Loans Held for Investment and Allowance for Credit Losses on Loans - Gross Charges-offs by Year of Orgination (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
	Sep. 30, 2023	Sep. 30, 2023
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year gross charge-offs	$ 385	$ 456
Fiscal year before current fiscal year gross charge-offs	500	882
Two years before current fiscal year gross charge-offs	207	456
Three years before current fiscal year gross charge-offs	135	546
Four years before current fiscal year gross charge-offs	199	269
Prior gross charge-offs	302	384
Revolving Loans Amortized Cost Basis gross charge-offs	2	19
Total current-period gross charge-offs	1,730	3,012
Real Estate [Member] | Commercial Real Estate Owner Occupied [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year gross charge-offs	174	174
Fiscal year before current fiscal year gross charge-offs	189	196
Two years before current fiscal year gross charge-offs	25	26
Three years before current fiscal year gross charge-offs	112	134
Four years before current fiscal year gross charge-offs	147	165
Prior gross charge-offs	158	158
Total current-period gross charge-offs	805	853
Real Estate [Member] | Commercial Real Estate Non-Owner Occupied [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Prior gross charge-offs		3
Total current-period gross charge-offs		3
Real Estate [Member] | Construction and Development Less than 60 Months [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Fiscal year before current fiscal year gross charge-offs		2
Three years before current fiscal year gross charge-offs		2
Prior gross charge-offs
Total current-period gross charge-offs		4
Real Estate [Member] | Residential Real Estate First Lien [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Two years before current fiscal year gross charge-offs	71	90
Three years before current fiscal year gross charge-offs	11	32
Prior gross charge-offs	18	22
Total current-period gross charge-offs	100	144
Real Estate [Member] | Residential Real Estate All Other [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Fiscal year before current fiscal year gross charge-offs		4
Two years before current fiscal year gross charge-offs		19
Four years before current fiscal year gross charge-offs		1
Prior gross charge-offs		4
Total current-period gross charge-offs		28
Real Estate [Member] | Agriculture [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Fiscal year before current fiscal year gross charge-offs	150	154
Two years before current fiscal year gross charge-offs	9	9
Three years before current fiscal year gross charge-offs		317
Four years before current fiscal year gross charge-offs		14
Prior gross charge-offs		2
Total current-period gross charge-offs	159	496
Commercial Non-real Estate [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year gross charge-offs	19	61
Fiscal year before current fiscal year gross charge-offs	15	116
Two years before current fiscal year gross charge-offs	46	109
Three years before current fiscal year gross charge-offs		20
Four years before current fiscal year gross charge-offs	51	51
Prior gross charge-offs	108	160
Total current-period gross charge-offs	239	517
Consumer Non-real Estate [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year gross charge-offs	192	221
Fiscal year before current fiscal year gross charge-offs	146	408
Two years before current fiscal year gross charge-offs	56	203
Three years before current fiscal year gross charge-offs	12	41
Four years before current fiscal year gross charge-offs	1	38
Prior gross charge-offs	18	35
Revolving Loans Amortized Cost Basis gross charge-offs	2	19
Total current-period gross charge-offs	$ 427	965
Oil and Gas [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Fiscal year before current fiscal year gross charge-offs		2
Total current-period gross charge-offs		$ 2