Organization and Nature Of Business	3 Months Ended
Mar. 31, 2013
Notes to Consolidated Financial Statements
Organization and nature of business	1. Organization and Nature of Business Interactive Brokers Group, Inc. (“IBG, Inc.” or the “Company”) is a Delaware holding company whose primary asset is its ownership of approximately 11.9% of the membership interests of IBG LLC, which, in turn, owns operating subsidiaries (collectively, “IBG LLC” or the “Group”). The accompanying unaudited condensed consolidated financial statements of IBG, Inc. reflect the consolidation of IBG, Inc.’s investment in IBG LLC for all periods presented (Note 4). IBG LLC is an automated global electronic broker and market maker specializing in routing orders and processing trades in securities, futures and foreign exchange instruments. IBG LLC is a Connecticut limited liability company that conducts its business through its operating subsidiaries (collectively called the “Operating Companies”): Timber Hill LLC (“TH LLC”), Timber Hill Europe AG (“THE”), Timber Hill Securities Hong Kong Limited (“THSHK”), Timber Hill Australia Pty Limited (“THA”), Timber Hill Canada Company (“THC”), Interactive Brokers LLC (“IB LLC”) and subsidiary, Interactive Brokers Canada Inc. (“IBC”), Interactive Brokers (U.K.) Limited (“IBUK”), Interactive Brokers (India) Private Limited (“IBI”), Interactive Brokers Financial Products S.A. (“IBFP”), Interactive Brokers Hungary KFT (“IBH”), IB Exchange Corp. (“IBEC”), Interactive Brokers Securities Japan, Inc. (“IBSJ”), IB Brasil Participações Ltda (“IBBH”), Interactive Brokers Software Services Estonia OU (“IBEST”) and Interactive Brokers Software Services Russia (“IBRUS”). IBG, Inc. operates in two business segments, electronic brokerage and market making. IBG, Inc. conducts its electronic brokerage business through certain Interactive Brokers subsidiaries, which provide electronic execution and clearing services to customers worldwide. The Company conducts its market making business principally through its Timber Hill subsidiaries on the world’s leading exchanges and market centers, primarily in exchange-traded equities, equity options and equity-index options and futures. Certain of the Operating Companies are members of various securities and commodities exchanges in North America, Europe and the Asia/Pacific region and are subject to regulatory capital and other requirements (Note 14). IB LLC, IBUK, IBC, IBI and IBSJ carry securities accounts for customers or perform custodial functions relating to customer securities.

Interactive Brokers Group, Inc. (“IBG, Inc.” or the “Company”) is a Delaware holding company whose primary asset is its ownership of approximately 11.9% of the membership interests of IBG LLC, which, in turn, owns operating subsidiaries (collectively, “IBG LLC” or the “Group”). The accompanying unaudited condensed consolidated financial statements of IBG, Inc. reflect the consolidation of IBG, Inc.’s investment in IBG LLC for all periods presented (Note 4). IBG LLC is an automated global electronic broker and market maker specializing in routing orders and processing trades in securities, futures and foreign exchange instruments.

IBG LLC is a Connecticut limited liability company that conducts its business through its operating subsidiaries (collectively called the “Operating Companies”): Timber Hill LLC (“TH LLC”), Timber Hill Europe AG (“THE”), Timber Hill Securities Hong Kong Limited (“THSHK”), Timber Hill Australia Pty Limited (“THA”), Timber Hill Canada Company (“THC”), Interactive Brokers LLC (“IB LLC”) and subsidiary, Interactive Brokers Canada Inc. (“IBC”), Interactive Brokers (U.K.) Limited (“IBUK”), Interactive Brokers (India) Private Limited (“IBI”), Interactive Brokers Financial Products S.A. (“IBFP”), Interactive Brokers Hungary KFT (“IBH”), IB Exchange Corp. (“IBEC”), Interactive Brokers Securities Japan, Inc. (“IBSJ”), IB Brasil Participações Ltda (“IBBH”), Interactive Brokers Software Services Estonia OU (“IBEST”) and Interactive Brokers Software Services Russia (“IBRUS”).

IBG, Inc. operates in two business segments, electronic brokerage and market making. IBG, Inc. conducts its electronic brokerage business through certain Interactive Brokers subsidiaries, which provide electronic execution and clearing services to customers worldwide. The Company conducts its market making business principally through its Timber Hill subsidiaries on the world’s leading exchanges and market centers, primarily in exchange-traded equities, equity options and equity-index options and futures.

Certain of the Operating Companies are members of various securities and commodities exchanges in North America, Europe and the Asia/Pacific region and are subject to regulatory capital and other requirements (Note 14). IB LLC, IBUK, IBC, IBI and IBSJ carry securities accounts for customers or perform custodial functions relating to customer securities.