XML 82 R67.htm IDEA: XBRL DOCUMENT
v3.10.0.1

Allowance for Probable Loan Losses (Aging By Loan Class) (Details) - USD ($) | Dec. 31, 2018 | Dec. 31, 2017 | Dec. 31, 2016
--- | --- | --- | ---
Financing receivable recorded investment |  |  |
Past due 90 days or Greater and Still Accruing | $ 40,674,000 | $ 7,257,000 | $ 5,226,000
Past due | 75,833,000 | 77,053,000 |
Loans, current | 6,485,456,000 | 6,271,119,000 |
Total loans | 6,561,289,000 | 6,348,172,000 |
30 to 59 Days |  |  |
Financing receivable recorded investment |  |  |
Past due | 15,978,000 | 15,855,000 |
60 to 89 Days |  |  |
Financing receivable recorded investment |  |  |
Past due | 6,011,000 | 4,429,000 |
90 Days or Greater |  |  |
Financing receivable recorded investment |  |  |
Past due | 53,844,000 | 56,769,000 |
Commercial |  |  |
Financing receivable recorded investment |  |  |
Past due 90 days or Greater and Still Accruing | 10,890,000 | 537,000 |
Past due | 25,591,000 | 22,496,000 |
Loans, current | 1,103,378,000 | 1,063,971,000 |
Total loans | 1,128,969,000 | 1,086,467,000 |
Commercial | 30 to 59 Days |  |  |
Financing receivable recorded investment |  |  |
Past due | 4,651,000 | 3,790,000 |
Commercial | 60 to 89 Days |  |  |
Financing receivable recorded investment |  |  |
Past due | 1,089,000 | 398,000 |
Commercial | 90 Days or Greater |  |  |
Financing receivable recorded investment |  |  |
Past due | 19,851,000 | 18,308,000 |
Commercial Real Estate:Other Construction and Land Development |  |  |
Financing receivable recorded investment |  |  |
Past due 90 days or Greater and Still Accruing | 16,000 | 6,000 |
Past due | 3,356,000 | 1,482,000 |
Loans, current | 1,882,875,000 | 1,682,068,000 |
Total loans | 1,886,231,000 | 1,683,550,000 |
Commercial Real Estate:Other Construction and Land Development | 30 to 59 Days |  |  |
Financing receivable recorded investment |  |  |
Past due | 727,000 | 354,000 |
Commercial Real Estate:Other Construction and Land Development | 60 to 89 Days |  |  |
Financing receivable recorded investment |  |  |
Past due | 1,707,000 | 308,000 |
Commercial Real Estate:Other Construction and Land Development | 90 Days or Greater |  |  |
Financing receivable recorded investment |  |  |
Past due | 922,000 | 820,000 |
Commercial Real Estate: Farmland and Commercial |  |  |
Financing receivable recorded investment |  |  |
Past due 90 days or Greater and Still Accruing | 24,910,000 | 954,000 |
Past due | 30,951,000 | 35,576,000 |
Loans, current | 1,918,947,000 | 2,007,709,000 |
Total loans | 1,949,898,000 | 2,043,285,000 |
Commercial Real Estate: Farmland and Commercial | 30 to 59 Days |  |  |
Financing receivable recorded investment |  |  |
Past due | 2,928,000 | 3,925,000 |
Commercial Real Estate: Farmland and Commercial | 60 to 89 Days |  |  |
Financing receivable recorded investment |  |  |
Past due | 784,000 | 518,000 |
Commercial Real Estate: Farmland and Commercial | 90 Days or Greater |  |  |
Financing receivable recorded investment |  |  |
Past due | 27,239,000 | 31,133,000 |
Commercial Real Estate: Multifamily |  |  |
Financing receivable recorded investment |  |  |
Past due 90 days or Greater and Still Accruing | 71,000 |  |
Past due | 1,505,000 | 560,000 |
Loans, current | 224,752,000 | 192,356,000 |
Total loans | 226,257,000 | 192,916,000 |
Commercial Real Estate: Multifamily | 30 to 59 Days |  |  |
Financing receivable recorded investment |  |  |
Past due | 927,000 | 84,000 |
Commercial Real Estate: Multifamily | 90 Days or Greater |  |  |
Financing receivable recorded investment |  |  |
Past due | 578,000 | 476,000 |
Residential First Lien |  |  |
Financing receivable recorded investment |  |  |
Past due 90 days or Greater and Still Accruing | 3,079,000 | 3,861,000 |
Past due | 9,037,000 | 10,848,000 |
Loans, current | 436,763,000 | 421,929,000 |
Total loans | 445,800,000 | 432,777,000 |
Residential First Lien | 30 to 59 Days |  |  |
Financing receivable recorded investment |  |  |
Past due | 3,998,000 | 4,295,000 |
Residential First Lien | 60 to 89 Days |  |  |
Financing receivable recorded investment |  |  |
Past due | 1,677,000 | 2,458,000 |
Residential First Lien | 90 Days or Greater |  |  |
Financing receivable recorded investment |  |  |
Past due | 3,362,000 | 4,095,000 |
Residential Junior Lien |  |  |
Financing receivable recorded investment |  |  |
Past due 90 days or Greater and Still Accruing | 937,000 | 1,099,000 |
Past due | 2,881,000 | 3,000,000 |
Loans, current | 724,420,000 | 697,748,000 |
Total loans | 727,301,000 | 700,748,000 |
Residential Junior Lien | 30 to 59 Days |  |  |
Financing receivable recorded investment |  |  |
Past due | 1,155,000 | 1,310,000 |
Residential Junior Lien | 60 to 89 Days |  |  |
Financing receivable recorded investment |  |  |
Past due | 618,000 | 580,000 |
Residential Junior Lien | 90 Days or Greater |  |  |
Financing receivable recorded investment |  |  |
Past due | 1,108,000 | 1,110,000 |
Consumer |  |  |
Financing receivable recorded investment |  |  |
Past due 90 days or Greater and Still Accruing | 32,000 | 133,000 |
Past due | 550,000 | 1,126,000 |
Loans, current | 45,766,000 | 48,417,000 |
Total loans | 46,316,000 | 49,543,000 |
Consumer | 30 to 59 Days |  |  |
Financing receivable recorded investment |  |  |
Past due | 486,000 | 868,000 |
Consumer | 60 to 89 Days |  |  |
Financing receivable recorded investment |  |  |
Past due | 19,000 | 98,000 |
Consumer | 90 Days or Greater |  |  |
Financing receivable recorded investment |  |  |
Past due | 45,000 | 160,000 |
Foreign |  |  |
Financing receivable recorded investment |  |  |
Past due 90 days or Greater and Still Accruing | 739,000 | 667,000 |
Past due | 1,962,000 | 1,965,000 |
Loans, current | 148,555,000 | 156,921,000 |
Total loans | 150,517,000 | 158,886,000 |
Foreign | 30 to 59 Days |  |  |
Financing receivable recorded investment |  |  |
Past due | 1,106,000 | 1,229,000 |
Foreign | 60 to 89 Days |  |  |
Financing receivable recorded investment |  |  |
Past due | 117,000 | 69,000 |
Foreign | 90 Days or Greater |  |  |
Financing receivable recorded investment |  |  |
Past due | $ 739,000 | $ 667,000 |

X
- Definition Recorded investment in financing receivables that are 90 days or more past due and still accruing. + References Reference 1: 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=84173941&loc=d3e5111-111524 + Details
Name: | us-gaap_FinancingReceivableRecordedInvestment90DaysPastDueAndStillAccruing
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- References No definition available. + 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://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 7A -URI http://asc.fasb.org/extlink&oid=84173941&loc=SL6953401-111524 + Details
Name: | us-gaap_FinancingReceivableRecordedInvestmentCurrent
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://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 7A -URI http://asc.fasb.org/extlink&oid=84173941&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://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 45 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=82891408&loc=d3e4428-111522 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 4 -URI http://asc.fasb.org/extlink&oid=84173941&loc=d3e5074-111524 + Details
Name: | us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

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_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis=us-gaap_CommercialLoanMember
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_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_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_ConsumerLoanMember
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: |