Document and Entity Information - shares
3 Months Ended
Mar. 31, 2018
Sep. 17, 2018
Document and Entity Information    
Entity Registrant Name Hill International, Inc.  
Entity Central Index Key 0001287808  
Document Type 10-Q  
Document Period End Date Mar. 31, 2018  
Amendment Flag false  
Current Fiscal Year End Date --12-31  
Entity Filer Category Accelerated Filer  
Entity Common Stock, Shares Outstanding   55,294,670
Document Fiscal Year Focus 2018  
Document Fiscal Period Focus Q1