XML 68 R57.htm IDEA: XBRL DOCUMENT v3.7.0.1

Regulatory Requirements (Summary Of Capital, Capital Requirements And Excess Capital) (Details) $ in Millions	Jun. 30, 2017 USD ($)
Net Capital / Eligible Equity	$ 5,471
Required net capital	543
Excess regulatory capital	4,928
IB LLC [Member]
Net Capital / Eligible Equity	3,727
Required net capital	345
Excess regulatory capital	3,382
TH LLC [Member]
Net Capital / Eligible Equity	368
Required net capital	1
Excess regulatory capital	367
THE [Member]
Net Capital / Eligible Equity	619
Required net capital	104
Excess regulatory capital	515
Other Regulated Operating Companies [Member]
Net Capital / Eligible Equity	757
Required net capital	93
Excess regulatory capital	$ 664

X

- Definition

Eligible equity is equal to the sum of audited capital and reserves and the eligible portion of subordinated debt. Net capital is equal to the net worth of the broker dealer, less certain items such as exchange memberships, carrying value of securities not readily marketable, haircuts on marketable securities in proprietary accounts, furniture and equipment and other illiquid assets as defined.

+ References

No definition available.

+ Details

Name:	ibkr_NetCapitalEligibleEquity
Namespace Prefix:	ibkr_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

X

- Definition

The amount by which the company's Total Capital exceeds the minimum required for capital adequacy purposes.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 505
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=35709795&loc=SL5958568-112826

+ Details

Name:	us-gaap_ExcessCapital
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

X

- Definition

Minimum amount of net capital required to be maintained by the entity to engage in securities transactions.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Rule 15c3-1
-Number 240
-Section 15c3-1

+ Details

Name:	us-gaap_MinimumNetCapitalRequiredForEntity1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

X

- Details

Name:	ibkr_RegulatoryRequirementsAxis=ibkr_IBLLCMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	ibkr_RegulatoryRequirementsAxis=ibkr_THLLCMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	ibkr_RegulatoryRequirementsAxis=ibkr_THEMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	ibkr_RegulatoryRequirementsAxis=ibkr_OtherRegulatedOperatingCompaniesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: