XML 38 R36.htm IDEA: XBRL DOCUMENT
v2.4.1.9

Allowance for Probable Loan Losses (Details 5) (USD $) In Thousands, unless otherwise specified | Mar. 31, 2015 | Dec. 31, 2014
--- | --- | ---
Financing receivable recorded investment |  |
Past due 30-59 days | $ 24,390 us-gaap_FinancingReceivableRecordedInvestment30To59DaysPastDue | $ 17,261 us-gaap_FinancingReceivableRecordedInvestment30To59DaysPastDue
Past due 60-89 days | 9,270 us-gaap_FinancingReceivableRecordedInvestment60To89DaysPastDue | 12,215 us-gaap_FinancingReceivableRecordedInvestment60To89DaysPastDue
Past due 90 days or greater | 55,964 us-gaap_FinancingReceivableRecordedInvestmentEqualToGreaterThan90DaysPastDue | 67,770 us-gaap_FinancingReceivableRecordedInvestmentEqualToGreaterThan90DaysPastDue
Past due 90 days or greater and still accruing | 7,008 us-gaap_FinancingReceivableRecordedInvestment90DaysPastDueAndStillAccruing | 9,988 us-gaap_FinancingReceivableRecordedInvestment90DaysPastDueAndStillAccruing
Past due, total | 89,624 us-gaap_FinancingReceivableRecordedInvestmentPastDue | 97,246 us-gaap_FinancingReceivableRecordedInvestmentPastDue
Loans, current | 5,689,118 us-gaap_FinancingReceivableRecordedInvestmentCurrent | 5,581,999 us-gaap_FinancingReceivableRecordedInvestmentCurrent
Total loans | 5,778,742 us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome | 5,679,245 us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome
Commercial |  |
Financing receivable recorded investment |  |
Past due 30-59 days | 8,388 us-gaap_FinancingReceivableRecordedInvestment30To59DaysPastDue / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_CommercialLoanMember | 4,103 us-gaap_FinancingReceivableRecordedInvestment30To59DaysPastDue / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_CommercialLoanMember
Past due 60-89 days | 2,950 us-gaap_FinancingReceivableRecordedInvestment60To89DaysPastDue / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_CommercialLoanMember | 2,665 us-gaap_FinancingReceivableRecordedInvestment60To89DaysPastDue / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_CommercialLoanMember
Past due 90 days or greater | 35,685 us-gaap_FinancingReceivableRecordedInvestmentEqualToGreaterThan90DaysPastDue / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_CommercialLoanMember | 40,665 us-gaap_FinancingReceivableRecordedInvestmentEqualToGreaterThan90DaysPastDue / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_CommercialLoanMember
Past due 90 days or greater and still accruing | 595 us-gaap_FinancingReceivableRecordedInvestment90DaysPastDueAndStillAccruing / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_CommercialLoanMember | 2,890 us-gaap_FinancingReceivableRecordedInvestment90DaysPastDueAndStillAccruing / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_CommercialLoanMember
Past due, total | 47,023 us-gaap_FinancingReceivableRecordedInvestmentPastDue / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_CommercialLoanMember | 47,433 us-gaap_FinancingReceivableRecordedInvestmentPastDue / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_CommercialLoanMember
Loans, current | 1,046,260 us-gaap_FinancingReceivableRecordedInvestmentCurrent / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_CommercialLoanMember | 1,042,053 us-gaap_FinancingReceivableRecordedInvestmentCurrent / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_CommercialLoanMember
Total loans | 1,093,283 us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_CommercialLoanMember | 1,089,486 us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_CommercialLoanMember
Commercial real estate: other construction and land development |  |
Financing receivable recorded investment |  |
Past due 30-59 days | 1,222 us-gaap_FinancingReceivableRecordedInvestment30To59DaysPastDue / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = iboc_CommercialRealEstateOtherConstructionAndLandDevelopmentReceivableMember | 596 us-gaap_FinancingReceivableRecordedInvestment30To59DaysPastDue / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = iboc_CommercialRealEstateOtherConstructionAndLandDevelopmentReceivableMember
Past due 60-89 days | 580 us-gaap_FinancingReceivableRecordedInvestment60To89DaysPastDue / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = iboc_CommercialRealEstateOtherConstructionAndLandDevelopmentReceivableMember | 10 us-gaap_FinancingReceivableRecordedInvestment60To89DaysPastDue / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = iboc_CommercialRealEstateOtherConstructionAndLandDevelopmentReceivableMember
Past due 90 days or greater | 7,432 us-gaap_FinancingReceivableRecordedInvestmentEqualToGreaterThan90DaysPastDue / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = iboc_CommercialRealEstateOtherConstructionAndLandDevelopmentReceivableMember | 8,707 us-gaap_FinancingReceivableRecordedInvestmentEqualToGreaterThan90DaysPastDue / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = iboc_CommercialRealEstateOtherConstructionAndLandDevelopmentReceivableMember
Past due 90 days or greater and still accruing | 51 us-gaap_FinancingReceivableRecordedInvestment90DaysPastDueAndStillAccruing / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = iboc_CommercialRealEstateOtherConstructionAndLandDevelopmentReceivableMember | 439 us-gaap_FinancingReceivableRecordedInvestment90DaysPastDueAndStillAccruing / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = iboc_CommercialRealEstateOtherConstructionAndLandDevelopmentReceivableMember
Past due, total | 9,234 us-gaap_FinancingReceivableRecordedInvestmentPastDue / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = iboc_CommercialRealEstateOtherConstructionAndLandDevelopmentReceivableMember | 9,313 us-gaap_FinancingReceivableRecordedInvestmentPastDue / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = iboc_CommercialRealEstateOtherConstructionAndLandDevelopmentReceivableMember
Loans, current | 1,513,337 us-gaap_FinancingReceivableRecordedInvestmentCurrent / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = iboc_CommercialRealEstateOtherConstructionAndLandDevelopmentReceivableMember | 1,405,664 us-gaap_FinancingReceivableRecordedInvestmentCurrent / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = iboc_CommercialRealEstateOtherConstructionAndLandDevelopmentReceivableMember
Total loans | 1,522,571 us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = iboc_CommercialRealEstateOtherConstructionAndLandDevelopmentReceivableMember | 1,414,977 us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = iboc_CommercialRealEstateOtherConstructionAndLandDevelopmentReceivableMember
Commercial real estate: farmland and commercial |  |
Financing receivable recorded investment |  |
Past due 30-59 days | 8,229 us-gaap_FinancingReceivableRecordedInvestment30To59DaysPastDue / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = iboc_CommercialRealEstateFarmlandAndCommercialReceivableMember | 2,905 us-gaap_FinancingReceivableRecordedInvestment30To59DaysPastDue / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = iboc_CommercialRealEstateFarmlandAndCommercialReceivableMember
Past due 60-89 days | 3,446 us-gaap_FinancingReceivableRecordedInvestment60To89DaysPastDue / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = iboc_CommercialRealEstateFarmlandAndCommercialReceivableMember | 7,131 us-gaap_FinancingReceivableRecordedInvestment60To89DaysPastDue / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = iboc_CommercialRealEstateFarmlandAndCommercialReceivableMember
Past due 90 days or greater | 6,267 us-gaap_FinancingReceivableRecordedInvestmentEqualToGreaterThan90DaysPastDue / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = iboc_CommercialRealEstateFarmlandAndCommercialReceivableMember | 10,724 us-gaap_FinancingReceivableRecordedInvestmentEqualToGreaterThan90DaysPastDue / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = iboc_CommercialRealEstateFarmlandAndCommercialReceivableMember
Past due 90 days or greater and still accruing | 866 us-gaap_FinancingReceivableRecordedInvestment90DaysPastDueAndStillAccruing / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = iboc_CommercialRealEstateFarmlandAndCommercialReceivableMember | 1,711 us-gaap_FinancingReceivableRecordedInvestment90DaysPastDueAndStillAccruing / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = iboc_CommercialRealEstateFarmlandAndCommercialReceivableMember
Past due, total | 17,962 us-gaap_FinancingReceivableRecordedInvestmentPastDue / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = iboc_CommercialRealEstateFarmlandAndCommercialReceivableMember | 20,760 us-gaap_FinancingReceivableRecordedInvestmentPastDue / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = iboc_CommercialRealEstateFarmlandAndCommercialReceivableMember
Loans, current | 1,878,031 us-gaap_FinancingReceivableRecordedInvestmentCurrent / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = iboc_CommercialRealEstateFarmlandAndCommercialReceivableMember | 1,880,639 us-gaap_FinancingReceivableRecordedInvestmentCurrent / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = iboc_CommercialRealEstateFarmlandAndCommercialReceivableMember
Total loans | 1,895,993 us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = iboc_CommercialRealEstateFarmlandAndCommercialReceivableMember | 1,901,399 us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = iboc_CommercialRealEstateFarmlandAndCommercialReceivableMember
Commercial real estate: multifamily |  |
Financing receivable recorded investment |  |
Past due 30-59 days | 204 us-gaap_FinancingReceivableRecordedInvestment30To59DaysPastDue / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = iboc_CommercialRealEstateMultifamilyReceivableMember | 351 us-gaap_FinancingReceivableRecordedInvestment30To59DaysPastDue / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = iboc_CommercialRealEstateMultifamilyReceivableMember
Past due 90 days or greater | 976 us-gaap_FinancingReceivableRecordedInvestmentEqualToGreaterThan90DaysPastDue / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = iboc_CommercialRealEstateMultifamilyReceivableMember | 856 us-gaap_FinancingReceivableRecordedInvestmentEqualToGreaterThan90DaysPastDue / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = iboc_CommercialRealEstateMultifamilyReceivableMember
Past due 90 days or greater and still accruing | 156 us-gaap_FinancingReceivableRecordedInvestment90DaysPastDueAndStillAccruing / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = iboc_CommercialRealEstateMultifamilyReceivableMember | 21 us-gaap_FinancingReceivableRecordedInvestment90DaysPastDueAndStillAccruing / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = iboc_CommercialRealEstateMultifamilyReceivableMember
Past due, total | 1,180 us-gaap_FinancingReceivableRecordedInvestmentPastDue / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = iboc_CommercialRealEstateMultifamilyReceivableMember | 1,207 us-gaap_FinancingReceivableRecordedInvestmentPastDue / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = iboc_CommercialRealEstateMultifamilyReceivableMember
Loans, current | 104,066 us-gaap_FinancingReceivableRecordedInvestmentCurrent / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = iboc_CommercialRealEstateMultifamilyReceivableMember | 115,492 us-gaap_FinancingReceivableRecordedInvestmentCurrent / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = iboc_CommercialRealEstateMultifamilyReceivableMember
Total loans | 105,246 us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = iboc_CommercialRealEstateMultifamilyReceivableMember | 116,699 us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = iboc_CommercialRealEstateMultifamilyReceivableMember
Residential: first lien |  |
Financing receivable recorded investment |  |
Past due 30-59 days | 3,382 us-gaap_FinancingReceivableRecordedInvestment30To59DaysPastDue / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = iboc_ResidentialFirstMortgageFinancingReceivableMember | 5,895 us-gaap_FinancingReceivableRecordedInvestment30To59DaysPastDue / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = iboc_ResidentialFirstMortgageFinancingReceivableMember
Past due 60-89 days | 1,635 us-gaap_FinancingReceivableRecordedInvestment60To89DaysPastDue / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = iboc_ResidentialFirstMortgageFinancingReceivableMember | 1,864 us-gaap_FinancingReceivableRecordedInvestment60To89DaysPastDue / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = iboc_ResidentialFirstMortgageFinancingReceivableMember
Past due 90 days or greater | 4,460 us-gaap_FinancingReceivableRecordedInvestmentEqualToGreaterThan90DaysPastDue / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = iboc_ResidentialFirstMortgageFinancingReceivableMember | 4,267 us-gaap_FinancingReceivableRecordedInvestmentEqualToGreaterThan90DaysPastDue / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = iboc_ResidentialFirstMortgageFinancingReceivableMember
Past due 90 days or greater and still accruing | 4,214 us-gaap_FinancingReceivableRecordedInvestment90DaysPastDueAndStillAccruing / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = iboc_ResidentialFirstMortgageFinancingReceivableMember | 3,901 us-gaap_FinancingReceivableRecordedInvestment90DaysPastDueAndStillAccruing / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = iboc_ResidentialFirstMortgageFinancingReceivableMember
Past due, total | 9,477 us-gaap_FinancingReceivableRecordedInvestmentPastDue / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = iboc_ResidentialFirstMortgageFinancingReceivableMember | 12,026 us-gaap_FinancingReceivableRecordedInvestmentPastDue / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = iboc_ResidentialFirstMortgageFinancingReceivableMember
Loans, current | 414,331 us-gaap_FinancingReceivableRecordedInvestmentCurrent / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = iboc_ResidentialFirstMortgageFinancingReceivableMember | 410,000 us-gaap_FinancingReceivableRecordedInvestmentCurrent / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = iboc_ResidentialFirstMortgageFinancingReceivableMember
Total loans | 423,808 us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = iboc_ResidentialFirstMortgageFinancingReceivableMember | 422,026 us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = iboc_ResidentialFirstMortgageFinancingReceivableMember
Residential: junior lien |  |
Financing receivable recorded investment |  |
Past due 30-59 days | 989 us-gaap_FinancingReceivableRecordedInvestment30To59DaysPastDue / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = iboc_ResidentialSecondMortgageFinancingReceivableMember | 899 us-gaap_FinancingReceivableRecordedInvestment30To59DaysPastDue / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = iboc_ResidentialSecondMortgageFinancingReceivableMember
Past due 60-89 days | 173 us-gaap_FinancingReceivableRecordedInvestment60To89DaysPastDue / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = iboc_ResidentialSecondMortgageFinancingReceivableMember | 231 us-gaap_FinancingReceivableRecordedInvestment60To89DaysPastDue / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = iboc_ResidentialSecondMortgageFinancingReceivableMember
Past due 90 days or greater | 538 us-gaap_FinancingReceivableRecordedInvestmentEqualToGreaterThan90DaysPastDue / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = iboc_ResidentialSecondMortgageFinancingReceivableMember | 1,931 us-gaap_FinancingReceivableRecordedInvestmentEqualToGreaterThan90DaysPastDue / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = iboc_ResidentialSecondMortgageFinancingReceivableMember
Past due 90 days or greater and still accruing | 538 us-gaap_FinancingReceivableRecordedInvestment90DaysPastDueAndStillAccruing / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = iboc_ResidentialSecondMortgageFinancingReceivableMember | 431 us-gaap_FinancingReceivableRecordedInvestment90DaysPastDueAndStillAccruing / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = iboc_ResidentialSecondMortgageFinancingReceivableMember
Past due, total | 1,700 us-gaap_FinancingReceivableRecordedInvestmentPastDue / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = iboc_ResidentialSecondMortgageFinancingReceivableMember | 3,061 us-gaap_FinancingReceivableRecordedInvestmentPastDue / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = iboc_ResidentialSecondMortgageFinancingReceivableMember
Loans, current | 491,430 us-gaap_FinancingReceivableRecordedInvestmentCurrent / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = iboc_ResidentialSecondMortgageFinancingReceivableMember | 485,239 us-gaap_FinancingReceivableRecordedInvestmentCurrent / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = iboc_ResidentialSecondMortgageFinancingReceivableMember
Total loans | 493,130 us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = iboc_ResidentialSecondMortgageFinancingReceivableMember | 488,300 us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = iboc_ResidentialSecondMortgageFinancingReceivableMember
Consumer Loan |  |
Financing receivable recorded investment |  |
Past due 30-59 days | 560 us-gaap_FinancingReceivableRecordedInvestment30To59DaysPastDue / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_ConsumerLoanMember | 896 us-gaap_FinancingReceivableRecordedInvestment30To59DaysPastDue / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_ConsumerLoanMember
Past due 60-89 days | 242 us-gaap_FinancingReceivableRecordedInvestment60To89DaysPastDue / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_ConsumerLoanMember | 216 us-gaap_FinancingReceivableRecordedInvestment60To89DaysPastDue / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_ConsumerLoanMember
Past due 90 days or greater | 337 us-gaap_FinancingReceivableRecordedInvestmentEqualToGreaterThan90DaysPastDue / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_ConsumerLoanMember | 507 us-gaap_FinancingReceivableRecordedInvestmentEqualToGreaterThan90DaysPastDue / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_ConsumerLoanMember
Past due 90 days or greater and still accruing | 319 us-gaap_FinancingReceivableRecordedInvestment90DaysPastDueAndStillAccruing / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_ConsumerLoanMember | 482 us-gaap_FinancingReceivableRecordedInvestment90DaysPastDueAndStillAccruing / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_ConsumerLoanMember
Past due, total | 1,139 us-gaap_FinancingReceivableRecordedInvestmentPastDue / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_ConsumerLoanMember | 1,619 us-gaap_FinancingReceivableRecordedInvestmentPastDue / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_ConsumerLoanMember
Loans, current | 58,115 us-gaap_FinancingReceivableRecordedInvestmentCurrent / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_ConsumerLoanMember | 59,518 us-gaap_FinancingReceivableRecordedInvestmentCurrent / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_ConsumerLoanMember
Total loans | 59,254 us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_ConsumerLoanMember | 61,137 us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_ConsumerLoanMember
Foreign |  |
Financing receivable recorded investment |  |
Past due 30-59 days | 1,416 us-gaap_FinancingReceivableRecordedInvestment30To59DaysPastDue / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = iboc_ForeignReceivablesMember | 1,616 us-gaap_FinancingReceivableRecordedInvestment30To59DaysPastDue / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = iboc_ForeignReceivablesMember
Past due 60-89 days | 224 us-gaap_FinancingReceivableRecordedInvestment60To89DaysPastDue / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = iboc_ForeignReceivablesMember | 98 us-gaap_FinancingReceivableRecordedInvestment60To89DaysPastDue / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = iboc_ForeignReceivablesMember
Past due 90 days or greater | 269 us-gaap_FinancingReceivableRecordedInvestmentEqualToGreaterThan90DaysPastDue / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = iboc_ForeignReceivablesMember | 113 us-gaap_FinancingReceivableRecordedInvestmentEqualToGreaterThan90DaysPastDue / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = iboc_ForeignReceivablesMember
Past due 90 days or greater and still accruing | 269 us-gaap_FinancingReceivableRecordedInvestment90DaysPastDueAndStillAccruing / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = iboc_ForeignReceivablesMember | 113 us-gaap_FinancingReceivableRecordedInvestment90DaysPastDueAndStillAccruing / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = iboc_ForeignReceivablesMember
Past due, total | 1,909 us-gaap_FinancingReceivableRecordedInvestmentPastDue / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = iboc_ForeignReceivablesMember | 1,827 us-gaap_FinancingReceivableRecordedInvestmentPastDue / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = iboc_ForeignReceivablesMember
Loans, current | 183,548 us-gaap_FinancingReceivableRecordedInvestmentCurrent / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = iboc_ForeignReceivablesMember | 183,394 us-gaap_FinancingReceivableRecordedInvestmentCurrent / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = iboc_ForeignReceivablesMember
Total loans | $ 185,457 us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = iboc_ForeignReceivablesMember | $ 185,221 us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = iboc_ForeignReceivablesMember

X
- Definition Financing receivables that are less than 60 days past due but more than 29 days past due. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 7A -URI http://asc.fasb.org/extlink&oid=35738203&loc=SL6953401-111524 + Details
Name: | us-gaap_FinancingReceivableRecordedInvestment30To59DaysPastDue
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Financing receivables that are less than 90 days past due but more than 59 days past due. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 7A -URI http://asc.fasb.org/extlink&oid=35738203&loc=SL6953401-111524 + Details
Name: | us-gaap_FinancingReceivableRecordedInvestment60To89DaysPastDue
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Recorded investment in financing receivables that are 90 days or more past due and still accruing. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 7 -Subparagraph (d) -URI http://asc.fasb.org/extlink&oid=35738203&loc=d3e5111-111524 + Details
Name: | us-gaap_FinancingReceivableRecordedInvestment90DaysPastDueAndStillAccruing
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Details
Name: | us-gaap_FinancingReceivableRecordedInvestmentAgingAbstract
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Financing receivables that are current. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 7A -URI http://asc.fasb.org/extlink&oid=35738203&loc=SL6953401-111524 + Details
Name: | us-gaap_FinancingReceivableRecordedInvestmentCurrent
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Financing receivables that are equal to or greater than 90 days past due. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 7A -URI http://asc.fasb.org/extlink&oid=35738203&loc=SL6953401-111524 + Details
Name: | us-gaap_FinancingReceivableRecordedInvestmentEqualToGreaterThan90DaysPastDue
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Recorded Investment in financing receivables that are past due at the balance sheet date. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 7A -URI http://asc.fasb.org/extlink&oid=35738203&loc=SL6953401-111524 + Details
Name: | us-gaap_FinancingReceivableRecordedInvestmentPastDue
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amount before allowance and after deduction of deferred interest and fees, unamortized costs and premiums and discounts from face amounts, of loans and leases held in portfolio, including but not limited to, commercial and consumer loans. Excludes loans and leases covered under loss sharing agreements. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 4 -URI http://asc.fasb.org/extlink&oid=35738203&loc=d3e5074-111524 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 45 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=28367877&loc=d3e4428-111522 + Details
Name: | us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

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

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

X
- Details
Name: | us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis=iboc_CommercialRealEstateOtherConstructionAndLandDevelopmentReceivableMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis=iboc_ForeignReceivablesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis=iboc_ResidentialFirstMortgageFinancingReceivableMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis=iboc_ResidentialSecondMortgageFinancingReceivableMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis=us-gaap_CommercialLoanMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis=us-gaap_ConsumerLoanMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |