v2.4.0.6

Commitments and Contingent Liabilities (Details) (USD $) In Thousands, unless otherwise specified | 12 Months Ended |
--- | --- | ---
Dec. 31, 2012 | Dec. 31, 2011
Commitments to Extend Credit [Member] |  |
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items] |  |
Commercial real estate | $ 27,800 | $ 33,970
Commercial operating | 132,040 | 119,102
Home equity | 25,255 | 24,804
Other | 46,430 | 44,433
Fair Value Disclosure, Off-balance Sheet Risks, Face Amount, Asset | 231,525 | 222,309
Number of expected days to fund commitments | ninety days |
Financial Standby Letter of Credit [Member] |  |
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items] |  |
Fair Value Disclosure, Off-balance Sheet Risks, Face Amount, Asset | $ 3,351 | $ 6,267
Period when letters of credit expire | one year or less |

X
- Definition The face amount of Commercial Operating financial assets, which are not recognized in the financial statements (off-balance sheet) because they fail to meet some other criterion for recognition. + References No definition available. + Details
Name: | fmbh_FairValueDisclosureOffBalanceSheetRisksFaceAmountAssetCommercialOperating
Namespace Prefix: | fmbh_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition The face amount of Commercial Real Estate financial assets, which are not recognized in the financial statements (off-balance sheet) because they fail to meet some other criterion for recognition. + References No definition available. + Details
Name: | fmbh_FairValueDisclosureOffBalanceSheetRisksFaceAmountAssetCommercialRe
Namespace Prefix: | fmbh_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition The face amount of Home Equity financial assets, which are not recognized in the financial statements (off-balance sheet) because they fail to meet some other criterion for recognition. + References No definition available. + Details
Name: | fmbh_FairValueDisclosureOffBalanceSheetRisksFaceAmountAssetHomeEquity
Namespace Prefix: | fmbh_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition The face amount of Other financial assets, which are not recognized in the financial statements (off-balance sheet) because they fail to meet some other criterion for recognition. + References No definition available. + Details
Name: | fmbh_FairValueDisclosureOffBalanceSheetRisksFaceAmountAssetOther
Namespace Prefix: | fmbh_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Number of expected days until commitments to originate credit are funded. + References No definition available. + Details
Name: | fmbh_NumberOfExpectedDaysToFundCommitments
Namespace Prefix: | fmbh_
Data Type: | us-types:durationStringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Period after which standby letters of credit generally expire + References No definition available. + Details
Name: | fmbh_PeriodWhenLettersOfCreditExpire
Namespace Prefix: | fmbh_
Data Type: | us-types:durationStringItemType
Balance Type: | na
Period Type: | duration

X
- Definition The face amount of financial assets, which are not recognized in the financial statements (off-balance sheet) because they fail to meet some other criterion for recognition. + References No definition available. + Details
Name: | us-gaap_FairValueDisclosureOffbalanceSheetRisksFaceAmountAsset
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Details
Name: | us-gaap_FairValueOffBalanceSheetRisksDisclosureInformationLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration