XML 47 R36.htm IDEA: XBRL DOCUMENT
v3.21.2

Allowance for Credit Losses (Aging By Loan Class) (Details) - USD ($) $ in Thousands | Sep. 30, 2021 | Dec. 31, 2020
--- | --- | ---
Financing receivable recorded investment |  |
Past due 90 days or Greater and Still Accruing | $ 7,072 | $ 8,238
Loans | 7,404,158 | 7,541,754
Current |  |
Financing receivable recorded investment |  |
Loans | 7,354,539 | 7,503,496
Total Past Due |  |
Financing receivable recorded investment |  |
Loans | 49,619 | 38,258
30 to 59 Days |  |
Financing receivable recorded investment |  |
Loans | 37,343 | 9,307
60 to 89 Days |  |
Financing receivable recorded investment |  |
Loans | 4,824 | 3,606
90 Days or Greater |  |
Financing receivable recorded investment |  |
Loans | 7,452 | 25,345
Commercial, financial and agricultural |  |
Financing receivable recorded investment |  |
Loans | 4,680,091 | 4,516,288
Commercial, financial and agricultural | Domestic | Commercial Loan [Member] |  |
Financing receivable recorded investment |  |
Past due 90 days or Greater and Still Accruing | 89 | 318
Loans | 1,596,849 | 1,785,936
Commercial, financial and agricultural | Domestic | Commercial Loan [Member] | Current |  |
Financing receivable recorded investment |  |
Loans | 1,591,416 | 1,782,333
Commercial, financial and agricultural | Domestic | Commercial Loan [Member] | Total Past Due |  |
Financing receivable recorded investment |  |
Loans | 5,433 | 3,603
Commercial, financial and agricultural | Domestic | Commercial Loan [Member] | 30 to 59 Days |  |
Financing receivable recorded investment |  |
Loans | 5,123 | 1,931
Commercial, financial and agricultural | Domestic | Commercial Loan [Member] | 60 to 89 Days |  |
Financing receivable recorded investment |  |
Loans | 221 | 1,109
Commercial, financial and agricultural | Domestic | Commercial Loan [Member] | 90 Days or Greater |  |
Financing receivable recorded investment |  |
Loans | 89 | 563
Commercial, financial and agricultural | Domestic | Commercial Real Estate Farmland and Commercial Receivable [Member] |  |
Financing receivable recorded investment |  |
Past due 90 days or Greater and Still Accruing |  | 186
Loans | 2,716,077 | 2,289,308
Commercial, financial and agricultural | Domestic | Commercial Real Estate Farmland and Commercial Receivable [Member] | Current |  |
Financing receivable recorded investment |  |
Loans | 2,707,253 | 2,286,468
Commercial, financial and agricultural | Domestic | Commercial Real Estate Farmland and Commercial Receivable [Member] | Total Past Due |  |
Financing receivable recorded investment |  |
Loans | 8,824 | 2,840
Commercial, financial and agricultural | Domestic | Commercial Real Estate Farmland and Commercial Receivable [Member] | 30 to 59 Days |  |
Financing receivable recorded investment |  |
Loans | 6,535 | 2,435
Commercial, financial and agricultural | Domestic | Commercial Real Estate Farmland and Commercial Receivable [Member] | 60 to 89 Days |  |
Financing receivable recorded investment |  |
Loans | 2,104 | 219
Commercial, financial and agricultural | Domestic | Commercial Real Estate Farmland and Commercial Receivable [Member] | 90 Days or Greater |  |
Financing receivable recorded investment |  |
Loans | 185 | 186
Commercial, financial and agricultural | Domestic | Commercial Real Estate Multifamily Receivable [Member] |  |
Financing receivable recorded investment |  |
Loans | 367,165 | 441,044
Commercial, financial and agricultural | Domestic | Commercial Real Estate Multifamily Receivable [Member] | Current |  |
Financing receivable recorded investment |  |
Loans | 367,165 | 440,918
Commercial, financial and agricultural | Domestic | Commercial Real Estate Multifamily Receivable [Member] | Total Past Due |  |
Financing receivable recorded investment |  |
Loans |  | 126
Commercial, financial and agricultural | Domestic | Commercial Real Estate Multifamily Receivable [Member] | 30 to 59 Days |  |
Financing receivable recorded investment |  |
Loans |  | 126
Commercial Real Estate Portfolio Segment [Member] |  |
Financing receivable recorded investment |  |
Loans | 1,671,212 | 1,846,757
Commercial Real Estate Portfolio Segment [Member] | Domestic | Commercial Real Estate: other construction and land development |  |
Financing receivable recorded investment |  |
Loans | 1,671,212 | 1,846,757
Commercial Real Estate Portfolio Segment [Member] | Domestic | Commercial Real Estate: other construction and land development | Current |  |
Financing receivable recorded investment |  |
Loans | 1,649,591 | 1,828,257
Commercial Real Estate Portfolio Segment [Member] | Domestic | Commercial Real Estate: other construction and land development | Total Past Due |  |
Financing receivable recorded investment |  |
Loans | 21,621 | 18,500
Commercial Real Estate Portfolio Segment [Member] | Domestic | Commercial Real Estate: other construction and land development | 30 to 59 Days |  |
Financing receivable recorded investment |  |
Loans | 21,433 | 1,059
Commercial Real Estate Portfolio Segment [Member] | Domestic | Commercial Real Estate: other construction and land development | 60 to 89 Days |  |
Financing receivable recorded investment |  |
Loans | 188 | 854
Commercial Real Estate Portfolio Segment [Member] | Domestic | Commercial Real Estate: other construction and land development | 90 Days or Greater |  |
Financing receivable recorded investment |  |
Loans |  | 16,587
Real estate - mortgage |  |
Financing receivable recorded investment |  |
Loans | 876,313 | 999,144
Real estate - mortgage | Domestic | Residential First Mortgage Financing Receivable [Member] |  |
Financing receivable recorded investment |  |
Past due 90 days or Greater and Still Accruing | 4,735 | 5,890
Loans | 385,633 | 405,119
Real estate - mortgage | Domestic | Residential First Mortgage Financing Receivable [Member] | Current |  |
Financing receivable recorded investment |  |
Loans | 377,782 | 395,629
Real estate - mortgage | Domestic | Residential First Mortgage Financing Receivable [Member] | Total Past Due |  |
Financing receivable recorded investment |  |
Loans | 7,851 | 9,490
Real estate - mortgage | Domestic | Residential First Mortgage Financing Receivable [Member] | 30 to 59 Days |  |
Financing receivable recorded investment |  |
Loans | 2,266 | 2,399
Real estate - mortgage | Domestic | Residential First Mortgage Financing Receivable [Member] | 60 to 89 Days |  |
Financing receivable recorded investment |  |
Loans | 655 | 926
Real estate - mortgage | Domestic | Residential First Mortgage Financing Receivable [Member] | 90 Days or Greater |  |
Financing receivable recorded investment |  |
Loans | 4,930 | 6,165
Real estate - mortgage | Domestic | Residential Junior Lien |  |
Financing receivable recorded investment |  |
Past due 90 days or Greater and Still Accruing | 1,842 | 1,197
Loans | 490,680 | 594,025
Real estate - mortgage | Domestic | Residential Junior Lien | Current |  |
Financing receivable recorded investment |  |
Loans | 488,219 | 592,020
Real estate - mortgage | Domestic | Residential Junior Lien | Total Past Due |  |
Financing receivable recorded investment |  |
Loans | 2,461 | 2,005
Real estate - mortgage | Domestic | Residential Junior Lien | 30 to 59 Days |  |
Financing receivable recorded investment |  |
Loans | 515 | 561
Real estate - mortgage | Domestic | Residential Junior Lien | 60 to 89 Days |  |
Financing receivable recorded investment |  |
Loans | 104 | 247
Real estate - mortgage | Domestic | Residential Junior Lien | 90 Days or Greater |  |
Financing receivable recorded investment |  |
Loans | 1,842 | 1,197
Consumer |  |
Financing receivable recorded investment |  |
Loans | 40,699 | 40,595
Consumer | Domestic |  |
Financing receivable recorded investment |  |
Past due 90 days or Greater and Still Accruing | 46 | 79
Loans | 40,699 | 40,595
Consumer | Domestic | Current |  |
Financing receivable recorded investment |  |
Loans | 40,343 | 40,127
Consumer | Domestic | Total Past Due |  |
Financing receivable recorded investment |  |
Loans | 356 | 468
Consumer | Domestic | 30 to 59 Days |  |
Financing receivable recorded investment |  |
Loans | 240 | 318
Consumer | Domestic | 60 to 89 Days |  |
Financing receivable recorded investment |  |
Loans | 70 | 71
Consumer | Domestic | 90 Days or Greater |  |
Financing receivable recorded investment |  |
Loans | 46 | 79
Foreign. |  |
Financing receivable recorded investment |  |
Loans | 135,843 | 138,970
Foreign. | Foreign |  |
Financing receivable recorded investment |  |
Past due 90 days or Greater and Still Accruing | 360 | 568
Loans | 135,843 | 138,970
Foreign. | Foreign | Current |  |
Financing receivable recorded investment |  |
Loans | 132,770 | 137,744
Foreign. | Foreign | Total Past Due |  |
Financing receivable recorded investment |  |
Loans | 3,073 | 1,226
Foreign. | Foreign | 30 to 59 Days |  |
Financing receivable recorded investment |  |
Loans | 1,231 | 478
Foreign. | Foreign | 60 to 89 Days |  |
Financing receivable recorded investment |  |
Loans | 1,482 | 180
Foreign. | Foreign | 90 Days or Greater |  |
Financing receivable recorded investment |  |
Loans | $ 360 | $ 568

X
- Definition Amount of financing receivable 90 days or more past due and still accruing. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 20 -Section 50 -Paragraph 16 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=124255953&loc=SL82919258-210447 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 7 -Subparagraph (d) -URI http://asc.fasb.org/extlink&oid=123577603&loc=d3e5111-111524 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=124267575&loc=SL82922355-210448 + Details
Name: | us-gaap_FinancingReceivableRecordedInvestment90DaysPastDueAndStillAccruing
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

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 310 -SubTopic 10 -Section 50 -Paragraph 7A -URI http://asc.fasb.org/extlink&oid=123577603&loc=SL6953401-111524 Reference 2: 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=124267575&loc=SL82922352-210448 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 20 -Section 50 -Paragraph 14 -URI http://asc.fasb.org/extlink&oid=124255953&loc=SL82919253-210447 Reference 4: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 20 -Section 45 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=124255206&loc=SL82895884-210446 Reference 5: 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=124255953&loc=SL82919230-210447 Reference 6: 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=124267575&loc=SL82922355-210448 Reference 7: http://www.xbrl.org/2003/role/disclosureRef -Publisher SEC -Name Regulation S-K (SK) -Number 229 -Section 1405 -Paragraph (a) -Subparagraph (1) Reference 8: http://www.xbrl.org/2003/role/disclosureRef -Publisher SEC -Name Regulation S-K (SK) -Number 229 -Section 1405 -Paragraph (a) -Subparagraph (2) Reference 9: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher SEC -Name Regulation S-K (SK) -Number 229 -Section 1404 -Paragraph (a) + Details
Name: | us-gaap_NotesReceivableGross
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

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

X
- Details
Name: | us-gaap_FinancingReceivablesPeriodPastDueAxis=us-gaap_FinancialAssetNotPastDueMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancingReceivablesPeriodPastDueAxis=us-gaap_FinancialAssetPastDueMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancingReceivablesPeriodPastDueAxis=us-gaap_FinancingReceivables30To59DaysPastDueMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancingReceivablesPeriodPastDueAxis=us-gaap_FinancingReceivables60To89DaysPastDueMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancingReceivablesPeriodPastDueAxis=us-gaap_FinancingReceivablesEqualToGreaterThan90DaysPastDueMember
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: |