Loans Held for Investment and Allowance for Loan Losses - Changes in Allowance for Loan Losses (Detail) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	$ 0	$ 66,913,000	$ 75,834,000	$ 63,465,000
Provision for Loan and Lease Losses	6,522,000	4,103,000	11,229,000	7,850,000
Recoveries	0	1,191,000	0	1,551,000
Charge-offs	(0)	(275,000)	(0)	(934,000)
Ending balance	86,541,000	71,932,000	86,541,000	71,932,000
C&I [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	16,083,000	15,737,000	16,129,000	12,280,000
Provision for Loan and Lease Losses	(0)	2,521,000	924,000	5,976,000
Recoveries	113,000	402,000	165,000	558,000
Charge-offs	(654,000)	(71,000)	(688,000)	(225,000)
Ending balance	16,530,000	18,589,000	16,530,000	18,589,000
Municipal [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	1,067,000	1,418,000	1,026,000	348,000
Provision for Loan and Lease Losses	0	66,000	(839,000)	1,004,000
Recoveries	0	0	0	0
Charge-offs	0	0	0	0
Ending balance	187,000	1,352,000	187,000	1,352,000
Construction & Development [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	28,627,000	17,887,000	26,443,000	17,627,000
Provision for Loan and Lease Losses	0	3,198,000	2,423,000	3,558,000
Recoveries	0	0	100,000	0
Charge-offs	(0)	(0)	0	(100,000)
Ending balance	28,966,000	21,085,000	28,966,000	21,085,000
Farm [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	1,937,000	873,000	1,957,000	663,000
Provision for Loan and Lease Losses	0	133,000	847,000	343,000
Recoveries	0	0	0	0
Charge-offs	0	0	0	0
Ending balance	2,804,000	1,006,000	2,804,000	1,006,000
Non-Owner Occupied CRE [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	9,051,000	8,499,000	9,075,000	10,722,000
Provision for Loan and Lease Losses	(0)	(576,000)	4,349,000	(2,854,000)
Recoveries	22,000	487,000	47,000	542,000
Charge-offs	0	0	0	0
Ending balance	13,471,000	8,410,000	13,471,000	8,410,000
Owner Occupied CRE [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	11,948,000	11,536,000	9,928,000	10,828,000
Provision for Loan and Lease Losses	0	809,000	2,623,000	(20,000)
Recoveries	14,000	13,000	21,000	20,000
Charge-offs	(0)	(0)	0	(88,000)
Ending balance	12,572,000	10,740,000	12,572,000	10,740,000
Residential [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	9,702,000	7,829,000	9,075,000	8,133,000
Provision for Loan and Lease Losses	0	(466,000)	791,000	303,000
Recoveries	12,000	12,000	15,000	17,000
Charge-offs	(114,000)	(3,000)	(114,000)	(149,000)
Ending balance	9,767,000	8,304,000	9,767,000	8,304,000
Auto [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	857,000	869,000	845,000	896,000
Provision for Loan and Lease Losses	0	(64,000)	169,000	44,000
Recoveries	101,000	102,000	233,000	168,000
Charge-offs	(228,000)	(123,000)	(418,000)	(196,000)
Ending balance	829,000	912,000	829,000	912,000
Non-Auto [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	332,000	354,000	315,000	371,000
Provision for Loan and Lease Losses	0	4,000	123,000	39,000
Recoveries	36,000	83,000	81,000	129,000
Charge-offs	(122,000)	(69,000)	(186,000)	(167,000)
Ending balance	333,000	372,000	333,000	372,000
Agriculture [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	1,214,000	1,911,000	1,041,000	1,597,000
Provision for Loan and Lease Losses	0	832,000	(181,000)	(543,000)
Recoveries	21,000	92,000	222,000	117,000
Charge-offs	0	9,000	0	(9,000)
Ending balance	$ 1,082,000	$ 1,162,000	$ 1,082,000	$ 1,162,000