XML 45 R34.htm IDEA: XBRL DOCUMENT
v3.25.2

Allowance for Credit Losses - Commercial real estate loan portfolio (Details) - Commercial real estate - USD ($) $ in Thousands | Jun. 30, 2025 | Dec. 31, 2024
--- | --- | ---
Loan loss allowances, real estate securing credit |  |
Amount of real estate securing the credit | $ 6,063,363 | $ 5,722,372
Percent of total of real estate securing the credit | 100.00% | 100.00%
Commercial real estate construction development |  |
Loan loss allowances, real estate securing credit |  |
Amount of real estate securing the credit | $ 1,232,306 | $ 1,313,984
Percent of total of real estate securing the credit | 20.40% | 23.00%
Hotel |  |
Loan loss allowances, real estate securing credit |  |
Amount of real estate securing the credit | $ 1,087,224 | $ 1,080,706
Percent of total of real estate securing the credit | 17.90% | 18.90%
Retail multi-tenant |  |
Loan loss allowances, real estate securing credit |  |
Amount of real estate securing the credit | $ 737,880 | $ 738,874
Percent of total of real estate securing the credit | 12.20% | 12.90%
Lot development: residential and commercial lots |  |
Loan loss allowances, real estate securing credit |  |
Amount of real estate securing the credit | $ 583,601 | $ 513,760
Percent of total of real estate securing the credit | 9.60% | 9.00%
Warehouse |  |
Loan loss allowances, real estate securing credit |  |
Amount of real estate securing the credit | $ 439,255 | $ 435,783
Percent of total of real estate securing the credit | 7.20% | 7.60%
Office/Professional buildings |  |
Loan loss allowances, real estate securing credit |  |
Amount of real estate securing the credit | $ 457,096 | $ 416,014
Percent of total of real estate securing the credit | 7.50% | 7.30%
1 - 4 family construction |  |
Loan loss allowances, real estate securing credit |  |
Amount of real estate securing the credit | $ 374,356 | $ 338,832
Percent of total of real estate securing the credit | 6.20% | 5.90%
Multi-family |  |
Loan loss allowances, real estate securing credit |  |
Amount of real estate securing the credit | $ 376,628 | $ 310,115
Percent of total of real estate securing the credit | 6.20% | 5.40%
Owner occupied real estate |  |
Loan loss allowances, real estate securing credit |  |
Amount of real estate securing the credit | $ 354,928 | $ 270,584
Percent of total of real estate securing the credit | 5.90% | 4.70%
Commercial leased properties |  |
Loan loss allowances, real estate securing credit |  |
Amount of real estate securing the credit | $ 291,943 | $ 194,023
Percent of total of real estate securing the credit | 4.80% | 3.40%
Farmland |  |
Loan loss allowances, real estate securing credit |  |
Amount of real estate securing the credit | $ 128,146 | $ 109,697
Percent of total of real estate securing the credit | 2.10% | 1.90%

X
- Definition The value of real estate that is held as collateral for financing receivable. + References No definition available. + Details
Name: | iboc_RealEstateCollateralForFinancialReceivables
Namespace Prefix: | iboc_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Percentage of real estate that is collateral for financing receivable to total real estate collateral. + References No definition available. + Details
Name: | iboc_RealEstateCollateralToTotalPercent
Namespace Prefix: | iboc_
Data Type: | dtr-types:percentItemType
Balance Type: | na
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 Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 326 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 13 -Subparagraph (f) -Publisher FASB -URI https://asc.fasb.org/1943274/2147479319/326-20-50-13 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Topic 326 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 13 -Subparagraph (e) -Publisher FASB -URI https://asc.fasb.org/1943274/2147479319/326-20-50-13 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Topic 326 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 13 -Subparagraph (d) -Publisher FASB -URI https://asc.fasb.org/1943274/2147479319/326-20-50-13 Reference 4: http://www.xbrl.org/2003/role/disclosureRef -Topic 326 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 13 -Subparagraph (c) -Publisher FASB -URI https://asc.fasb.org/1943274/2147479319/326-20-50-13 Reference 5: http://www.xbrl.org/2003/role/disclosureRef -Topic 326 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 13 -Subparagraph (b) -Publisher FASB -URI https://asc.fasb.org/1943274/2147479319/326-20-50-13 Reference 6: http://www.xbrl.org/2003/role/disclosureRef -Topic 326 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 13 -Subparagraph (a) -Publisher FASB -URI https://asc.fasb.org/1943274/2147479319/326-20-50-13 Reference 7: http://www.xbrl.org/2003/role/disclosureRef -Name Regulation S-K (SK) -Number 229 -Section 1405 -Paragraph c -Publisher SEC + Details
Name: | us-gaap_FinancingReceivableAllowanceForCreditLossesLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

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

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

X
- Details
Name: | us-gaap_CollateralAxis=srt_HotelMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_CollateralAxis=iboc_RetailMultiTenantMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_CollateralAxis=iboc_ResidentialAndCommercialMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_CollateralAxis=srt_WarehouseMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_CollateralAxis=srt_OfficeBuildingMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_CollateralAxis=iboc_OneToFourFamilyConstructionMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_CollateralAxis=srt_MultifamilyMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_CollateralAxis=iboc_OwnerOccupiedRealEstateMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_CollateralAxis=iboc_CommercialLeasedPropertyMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_CollateralAxis=iboc_FarmlandMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |