XML 66 R55.htm IDEA: XBRL DOCUMENT
v3.10.0.1

Recent Accounting Pronouncements - Additional Information (Detail) - USD ($) $ in Thousands | 1 Months Ended | 6 Months Ended
--- | --- | ---
Mar. 31, 2017 | Jun. 30, 2018
Summary Of Significant Accounting Policies [Line Items] |  |
Corporate income tax rate |  | 21.00%
Reclassification of tax effects from AOCI due to adoption of new Tax Cuts and Job Acts |  | $ 360
Accounting Standards Update 2017-08 [Member] |  |
Summary Of Significant Accounting Policies [Line Items] |  |
Accelerated amortization expense adjustment | $ 30 |

X
- Definition Summary Of Significant Accounting Policies [Line Items] + References No definition available. + Details
Name: | fmao_SummaryOfSignificantAccountingPoliciesLineItems
Namespace Prefix: | fmao_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Tax Cuts and Jobs Act of 2017, reclassification from AOCI to retained earnings. + References No definition available. + Details
Name: | fmao_TaxCutsAndJobsActOf2017ReclassificationFromAociToRetainedEarnings
Namespace Prefix: | fmao_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition The aggregate amount of recurring noncash expense charged against earnings in the period to allocate the cost of assets over their estimated remaining economic lives. + References Reference 1: 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 2: 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=109223946&loc=d3e3602-108585 + Details
Name: | us-gaap_AdjustmentForAmortization
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Percentage of domestic federal statutory tax rate applicable to pretax income (loss). + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SAB TOPIC 6.I) -URI http://asc.fasb.org/extlink&oid=34349781&loc=d3e330036-122817 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 50 -Paragraph 12 -URI http://asc.fasb.org/extlink&oid=84230637&loc=d3e32687-109319 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 50 -Paragraph 13 -URI http://asc.fasb.org/extlink&oid=84230637&loc=d3e32698-109319 + Details
Name: | us-gaap_EffectiveIncomeTaxRateReconciliationAtFederalStatutoryIncomeTaxRate
Namespace Prefix: | us-gaap_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | us-gaap_AdjustmentsForNewAccountingPronouncementsAxis=us-gaap_AccountingStandardsUpdate201708Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |