Restrictions on Cash and Dividends (Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2015	Dec. 31, 2014
Restrictions on Cash and Dividends [Abstract]
Average Balance On Deposit To Satisfy Reserve Requirements	$ 15.3	$ 5.9
Cash And Due Deposited With The Federal Reserve Bank	$ 0.3

Average Balance On Deposit To Satisfy Federal Reserve Requirements

No definition available.

Name:	fmer_AverageBalanceOnDepositToSatisfyFederalReserveRequirements
Namespace Prefix:	fmer_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration