XML 47 R40.htm IDEA: XBRL DOCUMENT
v3.24.3

Investment Securities - Realized Gains and Losses From Sale of Securities (Details) - USD ($) $ in Thousands | 3 Months Ended | 9 Months Ended
--- | --- | ---
Sep. 30, 2024 | Sep. 30, 2023 | Sep. 30, 2024 | Sep. 30, 2023
Realized Investment Gains (Losses) [Abstract] |  |  |  |
Gross gains | $ 11 | $ 3,823 | $ 46 | $ 3,829
Gross losses | $ (288) | $ (434) | $ (479) | $ (492)

X
- Definition Debt and equity securities available for sale realized gain. + References No definition available. + Details
Name: | fmbh_DebtAndEquitySecuritiesAvailableForSaleRealizedGain
Namespace Prefix: | fmbh_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Debt and equity securities available for sale realized loss. + References No definition available. + Details
Name: | fmbh_DebtAndEquitySecuritiesAvailableForSaleRealizedLoss
Namespace Prefix: | fmbh_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- References No definition available. + Details
Name: | us-gaap_RealizedInvestmentGainsLossesAbstract
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration