XML 102 R87.htm IDEA: XBRL DOCUMENT v3.8.0.1

Loans and Allowance for Credit Losses - Recorded Investment and Unpaid Principal Balance for Impaired Loans with Associated Allowance (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Financing Receivable, Impaired [Line Items]
Average Recorded Investment			$ 45,458
Interest Income Recognized			615
Commercial, financial, agricultural and other with no related allowance recorded [Member]
Financing Receivable, Impaired [Line Items]
Average Recorded Investment			17,692
Interest Income Recognized			216
Real estate construction with no related allowance recorded [Member]
Financing Receivable, Impaired [Line Items]
Average Recorded Investment			95
Interest Income Recognized			0
Residential real estate with no related allowance recorded [Member]
Financing Receivable, Impaired [Line Items]
Average Recorded Investment			10,635
Interest Income Recognized			172
Commercial real estate with no related allowance recorded [Member]
Financing Receivable, Impaired [Line Items]
Average Recorded Investment			7,890
Interest Income Recognized			90
Loans to individuals with no related allowance recorded [Member]
Financing Receivable, Impaired [Line Items]
Average Recorded Investment			338
Interest Income Recognized			4
Subtotal with no related allowance recorded [Member]
Financing Receivable, Impaired [Line Items]
Average Recorded Investment			36,650
Interest Income Recognized			482
Commercial, financial, agricultural and other With an allowance recorded [Member]
Financing Receivable, Impaired [Line Items]
Average Recorded Investment			7,731
Interest Income Recognized			129
Real estate construction with an allowance recorded [Member]
Financing Receivable, Impaired [Line Items]
Average Recorded Investment			0
Interest Income Recognized			0
Residential real estate With an allowance recorded [Member]
Financing Receivable, Impaired [Line Items]
Average Recorded Investment			403
Interest Income Recognized			0
Commercial real estate With an allowance recorded [Member]
Financing Receivable, Impaired [Line Items]
Average Recorded Investment			674
Interest Income Recognized			4
Loans to individuals With an allowance recorded [Member]
Financing Receivable, Impaired [Line Items]
Average Recorded Investment			0
Interest Income Recognized			0
Subtotal With an allowance recorded [Member]
Financing Receivable, Impaired [Line Items]
Average Recorded Investment			8,808
Interest Income Recognized			$ 133
Originated Loans [Member]
Financing Receivable, Impaired [Line Items]
Recorded Investment	$ 39,951	$ 41,226
Unpaid Principal Balance	53,021	56,296
Related Allowance	3,713	3,128
Average Recorded Investment	38,171	55,915
Interest Income Recognized	1,451	1,245
Originated Loans [Member] | Commercial, financial, agricultural and other with no related allowance recorded [Member]
Financing Receivable, Impaired [Line Items]
Recorded Investment	5,548	9,549
Unpaid Principal Balance	12,153	15,369
Average Recorded Investment	10,282	23,146
Interest Income Recognized	394	576
Originated Loans [Member] | Real estate construction with no related allowance recorded [Member]
Financing Receivable, Impaired [Line Items]
Recorded Investment	0	0
Unpaid Principal Balance	0	0
Average Recorded Investment	0	4
Interest Income Recognized	0	44
Originated Loans [Member] | Residential real estate with no related allowance recorded [Member]
Financing Receivable, Impaired [Line Items]
Recorded Investment	10,625	10,873
Unpaid Principal Balance	12,470	13,004
Average Recorded Investment	11,366	10,957
Interest Income Recognized	355	312
Originated Loans [Member] | Commercial real estate with no related allowance recorded [Member]
Financing Receivable, Impaired [Line Items]
Recorded Investment	5,155	5,765
Unpaid Principal Balance	5,489	6,905
Average Recorded Investment	6,469	6,718
Interest Income Recognized	583	170
Originated Loans [Member] | Loans to individuals with no related allowance recorded [Member]
Financing Receivable, Impaired [Line Items]
Recorded Investment	347	382
Unpaid Principal Balance	383	507
Average Recorded Investment	353	409
Interest Income Recognized	19	15
Originated Loans [Member] | Subtotal with no related allowance recorded [Member]
Financing Receivable, Impaired [Line Items]
Recorded Investment	21,675	26,569
Unpaid Principal Balance	30,495	35,785
Average Recorded Investment	28,470	41,234
Interest Income Recognized	1,351	1,117
Originated Loans [Member] | Commercial, financial, agricultural and other With an allowance recorded [Member]
Financing Receivable, Impaired [Line Items]
Recorded Investment	16,866	13,423
Unpaid Principal Balance	21,094	19,226
Related Allowance	3,478	2,530
Average Recorded Investment	9,391	13,885
Interest Income Recognized	96	99
Originated Loans [Member] | Real estate construction with an allowance recorded [Member]
Financing Receivable, Impaired [Line Items]
Recorded Investment	0	0
Unpaid Principal Balance	0	0
Related Allowance	0	0
Average Recorded Investment	0	0
Interest Income Recognized	0	0
Originated Loans [Member] | Residential real estate With an allowance recorded [Member]
Financing Receivable, Impaired [Line Items]
Recorded Investment	456	424
Unpaid Principal Balance	478	475
Related Allowance	107	164
Average Recorded Investment	167	241
Interest Income Recognized	0	4
Originated Loans [Member] | Commercial real estate With an allowance recorded [Member]
Financing Receivable, Impaired [Line Items]
Recorded Investment	954	810
Unpaid Principal Balance	954	810
Related Allowance	128	434
Average Recorded Investment	143	555
Interest Income Recognized	4	25
Originated Loans [Member] | Loans to individuals With an allowance recorded [Member]
Financing Receivable, Impaired [Line Items]
Recorded Investment	0	0
Unpaid Principal Balance	0	0
Related Allowance	0	0
Average Recorded Investment	0	0
Interest Income Recognized	0	0
Originated Loans [Member] | Subtotal With an allowance recorded [Member]
Financing Receivable, Impaired [Line Items]
Recorded Investment	18,276	14,657
Unpaid Principal Balance	22,526	20,511
Related Allowance	3,713	3,128
Average Recorded Investment	9,701	14,681
Interest Income Recognized	100	128
Acquired Loans [Member]
Financing Receivable, Impaired [Line Items]
Recorded Investment	2,289	587
Unpaid Principal Balance	3,545	661
Related Allowance	33	16
Average Recorded Investment	3,406	587
Interest Income Recognized	0	0
Acquired Loans [Member] | Commercial, financial, agricultural and other with no related allowance recorded [Member]
Financing Receivable, Impaired [Line Items]
Recorded Investment	436	0
Unpaid Principal Balance	449	0
Average Recorded Investment	476	0
Interest Income Recognized	0	0
Acquired Loans [Member] | Real estate construction with no related allowance recorded [Member]
Financing Receivable, Impaired [Line Items]
Recorded Investment	0	0
Unpaid Principal Balance	0	0
Average Recorded Investment	25	0
Interest Income Recognized	0	0
Acquired Loans [Member] | Residential real estate with no related allowance recorded [Member]
Financing Receivable, Impaired [Line Items]
Recorded Investment	666	406
Unpaid Principal Balance	965	480
Average Recorded Investment	535	406
Interest Income Recognized	0	0
Acquired Loans [Member] | Commercial real estate with no related allowance recorded [Member]
Financing Receivable, Impaired [Line Items]
Recorded Investment	940	162
Unpaid Principal Balance	1,842	162
Average Recorded Investment	2,135	162
Interest Income Recognized	0	0
Acquired Loans [Member] | Loans to individuals with no related allowance recorded [Member]
Financing Receivable, Impaired [Line Items]
Recorded Investment	17	3
Unpaid Principal Balance	17	3
Average Recorded Investment	6	3
Interest Income Recognized	0	0
Acquired Loans [Member] | Subtotal with no related allowance recorded [Member]
Financing Receivable, Impaired [Line Items]
Recorded Investment	2,059	571
Unpaid Principal Balance	3,273	645
Average Recorded Investment	3,177	571
Interest Income Recognized	0	0
Acquired Loans [Member] | Commercial, financial, agricultural and other With an allowance recorded [Member]
Financing Receivable, Impaired [Line Items]
Recorded Investment	0	0
Unpaid Principal Balance	0	0
Related Allowance	0	0
Average Recorded Investment	0	0
Interest Income Recognized	0	0
Acquired Loans [Member] | Real estate construction with an allowance recorded [Member]
Financing Receivable, Impaired [Line Items]
Recorded Investment	0	0
Unpaid Principal Balance	0	0
Related Allowance	0	0
Average Recorded Investment	0	0
Interest Income Recognized	0	0
Acquired Loans [Member] | Residential real estate With an allowance recorded [Member]
Financing Receivable, Impaired [Line Items]
Recorded Investment	93	16
Unpaid Principal Balance	122	16
Related Allowance	4	16
Average Recorded Investment	74	16
Interest Income Recognized	0	0
Acquired Loans [Member] | Commercial real estate With an allowance recorded [Member]
Financing Receivable, Impaired [Line Items]
Recorded Investment	137	0
Unpaid Principal Balance	150	0
Related Allowance	29	0
Average Recorded Investment	155	0
Interest Income Recognized	0	0
Acquired Loans [Member] | Loans to individuals With an allowance recorded [Member]
Financing Receivable, Impaired [Line Items]
Recorded Investment	0	0
Unpaid Principal Balance	0	0
Related Allowance	0	0
Average Recorded Investment	0	0
Interest Income Recognized	0	0
Acquired Loans [Member] | Subtotal With an allowance recorded [Member]
Financing Receivable, Impaired [Line Items]
Recorded Investment	230	16
Unpaid Principal Balance	272	16
Related Allowance	33	16
Average Recorded Investment	229	16
Interest Income Recognized	$ 0	$ 0

X

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

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

X

- Definition

Average amount of investment of impaired financing receivables with related allowance for credit losses and without a related allowance for credit losses.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 15
-Subparagraph (c)(1)
-URI http://asc.fasb.org/extlink&oid=84173941&loc=d3e5212-111524

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 17
-URI http://asc.fasb.org/extlink&oid=84173941&loc=d3e5258-111524

+ Details

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

X

- Definition

Amount of interest income recognized that the financing receivables (with related allowance for credit losses and without a related allowance for credit losses) were impaired.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 15
-Subparagraph (c)(2)
-URI http://asc.fasb.org/extlink&oid=84173941&loc=d3e5212-111524

+ Details

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

X

- Definition

Amount of investment of impaired financing receivables with related allowance for credit losses and without a related allowance for credit losses.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 14A
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=84173941&loc=SL6953550-111524

+ Details

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

X

- Definition

Amount of allowance for credit losses related to recorded investment.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 15
-Subparagraph (a)(3)
-URI http://asc.fasb.org/extlink&oid=84173941&loc=d3e5212-111524

+ Details

Name:	us-gaap_ImpairedFinancingReceivableRelatedAllowance
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

X

- Definition

Amount of unpaid principal balance of impaired financing receivables with related allowance for credit losses and without related allowance for credit losses.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 15
-Subparagraph (a)(4)
-URI http://asc.fasb.org/extlink&oid=84173941&loc=d3e5212-111524

+ Details

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

X

- Details

Name:	us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=fcf_CommercialFinancialAgriculturalAndOtherWithNoRelatedAllowanceMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=fcf_RealEstateConstructionWithNoRelatedAllowanceMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=fcf_ResidentialRealEstateWithNoRelatedAllowanceMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=fcf_CommercialRealEstateWithNoRelatedAllowanceMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=fcf_LoansToIndividualsWithNoRelatedAllowanceMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=fcf_WithNoRelatedAllowanceMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=fcf_CommercialFinancialAgriculturalAndOtherWithRelatedAllowanceMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=fcf_RealEstateConstructionWithRelatedAllowanceMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=fcf_ResidentialRealEstateWithRelatedAllowanceMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=fcf_CommercialRealEstateWithRelatedAllowanceMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=fcf_LoansToIndividualsWithRelatedAllowanceMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=fcf_WithRelatedAllowanceMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_StatementBusinessSegmentsAxis=fcf_OriginatedLoansMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_StatementBusinessSegmentsAxis=fcf_AcquiredLoansMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: