| r0.c0 | Current payables to group companies/Current | venj-bw2-i:PayablesGroupCompaniesCurrent | nl-types:monetaryNoDecimalsItemType | instant | ocw-dm:ActualsMember | xs:date('2017-12-31') | venj-bw2-dm:SeparateMember |
| r0.c1 | Current payables to group companies/Previous | venj-bw2-i:PayablesGroupCompaniesCurrent | nl-types:monetaryNoDecimalsItemType | instant | ocw-dm:ActualsMember | xs:date('2016-12-31') | venj-bw2-dm:SeparateMember |
| r1.c0 | Payables to other participations (current)/Current | ocw-i:PayablesOtherParticipationsCurrent | nl-types:monetaryNoDecimalsItemType | instant | ocw-dm:ActualsMember | xs:date('2017-12-31') | venj-bw2-dm:SeparateMember |
| r1.c1 | Payables to other participations (current)/Previous | ocw-i:PayablesOtherParticipationsCurrent | nl-types:monetaryNoDecimalsItemType | instant | ocw-dm:ActualsMember | xs:date('2016-12-31') | venj-bw2-dm:SeparateMember |
| r2.c0 | Current payables to credit institutions/Current | venj-bw2-i:PayablesCreditInstitutionsCurrent | nl-types:monetaryNoDecimalsItemType | instant | ocw-dm:ActualsMember | xs:date('2017-12-31') | venj-bw2-dm:SeparateMember |
| r2.c1 | Current payables to credit institutions/Previous | venj-bw2-i:PayablesCreditInstitutionsCurrent | nl-types:monetaryNoDecimalsItemType | instant | ocw-dm:ActualsMember | xs:date('2016-12-31') | venj-bw2-dm:SeparateMember |
| r3.c0 | Payables to OCW and EZ (current)/Current | ocw-i:PayablesOCWAndEZCurrent | nl-types:monetaryNoDecimalsItemType | instant | ocw-dm:ActualsMember | xs:date('2017-12-31') | venj-bw2-dm:SeparateMember |
| r3.c1 | Payables to OCW and EZ (current)/Previous | ocw-i:PayablesOCWAndEZCurrent | nl-types:monetaryNoDecimalsItemType | instant | ocw-dm:ActualsMember | xs:date('2016-12-31') | venj-bw2-dm:SeparateMember |
| r4.c0 | Payables to FIN (current)/Current | ocw-i:PayablesFINCurrent | nl-types:monetaryNoDecimalsItemType | instant | ocw-dm:ActualsMember | xs:date('2017-12-31') | venj-bw2-dm:SeparateMember |
| r4.c1 | Payables to FIN (current)/Previous | ocw-i:PayablesFINCurrent | nl-types:monetaryNoDecimalsItemType | instant | ocw-dm:ActualsMember | xs:date('2016-12-31') | venj-bw2-dm:SeparateMember |
| r5.c0 | Payables to local government and common regulations (current)/Current | ocw-i:PayablesLocalGovernmentCommonRegulationsCurrent | nl-types:monetaryNoDecimalsItemType | instant | ocw-dm:ActualsMember | xs:date('2017-12-31') | venj-bw2-dm:SeparateMember |
| r5.c1 | Payables to local government and common regulations (current)/Previous | ocw-i:PayablesLocalGovernmentCommonRegulationsCurrent | nl-types:monetaryNoDecimalsItemType | instant | ocw-dm:ActualsMember | xs:date('2016-12-31') | venj-bw2-dm:SeparateMember |
| r6.c0 | Construction contracts (liabilities)/Current | rj-i:ConstructionContractsLiabilities | nl-types:monetaryNoDecimalsItemType | instant | ocw-dm:ActualsMember | xs:date('2017-12-31') | venj-bw2-dm:SeparateMember |
| r6.c1 | Construction contracts (liabilities)/Previous | rj-i:ConstructionContractsLiabilities | nl-types:monetaryNoDecimalsItemType | instant | ocw-dm:ActualsMember | xs:date('2016-12-31') | venj-bw2-dm:SeparateMember |
| r7.c0 | Current trade payables/Current | venj-bw2-i:TradePayablesCurrent | nl-types:monetaryNoDecimalsItemType | instant | ocw-dm:ActualsMember | xs:date('2017-12-31') | venj-bw2-dm:SeparateMember |
| r7.c1 | Current trade payables/Previous | venj-bw2-i:TradePayablesCurrent | nl-types:monetaryNoDecimalsItemType | instant | ocw-dm:ActualsMember | xs:date('2016-12-31') | venj-bw2-dm:SeparateMember |
| r8.c0 | Current taxes payable and social security contributions payable/Current | venj-bw2-i:TaxesSocialSecurityContributionsPayableCurrent | nl-types:monetaryNoDecimalsItemType | instant | ocw-dm:ActualsMember | xs:date('2017-12-31') | venj-bw2-dm:SeparateMember |
| r8.c1 | Current taxes payable and social security contributions payable/Previous | venj-bw2-i:TaxesSocialSecurityContributionsPayableCurrent | nl-types:monetaryNoDecimalsItemType | instant | ocw-dm:ActualsMember | xs:date('2016-12-31') | venj-bw2-dm:SeparateMember |
| r9.c0 | Current pension related payables/Current | venj-bw2-i:PensionPayablesCurrent | nl-types:monetaryNoDecimalsItemType | instant | ocw-dm:ActualsMember | xs:date('2017-12-31') | venj-bw2-dm:SeparateMember |
| r9.c1 | Current pension related payables/Previous | venj-bw2-i:PensionPayablesCurrent | nl-types:monetaryNoDecimalsItemType | instant | ocw-dm:ActualsMember | xs:date('2016-12-31') | venj-bw2-dm:SeparateMember |
| r10.c0 | Payables to contracted third parties/Current | ocw-i:PayablesThirdPartyContracts | nl-types:monetaryNoDecimalsItemType | instant | ocw-dm:ActualsMember | xs:date('2017-12-31') | venj-bw2-dm:SeparateMember |
| r10.c1 | Payables to contracted third parties/Previous | ocw-i:PayablesThirdPartyContracts | nl-types:monetaryNoDecimalsItemType | instant | ocw-dm:ActualsMember | xs:date('2016-12-31') | venj-bw2-dm:SeparateMember |
| r11.c0 | Current other payables/Current | venj-bw2-i:PayablesOtherCurrent | nl-types:monetaryNoDecimalsItemType | instant | ocw-dm:ActualsMember | xs:date('2017-12-31') | venj-bw2-dm:SeparateMember |
| r11.c1 | Current other payables/Previous | venj-bw2-i:PayablesOtherCurrent | nl-types:monetaryNoDecimalsItemType | instant | ocw-dm:ActualsMember | xs:date('2016-12-31') | venj-bw2-dm:SeparateMember |
| r12.c0 | Liabilities current excluding accruals, subtotal/Current | ocw-i:LiabilitiesCurrentExcludingAccrualsSubtotal | nl-types:monetaryNoDecimalsItemType | instant | ocw-dm:ActualsMember | xs:date('2017-12-31') | venj-bw2-dm:SeparateMember |
| r12.c1 | Liabilities current excluding accruals, subtotal/Previous | ocw-i:LiabilitiesCurrentExcludingAccrualsSubtotal | nl-types:monetaryNoDecimalsItemType | instant | ocw-dm:ActualsMember | xs:date('2016-12-31') | venj-bw2-dm:SeparateMember |
| r13.c0 | Advances received on government subsidies from OCW and EZ/Current | ocw-i:AdvancesReceivedGovernmentSubsidiesOCWAndEZ | nl-types:monetaryNoDecimalsItemType | instant | ocw-dm:ActualsMember | xs:date('2017-12-31') | venj-bw2-dm:SeparateMember |
| r13.c1 | Advances received on government subsidies from OCW and EZ/Previous | ocw-i:AdvancesReceivedGovernmentSubsidiesOCWAndEZ | nl-types:monetaryNoDecimalsItemType | instant | ocw-dm:ActualsMember | xs:date('2016-12-31') | venj-bw2-dm:SeparateMember |
| r14.c0 | Advances received on investment subsidies/Current | ocw-i:AdvancesReceivedGovernmentSubsidiesInvestment | nl-types:monetaryNoDecimalsItemType | instant | ocw-dm:ActualsMember | xs:date('2017-12-31') | venj-bw2-dm:SeparateMember |
| r14.c1 | Advances received on investment subsidies/Previous | ocw-i:AdvancesReceivedGovernmentSubsidiesInvestment | nl-types:monetaryNoDecimalsItemType | instant | ocw-dm:ActualsMember | xs:date('2016-12-31') | venj-bw2-dm:SeparateMember |
| r15.c0 | Advances received/Current | ocw-i:AdvancesReceivedPeriodicPayments | nl-types:monetaryNoDecimalsItemType | instant | ocw-dm:ActualsMember | xs:date('2017-12-31') | venj-bw2-dm:SeparateMember |
| r15.c1 | Advances received/Previous | ocw-i:AdvancesReceivedPeriodicPayments | nl-types:monetaryNoDecimalsItemType | instant | ocw-dm:ActualsMember | xs:date('2016-12-31') | venj-bw2-dm:SeparateMember |
| r16.c0 | Payables holidays and holiday pay/Current | ocw-i:PayablesHolidaysAndHolidayPay | nl-types:monetaryNoDecimalsItemType | instant | ocw-dm:ActualsMember | xs:date('2017-12-31') | venj-bw2-dm:SeparateMember |
| r16.c1 | Payables holidays and holiday pay/Previous | ocw-i:PayablesHolidaysAndHolidayPay | nl-types:monetaryNoDecimalsItemType | instant | ocw-dm:ActualsMember | xs:date('2016-12-31') | venj-bw2-dm:SeparateMember |
| r17.c0 | Interest payable/Current | ocw-i:InterestPayable | nl-types:monetaryNoDecimalsItemType | instant | ocw-dm:ActualsMember | xs:date('2017-12-31') | venj-bw2-dm:SeparateMember |
| r17.c1 | Interest payable/Previous | ocw-i:InterestPayable | nl-types:monetaryNoDecimalsItemType | instant | ocw-dm:ActualsMember | xs:date('2016-12-31') | venj-bw2-dm:SeparateMember |
| r18.c0 | Other accruals and deferred income (current)/Current | ocw-i:AccrualsOtherCurrent | nl-types:monetaryNoDecimalsItemType | instant | ocw-dm:ActualsMember | xs:date('2017-12-31') | venj-bw2-dm:SeparateMember |
| r18.c1 | Other accruals and deferred income (current)/Previous | ocw-i:AccrualsOtherCurrent | nl-types:monetaryNoDecimalsItemType | instant | ocw-dm:ActualsMember | xs:date('2016-12-31') | venj-bw2-dm:SeparateMember |
| r19.c0 | Current accruals and deferred income/Current | venj-bw2-i:AccrualsAndDeferredIncomeCurrent | nl-types:monetaryNoDecimalsItemType | instant | ocw-dm:ActualsMember | xs:date('2017-12-31') | venj-bw2-dm:SeparateMember |
| r19.c1 | Current accruals and deferred income/Previous | venj-bw2-i:AccrualsAndDeferredIncomeCurrent | nl-types:monetaryNoDecimalsItemType | instant | ocw-dm:ActualsMember | xs:date('2016-12-31') | venj-bw2-dm:SeparateMember |
| r20.c0 | Accruals and deferred income, breakdown [title]/Current | ocw-abstr:AccrualsBreakdownTitle | xbrli:stringItemType | duration | ocw-dm:ActualsMember | xs:date('2017-12-31') | venj-bw2-dm:SeparateMember |
| r20.c1 | Accruals and deferred income, breakdown [title]/Previous | ocw-abstr:AccrualsBreakdownTitle | xbrli:stringItemType | duration | ocw-dm:ActualsMember | xs:date('2016-12-31') | venj-bw2-dm:SeparateMember |
| r21.c0 | Current liabilities/Current | venj-bw2-i:LiabilitiesCurrent | nl-types:monetaryNoDecimalsItemType | instant | ocw-dm:ActualsMember | xs:date('2017-12-31') | venj-bw2-dm:SeparateMember |
| r21.c1 | Current liabilities/Previous | venj-bw2-i:LiabilitiesCurrent | nl-types:monetaryNoDecimalsItemType | instant | ocw-dm:ActualsMember | xs:date('2016-12-31') | venj-bw2-dm:SeparateMember |