Loans Held for investment and Allowance for Credit Losses on Loans - Gross charge-offs by year of origination (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2025	Jun. 30, 2024	Jun. 30, 2025	Jun. 30, 2024
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year gross charge-offs	$ 30	$ 29	$ 49	$ 30
Fiscal year before current fiscal year gross charge-offs	324	434	531	1,703
Two years before current fiscal year gross charge-offs	377	199	624	685
Three years before current fiscal year gross charge-offs	176	52	281	251
Four years before current fiscal year gross charge-offs	3,765	25	3,819	51
Prior gross charge-offs	282	256	397	420
Revolving Loans Amortized Cost Basis gross charge-offs	112	382	148	1,928
Total current-period gross charge-offs	5,066	1,377	5,849	5,068
Real Estate Portfolio Segment [Member] | Commercial Real Estate Owner Occupied [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Three years before current fiscal year gross charge-offs			17	15
Four years before current fiscal year gross charge-offs			6
Revolving Loans Amortized Cost Basis gross charge-offs	58		58
Total current-period gross charge-offs	58		81	15
Real Estate Portfolio Segment [Member] | Commercial Real Estate Non Owner Occupied [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Fiscal year before current fiscal year gross charge-offs	227		227	12
Three years before current fiscal year gross charge-offs	1	1	1	1
Four years before current fiscal year gross charge-offs				1
Total current-period gross charge-offs	228	1	228	14
Real Estate Portfolio Segment [Member] | Construction And Development Less Than Sixty Months [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Four years before current fiscal year gross charge-offs	3,741		3,744
Total current-period gross charge-offs	3,741		3,744
Real Estate Portfolio Segment [Member] | Construction Residential Real Estate Less Than Sixty Months [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Fiscal year before current fiscal year gross charge-offs			25	3
Total current-period gross charge-offs		0	25	3
Real Estate Portfolio Segment [Member] | Residential Real Estate First Lien [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year gross charge-offs		2		3
Fiscal year before current fiscal year gross charge-offs		23	6	23
Two years before current fiscal year gross charge-offs	1		3
Three years before current fiscal year gross charge-offs	1	2	2	3
Four years before current fiscal year gross charge-offs		4	5	4
Prior gross charge-offs	3	36	40	57
Total current-period gross charge-offs	5	67	56	90
Real Estate Portfolio Segment [Member] | Residential Real Estate All Other [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Prior gross charge-offs				2
Revolving Loans Amortized Cost Basis gross charge-offs	7		13	27
Total current-period gross charge-offs	7		13	29
Real Estate Portfolio Segment [Member] | Agriculture Member
Financing Receivable, Credit Quality Indicator [Line Items]
Fiscal year before current fiscal year gross charge-offs	1		10
Two years before current fiscal year gross charge-offs	2	6	2	37
Three years before current fiscal year gross charge-offs		13		13
Four years before current fiscal year gross charge-offs	4	0	5
Revolving Loans Amortized Cost Basis gross charge-offs			17
Total current-period gross charge-offs	7	19	34	50
Commercial Non Real Estate Member
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year gross charge-offs	5	6	24	6
Fiscal year before current fiscal year gross charge-offs	6	155	16	1,156
Two years before current fiscal year gross charge-offs	127	43	148	318
Three years before current fiscal year gross charge-offs	94	8	127	140
Four years before current fiscal year gross charge-offs	14	0	47	12
Prior gross charge-offs	238	190	310	316
Revolving Loans Amortized Cost Basis gross charge-offs	42	378	55	1,886
Total current-period gross charge-offs	526	780	727	3,834
Consumer Non Real Estate [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year gross charge-offs	25	21	25	21
Fiscal year before current fiscal year gross charge-offs	90	256	247	500
Two years before current fiscal year gross charge-offs	247	150	471	247
Three years before current fiscal year gross charge-offs	80	28	134	79
Four years before current fiscal year gross charge-offs	6	21	12	34
Prior gross charge-offs	41	30	47	45
Revolving Loans Amortized Cost Basis gross charge-offs	5	4	5	15
Total current-period gross charge-offs	$ 494	$ 510	$ 941	941
Oil and Gas [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Fiscal year before current fiscal year gross charge-offs				9
Two years before current fiscal year gross charge-offs				83
Total current-period gross charge-offs				$ 92