Amount of Loan Portfolio reclassified from spoecial mention ratings to pass rating.

No definition available.

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

- Definition

Business lines of credit, maturity period

+ References

No definition available.

+ Details

Name:	juvf_BusinessLinesOfCreditMaturityPeriod
Namespace Prefix:	juvf_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Loans And Leases Receivable Period for loan to be Nonaccrual

+ References

No definition available.

+ Details

Name:	juvf_LoansAndLeasesReceivablePeriodForLoanToBeNonaccrual
Namespace Prefix:	juvf_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Maximum Loan To Value Ratio

+ References

No definition available.

+ Details

Name:	juvf_MaximumLoanToValueRatio
Namespace Prefix:	juvf_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Maximum terms offered to loans

+ References

No definition available.

+ Details

Name:	juvf_MaximumTermsOfferedToLoans
Namespace Prefix:	juvf_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Period for loans to be considered for charge off.

+ References

No definition available.

+ Details

Name:	juvf_PeriodForLoansToBeConsideredForChargeOff
Namespace Prefix:	juvf_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

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

- Definition

The amount of the outstanding recorded investment related to financing receivables that have been modified by troubled debt restructurings.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 40
-Section 50
-Paragraph 4
-URI http://asc.fasb.org/extlink&oid=82895541&loc=d3e18845-111554

+ Details

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

- Definition

Reflects the amount of the write-down related to a troubled debt restructuring.

+ References

+ Details

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

- Definition

Recorded investment of consumer mortgage loan receivables secured by residential real estate properties for which formal foreclosure proceedings are in process.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 35
-URI http://asc.fasb.org/extlink&oid=84173941&loc=SL49126937-111524

+ Details

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

- Details

Name:	us-gaap_LoanRestructuringModificationAxis=juvf_NonAccruingTroubledDebtRestructuringsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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

- Details

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

- Details

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

- Details

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

- Details

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

- Details

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

- Details

Name:	us-gaap_LoanRestructuringModificationAxis=juvf_AccruingTroubledDebtRestructuringsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	juvf_TermModificationResultingInTroubleDebtRestructuringAxis=juvf_RestructuredLoanMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Loans and Related Allowance for Credit Losses (Narrative) (Details) - USD ($)	6 Months Ended	12 Months Ended
	Jun. 30, 2018	Dec. 31, 2017	Jun. 30, 2017
Financing Receivable, Allowance for Credit Losses [Line Items]
Period for loan to be nonaccrual	90 days
Business lines of credit, maturity period	5 years
Period for loans to be considered for charge off	120 days
Troubled debt restructured Number of loans	$ 469,000	$ 339,000
Trouble debt restructured loan	469,000	339,000
Amount of Loan Portfolio reclassified from spoecial mention ratings to pass rating	$ 32,603,000
Non-Accruing Troubled Debt Restructurings [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Troubled debt restructurings, charge-off		8,000
Troubled debt restructured Number of loans		4,000
Trouble debt restructured loan		4,000
Home Equity Lines of Credit [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Maximum terms offered to loans	20 years
Maximum loan-to-value ratio	90.00%
Fixed Rate and Adjustable Rate Mortgage Loans [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Maximum terms offered to loans	25 years
Home Equity Installment Loans [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Maximum terms offered to loans	15 years
Maximum loan-to-value ratio	95.00%
Real Estate Portfolio Segment [Member] \| Commercial Loan [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Maximum terms offered to loans	20 years
Maximum loan-to-value ratio	80.00%
Real Estate Portfolio Segment [Member] \| Mortgage Loan [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Maximum loan-to-value ratio	80.00%
Loan balance in the process of foreclosure	$ 788,000	1,285,000
Real Estate Portfolio Segment [Member] \| Mortgage Loan [Member] \| Non-Accruing Troubled Debt Restructurings [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Troubled debt restructured Number of loans	19,000	20,000
Trouble debt restructured loan	19,000	20,000
Real Estate Portfolio Segment [Member] \| Mortgage Loan [Member] \| Accruing Troubled Debt Restructurings [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Troubled debt restructured Number of loans	450,000	315,000
Trouble debt restructured loan	450,000	$ 315,000
Restructured Loan [Member] \| Accruing Troubled Debt Restructurings [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Troubled debt restructured Number of loans	153,000		$ 16,000
Trouble debt restructured loan	153,000		$ 16,000
Restructured Loan [Member] \| Real Estate Portfolio Segment [Member] \| Mortgage Loan [Member] \| Accruing Troubled Debt Restructurings [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Troubled debt restructured Number of loans	153,000
Trouble debt restructured loan	$ 153,000