Financial Instruments with Off Balance Sheet Risk - Narrative (Details) - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2023	Dec. 31, 2022
Financial Instruments with Off Balance Sheet Risk
Provision for off-balance sheet credit loss	$ 230
Unfunded commitments
Financial Instruments with Off Balance Sheet Risk
Allowance for credit loss	5,200	$ 3,244
Provision for off-balance sheet credit loss	230
Unfunded commitments \| Adoption of CECL
Financial Instruments with Off Balance Sheet Risk
Allowance for credit loss		1,900
Letter of credit with FHLB
Financial Instruments with Off Balance Sheet Risk
Outstanding letters of credit	0	0
Letter of credit with Bank of North Dakota
Financial Instruments with Off Balance Sheet Risk
Outstanding letters of credit	70,000	0
Collateralized loans	$ 223,200	$ 215,500

Amount of assets pledged to secure a debt instrument.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 470
-Section 50
-Paragraph 3
-Subparagraph (d)
-URI https://asc.fasb.org/extlink&oid=123599511&loc=d3e64711-112823

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+ References

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

+ References

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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
-Publisher FASB
-Name Accounting Standards Codification
-Topic 460
-SubTopic 10
-Section 45
-Paragraph 1
-URI https://asc.fasb.org/extlink&oid=121611286&loc=d3e11927-110247

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 20
-Section 45
-Paragraph 2
-URI https://asc.fasb.org/extlink&oid=124255206&loc=SL82919202-210446

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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
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 20
-Section 50
-Paragraph 13
-Subparagraph (b)
-URI https://asc.fasb.org/extlink&oid=124255953&loc=SL82919249-210447

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