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
Mar. 31, 2025	Mar. 31, 2024
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year gross charge-offs	$ 19	$ 1
Fiscal year before current fiscal year gross charge-offs	207	1,269
Two years before current fiscal year gross charge-offs	247	486
Three years before current fiscal year gross charge-offs	105	199
Four years before current fiscal year gross charge-offs	54	26
Prior gross charge-offs	115	164
Revolving Loans Amortized Cost Basis gross charge-offs	36	1,546
Total current-period gross charge-offs	783	3,691
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
Total current-period gross charge-offs	23	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		12
Four years before current fiscal year gross charge-offs		1
Total current-period gross charge-offs		13
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
Total current-period gross charge-offs	3
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	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		1
Fiscal year before current fiscal year gross charge-offs	6
Two years before current fiscal year gross charge-offs	2
Three years before current fiscal year gross charge-offs	1	1
Four years before current fiscal year gross charge-offs	5
Prior gross charge-offs	37	21
Total current-period gross charge-offs	51	23
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	6	27
Total current-period gross charge-offs	6	29
Real Estate Portfolio Segment [Member] \| Agriculture 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		31
Four years before current fiscal year gross charge-offs	1
Revolving Loans Amortized Cost Basis gross charge-offs	17
Total current-period gross charge-offs	27	31
Commercial Non Real Estate Member
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year gross charge-offs	19
Fiscal year before current fiscal year gross charge-offs	10	1,001
Two years before current fiscal year gross charge-offs	21	275
Three years before current fiscal year gross charge-offs	33	132
Four years before current fiscal year gross charge-offs	33	12
Prior gross charge-offs	72	126
Revolving Loans Amortized Cost Basis gross charge-offs	13	1,508
Total current-period gross charge-offs	201	3,054
Consumer Non Real Estate [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Fiscal year before current fiscal year gross charge-offs	157	244
Two years before current fiscal year gross charge-offs	224	97
Three years before current fiscal year gross charge-offs	54	51
Four years before current fiscal year gross charge-offs	6	13
Prior gross charge-offs	6	15
Revolving Loans Amortized Cost Basis gross charge-offs		11
Total current-period gross charge-offs	$ 447	431
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

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Financing receivable originated in current fiscal year write-offs.

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Financing receivable originated in fiscal year before latest fiscal year write-offs.

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Financing receivable originated in five or more years before latest fiscal year write-offs.

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Financing receivable originated in four years before latest fiscal year write-offs.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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