Merger (Schedule of Fair Value Adjustments for Acquired Loans) (Details) - Liverpool Community Bank [Member]	Apr. 30, 2018 USD ($)
Business Acquisition [Line Items]
Gross amortized cost basis at April 30, 2018	$ 32,091,000
Market rate adjustment	272,000
Credit fair value adjustment on pools of homogeneous loans	(496,000)
Credit fair value adjustment on impaired loans	(622,000)
Reversal of existing deferred fees and premiums	86,000
Fair value of purchased loans at April 30, 2018	$ 31,331,000

Credit fair value adjustment on impaired loans.

No definition available.

Name:	juvf_CreditFairValueAdjustmentOnImpairedLoans
Namespace Prefix:	juvf_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Credit fair value adjustment on pools of homogeneous loans.

+ References

No definition available.

+ Details

Name:	juvf_CreditFairValueAdjustmentOnPoolsOfHomogeneousLoans
Namespace Prefix:	juvf_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Fair value adjustment, market rate.

+ References

No definition available.

+ Details

Name:	juvf_FairValueAdjustmentMarketRate
Namespace Prefix:	juvf_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Reversal of existing deferred fees and premiums

+ References

No definition available.

+ Details

Name:	juvf_ReversalOfExistingDeferredFeesAndPremiums
Namespace Prefix:	juvf_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

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

- Definition

Fair value at acquisition of acquired loans accounted for as available-for-sale 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=82894507&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)(3)
-URI http://asc.fasb.org/extlink&oid=82894903&loc=d3e15032-111544

+ Details

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

- Definition

Fair value at acquisition of acquired loans accounted for as debt securities with evidence of deterioration of credit quality.

+ References

+ Details

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

- Details

Name:	us-gaap_BusinessAcquisitionAxis=juvf_LiverpoolCommunityBankMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: