XML 82 R66.htm IDEA: XBRL DOCUMENT
v3.20.4

Allowance for Credit Losses (Portfolio Credit Quality By Loan Class) (Details) $ in Thousands | 12 Months Ended |
--- | --- | ---
Dec. 31, 2020 USD ($) item | Dec. 31, 2019 USD ($)
Loan portfolio by credit quality indicator |  |
Portfolio, total | $ 7,541,754 | $ 6,894,946
Pass [Member] |  |
Loan portfolio by credit quality indicator |  |
Portfolio, total |  | 6,538,085
Special Mention [Member] |  |
Loan portfolio by credit quality indicator |  |
Portfolio, total |  | 33,553
Special Pass [Member] |  |
Loan portfolio by credit quality indicator |  |
Portfolio, total |  | 62,315
Substandard [Member] |  |
Loan portfolio by credit quality indicator |  |
Portfolio, total |  | 248,318
Nonperforming Financing Receivable [Member] |  |
Loan portfolio by credit quality indicator |  |
Portfolio, total |  | 12,675
Commercial Loan [Member] |  |
Loan portfolio by credit quality indicator |  |
Number of additional relationships reclassified from Pass to Watch List - Pass | item | 2 |
Number of relationships secured by oil and gas properties reclassified from pass to watch list pass | item | 1 |
Number of relationships secured by accounts receivable and inventory that were reclassified from pass category to watch list - pass | item | 1 |
Commercial Real Estate: other construction and land development |  |
Loan portfolio by credit quality indicator |  |
Number of relationships secured by real estate planned for lot development that were reclassified from Watch List pass category to special review category. | item | 1 |
Number of relationships secured by commercial property that were reclassified from Watch List pass category to special review category. | item | 1 |
Number of relationships secured by commercial real estate that were reclassified from Watch List pass category to special review category. | item | 1 |
Commercial Real Estate Farmland and Commercial Receivable [Member] |  |
Loan portfolio by credit quality indicator |  |
Number of relationships secured by commercial real estate that were reclassified from Pass category. | item | 2 |
Domestic | Commercial Loan [Member] |  |
Loan portfolio by credit quality indicator |  |
Portfolio, total | $ 1,785,936 |
Domestic | Commercial Loan [Member] | Pass [Member] |  |
Loan portfolio by credit quality indicator |  |
Portfolio, total | 1,664,545 | 1,228,110
Domestic | Commercial Loan [Member] | Special Mention [Member] |  |
Loan portfolio by credit quality indicator |  |
Portfolio, total | 75,638 | 569
Domestic | Commercial Loan [Member] | Special Pass [Member] |  |
Loan portfolio by credit quality indicator |  |
Portfolio, total | 39,917 | 39
Domestic | Commercial Loan [Member] | Substandard [Member] |  |
Loan portfolio by credit quality indicator |  |
Portfolio, total | 4,647 | 62,007
Domestic | Commercial Loan [Member] | Watch List - Doubtful |  |
Loan portfolio by credit quality indicator |  |
Portfolio, total | 1,189 |
Domestic | Commercial Loan [Member] | Nonperforming Financing Receivable [Member] |  |
Loan portfolio by credit quality indicator |  |
Portfolio, total |  | 1,935
Domestic | Commercial Real Estate: other construction and land development |  |
Loan portfolio by credit quality indicator |  |
Portfolio, total | 1,846,757 |
Domestic | Commercial Real Estate: other construction and land development | Pass [Member] |  |
Loan portfolio by credit quality indicator |  |
Portfolio, total | 1,762,231 |
Domestic | Commercial Real Estate: other construction and land development | Special Mention [Member] |  |
Loan portfolio by credit quality indicator |  |
Portfolio, total | 42,478 |
Domestic | Commercial Real Estate: other construction and land development | Special Pass [Member] |  |
Loan portfolio by credit quality indicator |  |
Portfolio, total | 24,552 |
Domestic | Commercial Real Estate: other construction and land development | Watch List - Doubtful |  |
Loan portfolio by credit quality indicator |  |
Portfolio, total | 17,496 |
Domestic | Commercial Real Estate Farmland and Commercial Receivable [Member] |  |
Loan portfolio by credit quality indicator |  |
Portfolio, total | 2,289,308 |
Domestic | Commercial Real Estate Farmland and Commercial Receivable [Member] | Pass [Member] |  |
Loan portfolio by credit quality indicator |  |
Portfolio, total | 2,153,199 | 1,710,446
Domestic | Commercial Real Estate Farmland and Commercial Receivable [Member] | Special Mention [Member] |  |
Loan portfolio by credit quality indicator |  |
Portfolio, total | 11,194 | 13,184
Domestic | Commercial Real Estate Farmland and Commercial Receivable [Member] | Special Pass [Member] |  |
Loan portfolio by credit quality indicator |  |
Portfolio, total | 62,936 | 20,183
Domestic | Commercial Real Estate Farmland and Commercial Receivable [Member] | Substandard [Member] |  |
Loan portfolio by credit quality indicator |  |
Portfolio, total | 61,540 | 151,726
Domestic | Commercial Real Estate Farmland and Commercial Receivable [Member] | Watch List - Doubtful |  |
Loan portfolio by credit quality indicator |  |
Portfolio, total | 439 |
Domestic | Commercial Real Estate Farmland and Commercial Receivable [Member] | Nonperforming Financing Receivable [Member] |  |
Loan portfolio by credit quality indicator |  |
Portfolio, total |  | 1,208
Domestic | Commercial Real Estate Multifamily Receivable [Member] |  |
Loan portfolio by credit quality indicator |  |
Portfolio, total | 441,044 |
Domestic | Commercial Real Estate Multifamily Receivable [Member] | Pass [Member] |  |
Loan portfolio by credit quality indicator |  |
Portfolio, total | 440,910 | 190,265
Domestic | Commercial Real Estate Multifamily Receivable [Member] | Watch List - Doubtful |  |
Loan portfolio by credit quality indicator |  |
Portfolio, total | 134 |
Domestic | Commercial Real Estate Multifamily Receivable [Member] | Nonperforming Financing Receivable [Member] |  |
Loan portfolio by credit quality indicator |  |
Portfolio, total |  | 165
Domestic | Residential First Mortgage Financing Receivable [Member] |  |
Loan portfolio by credit quality indicator |  |
Portfolio, total | 405,119 |
Domestic | Residential First Mortgage Financing Receivable [Member] | Pass [Member] |  |
Loan portfolio by credit quality indicator |  |
Portfolio, total | 404,774 | 426,546
Domestic | Residential First Mortgage Financing Receivable [Member] | Special Mention [Member] |  |
Loan portfolio by credit quality indicator |  |
Portfolio, total |  | 253
Domestic | Residential First Mortgage Financing Receivable [Member] | Special Pass [Member] |  |
Loan portfolio by credit quality indicator |  |
Portfolio, total | 145 | 144
Domestic | Residential First Mortgage Financing Receivable [Member] | Substandard [Member] |  |
Loan portfolio by credit quality indicator |  |
Portfolio, total | 49 | 680
Domestic | Residential First Mortgage Financing Receivable [Member] | Watch List - Doubtful |  |
Loan portfolio by credit quality indicator |  |
Portfolio, total | 151 |
Domestic | Residential First Mortgage Financing Receivable [Member] | Nonperforming Financing Receivable [Member] |  |
Loan portfolio by credit quality indicator |  |
Portfolio, total |  | 6,278
Domestic | Residential Junior Lien |  |
Loan portfolio by credit quality indicator |  |
Portfolio, total | 594,025 |
Domestic | Residential Junior Lien | Pass [Member] |  |
Loan portfolio by credit quality indicator |  |
Portfolio, total | 592,435 | 704,958
Domestic | Residential Junior Lien | Special Mention [Member] |  |
Loan portfolio by credit quality indicator |  |
Portfolio, total | 1,552 | 826
Domestic | Residential Junior Lien | Watch List - Doubtful |  |
Loan portfolio by credit quality indicator |  |
Portfolio, total | 38 |
Domestic | Residential Junior Lien | Nonperforming Financing Receivable [Member] |  |
Loan portfolio by credit quality indicator |  |
Portfolio, total |  | 692
Commercial, financial and agricultural |  |
Loan portfolio by credit quality indicator |  |
Portfolio, total | 4,516,288 | 3,379,837
Commercial, financial and agricultural | Domestic | Commercial Loan [Member] |  |
Loan portfolio by credit quality indicator |  |
Portfolio, total | 1,785,936 | 1,292,660
Commercial, financial and agricultural | Domestic | Commercial Real Estate Farmland and Commercial Receivable [Member] |  |
Loan portfolio by credit quality indicator |  |
Portfolio, total | 2,289,308 | 1,896,747
Commercial, financial and agricultural | Domestic | Commercial Real Estate Multifamily Receivable [Member] |  |
Loan portfolio by credit quality indicator |  |
Portfolio, total | 441,044 | 190,430
Commercial Real Estate Portfolio Segment [Member] |  |
Loan portfolio by credit quality indicator |  |
Portfolio, total | 1,846,757 | 2,185,883
Commercial Real Estate Portfolio Segment [Member] | Domestic | Commercial Real Estate: other construction and land development |  |
Loan portfolio by credit quality indicator |  |
Portfolio, total | 1,846,757 | 2,185,883
Commercial Real Estate Portfolio Segment [Member] | Domestic | Commercial Real Estate: other construction and land development | Pass [Member] |  |
Loan portfolio by credit quality indicator |  |
Portfolio, total |  | 2,090,370
Commercial Real Estate Portfolio Segment [Member] | Domestic | Commercial Real Estate: other construction and land development | Special Mention [Member] |  |
Loan portfolio by credit quality indicator |  |
Portfolio, total |  | 18,721
Commercial Real Estate Portfolio Segment [Member] | Domestic | Commercial Real Estate: other construction and land development | Special Pass [Member] |  |
Loan portfolio by credit quality indicator |  |
Portfolio, total |  | 41,949
Commercial Real Estate Portfolio Segment [Member] | Domestic | Commercial Real Estate: other construction and land development | Substandard [Member] |  |
Loan portfolio by credit quality indicator |  |
Portfolio, total |  | 33,905
Commercial Real Estate Portfolio Segment [Member] | Domestic | Commercial Real Estate: other construction and land development | Nonperforming Financing Receivable [Member] |  |
Loan portfolio by credit quality indicator |  |
Portfolio, total |  | 938
Real estate - mortgage |  |
Loan portfolio by credit quality indicator |  |
Portfolio, total | 999,144 | 1,140,377
Real estate - mortgage | Domestic | Residential First Mortgage Financing Receivable [Member] |  |
Loan portfolio by credit quality indicator |  |
Portfolio, total | 405,119 | 433,901
Real estate - mortgage | Domestic | Residential Junior Lien |  |
Loan portfolio by credit quality indicator |  |
Portfolio, total | 594,025 | 706,476
Consumer |  |
Loan portfolio by credit quality indicator |  |
Portfolio, total | 40,595 | 47,800
Consumer | Domestic |  |
Loan portfolio by credit quality indicator |  |
Portfolio, total | 40,595 | 47,800
Consumer | Domestic | Pass [Member] |  |
Loan portfolio by credit quality indicator |  |
Portfolio, total | 40,595 | 46,605
Consumer | Domestic | Nonperforming Financing Receivable [Member] |  |
Loan portfolio by credit quality indicator |  |
Portfolio, total |  | 1,195
Foreign |  |
Loan portfolio by credit quality indicator |  |
Portfolio, total | 138,970 | 141,049
Foreign | Foreign |  |
Loan portfolio by credit quality indicator |  |
Portfolio, total | 138,970 | 141,049
Foreign | Foreign | Pass [Member] |  |
Loan portfolio by credit quality indicator |  |
Portfolio, total | $ 138,970 | 140,785
Foreign | Foreign | Nonperforming Financing Receivable [Member] |  |
Loan portfolio by credit quality indicator |  |
Portfolio, total |  | $ 264

X
- Definition The number of relationships that were reclassified from pass category to watch list - pass category. + References No definition available. + Details
Name: | iboc_NumberOfRelationshipsReclassifiedFromPassToWatchListPass
Namespace Prefix: | iboc_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | duration

X
- Definition The number of relationships secured by accounts receivable and inventory that were reclassified from pass category to watch list - pass category. + References No definition available. + Details
Name: | iboc_NumberOfRelationshipsSecuredByAccountsReceivableAndInventoryReclassifiedFromPassToWatchListPass
Namespace Prefix: | iboc_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | duration

X
- Definition The number of relationships secured by commercial property that were reclassified from Watch List pass category to special review category. + References No definition available. + Details
Name: | iboc_NumberOfRelationshipsSecuredByCommercialPropertyThatWereReclassifiedFromWatchListPassCategoryToSpecialReviewCategory.
Namespace Prefix: | iboc_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | duration

X
- Definition The number of relationships secured by commercial real estate that were reclassified from Pass category. + References No definition available. + Details
Name: | iboc_NumberOfRelationshipsSecuredByCommercialRealEstateThatWereReclassifiedFromPassCategory.
Namespace Prefix: | iboc_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | duration

X
- Definition The number of relationships secured by commercial real estate that were reclassified from Watch List pass category to special review category. + References No definition available. + Details
Name: | iboc_NumberOfRelationshipsSecuredByCommercialRealEstateThatWereReclassifiedFromWatchListPassCategoryToSpecialReviewCategory.
Namespace Prefix: | iboc_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | duration

X
- Definition The number of relationships secured by oil and gas properties that were reclassified from pass category to watch list - pass category. + References No definition available. + Details
Name: | iboc_NumberOfRelationshipsSecuredByOilAndGasPropertiesReclassifiedFromPassToWatchListPass
Namespace Prefix: | iboc_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | duration

X
- Definition The number of relationships secured by real estate planned for lot development that were reclassified from Watch List pass category to special review category. + References No definition available. + Details
Name: | iboc_NumberOfRelationshipsSecuredByRealEstatePlannedForLotDevelopmentThatWereReclassifiedFromWatchListPassCategoryToSpecialReviewCategory.
Namespace Prefix: | iboc_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | duration

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 for credit loss, of financing receivable. + References Reference 1: http://www.xbrl.org/2003/role/exampleRef -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 20 -Section 55 -Paragraph 79 -URI http://asc.fasb.org/extlink&oid=121647567&loc=SL82922352-210448 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 20 -Section 50 -Paragraph 5 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=121599337&loc=SL82919230-210447 Reference 3: http://www.xbrl.org/2003/role/exampleRef -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 20 -Section 55 -Paragraph 80 -URI http://asc.fasb.org/extlink&oid=121647567&loc=SL82922355-210448 + Details
Name: | us-gaap_NotesReceivableGross
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_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=us-gaap_CommercialLoanMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=us-gaap_ConstructionLoansMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

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

X
- Details
Name: | us-gaap_GeographicDistributionAxis=us-gaap_GeographicDistributionDomesticMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

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

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

X
- Details
Name: | us-gaap_LienCategoryAxis=us-gaap_SeniorLienMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_LienCategoryAxis=us-gaap_JuniorLienMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancingReceivablePortfolioSegmentAxis=iboc_CommercialFinancialAndAgriculturalRealEstatePortfolioSegmentMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancingReceivablePortfolioSegmentAxis=us-gaap_CommercialRealEstatePortfolioSegmentMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancingReceivablePortfolioSegmentAxis=us-gaap_ResidentialPortfolioSegmentMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancingReceivablePortfolioSegmentAxis=us-gaap_ConsumerPortfolioSegmentMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancingReceivablePortfolioSegmentAxis=iboc_ForeignPortfolioSegmentMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_GeographicDistributionAxis=us-gaap_GeographicDistributionForeignMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |