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The minimum number of non-employee members of the Board authorized to issue restricted stock units. The members are appointed by the Board each of whom is both a non-employee director and an outside director.

No definition available.

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Represents the compensation cost capitalized during the period arising from equity-based compensation arrangements (for example, shares of stock, units, stock options or other equity instruments) with employees, directors and certain consultants qualifying for treatment as employees.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (h)(1)(ii)
-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

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Aggregate cash paid by the entity during the period to settle equity instruments granted under equity-based payment arrangements.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (k)
-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

No definition available.

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Name:	iboc_CPPStatusAxis=iboc_CPPCompliantLongTermRSUGrantedForPerformanceIn2012Member
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Name:	iboc_CPPStatusAxis=iboc_CPPCompliantLongTermRSUGrantedForPerformanceIn2011Member
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Name:	iboc_CPPStatusAxis=iboc_CPPCompliantLongTermRSUGrantedForPerformanceIn2010Member
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