v2.4.0.6

Summary of Significant Accounting Policies Summary of Significant Accounting Policies 1 (Details) | 12 Months Ended
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Dec. 31, 2012 | Dec. 31, 2011 | Dec. 31, 2010
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |
Maximum number of shares to be issued in stock incentive plan (in shares) | 300,000 |  |
Options, Grants in Period, Gross | 0 | 0 | 0
Stock Options [Member] |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |
Options, Grants in Period, Gross | 59,500 |  |
Stock Unit Awards and Stock Awards [Member] |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |
Options, Grants in Period, Gross | 15,162 | 17,409 |
Stock Awards [Member] |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |
Percentage of Awards Issued | 50.00% |  |
Stock Unit Awards [Member] |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |
Percentage of Awards Issued | 50.00% |  |

X
- Definition Represents the percentage of stock award types issued during the period. + References No definition available. + Details
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Namespace Prefix: | fmbh_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

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

X
- Definition The maximum number of shares (or other type of equity) originally approved (usually by shareholders and board of directors), net of any subsequent amendments and adjustments, for awards under the equity-based compensation plan. As stock or unit options and equity instruments other than options are awarded to participants, the shares or units remain authorized and become reserved for issuance under outstanding awards (not necessarily vested). + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 123R -Paragraph A240 -Subparagraph a -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy. Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (a)(3) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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Data Type: | xbrli:sharesItemType
Balance Type: | na
Period Type: | instant

X
- Definition Gross number of share options (or share units) granted during the period. + References No definition available. + Details
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Namespace Prefix: | us-gaap_
Data Type: | xbrli:sharesItemType
Balance Type: | na
Period Type: | duration