Interest rate of Non-Cumulative Perpetual Preferred Stock, Series A

No definition available.

Name:	fmer_InterestrateofNonCumulativePerpetualPreferredStockSeriesA
Namespace Prefix:	fmer_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Non-cumulative Perpetual Preferred Stock, Series A, Shares Authorized

+ References

No definition available.

+ Details

Name:	fmer_NoncumulativePerpetualPreferredStockSeriesASharesAuthorized
Namespace Prefix:	fmer_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

- Details

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

- Definition

Exercise price per share or per unit of warrants or rights outstanding.

+ References

+ Details

Name:	us-gaap_ClassOfWarrantOrRightExercisePriceOfWarrantsOrRights1
Namespace Prefix:	us-gaap_
Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	instant

- Definition

Number of securities into which the class of warrant or right may be converted. For example, but not limited to, 500,000 warrants may be converted into 1,000,000 shares.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 235

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.4-08.(i)(2))

-URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 08

-Paragraph i

-Subparagraph 2

-Article 4

+ Details

Name:	us-gaap_ClassOfWarrantOrRightNumberOfSecuritiesCalledByWarrantsOrRights
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

- Definition

The maximum number of nonredeemable preferred shares (or preferred stock redeemable solely at the option of the issuer) permitted to be issued by an entity's charter and bylaws.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.28)

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 29

-Article 5

+ Details

Name:	us-gaap_PreferredStockSharesAuthorized
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

- Definition

Aggregate share number for all nonredeemable preferred stock (or preferred stock redeemable solely at the option of the issuer) held by stockholders. Does not include preferred shares that have been repurchased.

+ References

+ Details

Name:	us-gaap_PreferredStockSharesOutstanding
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

- Definition

Amount by which the current fair value of the underlying stock exceeds the exercise price of options outstanding.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 718

-SubTopic 10

-Section 50

-Paragraph 2

-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

+ Details

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

Shareholders Equity Details Narrative (Details) (USD $) In Millions, except Share data, unless otherwise specified	Sep. 30, 2014	Dec. 31, 2013	Sep. 30, 2013	Sep. 30, 2014 Citizens Republic Bancorp	Apr. 12, 2013 Citizens Republic Bancorp FirstMerit	Sep. 30, 2014 Citizens Republic Bancorp
Shareholders Equity Narrative [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Intrinsic Value	$ 0.9		$ 1.5
Class of Warrant or Right, Number of Securities Called by Warrants or Rights					2,408,203	2,538,596
Class of Warrant or Right, Exercise Price of Warrants or Rights						$ 17.73
5.875% Non-Cumulative Perpetual Preferred stock, Series A, authorized 115,000 shares	7,000,000
Non-cumulative Perpetual Preferred Stock, Series A, Shares Authorized	115,000	115,000	115,000
Interest rate of Non-Cumulative Perpetual Preferred Stock, Series A				5.875%
5.875% Non-Cumulative Perpetual Preferred stock, Series A, 100,000 outstanding	100,000	100,000	100,000