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Regulatory Requirements (Summary Of Capital, Capital Requirements And Excess Capital) (Details) $ in Millions	Dec. 31, 2017 USD ($)
Net Capital / Eligible Equity	$ 5,214
Required net capital	709
Excess regulatory capital	4,505
IB LLC [Member]
Net Capital / Eligible Equity	3,548
Required net capital	495
Excess regulatory capital	3,053
TH LLC [Member]
Net Capital / Eligible Equity	279
Required net capital	1
Excess regulatory capital	278
THE [Member]
Net Capital / Eligible Equity	614
Required net capital	92
Excess regulatory capital	522
Other Regulated Operating Companies [Member]
Net Capital / Eligible Equity	773
Required net capital	121
Excess regulatory capital	$ 652

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

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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=84167132&loc=SL5958568-112826

+ Details

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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

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- Details

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- Details

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- Details

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