XML 83 R76.htm IDEA: XBRL DOCUMENT
v3.19.3.a.u2

Note 15 - Commitments and Contingencies (Details Textual) $ in Thousands | 1 Months Ended | 3 Months Ended | 12 Months Ended |
--- | --- | --- | --- | ---
Jan. 31, 2017 USD ($) | Dec. 31, 2019 USD ($) | Sep. 30, 2019 USD ($) | Dec. 31, 2019 USD ($) | Dec. 31, 2018 USD ($) | Dec. 31, 2017 USD ($) | Jun. 30, 2014 USD ($)
Number Of Potentially Responsible Parties | 150 |  |  |  |  |  |
Estimated Cost of EPA Selected Remedy | $ 1,000,000 |  |  |  |  |  |
Estimated Time to Complete Selected EPA Remedy | 13 years |  |  |  |  |  |
Proceeds from Insurance Settlement, Investing Activities |  |  |  | $ 2,123 |  |  |
Gain (Loss) on Insurance Proceeds |  |  |  | 1,641 |  |  |
Letters of Credit Outstanding, Amount |  | $ 1,600 |  | 1,600 |  |  |
Fire [Member] |  |  |  |  |  |  |
Proceeds from Insurance Settlement, Investing Activities |  |  |  | 2,600 |  |  |
Gain (Loss) on Insurance Proceeds |  | 1,200 | $ 400 | 1,600 |  |  |
Insurance Settlements Receivable |  | 500 |  | 500 |  |  |
Business Interruption Costs |  |  |  | 6,600 |  |  |
Business Interruption Insurance Proceeds |  | 4,000 | $ 1,000 | 5,000 |  |  |
Business Interruption Insurance Proceeds Receivable |  | $ 1,000 |  | 1,000 |  |  |
Fire [Member] | Property, Plant and Equipment [Member] |  |  |  |  |  |  |
Unusual or Infrequent Item, or Both, Net (Gain) Loss, Total |  |  |  | 900 |  |  |
Fire [Member] | Inventory [Member] |  |  |  |  |  |  |
Unusual or Infrequent Item, or Both, Net (Gain) Loss, Total |  |  |  | $ 100 |  |  |
Portland Harbor Natural Resources Trustee Council [Member] |  |  |  |  |  |  |
Loss Contingency, Accrual, Current |  |  |  |  |  |  | $ 400
Lower Willamette Group [Member] |  |  |  |  |  |  |
Number Of Potentially Responsible Parties | 14 |  |  |  |  |  |

X
- Definition Represents the amount of business interruption costs. + References No definition available. + Details
Name: | nwpx_BusinessInterruptionCosts
Namespace Prefix: | nwpx_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Represents the amount of business interruption insurance proceeds received. + References No definition available. + Details
Name: | nwpx_BusinessInterruptionInsuranceProceeds
Namespace Prefix: | nwpx_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Amount of business interruption insurance proceeds recorded as receivable. + References No definition available. + Details
Name: | nwpx_BusinessInterruptionInsuranceProceedsReceivable
Namespace Prefix: | nwpx_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition The estimated cost of the remedy selected by EPA. + References No definition available. + Details
Name: | nwpx_EstimatedCostOfEPASelectedRemedy
Namespace Prefix: | nwpx_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition The estimated amount of time to complete the selected EPA remedy. + References No definition available. + Details
Name: | nwpx_EstimatedTimeToCompleteSelectedEPARemedy
Namespace Prefix: | nwpx_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- Definition Amount of gain (loss) on insurance proceeds during the period. + References No definition available. + Details
Name: | nwpx_GainLossOnInsuranceProceeds
Namespace Prefix: | nwpx_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Number of potentially responsible parties for Portland Harbor Superfund site. + References No definition available. + Details
Name: | nwpx_NumberOfPotentiallyResponsibleParties
Namespace Prefix: | nwpx_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | instant

X
- Definition Amount due in settlement of a claim for reimbursement from an insurance company when the Company has suffered a loss covered under an insurance policy. + References No definition available. + Details
Name: | us-gaap_InsuranceSettlementsReceivable
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition The total amount of the contingent obligation under letters of credit outstanding as of the reporting date. + References No definition available. + Details
Name: | us-gaap_LettersOfCreditOutstandingAmount
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Amount of loss contingency liability expected to be resolved within one year or the normal operating cycle, if longer. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 450 -SubTopic 20 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=118942415&loc=d3e14326-108349 + Details
Name: | us-gaap_LossContingencyAccrualCarryingValueCurrent
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Amount of cash inflow for proceeds from settlement of insurance claim, classified as investing activities. Excludes insurance settlement classified as operating activities. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 21B -URI http://asc.fasb.org/extlink&oid=118932676&loc=SL94080549-108585 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 12 -URI http://asc.fasb.org/extlink&oid=118932676&loc=d3e3179-108585 + Details
Name: | us-gaap_ProceedsFromInsuranceSettlementInvestingActivities
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Amount of (gain) loss for an event or transaction that is unusual in nature or occurs infrequently, or both. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 220 -SubTopic 20 -Section 45 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=114868879&loc=SL114871939-224231 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 220 -SubTopic 20 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=114868883&loc=SL114871943-224233 + Details
Name: | us-gaap_UnusualOrInfrequentItemNetGainLoss
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Details
Name: | us-gaap_NoncatastrophicEventAxis=us-gaap_FireMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FairValueByAssetClassAxis=us-gaap_PropertyPlantAndEquipmentMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FairValueByAssetClassAxis=nwpx_InventoryMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_LossContingenciesByNatureOfContingencyAxis=nwpx_PortlandHarborNaturalreSourcesTrusteeCouncilMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_CounterpartyNameAxis=nwpx_LowerWillametteGroupMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |