XML 16 R1.htm IDEA: XBRL DOCUMENT v3.25.0.1
Document and Entity Information - USD ($)
$ / shares in Units, $ in Millions
 12 Months Ended
Dec. 27, 2024
Mar. 05, 2025
Jun. 28, 2024
Cover [Abstract]      
Document Type 10-K    
Document Annual Report true    
Document Period End Date Dec. 27, 2024    
Document Transition Report false    
Entity File Number 001-33076    
Entity Registrant Name WILLDAN GROUP, INC.    
Entity Incorporation, State or Country Code DE    
Entity Tax Identification Number 14-1951112    
Entity Address, Address Line One 2401 East Katella Avenue    
Entity Address, Address Line Two Suite 300    
Entity Address, City or Town Anaheim    
Entity Address, State or Province CA    
Entity Address, Postal Zip Code 92806    
City Area Code 800    
Local Phone Number 424-9144    
Title of 12(b) Security Common Stock, par value $0.01 per share    
Entity Listing, Par Value Per Share $ 0.01    
Trading Symbol WLDN    
Security Exchange Name NASDAQ    
Entity Well-known Seasoned Issuer No    
Entity Voluntary Filers No    
Entity Current Reporting Status Yes    
Entity Interactive Data Current Yes    
Entity Filer Category Accelerated Filer    
Entity Small Business false    
Entity Emerging Growth Company false    
ICFR Auditor Attestation Flag true    
Document Financial Statement Error Correction [Flag] false    
Entity Shell Company false    
Entity Public Float     $ 285.3
Entity Common Stock, Shares Outstanding   14,407,642  
Entity Central Index Key 0001370450    
Document Fiscal Period Focus FY    
Document Fiscal Year Focus 2024    
Amendment Flag false    
Current Fiscal Year End Date --12-27    
Auditor Name Crowe LLP    
Auditor Firm ID 173    
Auditor Location Los Angeles, California