Document and Entity Information - USD ($)
 12 Months Ended
Dec. 31, 2015
Mar. 04, 2016
Jun. 30, 2015
Document And Entity Information [Abstract]      
Document Type 10-K    
Amendment Flag false    
Document Period End Date Dec. 31, 2015    
Document Fiscal Year Focus 2015    
Document Fiscal Period Focus FY    
Trading Symbol WG    
Entity Registrant Name Willbros Group, Inc.\NEW\    
Entity Central Index Key 0001449732    
Current Fiscal Year End Date --12-31    
Entity Well-known Seasoned Issuer No    
Entity Current Reporting Status Yes    
Entity Voluntary Filers No    
Entity Filer Category Accelerated Filer    
Entity Common Stock, Shares Outstanding   62,089,514  
Entity Public Float     $ 64,331,296