v2.4.0.8

Collateralized Transactions (Narrative) (Details) (USD $) | Jun. 30, 2014 | Dec. 31, 2013
--- | --- | ---
Disclosure Collateralized Transactions [Abstract] |  |
Customer margin loans outstanding | $ 15,326,943,000 | $ 13,596,650,000
Securities repledged and deposited for customers | $ 5,910,000,000 | $ 6,730,000,000
Percentage of securities repledged and deposited for customers | 96.00% | 95.00%

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

X
- Definition Margin loans to clients stated net of allowance for doubtful accounts. + References No definition available. + Details
Name: | ibkr_ReceivablesFromCustomerNet
Namespace Prefix: | ibkr_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Percentage of securities acquired through agreements to resell that are shown as repledged and have been deposited in a separate bank account for the exclusive benefit of customers in accordance with SEC Rule 15c3-3. + References No definition available. + Details
Name: | ibkr_SecuritiesAcquiredThroughAgreementsToResellShownAsRepledgedDepositedPercentage
Namespace Prefix: | ibkr_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition The carrying value of funds, segregated for regulatory purposes and for the exclusive benefit of customers, outstanding loaned in the form of security resale agreements if the agreement requires the purchaser to resell the identical security purchased or a security that meets the definition of "substantially the same" in the case of a dollar roll. Also includes purchases of participations in pools of securities that are subject to a resale agreement. + References No definition available. + Details
Name: | ibkr_SegregatedSecuritiesPurchasedUnderAgreementsToResell
Namespace Prefix: | ibkr_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant