CertainLoansAcquiredInTransferNotAccountedForAsDebtSecuritiesCarryingAmountAccretion.

No definition available.

Name:	fmer_CertainLoansAcquiredInTransferNotAccountedForAsDebtSecuritiesCarryingAmountAccretion
Namespace Prefix:	fmer_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Certain Loans Acquired In Transfer Not Accounted For As Debt Securities FDIC Payments Received Under Loss Sharing Agreement.

+ References

No definition available.

+ Details

Name:	fmer_CertainLoansAcquiredInTransferNotAccountedForAsDebtSecuritiesFDICPaymentsReceivedUnderLossSharingAgreement
Namespace Prefix:	fmer_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Details

Name:	fmer_ChangesintheCarryingAmountofAccretableYieldforAcquiredImpairedLoansLineItems
Namespace Prefix:	fmer_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of the excess of a loan's cash flows expected to be collected over the investor's initial investment in acquired loans not accounted for as debt securities with evidence of deterioration of credit quality.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 310

-SubTopic 30

-Section 15

-Paragraph 2

-URI http://asc.fasb.org/extlink&oid=27045933&loc=d3e13503-111538

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 310

-SubTopic 30

-Section 50

-Paragraph 2

-Subparagraph (a)(2)

-URI http://asc.fasb.org/extlink&oid=6379141&loc=d3e15032-111544

+ Details

Name:	us-gaap_CertainLoansAcquiredInTransferNotAccountedForAsDebtSecuritiesAccretableYield
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount of decrease from accretion of the excess of a loan's cash flows expected to be collected over the investor's initial investment in acquired loans not accounted for as debt securities with evidence of deterioration of credit quality.

+ References

+ Details

Name:	us-gaap_CertainLoansAcquiredInTransferNotAccountedForAsDebtSecuritiesAccretableYieldAccretion
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Amount of reduction, resulting from a sale or transfer of a loan, in the excess of a loan's cash flows expected to be collected over the investor's initial investment in acquired loans not accounted for as debt securities with evidence of deterioration of credit quality.

+ References

+ Details

Name:	us-gaap_CertainLoansAcquiredInTransferNotAccountedForAsDebtSecuritiesAccretableYieldDisposalsOfLoans
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Amount of increase of reclassification from nonaccretable difference to the excess of a loan's cash flows expected to be collected over the investor's initial investment in acquired loans not accounted for as debt securities with evidence of deterioration of credit quality.

+ References

+ Details

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

- Definition

The recorded balance, net of any applicable reductions (for example, unamortized accretable yield and allowance for loan losses). This relates to loans not accounted for debt securities with evidence of deterioration of credit quality since origination that were acquired by completion of a transfer for which it is probable, at acquisition, that the investor will be unable to collect all contractually required payments receivable.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 310

-SubTopic 30

-Section 15

-Paragraph 2

-URI http://asc.fasb.org/extlink&oid=27045933&loc=d3e13503-111538

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 310

-SubTopic 30

-Section 50

-Paragraph 2

-Subparagraph (a)(1)

-URI http://asc.fasb.org/extlink&oid=6379141&loc=d3e15032-111544

+ Details

Name:	us-gaap_CertainLoansAcquiredInTransferNotAccountedForAsDebtSecuritiesCarryingAmountNet
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

The undiscounted sum of all amounts, including amounts deemed principal, interest, fees, penalties, and other under the loan, owed to the investor at the reporting date, whether or not currently due and whether or not any such amounts have been written or charged off by the investor. This relates to loans not accounted for as debt securities, with evidence of deterioration of credit quality since origination that were acquired by completion of a transfer for which it is probable, at acquisition, that the investor will be unable to collect all contractually required payments receivable.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 310

-SubTopic 30

-Section 15

-Paragraph 2

-URI http://asc.fasb.org/extlink&oid=27045933&loc=d3e13503-111538

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 310

-SubTopic 30

-Section 50

-Paragraph 2

-Subparagraph (a)(1)

-URI http://asc.fasb.org/extlink&oid=6379141&loc=d3e15032-111544

+ Details

Name:	us-gaap_CertainLoansAcquiredInTransferNotAccountedForAsDebtSecuritiesOutstandingBalance
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

Loans acquired impaired loans accretable yield and carrying amount (Details) (USD $)			3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014 Acquired Impaired Loans	Sep. 30, 2013 Acquired Impaired Loans	Sep. 30, 2014 Acquired Impaired Loans	Sep. 30, 2013 Acquired Impaired Loans	Jun. 30, 2014 Acquired Impaired Loans	Dec. 31, 2013 Acquired Impaired Loans	Jun. 30, 2013 Acquired Impaired Loans	Dec. 31, 2012 Acquired Impaired Loans	Sep. 30, 2014 Citizens Republic Bancorp Acquired Impaired Loans	Sep. 30, 2013 Citizens Republic Bancorp Acquired Impaired Loans	Apr. 12, 2013 Citizens Republic Bancorp Acquired Impaired Loans
Changes in the Carrying Amount of Accretable Yield for Acquired Impaired Loans [Line Items]
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Outstanding Balance	$ 659,700,000	$ 902,900,000
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Accretable Yield			126,424,000	106,607,000	126,424,000	106,607,000	137,442,000	136,646,000	120,067,000	0	0	0	131,558,000
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Carrying Amount, Net			479,050,000	670,867,000	479,050,000	670,867,000	519,250,000	601,000,000	752,682,000	0	0	0	819,715,000
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Accretable Yield, Accretion			(12,950,000)	(8,914,000)	(37,437,000)	(18,004,000)
Certain Loans Acquired in Transfer not Accounted for as Debt Securities Carrying Amount Accretion			12,950,000	8,914,000	37,437,000	18,004,000
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Accretable Yield, Reclassifications from Nonaccretable Difference			6,646,000	0	36,659,000	0
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities F D I C Payments Received under Loss Sharing Agreement			(53,150,000)	(90,729,000)	(159,387,000)	(166,852,000)
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Accretable Yield, Disposals of Loans			$ (4,714,000)	$ (4,546,000)	$ (9,444,000)	$ (6,947,000)