XML 53 R42.htm IDEA: XBRL DOCUMENT
v3.25.3

Note 6 - Stockholders' Equity (Details Textual) - USD ($) $ / shares in Units, $ in Thousands | 1 Months Ended | 3 Months Ended | 9 Months Ended |  |  |  |  |
--- | --- | --- | --- | --- | --- | --- | --- | ---
Oct. 28, 2025 | Sep. 30, 2025 | Sep. 30, 2024 | Sep. 30, 2025 | Sep. 30, 2024 | Aug. 31, 2025 | May 31, 2025 | Mar. 03, 2025 | Nov. 07, 2023 | Nov. 02, 2023
Stock Repurchased and Retired During Period, Value |  | $ 7,998 |  | $ 15,775 | $ 4,301 |  |  |  |  |
Share Repurchase Program [Member] |  |  |  |  |  |  |  |  |  |
Stock Repurchase Program, Authorized Amount |  |  |  |  |  |  |  |  |  | $ 30,000
Rule 10b5-1 Trading Plan, Designated Amount |  |  |  |  |  | $ 9,000 | $ 10,000 | $ 5,000 | $ 10,000 |
Stock Repurchased and Retired During Period, Shares (in shares) |  | 186,000 | 0 | 379,000 | 145,000 |  |  |  |  |
Stock Repurchased and Retired During Period, Value |  | $ 8,000 |  | $ 15,800 | $ 4,300 |  |  |  |  |
Share Repurchase Program, Remaining Authorized, Amount |  | $ 9,100 |  | $ 9,100 |  |  |  |  |  |
Share Repurchase Program [Member] | Subsequent Event [Member] |  |  |  |  |  |  |  |  |  |
Stock Repurchased and Retired During Period, Shares (in shares) | 25,000 |  |  |  |  |  |  |  |  |
Stock Repurchased and Retired During Period, Value | $ 1,300 |  |  |  |  |  |  |  |  |
Stock Repurchased and Retired During Period, Price Per Share (in dollars per share) | $ 51.95 |  |  |  |  |  |  |  |  |

X
- Definition The amount of stock designated for repurchase under the Company's Rule 10b5-1 trading plan. + References No definition available. + Details
Name: | nwpx_Rule10b51TradingPlanDesignatedAmount
Namespace Prefix: | nwpx_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Represents the price per share of shares repurchased. + References No definition available. + Details
Name: | nwpx_StockRepurchasedAndRetiredDuringPeriodPricePerShare
Namespace Prefix: | nwpx_
Data Type: | dtr-types:perShareItemType
Balance Type: | na
Period Type: | duration

X
- Definition Amount authorized for purchase of share under share repurchase plan. Includes, but is not limited to, repurchase of stock and unit of ownership. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 505 -SubTopic 30 -Name Accounting Standards Codification -Section 50 -Paragraph 4 -Publisher FASB -URI https://asc.fasb.org/1943274/2147481520/505-30-50-4 + Details
Name: | srt_StockRepurchaseProgramAuthorizedAmount1
Namespace Prefix: | srt_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Amount remaining authorized for purchase of share under share repurchase plan. Includes, but is not limited to, repurchase of stock and unit of ownership. + References No definition available. + Details
Name: | us-gaap_StockRepurchaseProgramRemainingAuthorizedRepurchaseAmount1
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Number of shares that have been repurchased and retired during the period. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Name Accounting Standards Codification -Section 50 -Paragraph 2 -SubTopic 10 -Topic 505 -Publisher FASB -URI https://asc.fasb.org/1943274/2147481112/505-10-50-2 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Topic 210 -SubTopic 10 -Name Accounting Standards Codification -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02(28)) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480566/210-10-S99-1 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Topic 210 -SubTopic 10 -Name Accounting Standards Codification -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02(29)) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480566/210-10-S99-1 Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef -Topic 505 -SubTopic 10 -Name Accounting Standards Codification -Section S99 -Paragraph 1 -Subparagraph (SX 210.3-04) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480008/505-10-S99-1 + Details
Name: | us-gaap_StockRepurchasedAndRetiredDuringPeriodShares
Namespace Prefix: | us-gaap_
Data Type: | xbrli:sharesItemType
Balance Type: | na
Period Type: | duration

X
- Definition Equity impact of the value of stock that has been repurchased and retired during the period. The excess of the purchase price over par value can be charged against retained earnings (once the excess is fully allocated to additional paid in capital). + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Name Accounting Standards Codification -Section 50 -Paragraph 2 -SubTopic 10 -Topic 505 -Publisher FASB -URI https://asc.fasb.org/1943274/2147481112/505-10-50-2 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Topic 210 -SubTopic 10 -Name Accounting Standards Codification -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02(28)) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480566/210-10-S99-1 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Topic 210 -SubTopic 10 -Name Accounting Standards Codification -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02(29)) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480566/210-10-S99-1 Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef -Topic 505 -SubTopic 10 -Name Accounting Standards Codification -Section S99 -Paragraph 1 -Subparagraph (SX 210.3-04) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480008/505-10-S99-1 + Details
Name: | us-gaap_StockRepurchasedAndRetiredDuringPeriodValue
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Details
Name: | srt_ShareRepurchaseProgramAxis=nwpx_ShareRepurchaseProgramMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_SubsequentEventTypeAxis=us-gaap_SubsequentEventMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |