Member] | Commercial [Member]
Financing Receivable, Modifications [Line Items]
Troubled Debt Restructured Loans				149
Combined Rate and Maturity [Member] | Commercial [Member] | C&I [Member]
Financing Receivable, Modifications [Line Items]
Troubled Debt Restructured Loans				149
Combined Rate and Maturity [Member] | Real Estate [Member]
Financing Receivable, Modifications [Line Items]
Troubled Debt Restructured Loans		59		1,303
Combined Rate and Maturity [Member] | Real Estate [Member] | Owner Occupied CRE [Member]
Financing Receivable, Modifications [Line Items]
Troubled Debt Restructured Loans				1,047
Combined Rate and Maturity [Member] | Real Estate [Member] | Residential [Member]
Financing Receivable, Modifications [Line Items]
Troubled Debt Restructured Loans	$ 130		$ 130	256
Combined Rate and Maturity [Member] | Consumer [Member]
Financing Receivable, Modifications [Line Items]
Troubled Debt Restructured Loans		28		60
Combined Rate and Maturity [Member] | Consumer [Member] | Auto [Member]
Financing Receivable, Modifications [Line Items]
Troubled Debt Restructured Loans		$ 19		$ 51