XML 70 R63.htm IDEA: XBRL DOCUMENT
v3.24.1.u1

Earnings Per Share - Additional Information (Detail) |  |  |  | 3 Months Ended
--- | --- | --- | --- | ---
Mar. 01, 2024 USD ($) shares | Jun. 02, 2023 USD ($) Director shares | Mar. 01, 2023 USD ($) shares | Sep. 30, 2023 USD ($) shares
Earnings Per Share [Line Items] |  |  |  |
Number of directors received shares | shares |  | 754 |  |
Number of directors received shares | Director |  | 12 |  |
Compensation annual basis committee award | $ |  | $ 14,997 |  |
Senior Management |  |  |  |
Earnings Per Share [Line Items] |  |  |  |
Restricted stock awards, Shares | shares | 23,369 |  | 21,700 |
Restricted stock awards | $ | $ 472,054,000 |  | $ 562,030,000 |
Other Members of Management |  |  |  |
Earnings Per Share [Line Items] |  |  |  |
Restricted stock awards, Shares | shares |  |  |  | 41,225
Restricted stock awards | $ |  |  |  | $ 844,018,000

X
- Definition Compensation annual basis committee award. + References No definition available. + Details
Name: | fmao_CompensationAnnualBasisCommitteeAward
Namespace Prefix: | fmao_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Earnings per share. + References No definition available. + Details
Name: | fmao_EarningsPerShareLineItems
Namespace Prefix: | fmao_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Number of director received shares. + References No definition available. + Details
Name: | fmao_NumberOfDirectorReceivedShares
Namespace Prefix: | fmao_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | duration

X
- Definition Number of directors received shares. + References No definition available. + Details
Name: | fmao_NumberOfDirectorsReceivedShares
Namespace Prefix: | fmao_
Data Type: | xbrli:sharesItemType
Balance Type: | na
Period Type: | instant

X
- Definition Number of shares issued during the period related to Restricted Stock Awards, net of any shares forfeited. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Name Accounting Standards Codification -Section 50 -Paragraph 2 -SubTopic 10 -Topic 505 -Publisher FASB -URI https://asc.fasb.org//1943274/2147481112/505-10-50-2 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Topic 210 -SubTopic 10 -Name Accounting Standards Codification -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02(28)) -Publisher FASB -URI https://asc.fasb.org//1943274/2147480566/210-10-S99-1 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Topic 505 -SubTopic 10 -Name Accounting Standards Codification -Section S99 -Paragraph 1 -Subparagraph (SX 210.3-04) -Publisher FASB -URI https://asc.fasb.org//1943274/2147480008/505-10-S99-1 Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef -Topic 210 -SubTopic 10 -Name Accounting Standards Codification -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02(29)) -Publisher FASB -URI https://asc.fasb.org//1943274/2147480566/210-10-S99-1 + Details
Name: | us-gaap_StockIssuedDuringPeriodSharesRestrictedStockAwardNetOfForfeitures
Namespace Prefix: | us-gaap_
Data Type: | xbrli:sharesItemType
Balance Type: | na
Period Type: | duration

X
- Definition Value of stock related to Restricted Stock Awards issued during the period, net of the stock value of such awards forfeited. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Name Accounting Standards Codification -Section 50 -Paragraph 2 -SubTopic 10 -Topic 505 -Publisher FASB -URI https://asc.fasb.org//1943274/2147481112/505-10-50-2 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Topic 505 -SubTopic 10 -Name Accounting Standards Codification -Section S99 -Paragraph 1 -Subparagraph (SX 210.3-04) -Publisher FASB -URI https://asc.fasb.org//1943274/2147480008/505-10-S99-1 + Details
Name: | us-gaap_StockIssuedDuringPeriodValueRestrictedStockAwardNetOfForfeitures
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Details
Name: | srt_TitleOfIndividualAxis=fmao_SeniorManagementMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_TitleOfIndividualAxis=fmao_OtherManagementMembersMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |