Repurchase Agreements and Other Borrowings (Details) (USD $) In Millions, unless otherwise specified	6 Months Ended
Jun. 30, 2013
Repurchase Agreements and Other Borrowings [Abstract]
Securities Sold under Agreements to Repurchase Increase (Decrease)	$ 18.8

The increase (decrease) in the carrying value as of the balance sheet date of securities that an institution sells and agrees to repurchase (the identical or substantially the same securities) as a seller-borrower at a specified date for a specified price, also known as a repurchase agreement, or repo. Most repos involve obligations of the federal government or its agencies, but other financial instruments, such as commercial paper, banker's acceptances, and negotiable certificates of deposit, are sometimes used in repos.

No definition available.

Name:	fmbh_SecuritiesSoldUnderAgreementsToRepurchaseIncreaseDecrease
Namespace Prefix:	fmbh_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration