XML 39 R28.htm IDEA: XBRL DOCUMENT
v3.21.2

Business Combination and Asset Purchase - Additional Information (Detail) |  |  |  | 3 Months Ended | 9 Months Ended | 12 Months Ended |
--- | --- | --- | --- | --- | --- | --- | ---
Apr. 30, 2021 USD ($) Office $ / shares shares | Nov. 16, 2020 USD ($) shares | Jan. 01, 2019 USD ($) Office $ / shares shares | Sep. 30, 2021 USD ($) Property shares | Sep. 30, 2021 USD ($) shares | Sep. 30, 2020 USD ($) | Dec. 31, 2020 USD ($) shares | Nov. 30, 2020 USD ($) Client
Business Acquisition [Line Items] |  |  |  |  |  |  |  |
Common stock, shares outstanding | shares |  |  |  | 12,230,000 | 12,230,000 |  | 12,230,000 |
Business combination, acquisition related costs |  |  |  | $ 1,200,000 | $ 2,100,000 |  | $ 42,500 |
Recognition of core deposit intangible asset with acquired purchase |  |  |  |  | $ 3,900,000 |  |  |
Remaining economic useful life |  |  |  |  | 7 years |  |  |
Goodwill |  |  |  | 55,214,000 | $ 55,214,000 |  | 47,340,000 |
Goodwill deductible for tax purpose, period | 15 years |  |  |  |  |  |  |
Fair value of assets acquired |  |  |  | 52,400,000 | 52,400,000 |  |  |
Gross principal and contractual interest |  |  |  | 58,600,000 | 58,600,000 |  |  |
Acquisition expected to be uncollectible |  |  |  | 1,100,000 | $ 1,100,000 |  |  |
Loan receivable weighted average life |  |  |  |  | 52 months |  |  |
Business combination, premises and equipment written down value |  |  |  |  | $ 596,000 |  |  |
Business combination, average remaining life |  |  |  |  | 39 years |  |  |
Fair value for certificate of deposit, valuation amount |  |  |  | $ 59,000 | $ 59,000 |  |  |
Fair value for certificate of deposit, amortization period |  |  |  |  | 1 year 4 months 24 days |  |  |
Number of agricultural purchased credit impaired loans paid off | Property |  |  |  | 2 |  |  |  |
Pro-forma operating revenue, net of tax |  |  |  |  | $ 348,000 |  |  |
Amortization expense |  |  |  |  | 478,000 | $ 546,000 |  |
Amortization expense for 2021 |  |  |  | $ 653,000 | 653,000 |  |  |
Custar [Member] |  |  |  |  |  |  |  |
Business Acquisition [Line Items] |  |  |  |  |  |  |  |
Amortization expense |  |  |  |  |  | $ 84,000 |  |
Building |  |  |  |  |  |  |  |
Business Acquisition [Line Items] |  |  |  |  |  |  |  |
Business combination, premises and equipment written down value |  |  |  |  | 244,000 |  |  |
Customer Lists [Member] |  |  |  |  |  |  |  |
Business Acquisition [Line Items] |  |  |  |  |  |  |  |
Amortization expense |  |  |  |  | 92,000 |  |  |
Amortization expense for 2021 |  |  |  | 123,000 | 123,000 |  |  |
Other General and Administrative Expenses [Member] |  |  |  |  |  |  |  |
Business Acquisition [Line Items] |  |  |  |  |  |  |  |
Business combination, acquisition related costs |  |  |  | 61,500 | 241,300 |  | 30,000.0 |
Consulting Fees [Member] |  |  |  |  |  |  |  |
Business Acquisition [Line Items] |  |  |  |  |  |  |  |
Business combination, acquisition related costs |  |  |  | 10,300 | 255,200 |  | $ 12,500 |
Employee Benefits [Member] |  |  |  |  |  |  |  |
Business Acquisition [Line Items] |  |  |  |  |  |  |  |
Business combination, acquisition related costs |  |  |  | 152,600 | 694,100 |  |  |
Data Processing Costs [Member] |  |  |  |  |  |  |  |
Business Acquisition [Line Items] |  |  |  |  |  |  |  |
Business combination, acquisition related costs |  |  |  | 938,900 | 938,900 |  |  |
ATM Expense [Member] |  |  |  |  |  |  |  |
Business Acquisition [Line Items] |  |  |  |  |  |  |  |
Business combination, acquisition related costs |  |  |  | 2,600 | 13,800 |  |  |
Ossian State Bank [Member] |  |  |  |  |  |  |  |
Business Acquisition [Line Items] |  |  |  |  |  |  |  |
Number of full-service offices | Office | 2 |  |  |  |  |  |  |
Ossian Financial Services, Inc. [Member] |  |  |  |  |  |  |  |
Business Acquisition [Line Items] |  |  |  |  |  |  |  |
Cash payment for exchange of each share | $ / shares | $ 67.71 |  |  |  |  |  |  |
Common stock, shares outstanding | shares | 295,388 |  |  |  |  |  |  |
Total consideration for acquisition | $ 20,001,000 |  |  |  |  |  |  |
Goodwill | 7,874,000 |  |  |  |  |  |  |
Cash paid for the capital stock | 20,001,000 |  |  |  | 20,001,000 |  |  |
Amortization expense for 2021 |  |  |  | 93,000 | 93,000 |  |  |
Ossian Financial Services, Inc. [Member] | Core Deposits [Member] |  |  |  |  |  |  |  |
Business Acquisition [Line Items] |  |  |  |  |  |  |  |
Recognition of core deposit intangible asset with acquired purchase | $ 980,200 |  |  |  |  |  |  |
Remaining economic useful life | 7 years |  |  |  |  |  |  |
Bank of Geneva [Member] |  |  |  |  |  |  |  |
Business Acquisition [Line Items] |  |  |  |  |  |  |  |
Number of full-service offices | Office |  |  | 6 |  |  |  |  |
Limberlost Bancshares, Inc. [Member] |  |  |  |  |  |  |  |
Business Acquisition [Line Items] |  |  |  |  |  |  |  |
Cash payment for exchange of each share | $ / shares |  |  | $ 8,465.00 |  |  |  |  |
Common stock, shares outstanding | shares |  |  | 1,000 |  |  |  |  |
Total consideration for acquisition |  |  | $ 78,900,000 |  |  |  |  |
Goodwill |  |  | $ 43,300,000 |  |  |  |  |
Common stock issued in exchange of each outstanding share | shares |  |  | 1,830,000 |  |  |  |  |
Share price | $ / shares |  |  | $ 38.49 |  |  |  |  |
Cash paid for the capital stock |  |  | $ 8,500,000 |  |  |  |  |
Stock issued for acquisition |  |  | 70,400,000 |  |  |  |  |
Limberlost Bancshares, Inc. [Member] | Core Deposits [Member] |  |  |  |  |  |  |  |
Business Acquisition [Line Items] |  |  |  |  |  |  |  |
Recognition of core deposit intangible asset with acquired purchase |  |  | $ 3,900,000 |  |  |  |  |
Remaining economic useful life |  |  | 7 years |  |  |  |  |
Adams County Financial Resources [Member] |  |  |  |  |  |  |  |
Business Acquisition [Line Items] |  |  |  |  |  |  |  |
Total consideration for acquisition |  | $ 825,000 |  |  |  |  |  |
Common stock issued in exchange of each outstanding share | shares |  | 40,049 |  |  |  |  |  |
Stock issued for acquisition |  | $ 825,000 |  |  |  |  |  |
Assets under management amount |  |  |  |  |  |  |  | $ 83,000,000
Number of clients assets under management | Client |  |  |  |  |  |  |  | 450
Increase to noninterest income |  | 500,000 |  |  |  |  |  |
Adams County Financial Resources [Member] | Customer Lists [Member] |  |  |  |  |  |  |  |
Business Acquisition [Line Items] |  |  |  |  |  |  |  |
Recognition of core deposit intangible asset with acquired purchase |  | $ 800,000 |  |  |  |  |  |
Remaining economic useful life |  | 6 years 6 months |  |  |  |  |  |
Amortization expense for 2021 |  |  |  | $ 123,000 | $ 123,000 |  |  |

X
- Definition Business combination average remaining useful life. + References No definition available. + Details
Name: | fmao_BusinessCombinationAverageRemainingUsefulLife
Namespace Prefix: | fmao_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- Definition Business combination identifiable assets in premises and equipment written down value. + References No definition available. + Details
Name: | fmao_BusinessCombinationIdentifiableAssetsInPremisesAndEquipmentWrittenDownValue
Namespace Prefix: | fmao_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Cash consideration payable on acquisition, per share. + References No definition available. + Details
Name: | fmao_CashConsiderationPayableOnAcquisitionPerShare
Namespace Prefix: | fmao_
Data Type: | dtr-types:perShareItemType
Balance Type: | na
Period Type: | instant

X
- Definition Fair value for certificate of deposit amortization period. + References No definition available. + Details
Name: | fmao_FairValueForCertificateOfDepositAmortizationPeriod
Namespace Prefix: | fmao_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- Definition Fair value for certificate of deposit valuation amount. + References No definition available. + Details
Name: | fmao_FairValueForCertificateOfDepositValuationAmount
Namespace Prefix: | fmao_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Goodwill deductible for tax purpose, period. + References No definition available. + Details
Name: | fmao_GoodwillDeductibleForTaxPurposePeriod
Namespace Prefix: | fmao_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- Definition Increase decrease to noninterest income. + References No definition available. + Details
Name: | fmao_IncreaseDecreaseToNoninterestIncome
Namespace Prefix: | fmao_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Loan receivable weighted average useful life. + References No definition available. + Details
Name: | fmao_LoanReceivableWeightedAverageUsefulLife
Namespace Prefix: | fmao_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- Definition Number of agricultural purchased credit impaired loans paid off. + References No definition available. + Details
Name: | fmao_NumberOfAgriculturalPurchasedCreditImpairedLoansPaidOff
Namespace Prefix: | fmao_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | duration

X
- Definition Number of clients assets under management. + References No definition available. + Details
Name: | fmao_NumberOfClientsAssetsUnderManagement
Namespace Prefix: | fmao_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | instant

X
- Definition Number of full service offices. + References No definition available. + Details
Name: | fmao_NumberOfFullServiceOffices
Namespace Prefix: | fmao_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | instant

X
- Definition The aggregate expense charged against earnings to allocate the cost of intangible assets (nonphysical assets not used in production) in a systematic and rational manner to the periods expected to benefit from such assets. As a noncash expense, this element is added back to net income when calculating cash provided by or used in operations using the indirect method. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 28 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=123570139&loc=d3e3602-108585 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 350 -SubTopic 30 -Section 50 -Paragraph 2 -Subparagraph (a)(2) -URI http://asc.fasb.org/extlink&oid=66006027&loc=d3e16323-109275 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 350 -SubTopic 30 -Section 45 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=6388964&loc=d3e16225-109274 + Details
Name: | us-gaap_AmortizationOfIntangibleAssets
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition The carrying amount of assets an investment adviser manages on behalf of investors. + References No definition available. + Details
Name: | us-gaap_AssetsUnderManagementCarryingAmount
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Number of shares of equity interests issued or issuable to acquire entity. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 805 -SubTopic 30 -Section 50 -Paragraph 1 -Subparagraph (b)(4) -URI http://asc.fasb.org/extlink&oid=120321790&loc=d3e6927-128479 + Details
Name: | us-gaap_BusinessAcquisitionEquityInterestsIssuedOrIssuableNumberOfSharesIssued
Namespace Prefix: | us-gaap_
Data Type: | xbrli:sharesItemType
Balance Type: | na
Period Type: | duration

X
- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. + References No definition available. + Details
Name: | us-gaap_BusinessAcquisitionLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Price of a single share of a number of saleable stocks paid or offered to be paid in a business combination. + References No definition available. + Details
Name: | us-gaap_BusinessAcquisitionSharePrice
Namespace Prefix: | us-gaap_
Data Type: | dtr-types:perShareItemType
Balance Type: | na
Period Type: | instant

X
- Definition Amount after tax of pro forma income from continuing operations as if the business combination had been completed at the beginning of a period. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 805 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (h)(2) -URI http://asc.fasb.org/extlink&oid=79982066&loc=d3e1392-128463 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 805 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (h)(3) -URI http://asc.fasb.org/extlink&oid=79982066&loc=d3e1392-128463 + Details
Name: | us-gaap_BusinessAcquisitionsProFormaIncomeLossFromContinuingOperationsBeforeChangesInAccountingAndExtraordinaryItemsNetOfTax
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition For receivables acquired in a business combination, excluding certain loans and debt securities acquired in a transfer (as defined), this element represents the best estimate at the acquisition date of the contractual cash flows not expected to be collected, by major class of receivable, such as loans, direct finance leases (as defined), and any other class of receivables. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 805 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (b)(3) -URI http://asc.fasb.org/extlink&oid=123413009&loc=d3e4845-128472 + Details
Name: | us-gaap_BusinessCombinationAcquiredReceivablesEstimatedUncollectible
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Fair value of acquired receivable from business combination, excluding certain loans and debt securities acquired in transfer. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 805 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (b)(1) -URI http://asc.fasb.org/extlink&oid=123413009&loc=d3e4845-128472 + Details
Name: | us-gaap_BusinessCombinationAcquiredReceivablesFairValue
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition For receivables acquired in a business combination, excluding certain loans and debt securities acquired in a transfer (as defined), this element represents the gross contractual amounts receivable, by major class of receivable, such as loans, direct finance leases (as defined), and any other class of receivables. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 805 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (b)(2) -URI http://asc.fasb.org/extlink&oid=123413009&loc=d3e4845-128472 + Details
Name: | us-gaap_BusinessCombinationAcquiredReceivablesGrossContractualAmount
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition This element represents acquisition-related costs incurred to effect a business combination which costs have been expensed during the period. Such costs include finder's fees; advisory, legal, accounting, valuation, and other professional or consulting fees; general administrative costs, including the costs of maintaining an internal acquisitions department; and may include costs of registering and issuing debt and equity securities. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 805 -SubTopic 10 -Section 25 -Paragraph 23 -URI http://asc.fasb.org/extlink&oid=123586518&loc=d3e1043-128460 + Details
Name: | us-gaap_BusinessCombinationAcquisitionRelatedCosts
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Amount of consideration transferred, consisting of acquisition-date fair value of assets transferred by the acquirer, liabilities incurred by the acquirer, and equity interest issued by the acquirer. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 805 -SubTopic 30 -Section 30 -Paragraph 8 -URI http://asc.fasb.org/extlink&oid=116859721&loc=d3e6613-128477 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 805 -SubTopic 30 -Section 50 -Paragraph 1 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=120321790&loc=d3e6927-128479 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 805 -SubTopic 30 -Section 30 -Paragraph 7 -URI http://asc.fasb.org/extlink&oid=116859721&loc=d3e6578-128477 + Details
Name: | us-gaap_BusinessCombinationConsiderationTransferred1
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Amount of equity interests of the acquirer, including instruments or interests issued or issuable in consideration for the business combination. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 805 -SubTopic 30 -Section 30 -Paragraph 8 -URI http://asc.fasb.org/extlink&oid=116859721&loc=d3e6613-128477 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 805 -SubTopic 30 -Section 30 -Paragraph 7 -URI http://asc.fasb.org/extlink&oid=116859721&loc=d3e6578-128477 + Details
Name: | us-gaap_BusinessCombinationConsiderationTransferredEquityInterestsIssuedAndIssuable
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Number of shares of common stock outstanding. Common stock represent the ownership interest in a corporation. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 505 -SubTopic 10 -Section 50 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=123467817&loc=d3e21463-112644 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02(29)) -URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682 + Details
Name: | us-gaap_CommonStockSharesOutstanding
Namespace Prefix: | us-gaap_
Data Type: | xbrli:sharesItemType
Balance Type: | na
Period Type: | instant

X
- Definition Amount of amortization for assets, excluding financial assets and goodwill, lacking physical substance with finite life expected to be recognized in remainder of current fiscal year. + References No definition available. + Details
Name: | us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseRemainderOfFiscalYear
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Remaining amortization period of finite-lived intangible assets, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 926 -SubTopic 20 -Section 50 -Paragraph 5 -URI http://asc.fasb.org/extlink&oid=120154696&loc=d3e54445-107959 + Details
Name: | us-gaap_FiniteLivedIntangibleAssetsRemainingAmortizationPeriod1
Namespace Prefix: | us-gaap_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- Definition Amount of increase in assets, excluding financial assets, lacking physical substance with a definite life, from an acquisition. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 350 -SubTopic 30 -Section 50 -Paragraph 1 -Subparagraph (a)(1) -URI http://asc.fasb.org/extlink&oid=66006027&loc=d3e16265-109275 + Details
Name: | us-gaap_FinitelivedIntangibleAssetsAcquired1
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Amount after accumulated impairment loss of an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-03(10)(1)) -URI http://asc.fasb.org/extlink&oid=120398452&loc=d3e534808-122878 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 350 -SubTopic 20 -Section 45 -Paragraph 5 -URI http://asc.fasb.org/extlink&oid=120320667&loc=SL49117168-202975 Reference 3: http://www.xbrl.org/2003/role/exampleRef -Publisher FASB -Name Accounting Standards Codification -Topic 852 -SubTopic 10 -Section 55 -Paragraph 10 -URI http://asc.fasb.org/extlink&oid=84165509&loc=d3e56426-112766 Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 350 -SubTopic 20 -Section 45 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=99380562&loc=d3e13770-109266 + Details
Name: | us-gaap_Goodwill
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition The cash outflow associated with the acquisition of business during the period. The cash portion only of the acquisition price. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 805 -SubTopic 30 -Section 50 -Paragraph 1 -Subparagraph (b)(1) -URI http://asc.fasb.org/extlink&oid=120321790&loc=d3e6927-128479 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 13 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=123570139&loc=d3e3213-108585 + Details
Name: | us-gaap_PaymentsToAcquireBusinessesGross
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Details
Name: | srt_StatementGeographicalAxis=fmao_CustarMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_PropertyPlantAndEquipmentByTypeAxis=us-gaap_BuildingMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis=us-gaap_CustomerListsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_IncomeStatementLocationAxis=us-gaap_GeneralAndAdministrativeExpenseMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_IncomeStatementLocationAxis=fmao_ConsultingFeesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_IncomeStatementLocationAxis=fmao_EmployeeBenefitsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_IncomeStatementLocationAxis=fmao_DataProcessingMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_IncomeStatementLocationAxis=fmao_ATMExpenseMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_BusinessAcquisitionAxis=fmao_OssianStateBankMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_BusinessAcquisitionAxis=fmao_OssianFinancialServicesIncorporatedMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis=us-gaap_CoreDepositsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_BusinessAcquisitionAxis=fmao_BankOfGenevaMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_BusinessAcquisitionAxis=fmao_LimberlostBancsharesIncMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_BusinessAcquisitionAxis=fmao_AdamsCountyFinancialResourcesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |