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Documentation and Entity Information - shares
6 Months Ended
Jun. 30, 2017
Aug. 04, 2017
Entity Registrant Name Interactive Brokers Group, Inc.  
Entity Central Index Key 0001381197  
Document Type 10-Q  
Document Period End Date Jun. 30, 2017  
Amendment Flag false  
Fiscal Year Focus 2017  
Fiscal Period Focus Q2  
Current Fiscal Year End Date --12-31  
Entity Filer Category Large Accelerated Filer  
Common Class A    
Common Stock Shares Outstanding   71,465,894
Common Class B    
Common Stock Shares Outstanding   100