XML 12 R1.htm IDEA: XBRL DOCUMENT v3.21.2
Document and Entity Information - shares
 6 Months Ended
Jun. 30, 2021
Jul. 31, 2021
Document and Entity Information    
Document Type 10-Q  
Document Quarterly Report true  
Document Period End Date Jun. 30, 2021  
Document Transition Report false  
Entity File Number 001-33287  
Entity Registrant Name Information Services Group Inc.  
Entity Incorporation, State or Country Code DE  
Entity Tax Identification Number 20-5261587  
Entity Address, Address Line One 2187 Atlantic Street  
Entity Address, City or Town Stamford  
Entity Address, State or Province CT  
Entity Address, Postal Zip Code 06902  
City Area Code 203  
Local Phone Number 517-3100  
Title of 12(b) Security Shares of Common Stock, $0.001 par value  
Trading Symbol III  
Security Exchange Name NASDAQ  
Entity Current Reporting Status Yes  
Entity Interactive Data Current Yes  
Entity Filer Category Accelerated Filer  
Entity Small Business true  
Entity Emerging Growth Company false  
Entity Shell Company false  
Entity Common Stock, Shares Outstanding   48,463,254
Entity Central Index Key 0001371489  
Current Fiscal Year End Date --12-31  
Document Fiscal Year Focus 2021  
Document Fiscal Period Focus Q2  
Amendment Flag false