XML 19 R37.htm IDEA: XBRL DOCUMENT
v3.2.0.727

Allowance for Probable Loan Losses (Details 6) - USD ($) $ in Thousands | Jun. 30, 2015 | Dec. 31, 2014
--- | --- | ---
Loan portfolio by credit quality indicator |  |
Portfolio, total | $ 5,774,462 | $ 5,679,245
Pass |  |
Loan portfolio by credit quality indicator |  |
Portfolio, total | 5,436,564 | 5,328,410
Special Review |  |
Loan portfolio by credit quality indicator |  |
Portfolio, total | 4,734 | 54,561
Watch List - Pass |  |
Loan portfolio by credit quality indicator |  |
Portfolio, total | 49,174 | 37,674
Watch List - Substandard |  |
Loan portfolio by credit quality indicator |  |
Portfolio, total | 225,459 | 182,429
Watch List - Impaired |  |
Loan portfolio by credit quality indicator |  |
Portfolio, total | 58,531 | 76,171
Commercial |  |
Loan portfolio by credit quality indicator |  |
Portfolio, total | 1,030,568 | 1,089,486
Commercial | Pass |  |
Loan portfolio by credit quality indicator |  |
Portfolio, total | 892,149 | 961,490
Commercial | Special Review |  |
Loan portfolio by credit quality indicator |  |
Portfolio, total |  | 38,382
Commercial | Watch List - Pass |  |
Loan portfolio by credit quality indicator |  |
Portfolio, total | 23,033 | 3,793
Commercial | Watch List - Substandard |  |
Loan portfolio by credit quality indicator |  |
Portfolio, total | 82,188 | 45,646
Commercial | Watch List - Impaired |  |
Loan portfolio by credit quality indicator |  |
Portfolio, total | 33,198 | 40,175
Commercial Real Estate: Other Construction and Land Development |  |
Loan portfolio by credit quality indicator |  |
Portfolio, total | 1,556,880 | 1,414,977
Commercial Real Estate: Other Construction and Land Development | Pass |  |
Loan portfolio by credit quality indicator |  |
Portfolio, total | 1,505,229 | 1,353,971
Commercial Real Estate: Other Construction and Land Development | Special Review |  |
Loan portfolio by credit quality indicator |  |
Portfolio, total | 331 | 1,005
Commercial Real Estate: Other Construction and Land Development | Watch List - Pass |  |
Loan portfolio by credit quality indicator |  |
Portfolio, total | 5,995 | 10,428
Commercial Real Estate: Other Construction and Land Development | Watch List - Substandard |  |
Loan portfolio by credit quality indicator |  |
Portfolio, total | 38,637 | 38,697
Commercial Real Estate: Other Construction and Land Development | Watch List - Impaired |  |
Loan portfolio by credit quality indicator |  |
Portfolio, total | 6,688 | 10,876
Commercial real estate: farmland and commercial |  |
Loan portfolio by credit quality indicator |  |
Portfolio, total | 1,917,665 | 1,901,399
Commercial real estate: farmland and commercial | Pass |  |
Loan portfolio by credit quality indicator |  |
Portfolio, total | 1,783,224 | 1,754,741
Commercial real estate: farmland and commercial | Special Review |  |
Loan portfolio by credit quality indicator |  |
Portfolio, total | 4,403 | 11,674
Commercial real estate: farmland and commercial | Watch List - Pass |  |
Loan portfolio by credit quality indicator |  |
Portfolio, total | 19,654 | 23,453
Commercial real estate: farmland and commercial | Watch List - Substandard |  |
Loan portfolio by credit quality indicator |  |
Portfolio, total | 100,755 | 97,365
Commercial real estate: farmland and commercial | Watch List - Impaired |  |
Loan portfolio by credit quality indicator |  |
Portfolio, total | 9,629 | 14,166
Commercial real estate: multifamily |  |
Loan portfolio by credit quality indicator |  |
Portfolio, total | 94,003 | 116,699
Commercial real estate: multifamily | Pass |  |
Loan portfolio by credit quality indicator |  |
Portfolio, total | 93,041 | 115,729
Commercial real estate: multifamily | Watch List - Substandard |  |
Loan portfolio by credit quality indicator |  |
Portfolio, total | 135 | 135
Commercial real estate: multifamily | Watch List - Impaired |  |
Loan portfolio by credit quality indicator |  |
Portfolio, total | 827 | 835
Residential: first lien |  |
Loan portfolio by credit quality indicator |  |
Portfolio, total | 414,463 | 422,026
Residential: first lien | Pass |  |
Loan portfolio by credit quality indicator |  |
Portfolio, total | 405,116 | 412,668
Residential: first lien | Special Review |  |
Loan portfolio by credit quality indicator |  |
Portfolio, total |  | 3,500
Residential: first lien | Watch List - Pass |  |
Loan portfolio by credit quality indicator |  |
Portfolio, total | 492 |
Residential: first lien | Watch List - Substandard |  |
Loan portfolio by credit quality indicator |  |
Portfolio, total | 3,483 | 18
Residential: first lien | Watch List - Impaired |  |
Loan portfolio by credit quality indicator |  |
Portfolio, total | 5,372 | 5,840
Residential: junior lien |  |
Loan portfolio by credit quality indicator |  |
Portfolio, total | 513,767 | 488,300
Residential: junior lien | Pass |  |
Loan portfolio by credit quality indicator |  |
Portfolio, total | 512,246 | 484,968
Residential: junior lien | Watch List - Substandard |  |
Loan portfolio by credit quality indicator |  |
Portfolio, total | 261 | 437
Residential: junior lien | Watch List - Impaired |  |
Loan portfolio by credit quality indicator |  |
Portfolio, total | 1,260 | 2,895
Consumer |  |
Loan portfolio by credit quality indicator |  |
Portfolio, total | 57,966 | 61,137
Consumer | Pass |  |
Loan portfolio by credit quality indicator |  |
Portfolio, total | 56,808 | 59,622
Consumer | Watch List - Substandard |  |
Loan portfolio by credit quality indicator |  |
Portfolio, total |  | 131
Consumer | Watch List - Impaired |  |
Loan portfolio by credit quality indicator |  |
Portfolio, total | 1,158 | 1,384
Foreign |  |
Loan portfolio by credit quality indicator |  |
Portfolio, total | 189,150 | 185,221
Foreign | Pass |  |
Loan portfolio by credit quality indicator |  |
Portfolio, total | 188,751 | $ 185,221
Foreign | Watch List - Impaired |  |
Loan portfolio by credit quality indicator |  |
Portfolio, total | $ 399 |

X
- Definition 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. + References No definition available. + Details
Name: | us-gaap_FinancingReceivableRecordedInvestmentLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Amount before allowance and after deduction of deferred interest and fees, unamortized costs and premiums and discounts from face amounts, of loans and leases held in portfolio, including but not limited to, commercial and consumer loans. Excludes loans and leases covered under loss sharing agreements. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 45 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=28367877&loc=d3e4428-111522 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 4 -URI http://asc.fasb.org/extlink&oid=35738203&loc=d3e5074-111524 + Details
Name: | us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Details
Name: | us-gaap_InternalCreditAssessmentAxis=us-gaap_PassMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_InternalCreditAssessmentAxis=us-gaap_SpecialMentionMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_InternalCreditAssessmentAxis=iboc_SpecialPassMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_InternalCreditAssessmentAxis=us-gaap_SubstandardMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_InternalCreditAssessmentAxis=us-gaap_NonperformingFinancingReceivableMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis=us-gaap_CommercialLoanMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis=iboc_CommercialRealEstateOtherConstructionAndLandDevelopmentReceivableMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis=iboc_CommercialRealEstateFarmlandAndCommercialReceivableMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis=iboc_CommercialRealEstateMultifamilyReceivableMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis=iboc_ResidentialFirstMortgageFinancingReceivableMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis=iboc_ResidentialSecondMortgageFinancingReceivableMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis=us-gaap_ConsumerLoanMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis=iboc_ForeignReceivablesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |