XML 68 R57.htm IDEA: XBRL DOCUMENT
v3.5.0.2

Regulatory Requirements (Summary Of Capital, Capital Requirements And Excess Capital) (Details) $ in Millions | Sep. 30, 2016 USD ($)
--- | ---
Net Capital / Eligible Equity | $ 4,817
Required net capital | 586
Excess regulatory capital | 4,231
IB LLC [Member] |
Net Capital / Eligible Equity | 3,217
Required net capital | 325
Excess regulatory capital | 2,892
TH LLC [Member] |
Net Capital / Eligible Equity | 318
Required net capital | 1
Excess regulatory capital | 317
THE [Member] |
Net Capital / Eligible Equity | 603
Required net capital | 181
Excess regulatory capital | 422
Other Regulated Operating Companies [Member] |
Net Capital / Eligible Equity | 679
Required net capital | 79
Excess regulatory capital | $ 600

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: |