Allowance for Loan Losses (Allowance for Loan Losses By Segment) (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Beginning Balance	$ 5,488	$ 6,577	$ 8,743
Charge-Offs	(1,483)	(1,322)	(4,163)
Recoveries	725	233	337
Provision for loan losses	350us-gaap_ProvisionForLoanAndLeaseLosses	0us-gaap_ProvisionForLoanAndLeaseLosses	1,660us-gaap_ProvisionForLoanAndLeaseLosses
Ending Balance	5,080	5,488	6,577
Ending balance: Individually evaluated for impairment	643	1,478
Ending balance: collectively evaluated for impairment	4,437	4,010
Financing receivables: Ending balance	469,820	444,273
Ending balance individually evaluated for impairment	17,055	13,699
Ending balance collectively evaluated for impairment	452,765	430,574
Construction And Farmland [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Beginning Balance	1,032	1,280
Charge-Offs	(482)	(20)
Recoveries	26	5
Provision for loan losses	375	(233)
Ending Balance	951	1,032
Ending balance: Individually evaluated for impairment	93	218
Ending balance: collectively evaluated for impairment	858	814
Financing receivables: Ending balance	36,489	36,933
Ending balance individually evaluated for impairment	2,669	2,674
Ending balance collectively evaluated for impairment	33,820	34,259
Residential Real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Beginning Balance	2,225	2,820
Charge-Offs	(808)	(507)
Recoveries	63	109
Provision for loan losses	497	(197)
Ending Balance	1,977	2,225
Ending balance: Individually evaluated for impairment	303	627
Ending balance: collectively evaluated for impairment	1,674	1,598
Financing receivables: Ending balance	227,710	221,483
Ending balance individually evaluated for impairment	6,557	4,922
Ending balance collectively evaluated for impairment	221,153	216,561
Commercial Real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Beginning Balance	1,337	1,182
Charge-Offs	(83)	(289)
Recoveries	381	7
Provision for loan losses	(288)	437
Ending Balance	1,347	1,337
Ending balance: Individually evaluated for impairment	203	299
Ending balance: collectively evaluated for impairment	1,144	1,038
Financing receivables: Ending balance	161,299	148,166
Ending balance individually evaluated for impairment	5,722	4,750
Ending balance collectively evaluated for impairment	155,577	143,416
Commercial [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Beginning Balance	555	880
Charge-Offs	0	(403)
Recoveries	164	47
Provision for loan losses	(255)	31
Ending Balance	464	555
Ending balance: Individually evaluated for impairment	44	334
Ending balance: collectively evaluated for impairment	420	221
Financing receivables: Ending balance	28,132	20,865
Ending balance individually evaluated for impairment	2,107	1,347
Ending balance collectively evaluated for impairment	26,025	19,518
Consumer [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Beginning Balance	102	107
Charge-Offs	(86)	(85)
Recoveries	87	54
Provision for loan losses	0	26
Ending Balance	103	102
Ending balance: Individually evaluated for impairment	0	0
Ending balance: collectively evaluated for impairment	103	102
Financing receivables: Ending balance	13,874	13,785
Ending balance individually evaluated for impairment	0	0
Ending balance collectively evaluated for impairment	13,874	13,785
All Other Loans [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Beginning Balance	82	122
Charge-Offs	(24)	(18)
Recoveries	4	11
Provision for loan losses	(20)	(33)
Ending Balance	42	82
Ending balance: Individually evaluated for impairment	0	0
Ending balance: collectively evaluated for impairment	42	82
Financing receivables: Ending balance	2,316	3,041
Ending balance individually evaluated for impairment	0	6
Ending balance collectively evaluated for impairment	2,316	3,035
Unallocated [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Beginning Balance	155	186
Charge-Offs	0	0
Recoveries	0	0
Provision for loan losses	41	(31)
Ending Balance	196	155
Ending balance: Individually evaluated for impairment		0
Ending balance: collectively evaluated for impairment	196	155
Financing receivables: Ending balance	0	0
Ending balance individually evaluated for impairment		0
Ending balance collectively evaluated for impairment	$ 0

A valuation allowance for financing receivables that are expected to be uncollectible.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 310

-SubTopic 10

-Section 50

-Paragraph 11B

-Subparagraph (c)(1)

-URI http://asc.fasb.org/extlink&oid=28368275&loc=SL6953423-111524

+ Details

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

- Definition

The valuation allowance for financing receivables that are expected to be uncollectible that were collectively evaluated for impairment.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 310

-SubTopic 10

-Section 50

-Paragraph 11B

-Subparagraph (g)

-URI http://asc.fasb.org/extlink&oid=28368275&loc=SL6953423-111524

+ Details

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

- Definition

Amount of valuation allowance for financing receivables that are expected to be uncollectible that were individually evaluated for impairment.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 310

-SubTopic 10

-Section 50

-Paragraph 11B

-Subparagraph (g)

-URI http://asc.fasb.org/extlink&oid=28368275&loc=SL6953423-111524

+ Details

Name:	us-gaap_FinancingReceivableAllowanceForCreditLossesIndividuallyEvaluatedForImpairment1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of recovery of financing receivables doubtful of collection that were previously charged off.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 310

-SubTopic 10

-Section 50

-Paragraph 11B

-Subparagraph (c)(4)

-URI http://asc.fasb.org/extlink&oid=28368275&loc=SL6953423-111524

+ Details

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

- Details

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

- Definition

Amount of direct write-downs of financing receivables charged against the allowance.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 310

-SubTopic 10

-Section 50

-Paragraph 11B

-Subparagraph (c)(3)

-URI http://asc.fasb.org/extlink&oid=28368275&loc=SL6953423-111524

+ Details

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

- Definition

The balance of financing receivables that were collectively evaluated for impairment.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 310

-SubTopic 10

-Section 50

-Paragraph 11B

-Subparagraph (h)

-URI http://asc.fasb.org/extlink&oid=28368275&loc=SL6953423-111524

+ Details

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

- Definition

The balance of financing receivables that were individually evaluated for impairment.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 310

-SubTopic 10

-Section 50

-Paragraph 11B

-Subparagraph (h)

-URI http://asc.fasb.org/extlink&oid=28368275&loc=SL6953423-111524

+ Details

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

- Definition

Amount before allowance of loans and leases held in portfolio, including but not limited to, commercial and consumer loans. Includes deferred interest and fees, undisbursed portion of loan balance, unamortized costs and premiums and discounts from face amounts. Excludes loans and leases covered under loss sharing agreements.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 310

-SubTopic 10

-Section 45

-Paragraph 2

-URI http://asc.fasb.org/extlink&oid=28367877&loc=d3e4428-111522

+ Details

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

- Definition

Amount of expense related to estimated loss from loan and lease transactions.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 45

-Paragraph 28

-Subparagraph (a)

-URI http://asc.fasb.org/extlink&oid=31042434&loc=d3e3602-108585

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 04

-Paragraph 11

-Article 9

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 942

-SubTopic 225

-Section S99

-Paragraph 1

-Subparagraph (SX 210.9-04.11)

-URI http://asc.fasb.org/extlink&oid=6879574&loc=d3e536633-122882

+ Details

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

- Details

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

- Details

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

- Details

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

- Details

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

- Details

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

- Details

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

- Details

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