XML 45 R34.htm IDEA: XBRL DOCUMENT
v3.10.0.1

Allowance for Probable Loan Losses (Aging By Loan Class) (Details) - USD ($) $ in Thousands | Sep. 30, 2018 | Dec. 31, 2017
--- | --- | ---
Financing receivable recorded investment |  |
Past due | $ 84,229 | $ 77,053
Past due 90 days or Greater and Still Accruing | 7,449 | 7,257
Loans, current | 6,390,912 | 6,271,119
Total loans | 6,475,141 | 6,348,172
30 to 59 Days |  |
Financing receivable recorded investment |  |
Past due | 51,390 | 15,855
60 to 89 Days |  |
Financing receivable recorded investment |  |
Past due | 4,392 | 4,429
90 Days or Greater |  |
Financing receivable recorded investment |  |
Past due | 28,447 | 56,769
Commercial |  |
Financing receivable recorded investment |  |
Past due | 33,259 | 22,496
Past due 90 days or Greater and Still Accruing | 886 | 537
Loans, current | 1,045,306 | 1,063,971
Total loans | 1,078,565 | 1,086,467
Commercial | 30 to 59 Days |  |
Financing receivable recorded investment |  |
Past due | 14,468 | 3,790
Commercial | 60 to 89 Days |  |
Financing receivable recorded investment |  |
Past due | 1,381 | 398
Commercial | 90 Days or Greater |  |
Financing receivable recorded investment |  |
Past due | 17,410 | 18,308
Commercial Real Estate:Other Construction and Land Development |  |
Financing receivable recorded investment |  |
Past due | 3,682 | 1,482
Past due 90 days or Greater and Still Accruing | 100 | 6
Loans, current | 1,874,758 | 1,682,068
Total loans | 1,878,440 | 1,683,550
Commercial Real Estate:Other Construction and Land Development | 30 to 59 Days |  |
Financing receivable recorded investment |  |
Past due | 2,596 | 354
Commercial Real Estate:Other Construction and Land Development | 60 to 89 Days |  |
Financing receivable recorded investment |  |
Past due | 81 | 308
Commercial Real Estate:Other Construction and Land Development | 90 Days or Greater |  |
Financing receivable recorded investment |  |
Past due | 1,005 | 820
Commercial Real Estate: Farmland and Commercial |  |
Financing receivable recorded investment |  |
Past due | 32,009 | 35,576
Past due 90 days or Greater and Still Accruing | 789 | 954
Loans, current | 1,949,545 | 2,007,709
Total loans | 1,981,554 | 2,043,285
Commercial Real Estate: Farmland and Commercial | 30 to 59 Days |  |
Financing receivable recorded investment |  |
Past due | 27,621 | 3,925
Commercial Real Estate: Farmland and Commercial | 60 to 89 Days |  |
Financing receivable recorded investment |  |
Past due | 733 | 518
Commercial Real Estate: Farmland and Commercial | 90 Days or Greater |  |
Financing receivable recorded investment |  |
Past due | 3,655 | 31,133
Commercial Real Estate: Multifamily |  |
Financing receivable recorded investment |  |
Past due | 868 | 560
Loans, current | 186,477 | 192,356
Total loans | 187,345 | 192,916
Commercial Real Estate: Multifamily | 30 to 59 Days |  |
Financing receivable recorded investment |  |
Past due | 282 | 84
Commercial Real Estate: Multifamily | 90 Days or Greater |  |
Financing receivable recorded investment |  |
Past due | 586 | 476
Residential First Lien |  |
Financing receivable recorded investment |  |
Past due | 8,276 | 10,848
Past due 90 days or Greater and Still Accruing | 3,435 | 3,861
Loans, current | 418,270 | 421,929
Total loans | 426,546 | 432,777
Residential First Lien | 30 to 59 Days |  |
Financing receivable recorded investment |  |
Past due | 4,029 | 4,295
Residential First Lien | 60 to 89 Days |  |
Financing receivable recorded investment |  |
Past due | 709 | 2,458
Residential First Lien | 90 Days or Greater |  |
Financing receivable recorded investment |  |
Past due | 3,538 | 4,095
Residential Junior Lien |  |
Financing receivable recorded investment |  |
Past due | 2,153 | 3,000
Past due 90 days or Greater and Still Accruing | 1,120 | 1,099
Loans, current | 718,933 | 697,748
Total loans | 721,086 | 700,748
Residential Junior Lien | 30 to 59 Days |  |
Financing receivable recorded investment |  |
Past due | 746 | 1,310
Residential Junior Lien | 60 to 89 Days |  |
Financing receivable recorded investment |  |
Past due | 287 | 580
Residential Junior Lien | 90 Days or Greater |  |
Financing receivable recorded investment |  |
Past due | 1,120 | 1,110
Consumer |  |
Financing receivable recorded investment |  |
Past due | 526 | 1,126
Past due 90 days or Greater and Still Accruing | 38 | 133
Loans, current | 46,120 | 48,417
Total loans | 46,646 | 49,543
Consumer | 30 to 59 Days |  |
Financing receivable recorded investment |  |
Past due | 410 | 868
Consumer | 60 to 89 Days |  |
Financing receivable recorded investment |  |
Past due | 64 | 98
Consumer | 90 Days or Greater |  |
Financing receivable recorded investment |  |
Past due | 52 | 160
Foreign |  |
Financing receivable recorded investment |  |
Past due | 3,456 | 1,965
Past due 90 days or Greater and Still Accruing | 1,081 | 667
Loans, current | 151,503 | 156,921
Total loans | 154,959 | 158,886
Foreign | 30 to 59 Days |  |
Financing receivable recorded investment |  |
Past due | 1,238 | 1,229
Foreign | 60 to 89 Days |  |
Financing receivable recorded investment |  |
Past due | 1,137 | 69
Foreign | 90 Days or Greater |  |
Financing receivable recorded investment |  |
Past due | $ 1,081 | $ 667

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: |