XML 49 R38.htm IDEA: XBRL DOCUMENT v3.20.2

Significant Accounting Policies (Schedule Of Securities Segregated For Regulatory Purposes) (Details) - USD ($) $ in Millions		Jun. 30, 2020	Dec. 31, 2019
Marketable Securities [Line Items]
Securities - segregated for regulatory purposes		$ 33,450	$ 17,824
US Government Securities [Member]
Marketable Securities [Line Items]
Securities - segregated for regulatory purposes		5,000	3,800
Securities Purchased Under Agreement To Resell [Member]
Marketable Securities [Line Items]
Securities - segregated for regulatory purposes	[1]	$ 28,500	$ 14,000
[1] These balances are collateralized by U.S. government securities.

X

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

Name:	us-gaap_MarketableSecuritiesLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

X

- Definition

Securities deposited in a special reserve account for the exclusive benefit of customers pursuant to SEC Regulations.

+ References

No definition available.

+ Details

Name:	us-gaap_SecuritiesReserveDepositRequiredAndMade
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

X

- Details

Name:	us-gaap_FinancialInstrumentAxis=us-gaap_USGovernmentAgenciesDebtSecuritiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_FinancialInstrumentAxis=ibkr_SecuritiesPurchasedUnderAgreementToResellMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: