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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.

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- 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

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- 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

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