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REVENUES (Tables) | 3 Months Ended
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Apr. 03, 2026
Revenue from Contract with Customer [Abstract] |
Schedule of contracts by reportable segments and type of contracts | ​
Segment | Contract Type | Revenue Recognition Method
​ | Time-and-materials | Time-and-materials
Energy | Unit-based | Unit-based
​ | Software license | Unit-based
​ | Fixed price | Percentage-of-completion
​ | Time-and-materials | Time-and-materials
Engineering and Consulting | Unit-based | Unit-based
​ | Fixed price | Percentage-of-completion

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- References No definition available. + Details
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Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

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- Definition Tabular disclosure of contracts for revenue generating activities by type and by reporting segment. + References No definition available. + Details
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Namespace Prefix: | wldn_
Data Type: | dtr-types:textBlockItemType
Balance Type: | na
Period Type: | duration