v2.4.0.8
Document and Entity Information (USD $)
In Millions, except Share data, unless otherwise specified
12 Months Ended
Dec. 27, 2013
Mar. 24, 2014
Jun. 28, 2013
Document and Entity Information      
Entity Registrant Name Willdan Group, Inc.    
Entity Central Index Key 0001370450    
Document Type 10-K    
Document Period End Date Dec. 27, 2013    
Amendment Flag false    
Current Fiscal Year End Date --12-27    
Entity Well-known Seasoned Issuer No    
Entity Voluntary Filers No    
Entity Current Reporting Status Yes    
Entity Filer Category Smaller Reporting Company    
Entity Public Float     $ 22.1
Entity Common Stock, Shares Outstanding   7,401,784  
Document Fiscal Year Focus 2013    
Document Fiscal Period Focus FY