LOANS AND LEASES (Details 6) (BRL) In Millions	Dec. 31, 2009	Feb. 18, 2009
Contractually required payments (including interest)		4,116
Less: non-accretable difference		(2,882)
Cash flow expected to be collected representing undiscounted principal and interest at acquisition		1,234
Less: Accretable yield	144	(144)
Fair value of loans acquired		1,090

Accretable yield on credit impaired loans acquired under business combination.

Name:	itub_BusinessAcquisitionCreditImpairedLoansAccretableYield
Namespace Prefix:	itub
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

Contractually required payments (including interest) on credit impaired loans acquired under business combination.

Name:	itub_BusinessAcquisitionCreditImpairedLoansContractuallyRequiredPaymentsIncludingInterest
Namespace Prefix:	itub
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

Fair value of credit impaired loans acquired under business combination.

Name:	itub_BusinessAcquisitionCreditImpairedLoansFairValue
Namespace Prefix:	itub
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

Non-accretable difference on credit impaired loans acquired under business combination.

Name:	itub_BusinessAcquisitionCreditImpairedLoansNonAccretableDifference
Namespace Prefix:	itub
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

Undiscounted principal and interest at acquisition on credit impaired loans acquired under business combination.

Name:	itub_BusinessAcquisitionCreditImpairedLoansUndiscountedPrincipalAndInterestAtAcquisition
Namespace Prefix:	itub
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant