XML 82 R71.htm IDEA: XBRL DOCUMENT
v3.25.3

Regulatory Requirements (Summary Of Capital, Capital Requirements And Excess Capital) (Details) $ in Millions | Sep. 30, 2025 USD ($)
--- | ---
Net Capital / Eligible Equity | $ 16,472
Requirement | 2,781
Excess | 13,691
IB LLC [Member] |
Net Capital / Eligible Equity | 10,443
Requirement | 1,628
Excess | 8,815
IBHK [Member] |
Net Capital / Eligible Equity | 1,553
Requirement | 592
Excess | 961
IBIE [Member] |
Net Capital / Eligible Equity | 1,696
Requirement | 382
Excess | 1,314
Other Regulated Operating Companies [Member] |
Net Capital / Eligible Equity | 2,780
Requirement | 179
Excess | $ 2,601

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 Minimum amount of net capital required to be maintained by broker-dealer parent, calculated under Aggregate Indebtedness Standard. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Name Rule 15c3-1 -Number 240 -Section 15c3-1 -Publisher SEC + Details
Name: | srt_MinimumNetCapitalRequiredForEntity1
Namespace Prefix: | srt_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Amount of total risk-based capital exceeding minimum required for capital adequacy as defined by regulatory framework. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 942 -SubTopic 505 -Name Accounting Standards Codification -Section 50 -Paragraph 1 -Subparagraph (c)(1) -Publisher FASB -URI https://asc.fasb.org/1943274/2147477270/942-505-50-1 + Details
Name: | us-gaap_ExcessCapital
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Details
Name: | dei_LegalEntityAxis=ibkr_IBLLCMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | dei_LegalEntityAxis=ibkr_IbhkMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | dei_LegalEntityAxis=ibkr_IbieMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | dei_LegalEntityAxis=ibkr_OtherRegulatedOperatingCompaniesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |