XML 49 R38.htm IDEA: XBRL DOCUMENT
v3.20.2

Allowance for Credit Losses (Portfolio Credit Quality By Loan Class) (Details) $ in Thousands | 6 Months Ended |
--- | --- | ---
Jun. 30, 2020 USD ($) loan | Dec. 31, 2019 USD ($)
Loan portfolio by credit quality indicator |  |
Portfolio, total | $ 7,501,807 | $ 6,894,946
Number of additional relationships reclassified from Pass to Watch List - Substandard | loan | 2 |
Pass |  |
Loan portfolio by credit quality indicator |  |
Portfolio, total |  | 6,538,085
Special Review |  |
Loan portfolio by credit quality indicator |  |
Portfolio, total |  | 33,553
Watch List - Pass |  |
Loan portfolio by credit quality indicator |  |
Portfolio, total |  | 62,315
Watch List - Substandard |  |
Loan portfolio by credit quality indicator |  |
Portfolio, total |  | 248,318
Watch - List Impaired |  |
Loan portfolio by credit quality indicator |  |
Portfolio, total |  | 12,675
Commercial, financial and agricultural |  |
Loan portfolio by credit quality indicator |  |
Portfolio, total | $ 3,967,980 | 3,379,837
Commercial, financial and agricultural | Domestic | Commercial |  |
Loan portfolio by credit quality indicator |  |
Portfolio, total | 1,807,491 | 1,292,660
Commercial, financial and agricultural | Domestic | Commercial | Pass |  |
Loan portfolio by credit quality indicator |  |
Portfolio, total | 1,668,592 | 1,228,110
Commercial, financial and agricultural | Domestic | Commercial | Special Review |  |
Loan portfolio by credit quality indicator |  |
Portfolio, total | 72,066 | 569
Commercial, financial and agricultural | Domestic | Commercial | Watch List - Pass |  |
Loan portfolio by credit quality indicator |  |
Portfolio, total | 64,148 | 39
Commercial, financial and agricultural | Domestic | Commercial | Watch List - Substandard |  |
Loan portfolio by credit quality indicator |  |
Portfolio, total | 1,089 | 62,007
Commercial, financial and agricultural | Domestic | Commercial | Watch - List Impaired |  |
Loan portfolio by credit quality indicator |  |
Portfolio, total |  | 1,935
Commercial, financial and agricultural | Domestic | Commercial Real Estate: farmland and commercial |  |
Loan portfolio by credit quality indicator |  |
Portfolio, total | 1,971,634 | 1,896,747
Commercial, financial and agricultural | Domestic | Commercial Real Estate: farmland and commercial | Pass |  |
Loan portfolio by credit quality indicator |  |
Portfolio, total | 1,826,749 | 1,710,446
Commercial, financial and agricultural | Domestic | Commercial Real Estate: farmland and commercial | Special Review |  |
Loan portfolio by credit quality indicator |  |
Portfolio, total | 9,442 | 13,184
Commercial, financial and agricultural | Domestic | Commercial Real Estate: farmland and commercial | Watch List - Pass |  |
Loan portfolio by credit quality indicator |  |
Portfolio, total | 69,260 | 20,183
Commercial, financial and agricultural | Domestic | Commercial Real Estate: farmland and commercial | Watch List - Substandard |  |
Loan portfolio by credit quality indicator |  |
Portfolio, total | 65,647 | 151,726
Commercial, financial and agricultural | Domestic | Commercial Real Estate: farmland and commercial | Watch - List Impaired |  |
Loan portfolio by credit quality indicator |  |
Portfolio, total |  | 1,208
Commercial, financial and agricultural | Domestic | Commercial Real Estate: multifamily |  |
Loan portfolio by credit quality indicator |  |
Portfolio, total | 188,855 | 190,430
Commercial, financial and agricultural | Domestic | Commercial Real Estate: multifamily | Pass |  |
Loan portfolio by credit quality indicator |  |
Portfolio, total | 188,718 | 190,265
Commercial, financial and agricultural | Domestic | Commercial Real Estate: multifamily | Watch - List Impaired |  |
Loan portfolio by credit quality indicator |  |
Portfolio, total |  | 165
Real estate - construction |  |
Loan portfolio by credit quality indicator |  |
Portfolio, total | 2,277,991 | 2,185,883
Real estate - construction | Domestic | Commercial Real Estate: other construction and land development |  |
Loan portfolio by credit quality indicator |  |
Portfolio, total | 2,277,991 | 2,185,883
Real estate - construction | Domestic | Commercial Real Estate: other construction and land development | Pass |  |
Loan portfolio by credit quality indicator |  |
Portfolio, total | 2,216,065 | 2,090,370
Real estate - construction | Domestic | Commercial Real Estate: other construction and land development | Special Review |  |
Loan portfolio by credit quality indicator |  |
Portfolio, total | 16,106 | 18,721
Real estate - construction | Domestic | Commercial Real Estate: other construction and land development | Watch List - Pass |  |
Loan portfolio by credit quality indicator |  |
Portfolio, total | 44,530 | 41,949
Real estate - construction | Domestic | Commercial Real Estate: other construction and land development | Watch List - Substandard |  |
Loan portfolio by credit quality indicator |  |
Portfolio, total | 376 | 33,905
Real estate - construction | Domestic | Commercial Real Estate: other construction and land development | Watch - List Impaired |  |
Loan portfolio by credit quality indicator |  |
Portfolio, total |  | 938
Real estate - mortgage |  |
Loan portfolio by credit quality indicator |  |
Portfolio, total | 1,081,380 | 1,140,377
Real estate - mortgage | Domestic | Residential First Lien |  |
Loan portfolio by credit quality indicator |  |
Portfolio, total | 421,538 | 433,901
Real estate - mortgage | Domestic | Residential First Lien | Pass |  |
Loan portfolio by credit quality indicator |  |
Portfolio, total | 420,781 | 426,546
Real estate - mortgage | Domestic | Residential First Lien | Special Review |  |
Loan portfolio by credit quality indicator |  |
Portfolio, total | 245 | 253
Real estate - mortgage | Domestic | Residential First Lien | Watch List - Pass |  |
Loan portfolio by credit quality indicator |  |
Portfolio, total | 143 | 144
Real estate - mortgage | Domestic | Residential First Lien | Watch List - Substandard |  |
Loan portfolio by credit quality indicator |  |
Portfolio, total | 117 | 680
Real estate - mortgage | Domestic | Residential First Lien | Watch - List Impaired |  |
Loan portfolio by credit quality indicator |  |
Portfolio, total |  | 6,278
Real estate - mortgage | Domestic | Residential Junior Lien |  |
Loan portfolio by credit quality indicator |  |
Portfolio, total | 659,842 | 706,476
Real estate - mortgage | Domestic | Residential Junior Lien | Pass |  |
Loan portfolio by credit quality indicator |  |
Portfolio, total | 658,991 | 704,958
Real estate - mortgage | Domestic | Residential Junior Lien | Special Review |  |
Loan portfolio by credit quality indicator |  |
Portfolio, total | 810 | 826
Real estate - mortgage | Domestic | Residential Junior Lien | Watch - List Impaired |  |
Loan portfolio by credit quality indicator |  |
Portfolio, total |  | 692
Consumer |  |
Loan portfolio by credit quality indicator |  |
Portfolio, total | 42,401 | 47,800
Consumer | Domestic |  |
Loan portfolio by credit quality indicator |  |
Portfolio, total | 42,401 | 47,800
Consumer | Domestic | Pass |  |
Loan portfolio by credit quality indicator |  |
Portfolio, total | 42,398 | 46,605
Consumer | Domestic | Watch - List Impaired |  |
Loan portfolio by credit quality indicator |  |
Portfolio, total |  | 1,195
Foreign |  |
Loan portfolio by credit quality indicator |  |
Portfolio, total | 132,055 | 141,049
Foreign | Foreign |  |
Loan portfolio by credit quality indicator |  |
Portfolio, total | 132,055 | 141,049
Foreign | Foreign | Pass |  |
Loan portfolio by credit quality indicator |  |
Portfolio, total | $ 132,055 | 140,785
Foreign | Foreign | Watch - List Impaired |  |
Loan portfolio by credit quality indicator |  |
Portfolio, total |  | $ 264

X
- Definition The number of relationships that were reclassified from pass category to watch list - substandard category. + References No definition available. + Details
Name: | iboc_NumberOfRelationshipsReclassifiedFromPassToWatchListSubstandard
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/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 20 -Section 50 -Paragraph 5 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=119407570&loc=SL82919230-210447 + 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_FinancingReceivablePortfolioSegmentAxis=iboc_CommercialFinancialAndAgriculturalRealEstatePortfolioSegmentMember
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_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=us-gaap_CommercialLoanMember
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_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=iboc_CommercialRealEstateMultifamilyReceivableMember
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_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=us-gaap_ConstructionLoansMember
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_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=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: |