Deposits (Details) (USD $)	Dec. 31, 2014	Dec. 31, 2013
Deposits [Abstract]
Number of public entities with large balances	5
Total of Public entitiy balances	$ 46,700,000fmbh_TotalOfPublicEntitiyBalances
Maturities of Time Deposits [Abstract]
Less than 1 year	152,490,000us-gaap_TimeDepositMaturitiesYearOne
1 year to 2 years	33,173,000us-gaap_TimeDepositMaturitiesYearTwo
2 years to 3 years	13,962,000us-gaap_TimeDepositMaturitiesYearThree
3 years to 4 years	10,812,000us-gaap_TimeDepositMaturitiesYearFour
4 years to 5 years	7,694,000us-gaap_TimeDepositMaturitiesYearFive
Over 5 years	146,000
Total	218,277,000us-gaap_TimeDeposits
Deposits, by Type [Abstract]
Noninterest-bearing Deposit Liabilities	222,116,000	235,448,000
Interest-bearing Domestic Deposit, Demand	306,631,000	291,035,000
Interest-bearing Domestic Deposit, Savings	273,958,000	279,227,000
Interest-bearing Domestic Deposit, Money Market	251,095,000	253,255,000
Interest-bearing Domestic Deposit, Time Deposits	218,277,000	228,651,000
Total deposits	$ 1,272,077,000us-gaap_Deposits	$ 1,287,616,000us-gaap_Deposits

Number of public entities with large balances

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- Definition

Total balance of Public entities with large balances

+ References

No definition available.

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- Definition

The aggregate of all deposit liabilities held by the entity, including foreign and domestic, interest and noninterest bearing; may include demand deposits, saving deposits, Negotiable Order of Withdrawal (NOW) and time deposits among others.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 942

-SubTopic 210

-Section S99

-Paragraph 1

-Subparagraph (SX 210.9-03.12)

-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 03

-Paragraph 12

-Article 9

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- Definition

Amount of money in interest-bearing domestic accounts that entitle the depositor to withdraw funds at any time without prior notice, also known as demand deposits.

+ References

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- Definition

Amount of interest-bearing domestic money market demand account deposit liabilities.

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- Definition

Amount of interest-bearing domestic savings deposit liabilities. Saving deposits bear interest and have no stated maturity.

+ References

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- Definition

Amount of interest-bearing domestic time deposits. Time deposits bear interest for a fixed, stated period of time and include certificate of deposits and individual retirement accounts.

+ References

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- Definition

The aggregate amount of all domestic and foreign noninterest-bearing deposits liabilities held by the entity.

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- Definition

Amount of time deposits maturing after the fifth fiscal year following the latest fiscal year. Time deposits include, but are not limited to, certificates of deposits. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 470

-SubTopic 10

-Section 50

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=6802200&loc=d3e1835-112601

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Amount of time deposits maturing in the fifth fiscal year following the latest fiscal year. Time deposits include, but are not limited to, certificates of deposits. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

+ References

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Amount of time deposits maturing in the fourth fiscal year following the latest fiscal year. Time deposits include, but are not limited to, certificates of deposits. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

+ References

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- Definition

Amount of time deposits maturing in the next fiscal year following the latest fiscal year. Time deposits include, but are not limited to, certificates of deposits. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

+ References

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- Definition

Amount of time deposits maturing in the third fiscal year following the latest fiscal year. Time deposits include, but are not limited to, certificates of deposits. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

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Amount of time deposits maturing in the second fiscal year following the latest fiscal year. Time deposits include, but are not limited to, certificates of deposits. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

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Amount of deposits that cannot be withdrawn before a set date without penalty or for which notice of withdrawal is required. Time deposits include, but are not limited to, certificates of deposits, individual retirement accounts and open accounts.

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