v2.4.0.8

Commitments, Contingencies and Guarantees (Details) (USD $) In Millions, unless otherwise specified | 1 Months Ended | 9 Months Ended | 6 Months Ended
--- | --- | --- | ---
Oct. 31, 2013 | Jun. 30, 2014 | Jun. 30, 2014 Scenario, Forecast [Member]
Commitment And Contingencies [Line Items] |  |  |
Percentage of loss on securities | 90.00% |  |
Loss on large positions on Singapore Exchange | $ 64.0 | $ 79.2 | $ 84.0

X
- Details
Name: | ibkr_CommitmentAndContingenciesLineItems
Namespace Prefix: | ibkr_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

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- Definition Loss from 4 large positions listed on Singapore Exchange that sharply decreased in value in October 2013 + References No definition available. + Details
Name: | ibkr_LossOnLargePositionsOnSingaporeExchange
Namespace Prefix: | ibkr_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

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- Definition Percentage of loss on securities based on original cost. + References No definition available. + Details
Name: | ibkr_PercentageOfLossOnSecurities
Namespace Prefix: | ibkr_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration