Subsequent Event (Details) (Lease, USD $)	1 Months Ended
Feb. 29, 2012 M Y sqft
Lease
Subsequent event
Square feet of office space under lease agreement	132,000
Term of lease (in years)	16
Period during which company will not be required to pay rent	12
Minimum rent payable per month for following 5 years of the initial term	$ 484,337
Period for minimum monthly rent, level one (in years)	5
Minimum monthly rent payable for 5 years thereafter	539,375
Period for minimum monthly rent, level two (in years)	5
Minimum rent per month through the expiration of the initial term	$ 594,414

Represents the term of lease agreement entered into by the entity.

No definition available.

Represents the level one term under lease term for minimum monthly rent payable by the entity.

No definition available.

Name:	itg_LeaseTermForMinimumMonthlyRentalLevelOne
Namespace Prefix:	itg_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

Represents the level two term under lease term for minimum monthly rent payable by the entity.

No definition available.

Name:	itg_LeaseTermForMinimumMonthlyRentalLevelTwo
Namespace Prefix:	itg_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

Represents the minimum monthly rent payable by the entity for level one term of the lease term.

No definition available.

Name:	itg_MinimumMonthlyRentalLevelOne
Namespace Prefix:	itg_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

Represents the minimum monthly rent payable by the entity for level three term of the lease term through expiration.

No definition available.

Name:	itg_MinimumMonthlyRentalLevelThreeThoughExpirationOfLeaseTerm
Namespace Prefix:	itg_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

Represents the minimum monthly rent payable by the entity for level two term of the lease term.

No definition available.

Name:	itg_MinimumMonthlyRentalLevelTwo
Namespace Prefix:	itg_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

Represents the period during which the entity is not required to pay rent under the lease.

No definition available.

The amount of square footage related to a real estate property.

No definition available.

Name:	us-gaap_SquareFootageOfRealEstateProperty
Namespace Prefix:	us-gaap_
Data Type:	xbrli:decimalItemType
Balance Type:	na
Period Type:	duration

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