v3.4.0.3
Documentation and Entity Information - shares
3 Months Ended
Mar. 31, 2016
May. 06, 2016
Entity Registrant Name Interactive Brokers Group, Inc.  
Entity Central Index Key 0001381197  
Document Type 10-Q  
Document Period End Date Mar. 31, 2016  
Amendment Flag false  
Fiscal Year Focus 2016  
Fiscal Period Focus Q1  
Current Fiscal Year End Date --12-31  
Entity Well-known Seasoned Issuer Yes  
Entity Voluntary Filers No  
Entity Current Reporting Status Yes  
Entity Filer Category Large Accelerated Filer  
Common Class A    
Common Stock Shares Outstanding   63,989,156
Common Class B    
Common Stock Shares Outstanding   100