Name:	ibkr_OtherIncomeLoss
Namespace Prefix:	ibkr_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

Percentage of unvested shares to be received by employees over the age of 59 who discontinue employment with the Company without cause and continue to meet the terms of the plans' post-employment provisions.

No definition available.

Name:	ibkr_OverFiftyNinePercentUnvestedSharesEligible
Namespace Prefix:	ibkr_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

Percent Of Income Before Income Taxes

No definition available.

Name:	ibkr_PercentOfIncomeBeforeIncomeTaxes
Namespace Prefix:	ibkr_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

Percent Of Segment's Net Revenue

No definition available.

Name:	ibkr_PercentOfSegmentSNetRevenue
Namespace Prefix:	ibkr_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

Percent of segment's total assets

No definition available.

Name:	ibkr_PercentOfSegmentSTotalAssets
Namespace Prefix:	ibkr_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

Percentage of unvested shares forfeited by employees who discontinue employment with the Company without cause and continue to meet the terms of the plans' post-employment provisions.

No definition available.

Name:	ibkr_PercentSharesForfeitedPostEmployment
Namespace Prefix:	ibkr_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

Significant Accounting Policies [Line Items]

No definition available.

Name:	ibkr_SignificantAccountingPoliciesLineItems
Namespace Prefix:	ibkr_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

Percent of fair value of stock grant expensed during the first year of the grant for employees who are over fifty nine years old.

No definition available.

Name:	ibkr_StockGrantedExpenseOverFiftyNine
Namespace Prefix:	ibkr_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

Percent of fair value of stock grant expensed over the related vesting period utilizing the “graded vesting” method permitted under ASC Topic 718.

No definition available.

Name:	ibkr_StockGrantedExpenseRemainingVestingPeriod
Namespace Prefix:	ibkr_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

Percent of fair value of stock grant expensed in the year of the grant.

No definition available.

Name:	ibkr_StockGrantedExpenseYearOfGrant
Namespace Prefix:	ibkr_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

Useful life of finite-lived intangible assets, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

No definition available.

Name:	us-gaap_FiniteLivedIntangibleAssetUsefulLife
Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

Represents the total of noninterest income derived from certain activities and assets including (for example): (1) venture capital investments; (2) bank owned life insurance; (3) foreign currency transactions; and (4) mortgage servicing rights.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 220
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-04.13)
-URI http://asc.fasb.org/extlink&oid=116637391&loc=SL114874048-224260

Name:	us-gaap_NoninterestIncomeOther
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

Describes the periods of time over which an entity anticipates to receive utility from its property, plant and equipment (that is, the periods of time over which an entity allocates the initial cost of its property, plant and equipment).

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 360
-SubTopic 10
-Section 35
-Paragraph 4
-URI http://asc.fasb.org/extlink&oid=68071081&loc=d3e1205-110223

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section 50
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=84158767&loc=d3e18780-107790

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

Useful life of long lived, physical assets used in the normal conduct of business and not intended for resale, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. Examples include, but not limited to, land, buildings, machinery and equipment, office equipment, furniture and fixtures, and computer equipment.

No definition available.

Name:	us-gaap_PropertyPlantAndEquipmentUsefulLife
Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

Name:	srt_RestatementAxis=srt_RestatementAdjustmentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	srt_RangeAxis=srt_MaximumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_StatementBusinessSegmentsAxis=ibkr_MarketMakingMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_PropertyPlantAndEquipmentByTypeAxis=us-gaap_ComputerEquipmentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_PropertyPlantAndEquipmentByTypeAxis=ibkr_OfficeFurnitureAndEquipmentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_PropertyPlantAndEquipmentByTypeAxis=us-gaap_SoftwareAndSoftwareDevelopmentCostsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_PropertyPlantAndEquipmentByTypeAxis=us-gaap_FiniteLivedIntangibleAssetsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: