XML 42 R31.htm IDEA: XBRL DOCUMENT v3.7.0.1

Loans - Additional Information (Detail) - USD ($) $ in Millions	Mar. 31, 2017	Dec. 31, 2016
Receivables [Abstract]
Residential mortgage loan	$ 17.8	$ 17.9

X

- Definition

Residential mortgage loan.

+ References

No definition available.

+ Details

Name:	fmao_ResidentialMortgageLoan
Namespace Prefix:	fmao_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

X

- References

No definition available.

+ Details

Name:	us-gaap_ReceivablesAbstract
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration