Loans Held-for-Investment and Allowance for Loan Losses - Schedule of Company's Internal Ratings of its Loans Held-for-Investment, Including The Year of Origination, by Portfolio Segments (Detail) - USD ($) $ in Thousands	Jun. 30, 2023	Dec. 31, 2022	Jun. 30, 2022
Financing Receivable, Credit Quality Indicator [Line Items]
2023	$ 1,252,000	$ 3,094,000	$ 1,721,000
2022	2,605,000	1,449,000	1,996,000
2021	1,217,000	650,000	760,000
2020	587,000	312,000	372,000
2019	274,000	220,000	256,000
Prior	694,000	567,000	650,000
Revolving Loans Amortized Cost Basis	149,000	150,000	123,000
Total	6,778,000	6,442,000	5,878,000
Charge-Off [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2021	1,000
Total	1,000
C&I [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2023	344,000	644,000	357,000
2022	476,000	163,000	323,000
2021	109,000	56,000	82,000
2020	46,000	24,000	33,000
2019	19,000	17,000	23,000
Prior	28,000	13,000	22,000
Revolving Loans Amortized Cost Basis		0	0
Total	1,022,000	917,000	840,000
Municipal [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2023	11,000	79,000	49,000
2022	84,000	19,000	21,000
2021	18,000	15,000	14,000
2020	14,000	4,000	5,000
2019	2,000	20,000	21,000
Prior	87,000	84,000	91,000
Revolving Loans Amortized Cost Basis		0	0
Total	216,000	221,000	201,000
Agriculture [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2023	30,000	60,000	41,000
2022	44,000	10,000	40,000
2021	5,000	3,000	4,000
2020	2,000	2,000	3,000
2019	1,000	1,000	1,000
Prior		1,000	1,000
Revolving Loans Amortized Cost Basis		0	0
Total	82,000	77,000	90,000
Construction & Development [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2023	254,000	643,000	332,000
2022	510,000	219,000	449,000
2021	104,000	70,000	104,000
2020	24,000	13,000	22,000
2019	11,000	8,000	11,000
Prior	12,000	7,000	11,000
Revolving Loans Amortized Cost Basis		0	0
Total	915,000	960,000	929,000
Farm [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2023	63,000	148,000	63,000
2022	127,000	85,000	104,000
2021	79,000	32,000	35,000
2020	31,000	11,000	13,000
2019	9,000	8,000	8,000
Prior	27,000	22,000	27,000
Revolving Loans Amortized Cost Basis		0	0
Total	336,000	306,000	250,000
Non-Owner Occupied CRE [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2023	101,000	266,000	136,000
2022	240,000	193,000	203,000
2021	190,000	102,000	111,000
2020	126,000	62,000	65,000
2019	59,000	22,000	25,000
Prior	95,000	87,000	96,000
Revolving Loans Amortized Cost Basis		0	0
Total	811,000	732,000	636,000
Owner Occupied CRE [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2023	69,000	318,000	241,000
2022	326,000	226,000	224,000
2021	241,000	130,000	126,000
2020	122,000	84,000	92,000
2019	80,000	72,000	82,000
Prior	174,000	124,000	145,000
Revolving Loans Amortized Cost Basis		0	0
Total	1,012,000	954,000	910,000
Residential [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2023	229,000	520,000	280,000
2022	469,000	361,000	404,000
2021	342,000	177,000	192,000
2020	177,000	84,000	72,000
2019	75,000	65,000	97,000
Prior	266,000	226,000	251,000
Revolving Loans Amortized Cost Basis	141,000	143,000	116,000
Total	1,699,000	1,576,000	1,412,000
Auto [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2023	110,000	331,000	168,000
2022	266,000	131,000	171,000
2021	100,000	56,000	77,000
2020	39,000	25,000	37,000
2019	16,000	6,000	11,000
Prior	4,000	2,000	4,000
Revolving Loans Amortized Cost Basis		0	0
Total	535,000	551,000	468,000
Non-Auto [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2023	41,000	85,000	55,000
2022	63,000	42,000	56,000
2021	29,000	9,000	15,000
2020	6,000	3,000	5,000
2019	2,000	1,000	2,000
Prior	1,000	1,000	2,000
Revolving Loans Amortized Cost Basis	8,000	7,000	7,000
Total	150,000	148,000	142,000
Pass [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2023	1,226,000	3,054,000	1,692,000
2022	2,562,000	1,430,000	1,970,000
2021	245,000	637,000	747,000
2020	573,000	285,000	346,000
2019	1,196,000	208,000	239,000
Prior	655,000	531,000	612,000
Revolving Loans Amortized Cost Basis	146,000	146,000	119,000
Total	6,603,000	6,291,000	5,725,000
Pass [Member] | C&I [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2023	333,000	627,000	342,000
2022	468,000	157,000	317,000
2021	105,000	52,000	79,000
2020	44,000	22,000	28,000
2019	18,000	16,000	20,000
Prior	26,000	13,000	22,000
Revolving Loans Amortized Cost Basis		0	0
Total	994,000	887,000	808,000
Pass [Member] | Municipal [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2023	11,000	79,000	49,000
2022	84,000	19,000	21,000
2021	17,000	15,000	14,000
2020	14,000	4,000	5,000
2019	1,000	20,000	21,000
Prior	87,000	84,000	91,000
Revolving Loans Amortized Cost Basis		0	0
Total	214,000	221,000	201,000
Pass [Member] | Agriculture [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2023	30,000	60,000	41,000
2022	42,000	9,000	39,000
2021	5,000	3,000	4,000
2020	2,000	2,000	3,000
2019	1,000	1,000	1,000
Prior		1,000	1,000
Revolving Loans Amortized Cost Basis		0	0
Total	80,000	76,000	89,000
Pass [Member] | Construction & Development [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2023	242,000	638,000	330,000
2022	498,000	218,000	440,000
2021	103,000	70,000	104,000
2020	24,000	13,000	22,000
2019	11,000	8,000	11,000
Prior	12,000	7,000	11,000
Revolving Loans Amortized Cost Basis		0	0
Total	890,000	954,000	918,000
Pass [Member] | Farm [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2023	63,000	147,000	63,000
2022	126,000	85,000	104,000
2021	78,000	32,000	35,000
2020	26,000	11,000	13,000
2019	9,000	8,000	8,000
Prior	26,000	21,000	26,000
Revolving Loans Amortized Cost Basis		0	0
Total	328,000	304,000	249,000
Pass [Member] | Non-Owner Occupied CRE [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2023	101,000	258,000	130,000
2022	234,000	191,000	203,000
2021	185,000	100,000	109,000
2020	125,000	49,000	52,000
2019	46,000	21,000	24,000
Prior	88,000	75,000	83,000
Revolving Loans Amortized Cost Basis		0	0
Total	779,000	694,000	601,000
Pass [Member] | Owner Occupied CRE [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2023	67,000	316,000	240,000
2022	321,000	224,000	218,000
2021	240,000	128,000	122,000
2020	121,000	74,000	88,000
2019	68,000	63,000	71,000
Prior	156,000	113,000	133,000
Revolving Loans Amortized Cost Basis		0	0
Total	973,000	918,000	872,000
Pass [Member] | Residential [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2023	228,000	513,000	277,000
2022	461,000	355,000	399,000
2021	335,000	173,000	188,000
2020	172,000	82,000	70,000
2019	73,000	64,000	94,000
Prior	255,000	214,000	239,000
Revolving Loans Amortized Cost Basis	138,000	139,000	112,000
Total	1,662,000	1,540,000	1,379,000
Pass [Member] | Auto [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2023	110,000	331,000	168,000
2022	265,000	131,000	171,000
2021	99,000	55,000	77,000
2020	39,000	25,000	36,000
2019	16,000	6,000	11,000
Prior	4,000	2,000	4,000
Revolving Loans Amortized Cost Basis		0	0
Total	533,000	550,000	467,000
Pass [Member] | Non-Auto [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2023	41,000	85,000	54,000
2022	63,000	41,000	56,000
2021	29,000	9,000	15,000
2020	6,000	3,000	5,000
2019	2,000	1,000	2,000
Prior	1,000	1,000	2,000
Revolving Loans Amortized Cost Basis	8,000	7,000	7,000
Total	150,000	147,000	141,000
Special Mention [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2023	16,000	7,000	6,000
2022	13,000	5,000	9,000
2021	19,000	6,000	5,000
2020	7,000	20,000	15,000
2019	4,000	0	0
Prior	6,000	11,000	12,000
Revolving Loans Amortized Cost Basis	1,000	1,000
Total	66,000	50,000	47,000
Special Mention [Member] | C&I [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2023	8,000	4,000	4,000
2022	1,000	1,000	1,000
2021		2,000
2020		1,000	2,000
2019	1,000
Total	10,000	8,000	7,000
Special Mention [Member] | Municipal [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2019	1,000
Total	1,000
Special Mention [Member] | Agriculture [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2022	1,000
Total	1,000
Special Mention [Member] | Construction & Development [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2023	8,000	1,000
2022	4,000		4,000
Total	12,000	1,000	4,000
Special Mention [Member] | Farm [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2020	5,000
Total	5,000
Special Mention [Member] | Non-Owner Occupied CRE [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2022	5,000	1,000
2021	1,000	1,000	1,000
2020		11,000	11,000
2019	11,000
Prior	2,000	7,000	7,000
Total	19,000	20,000	19,000
Special Mention [Member] | Owner Occupied CRE [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2023		1,000
2022		0	2,000
2021		1,000	2,000
2020		8,000	1,000
2019	6,000
Prior	1,000	1,000	1,000
Total	7,000	11,000	6,000
Special Mention [Member] | Residential [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2023		1,000	1,000
2022	2,000	3,000	2,000
2021	3,000	2,000	2,000
2020	2,000
2019		0	1,000
Prior	3,000	3,000	4,000
Revolving Loans Amortized Cost Basis	1,000	1,000	0
Total	11,000	10,000	10,000
Special Mention [Member] | Non-Auto [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2023			1,000
Total			1,000
Substandard [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2023	10,000	33,000	23,000
2022	30,000	14,000	17,000
2021	10,000	7,000	8,000
2020	7,000	7,000	11,000
2019	17,000	12,000	17,000
Prior	33,000	25,000	26,000
Revolving Loans Amortized Cost Basis	2,000	3,000	4,000
Total	109,000	101,000	106,000
Substandard [Member] | C&I [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2023	3,000	13,000	11,000
2022	7,000	5,000	5,000
2021	4,000	2,000	3,000
2020	2,000	1,000	3,000
2019		1,000	3,000
Prior	2,000
Total	18,000	22,000	25,000
Substandard [Member] | Municipal [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2021	1,000
Total	1,000
Substandard [Member] | Agriculture [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2022	1,000	1,000	1,000
Total	1,000	1,000	1,000
Substandard [Member] | Construction & Development [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2023	4,000	4,000	2,000
2022	8,000	1,000	5,000
2021	1,000
Total	13,000	5,000	7,000
Substandard [Member] | Farm [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2023		1,000
2022	1,000		0
2021	1,000
2019			0
Prior	1,000	1	1,000
Total	3,000	2,000	1,000
Substandard [Member] | Non-Owner Occupied CRE [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2023		8,000	6,000
2022	1,000	1,000
2021	4,000	1,000	1,000
2020	1,000	2,000	2,000
2019	2,000	1,000	1,000
Prior	5,000	5,000	6,000
Total	13,000	18,000	16,000
Substandard [Member] | Owner Occupied CRE [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2023	2,000	1,000	1,000
2022	5,000	2,000	4,000
2021	1,000	1,000	2,000
2020	1,000	2,000	3,000
2019	6,000	9,000	11,000
Prior	17,000	10,000	11,000
Total	32,000	25,000	32,000
Substandard [Member] | Residential [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2023	1,000	6,000	2,000
2022	6,000	3,000	3,000
2021	4,000	2,000	2,000
2020	3,000	2,000	2,000
2019	2,000	1,000	2,000
Prior	8,000	9,000	8,000
Revolving Loans Amortized Cost Basis	2,000	3,000	4,000
Total	26,000	26,000	23,000
Substandard [Member] | Auto [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2022	1,000
2021	1,000	1,000
2020			1,000
Total	$ 2,000	1,000	1,000
Substandard [Member] | Non-Auto [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2022		1,000
Total		$ 1,000	$ 0