| Document And Entity Information | Jul. 27, 2020 |
| Document And Entity Information [Abstract] | |
| Document Type | 8-K/A |
| Document Period End Date | Jul. 27, 2020 |
| Entity Registrant Name | INTERACTIVE BROKERS GROUP, INC. |
| Entity Incorporation, State or Country Code | DE |
| Entity File Number | 001-33440 |
| Entity Tax Identification Number | 30-0390693 |
| Entity Address, Address Line One | One Pickwick Plaza |
| Entity Address, City or Town | Greenwich |
| Entity Address, State or Province | CT |
| Entity Address, Postal Zip Code | 06830 |
| City Area Code | 203 |
| Local Phone Number | 618-5800 |
| Written Communications | false |
| Soliciting Material | false |
| Pre Commencement Tender Offer | false |
| Pre Commencement Issuer Tender Offer | false |
| Title of 12(b) Security | Common Stock, par value $.01 per share |
| Trading Symbol | IBKR |
| Security Exchange Name | NASDAQ |
| Entity Central Index Key | 0001381197 |
| Entity Emerging Growth Company | false |
| Amendment Flag | true |
| Amendment Description | Amendment filing revised table disclosing Supplemental Financial Information included in an 8-K filing on 7/27/2020. |
