v2.4.0.8

Related Party Transactions (Details) (USD $) In Millions, unless otherwise specified	Jun. 30, 2014	Dec. 31, 2013
Related Party Transactions [Abstract]
Due from Related Parties - Customers	$ 1.8	$ 0.4
Due to Related Parties - Customers	$ 409.8	$ 815.5

X

- Definition

Carrying amount as of the balance sheet date of obligations due from all related parties and included in the 'receivable from customers' balance sheet line item.

+ References

No definition available.

+ Details

Name:	ibkr_DueFromRelatedPartiesCustomers
Namespace Prefix:	ibkr_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

X

- Definition

Carrying amount as of the balance sheet date of obligations due all related parties.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 235

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.4-08.(k)(1))

-URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690



Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 850

-SubTopic 10

-Section 50

-Paragraph 1

-Subparagraph (d)

-URI http://asc.fasb.org/extlink&oid=6457730&loc=d3e39549-107864



Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 08

-Paragraph k

-Subparagraph 1

-Article 4



Reference 4: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 944

-SubTopic 210

-Section S99

-Paragraph 1

-Subparagraph (SX 210.7-03.17)

-URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910



Reference 5: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 03

-Paragraph 17

-Article 7



Reference 6: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 942

-SubTopic 210

-Section S99

-Paragraph 1

-Subparagraph (SX 210.9-03.15(3),(4))

-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878



Reference 7: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 03

-Paragraph 15

-Subparagraph 3, 4

-Article 9

+ Details

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

X

- Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration