XML 45 R34.htm IDEA: XBRL DOCUMENT
v3.5.0.2

Allowance for Probable Loan Losses (Non-accrual Basis By Loan Class) (Details) - USD ($) $ in Thousands | Sep. 30, 2016 | Dec. 31, 2015
--- | --- | ---
Loan loss allowances, financing receivable past due |  |
Non-accrual loans, total | $ 35,067 | $ 47,685
Commercial |  |
Loan loss allowances, financing receivable past due |  |
Non-accrual loans, total | 21,886 | 30,894
Commercial Real Estate: Other Construction and Land Development |  |
Loan loss allowances, financing receivable past due |  |
Non-accrual loans, total | 3,017 | 3,668
Commercial Real Estate: Farmland & Commercial |  |
Loan loss allowances, financing receivable past due |  |
Non-accrual loans, total | 8,235 | 11,543
Commercial Real Estate: Multifamily |  |
Loan loss allowances, financing receivable past due |  |
Non-accrual loans, total | 571 | 777
Residential First Lien |  |
Loan loss allowances, financing receivable past due |  |
Non-accrual loans, total | 792 | 383
Residential Junior Lien |  |
Loan loss allowances, financing receivable past due |  |
Non-accrual loans, total | 178 | 21
Consumer |  |
Loan loss allowances, financing receivable past due |  |
Non-accrual loans, total | 2 | 34
Foreign |  |
Loan loss allowances, financing receivable past due |  |
Non-accrual loans, total | $ 386 | $ 365

X
- Definition Recorded investment in financing receivables that are on nonaccrual status as of the balance sheet date. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Glossary Recorded Investment -URI http://asc.fasb.org/extlink&oid=65880944 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 7 -Subparagraph (d) -URI http://asc.fasb.org/extlink&oid=66008989&loc=d3e5111-111524 + Details
Name: | us-gaap_FinancingReceivableRecordedInvestmentNonaccrualStatus
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

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_FinancingReceivableRecordedInvestmentPastDueLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

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: |