REVENUES - General Information (Details)	6 Months Ended
Jul. 03, 2026
Revenue
Percent of revenue, low end of range (as a percent)	1.00%
Percent of revenue, high end of range (as a percent)	2.00%

Percent of Total Revenue Comprised of Contracts Which Include Separate Phases or Elements, High End of Range

No definition available.

Name:	wldn_PercentOfTotalRevenueComprisedOfContractsWhichIncludeSeparatePhasesOrElementsHighEndOfRange
Namespace Prefix:	wldn_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration