XML 27 R73.htm IDEA: XBRL DOCUMENT v2.4.1.9

Other Borrowed Funds (Details) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013
Federal Home Loan Bank advances
Balance at year end	$ 1,073,944,000us-gaap_AdvancesFromFederalHomeLoanBanks	$ 1,223,950,000us-gaap_AdvancesFromFederalHomeLoanBanks
Federal Home Loan Bank advances short-term
Federal Home Loan Bank advances
Balance at year end	1,067,700,000us-gaap_AdvancesFromFederalHomeLoanBanks / us-gaap_DebtInstrumentAxis = us-gaap_ShortTermDebtMember	1,215,000,000us-gaap_AdvancesFromFederalHomeLoanBanks / us-gaap_DebtInstrumentAxis = us-gaap_ShortTermDebtMember
Rate on balance outstanding at year end (as a percent)	0.15%us-gaap_FederalHomeLoanBankAdvancesActivityForYearAverageInterestRateAtPeriodEnd / us-gaap_DebtInstrumentAxis = us-gaap_ShortTermDebtMember	0.17%us-gaap_FederalHomeLoanBankAdvancesActivityForYearAverageInterestRateAtPeriodEnd / us-gaap_DebtInstrumentAxis = us-gaap_ShortTermDebtMember
Average daily balance	1,077,973,000us-gaap_FederalHomeLoanBankAdvancesActivityForYearAverageBalanceOfAgreementsOutstanding / us-gaap_DebtInstrumentAxis = us-gaap_ShortTermDebtMember	833,868,000us-gaap_FederalHomeLoanBankAdvancesActivityForYearAverageBalanceOfAgreementsOutstanding / us-gaap_DebtInstrumentAxis = us-gaap_ShortTermDebtMember
Average rate (as a percent)	0.16%us-gaap_FederalHomeLoanBankAdvancesActivityForYearAverageInterestRateForYear / us-gaap_DebtInstrumentAxis = us-gaap_ShortTermDebtMember	0.16%us-gaap_FederalHomeLoanBankAdvancesActivityForYearAverageInterestRateForYear / us-gaap_DebtInstrumentAxis = us-gaap_ShortTermDebtMember
Maximum amount outstanding at any month end	1,352,500,000us-gaap_FederalHomeLoanBankAdvancesActivityForYearMaximumOutstandingAtAnyMonthEnd / us-gaap_DebtInstrumentAxis = us-gaap_ShortTermDebtMember	1,280,500,000us-gaap_FederalHomeLoanBankAdvancesActivityForYearMaximumOutstandingAtAnyMonthEnd / us-gaap_DebtInstrumentAxis = us-gaap_ShortTermDebtMember
Federal Home Loan Bank advances long-term
Federal Home Loan Bank advances
Balance at year end	6,244,000us-gaap_AdvancesFromFederalHomeLoanBanks / us-gaap_DebtInstrumentAxis = us-gaap_LongTermDebtMember	8,950,000us-gaap_AdvancesFromFederalHomeLoanBanks / us-gaap_DebtInstrumentAxis = us-gaap_LongTermDebtMember
Rate on balance outstanding at year end (as a percent)	3.51%us-gaap_FederalHomeLoanBankAdvancesActivityForYearAverageInterestRateAtPeriodEnd / us-gaap_DebtInstrumentAxis = us-gaap_LongTermDebtMember	3.53%us-gaap_FederalHomeLoanBankAdvancesActivityForYearAverageInterestRateAtPeriodEnd / us-gaap_DebtInstrumentAxis = us-gaap_LongTermDebtMember
Average daily balance	7,338,000us-gaap_FederalHomeLoanBankAdvancesActivityForYearAverageBalanceOfAgreementsOutstanding / us-gaap_DebtInstrumentAxis = us-gaap_LongTermDebtMember	7,289,000us-gaap_FederalHomeLoanBankAdvancesActivityForYearAverageBalanceOfAgreementsOutstanding / us-gaap_DebtInstrumentAxis = us-gaap_LongTermDebtMember
Average rate (as a percent)	3.51%us-gaap_FederalHomeLoanBankAdvancesActivityForYearAverageInterestRateForYear / us-gaap_DebtInstrumentAxis = us-gaap_LongTermDebtMember	3.53%us-gaap_FederalHomeLoanBankAdvancesActivityForYearAverageInterestRateForYear / us-gaap_DebtInstrumentAxis = us-gaap_LongTermDebtMember
Maximum amount outstanding at any month end	8,934,000us-gaap_FederalHomeLoanBankAdvancesActivityForYearMaximumOutstandingAtAnyMonthEnd / us-gaap_DebtInstrumentAxis = us-gaap_LongTermDebtMember	8,993,000us-gaap_FederalHomeLoanBankAdvancesActivityForYearMaximumOutstandingAtAnyMonthEnd / us-gaap_DebtInstrumentAxis = us-gaap_LongTermDebtMember
Amortization of long-term advances for the next five years	$ 160,000iboc_FederalHomeLoanBankAdvancesActivityForNextFiveYearsAmortization / us-gaap_DebtInstrumentAxis = us-gaap_LongTermDebtMember
Period of amortization of long-term advances	5 years

X

- Definition

The annual amortization amount for Federal Home Loan Bank advances for the next five years. Update label as: Annual amortization of long-term advances for the next five years.

+ References

No definition available.

+ Details

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Namespace Prefix:	iboc_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

X

- Definition

This represents the period of amortization of the long-term advances in years.

+ References

No definition available.

+ Details

Name:	iboc_PeriodOfAmortizationOfLongTermAdvances
Namespace Prefix:	iboc_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

X

- Definition

Amount of borrowings as of the balance sheet date from the Federal Home Loan Bank, which are primarily used to cover shortages in the required reserve balance and liquidity shortages.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 942

-SubTopic 470

-Section 45

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=6479118&loc=d3e64650-112822

+ Details

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

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- Details

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

X

- Definition

The calculated average balance outstanding for the year for all Federal Home Loan Bank advances as of the Balance Sheet date.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 942

-SubTopic 210

-Section S99

-Paragraph 1

-Subparagraph (SX 210.9-03.13(3)(a))

-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

X

- Definition

The calculated weighted average interest rate for Federal Home Loan Bank advances outstanding as of the Balance Sheet date.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 942

-SubTopic 210

-Section S99

-Paragraph 1

-Subparagraph (SX 210.9-03.13(3)(a))

-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

X

- Definition

The calculated weighted average interest rate for Federal Home Loan Bank advances for the period ended as of the Balance Sheet date.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 942

-SubTopic 210

-Section S99

-Paragraph 1

-Subparagraph (SX 210.9-03.13(3)(a))

-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

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Namespace Prefix:	us-gaap_
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Balance Type:	na
Period Type:	duration

X

- Definition

The maximum balance outstanding at any month end during the period as of the Balance Sheet date.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 942

-SubTopic 210

-Section S99

-Paragraph 1

-Subparagraph (SX 210.9-03.13(3)(a))

-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

+ Details

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

X

- Details

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Namespace Prefix:
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- Details

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