v2.4.0.6

Leases Lease Terms Details (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Operating Leased Assets [Line Items]
Operating Leases, Rent Expense, Net	$ 1,293	$ 1,331	$ 884
Minimum [Member]
Operating Leased Assets [Line Items]
Term of Lease	one year
Renewal Term of Lease	one year
Maximum [Member]
Operating Leased Assets [Line Items]
Term of Lease	fifteen years
Renewal Term of Lease	five years

X

- Definition

Number of years in Renewal Term of Lease

+ References

No definition available.

+ Details

Name:	fmbh_RenewalTermOfLease
Namespace Prefix:	fmbh_
Data Type:	us-types:durationStringItemType
Balance Type:	na
Period Type:	duration

X

- Definition

Length of Term of Lease

+ References

No definition available.

+ Details

Name:	fmbh_TermOfLease
Namespace Prefix:	fmbh_
Data Type:	us-types:durationStringItemType
Balance Type:	na
Period Type:	duration

X

- Details

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

X

- Definition

Rental expense for the reporting period incurred under operating leases, including minimum and any contingent rent expense, net of related sublease income.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 840

-SubTopic 20

-Section 50

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=6453985&loc=d3e41499-112717

+ Details

Name:	us-gaap_OperatingLeasesRentExpenseNet
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration