Commitments and Contingencies -Narrative (Details) $ in Thousands	3 Months Ended
Mar. 31, 2024 USD ($) item	Mar. 31, 2023 USD ($)	Dec. 31, 2023 USD ($) item
Financial Instruments with Off-Balance Sheet Risk
Provision (recovery) for off-balance sheet credit loss	$ (793)	$ 230
Unfunded commitments
Financial Instruments with Off-Balance Sheet Risk
Allowance for credit loss	6,600		$ 7,400
Provision (recovery) for off-balance sheet credit loss	$ (794)	$ 230
Letter of credit with FHLB
Financial Instruments with Off-Balance Sheet Risk
Number of letter of credit outstanding \| item	0		0
Letter of credit with Bank of North Dakota
Financial Instruments with Off-Balance Sheet Risk
Outstanding letters of credit	$ 200,000		$ 182,000
Collateralized loans	$ 460,900		$ 454,600

Number of letter of credit outstanding.

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- Definition

Amount of assets pledged to secure a debt instrument.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Topic 942
-SubTopic 470
-Section 50
-Paragraph 3
-Subparagraph (d)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480848/942-470-50-3

+ Details

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- Definition

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.

+ References

No definition available.

+ Details

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- Definition

The total amount of the contingent obligation under letters of credit outstanding as of the reporting date.

+ References

No definition available.

+ Details

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- Definition

Amount of expected credit loss for credit exposure on off-balance-sheet commitment, including but not limited to, loan commitment, standby letter of credit, financial guarantee not accounted for as insurance. Excludes off-balance sheet credit exposure accounted for as insurance and instrument accounted for under derivatives and hedging.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 45
-Paragraph 2
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479344/326-20-45-2

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 460
-SubTopic 10
-Name Accounting Standards Codification
-Section 45
-Paragraph 1
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482454/460-10-45-1

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- Definition

Amount of expense (reversal of expense) for expected credit loss for off-balance sheet credit exposure. Excludes off-balance sheet credit exposure accounted for as insurance and instrument accounted for under derivatives and hedging.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 13
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479319/326-20-50-13

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