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Note 8 - Stockholders' Equity (Details Textual) - USD ($) | Sep. 30, 2022 | Sep. 02, 2022 | Dec. 31, 2021
--- | --- | --- | ---
Common Stock, Par or Stated Value Per Share (in dollars per share) | $ 0.01 | $ 0.01 | $ 0.01
At-the-Market Offering [Member] |  |  |
Equity Offering, Maximum Offering Amount |  | $ 50,000,000 |
Equity Offering, Commission, Percentage of Gross Proceeds |  | 3.00% |

X
- Definition Represents the cash commission percentage of gross proceeds + References No definition available. + Details
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X
- Definition Maximum value of company's equity authorized for issuance under equity offering. + References No definition available. + Details
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Namespace Prefix: | nwpx_
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Balance Type: | credit
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X
- Definition Face amount or stated value per share of common stock. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02(29)) -URI https://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682 + Details
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X
- Details
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