XML 43 R32.htm IDEA: XBRL DOCUMENT
v3.21.1

Allowance for Credit Losses (By Loan Class) (Details) - USD ($) $ in Thousands | 3 Months Ended
--- | ---
Mar. 31, 2021 | Mar. 31, 2020
Allowance for Credit Losses |  |
Balance at the beginning of the period | $ 109,059 | $ 60,278
Losses charged to allowance | (2,353) | (2,980)
Recoveries credited to allowance | 510 | 792
Net (losses) recoveries charged to allowance | (1,843) | (2,188)
credit loss expense | 1,192 | 16,836
Balance at the end of the period | 108,408 | 85,273
ASU 2016-13 | Adjustment |  |
Allowance for Credit Losses |  |
Balance at the end of the period |  | 10,347
Commercial, financial and agricultural | Domestic | Commercial Loan [Member] |  |
Allowance for Credit Losses |  |
Balance at the beginning of the period | 21,908 | 11,145
Losses charged to allowance | (1,893) | (2,819)
Recoveries credited to allowance | 458 | 671
Net (losses) recoveries charged to allowance | (1,435) | (2,148)
credit loss expense | 1,690 | 5,823
Balance at the end of the period | 22,163 | 19,067
Commercial, financial and agricultural | Domestic | Commercial Loan [Member] | ASU 2016-13 | Adjustment |  |
Allowance for Credit Losses |  |
Balance at the end of the period |  | 4,247
Commercial, financial and agricultural | Domestic | Commercial Real Estate Farmland and Commercial Receivable [Member] |  |
Allowance for Credit Losses |  |
Balance at the beginning of the period | 30,000 | 16,533
Losses charged to allowance | (356) | (55)
Recoveries credited to allowance | 12 | 9
Net (losses) recoveries charged to allowance | (344) | (46)
credit loss expense | 2,547 | 2,809
Balance at the end of the period | 32,203 | 15,004
Commercial, financial and agricultural | Domestic | Commercial Real Estate Farmland and Commercial Receivable [Member] | ASU 2016-13 | Adjustment |  |
Allowance for Credit Losses |  |
Balance at the end of the period |  | (4,292)
Commercial, financial and agricultural | Domestic | Commercial Real Estate Multifamily Receivable [Member] |  |
Allowance for Credit Losses |  |
Balance at the beginning of the period | 5,051 | 1,786
credit loss expense | 884 | 327
Balance at the end of the period | 5,935 | 1,758
Commercial, financial and agricultural | Domestic | Commercial Real Estate Multifamily Receivable [Member] | ASU 2016-13 | Adjustment |  |
Allowance for Credit Losses |  |
Balance at the end of the period |  | (355)
Real estate - construction | Domestic | Commercial Real Estate: other construction and land development |  |
Allowance for Credit Losses |  |
Balance at the beginning of the period | 37,612 | 18,152
credit loss expense | (3,206) | 5,878
Balance at the end of the period | 34,406 | 37,421
Real estate - construction | Domestic | Commercial Real Estate: other construction and land development | ASU 2016-13 | Adjustment |  |
Allowance for Credit Losses |  |
Balance at the end of the period |  | 13,391
Real estate - mortgage | Domestic | Residential First Mortgage Financing Receivable [Member] |  |
Allowance for Credit Losses |  |
Balance at the beginning of the period | 3,874 | 3,762
Losses charged to allowance | (72) | (36)
Recoveries credited to allowance | 11 | 1
Net (losses) recoveries charged to allowance | (61) | (35)
credit loss expense | 104 | 635
Balance at the end of the period | 3,917 | 2,782
Real estate - mortgage | Domestic | Residential First Mortgage Financing Receivable [Member] | ASU 2016-13 | Adjustment |  |
Allowance for Credit Losses |  |
Balance at the end of the period |  | (1,580)
Real estate - mortgage | Domestic | Residential Junior Lien |  |
Allowance for Credit Losses |  |
Balance at the beginning of the period | 9,570 | 7,535
Recoveries credited to allowance | 21 | 103
Net (losses) recoveries charged to allowance | 21 | 103
credit loss expense | (855) | 1,243
Balance at the end of the period | 8,736 | 8,452
Real estate - mortgage | Domestic | Residential Junior Lien | ASU 2016-13 | Adjustment |  |
Allowance for Credit Losses |  |
Balance at the end of the period |  | (429)
Consumer | Domestic |  |
Allowance for Credit Losses |  |
Balance at the beginning of the period | 291 | 542
Losses charged to allowance | (32) | (70)
Recoveries credited to allowance | 8 | 8
Net (losses) recoveries charged to allowance | (24) | (62)
credit loss expense | 12 | 68
Balance at the end of the period | 279 | 323
Consumer | Domestic | ASU 2016-13 | Adjustment |  |
Allowance for Credit Losses |  |
Balance at the end of the period |  | (225)
Foreign | Foreign |  |
Allowance for Credit Losses |  |
Balance at the beginning of the period | 753 | 823
credit loss expense | 16 | 53
Balance at the end of the period | $ 769 | 466
Foreign | Foreign | ASU 2016-13 | Adjustment |  |
Allowance for Credit Losses |  |
Balance at the end of the period |  | $ (410)

X
- Definition A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period. + References No definition available. + Details
Name: | us-gaap_AllowanceForLoanAndLeaseLossesRollForward
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Amount, after recovery, of writeoff of financing receivable, charged against allowance for credit loss. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 20 -Section 50 -Paragraph 13 -URI http://asc.fasb.org/extlink&oid=121599337&loc=SL82919249-210447 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=121647567&loc=SL82922352-210448 + Details
Name: | us-gaap_FinancingReceivableAllowanceForCreditLossWriteoffAfterRecovery
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Amount of allowance for credit loss on financing receivable. Excludes allowance for financing receivable covered under loss sharing agreement. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 11B -Subparagraph (c)(1) -URI http://asc.fasb.org/extlink&oid=121611835&loc=SL6953423-111524 Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-03(7)(2)) -URI http://asc.fasb.org/extlink&oid=120398452&loc=d3e534808-122878 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 20 -Section 45 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=121599878&loc=SL82895884-210446 Reference 4: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 20 -Section 50 -Paragraph 13 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=121599337&loc=SL82919249-210447 Reference 5: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 20 -Section 50 -Paragraph 13 -Subparagraph (f) -URI http://asc.fasb.org/extlink&oid=121599337&loc=SL82919249-210447 + Details
Name: | us-gaap_FinancingReceivableAllowanceForCreditLosses
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Amount of increase in allowance for credit loss on financing receivable from recovery. + 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 13 -Subparagraph (e) -URI http://asc.fasb.org/extlink&oid=121599337&loc=SL82919249-210447 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 11B -Subparagraph (c)(4) -URI http://asc.fasb.org/extlink&oid=121611835&loc=SL6953423-111524 + Details
Name: | us-gaap_FinancingReceivableAllowanceForCreditLossesRecovery
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Amount of writeoff of financing receivable, charged against allowance for credit loss. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 20 -Section 50 -Paragraph 13 -Subparagraph (d) -URI http://asc.fasb.org/extlink&oid=121599337&loc=SL82919249-210447 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 11B -Subparagraph (c)(3) -URI http://asc.fasb.org/extlink&oid=121611835&loc=SL6953423-111524 Reference 3: 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 + Details
Name: | us-gaap_FinancingReceivableAllowanceForCreditLossesWriteOffs
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Amount of credit loss expense (reversal of expense) for 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 13 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=121599337&loc=SL82919249-210447 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 220 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-04(11)) -URI http://asc.fasb.org/extlink&oid=120399700&loc=SL114874048-224260 + Details
Name: | us-gaap_ProvisionForLoanLossesExpensed
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Details
Name: | us-gaap_AdjustmentsForNewAccountingPronouncementsAxis=us-gaap_AccountingStandardsUpdate201613Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_CumulativeEffectPeriodOfAdoptionAxis=srt_CumulativeEffectPeriodOfAdoptionAdjustmentMember
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: |