Concentrations (Details) - Bank First Retirement Plan - USD ($)	Dec. 31, 2025	Dec. 31, 2024
Concentrations
Threshold Concentration percentage	10.00%	10.00%
Common Stock
Concentrations
Bank First Corporation	$ 22,368,772	$ 21,920,086

Fair value of investment held by employee stock purchase, saving, or similar plan (employee benefit plan (EBP)) as portion of net assets available for benefit representing concentration risk at or above applicable threshold.

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 275
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 18
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482861/275-10-50-18

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- Definition

Threshold percentage for investment applied to benchmark used for identifying concentration risk of employee stock purchase, saving, or similar plan (employee benefit plan (EBP)).

+ References

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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.

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