Annual report pursuant to Section 13 and 15(d)

Document and Entity Information

v3.21.1
Document and Entity Information - USD ($)
12 Months Ended
Dec. 31, 2020
Mar. 18, 2021
Jun. 26, 2020
Cover [Abstract]      
Document Type 10-K    
Document Period End Date Dec. 31, 2020    
Entity Registrant Name Williams Industrial Services Group Inc.    
Title of 12(b) Security Common Stock, par value $0.01 per share    
Trading Symbol WLMS    
Security Exchange Name NYSE    
Entity Well-known Seasoned Issuer No    
Entity Voluntary Filers No    
Entity Current Reporting Status Yes    
Entity Interactive Data Current Yes    
Entity Filer Category Non-accelerated Filer    
Entity Small Business true    
Entity Emerging Growth Company false    
ICFR Auditor Attestation Flag false    
Entity Shell Company false    
Entity Public Float     $ 22,869,113
Entity Common Stock, Shares Outstanding   25,583,715  
Entity Central Index Key 0001136294    
Current Fiscal Year End Date --12-31    
Document Fiscal Year Focus 2020    
Document Fiscal Period Focus FY    
Amendment Flag false