XML 44 R33.htm IDEA: XBRL DOCUMENT v3.19.2

Allowance for Probable Loan Losses (Impairment By Loan Class) (Details) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Loan loss allowances, impaired financing receivable, evaluated individually or collectively
Loans Individually Evaluated for Impairment, Recorded Investment	$ 23,707	$ 23,900
Loans Individually Evaluated for Impairment, Allowance	1,699	772
Loans Collectively Evaluated for Impairment, Recorded Investment	6,818,994	6,537,389
Loans Collectively Evaluated for Impairment, Allowance	56,504	60,612
Commercial
Loan loss allowances, impaired financing receivable, evaluated individually or collectively
Loans Individually Evaluated for Impairment, Recorded Investment	8,473	9,179
Loans Individually Evaluated for Impairment, Allowance	648	656
Loans Collectively Evaluated for Impairment, Recorded Investment	1,194,270	1,119,790
Loans Collectively Evaluated for Impairment, Allowance	11,132	11,940
Commercial Real Estate:Other Construction and Land Development
Loan loss allowances, impaired financing receivable, evaluated individually or collectively
Loans Individually Evaluated for Impairment, Recorded Investment	1,924	2,092
Loans Individually Evaluated for Impairment, Allowance	116	116
Loans Collectively Evaluated for Impairment, Recorded Investment	2,008,274	1,884,139
Loans Collectively Evaluated for Impairment, Allowance	15,157	15,007
Commercial Real Estate: Farmland and Commercial
Loan loss allowances, impaired financing receivable, evaluated individually or collectively
Loans Individually Evaluated for Impairment, Recorded Investment	4,160	3,509
Loans Individually Evaluated for Impairment, Allowance	935
Loans Collectively Evaluated for Impairment, Recorded Investment	2,023,836	1,946,389
Loans Collectively Evaluated for Impairment, Allowance	16,094	19,353
Commercial Real Estate: Multifamily
Loan loss allowances, impaired financing receivable, evaluated individually or collectively
Loans Individually Evaluated for Impairment, Recorded Investment	505	507
Loans Collectively Evaluated for Impairment, Recorded Investment	220,926	225,750
Loans Collectively Evaluated for Impairment, Allowance	1,849	1,808
Residential First Lien
Loan loss allowances, impaired financing receivable, evaluated individually or collectively
Loans Individually Evaluated for Impairment, Recorded Investment	6,297	6,244
Loans Collectively Evaluated for Impairment, Recorded Investment	453,881	439,556
Loans Collectively Evaluated for Impairment, Allowance	3,627	3,467
Residential Junior Lien
Loan loss allowances, impaired financing receivable, evaluated individually or collectively
Loans Individually Evaluated for Impairment, Recorded Investment	1,023	901
Loans Collectively Evaluated for Impairment, Recorded Investment	724,241	726,400
Loans Collectively Evaluated for Impairment, Allowance	7,312	7,719
Consumer
Loan loss allowances, impaired financing receivable, evaluated individually or collectively
Loans Individually Evaluated for Impairment, Recorded Investment	1,046	1,175
Loans Collectively Evaluated for Impairment, Recorded Investment	45,667	45,141
Loans Collectively Evaluated for Impairment, Allowance	488	447
Foreign
Loan loss allowances, impaired financing receivable, evaluated individually or collectively
Loans Individually Evaluated for Impairment, Recorded Investment	279	293
Loans Collectively Evaluated for Impairment, Recorded Investment	147,899	150,224
Loans Collectively Evaluated for Impairment, Allowance	$ 845	$ 871

X

- Definition

The valuation allowance for financing receivables that are expected to be uncollectible that were collectively evaluated for impairment.

+ 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 (g)
-URI http://asc.fasb.org/extlink&oid=118936363&loc=SL6953423-111524

+ Details

Name:	us-gaap_FinancingReceivableAllowanceForCreditLossesCollectivelyEvaluatedForImpairment
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

X

- Definition

Amount of valuation allowance for financing receivables that are expected to be uncollectible that were individually evaluated for impairment.

+ 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 (g)
-URI http://asc.fasb.org/extlink&oid=118936363&loc=SL6953423-111524

+ Details

Name:	us-gaap_FinancingReceivableAllowanceForCreditLossesIndividuallyEvaluatedForImpairment1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
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

No definition available.

+ Details

Name:	us-gaap_FinancingReceivableAllowanceForCreditLossesLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

X

- Definition

The balance of financing receivables that were collectively evaluated for impairment.

+ 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 (h)
-URI http://asc.fasb.org/extlink&oid=118936363&loc=SL6953423-111524

+ Details

Name:	us-gaap_FinancingReceivableCollectivelyEvaluatedForImpairment
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

X

- Definition

The balance of financing receivables that were individually evaluated for impairment.

+ 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 (h)
-URI http://asc.fasb.org/extlink&oid=118936363&loc=SL6953423-111524

+ Details

Name:	us-gaap_FinancingReceivableIndividuallyEvaluatedForImpairment
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

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: