Fair Value of Financial Instruments - Estimated Fair Values and Related Carrying or Notional Amounts (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Financial Assets:
Cash and Cash Equivalents	$ 24,295	$ 19,263
Securities - available for sale	248,492us-gaap_AvailableForSaleSecurities	324,509us-gaap_AvailableForSaleSecurities
Other Securities	3,717fmb_OtherSecurities	4,216fmb_OtherSecurities
Financial Liabilities:
Non-interest bearing Deposits	164,009	110,452
Time Deposits	195,500us-gaap_TimeDeposits	236,360us-gaap_TimeDeposits
Total deposits	762,560us-gaap_Deposits	776,464us-gaap_Deposits
Federal Funds purchased and Securities sold under agreement to repurchase	55,962	69,756
Federal Home Loan Bank advances	0	4,500
Dividends payable	965	967
Carrying Amount [Member]
Financial Assets:
Cash and Cash Equivalents	24,295	19,263
Securities - available for sale	248,492	324,509
Other Securities	3,717	4,216
Loans, net	616,021	570,919
Interest receivable	3,578	3,694
Total Assets	896,103	922,601
Financial Liabilities:
Interest bearing Deposits	403,051	429,652
Non-interest bearing Deposits	164,009	110,452
Time Deposits	195,500	236,360
Total deposits	762,560	776,464
Federal Funds purchased and Securities sold under agreement to repurchase	55,962	69,756
Federal Home Loan Bank advances		4,500
Interest payable	207	223
Dividends payable	965	967
Total Liabilities	819,694	851,910
Fair Value [Member]
Financial Assets:
Cash and Cash Equivalents	24,295	19,263
Securities - available for sale	248,492	324,509
Other Securities	3,717	4,216
Loans, net	625,377	579,992
Interest receivable	3,578	3,694
Total Assets	905,459	931,674
Financial Liabilities:
Interest bearing Deposits	403,801	429,750
Non-interest bearing Deposits	164,009	110,452
Time Deposits	196,545	236,027
Total deposits	764,355	776,229
Federal Funds purchased and Securities sold under agreement to repurchase	55,962	69,756
Federal Home Loan Bank advances		4,570
Interest payable	207	223
Dividends payable	965	967
Total Liabilities	821,489	851,745
Level 1 [Member]
Financial Assets:
Cash and Cash Equivalents	24,295	19,263
Securities - available for sale	25,393	25,272
Other Securities
Loans, net
Interest receivable
Total Assets	49,688	44,535
Financial Liabilities:
Interest bearing Deposits
Non-interest bearing Deposits
Time Deposits
Total deposits
Federal Funds purchased and Securities sold under agreement to repurchase
Federal Home Loan Bank advances
Interest payable
Dividends payable
Total Liabilities
Level 2 [Member]
Financial Assets:
Cash and Cash Equivalents
Securities - available for sale	215,168	288,891
Other Securities
Loans, net
Interest receivable
Total Assets	215,168	288,891
Financial Liabilities:
Interest bearing Deposits
Non-interest bearing Deposits	164,009	110,452
Time Deposits
Total deposits	164,009	110,452
Federal Funds purchased and Securities sold under agreement to repurchase
Federal Home Loan Bank advances
Interest payable
Dividends payable	965	967
Total Liabilities	164,974	111,419
Level 3 [Member]
Financial Assets:
Cash and Cash Equivalents
Securities - available for sale	7,931	10,346
Other Securities	3,717	4,216
Loans, net	625,377	579,992
Interest receivable	3,578	3,694
Total Assets	640,603	598,248
Financial Liabilities:
Interest bearing Deposits	403,801	429,750
Non-interest bearing Deposits
Time Deposits	196,545	236,027
Total deposits	600,346	665,777
Federal Funds purchased and Securities sold under agreement to repurchase	55,962	69,756
Federal Home Loan Bank advances		4,570
Interest payable	207	223
Dividends payable
Total Liabilities	$ 656,515	$ 740,326

Accrued interest payable.

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Accrued interest receivable.

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Other Securities consists of Federal Home Loan Bank of Cincinnati and Indianapolis stock and Farmer Mac stock. These stocks are carried at cost and are held to enable the Bank to conduct business with the entities. The Federal Home Loan Banks sell and purchase their stock at par; therefore cost approximates market value. The Federal Home Loan Bank of Cincinnati stock is held as collateral security for all indebtedness of the Bank to the Federal Home Loan Bank.

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Amount of borrowings as of the balance sheet date from the Federal Home Loan Bank, which are primarily used to cover shortages in the required reserve balance and liquidity shortages.

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-Publisher FASB

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Fair value portion of probable future economic benefits obtained or controlled by an entity as a result of past transactions or events.

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Amount of investment in debt and equity securities categorized neither as held-to-maturity nor trading.

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-Name Accounting Standards Codification

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The sum of cash and cash equivalents plus Federal Funds Sold. Cash and cash equivalents consist of short term, highly liquid investments that are readily convertible to known amounts of cash and are so near their maturity that they present negligible risk of changes in value due to changes in interest rates -- usually with an original maturity less than 90 days.

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-Glossary Cash Equivalents

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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.

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Carrying value as of the balance sheet date of dividends declared but unpaid on equity securities issued by the entity and outstanding.

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Amount after offset of short term borrowing where a bank borrows, at the federal funds rate, from another bank and securities that an entity sells and agrees to repurchase at a specified date for a specified price.

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The aggregate of all domestic and foreign interest-bearing deposit liabilities.

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Fair value of financial and nonfinancial obligations.

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Amount after allowance and deduction of deferred interest and fees, unamortized costs and premiums and discounts from face amounts, of loans and leases held in portfolio, including but not limited to, commercial and consumer loans. Includes loans held for sale. Excludes loans and leases covered under loss sharing agreements.

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

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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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