XML 20 R47.htm IDEA: XBRL DOCUMENT
v2.4.1.9

Capital Ratios (Details) (USD $) | 0 Months Ended | 3 Months Ended |  |
--- | --- | --- | --- | ---
Jan. 01, 2015 | Mar. 31, 2015 | Dec. 31, 2014 | Jul. 31, 2013
Common Equity Tier 1 ("CET1") ratio |  | 15.60%iboc_CommonEquityTierOneRatio |  |
Tier 1 Capital (to Average Assets), Actual Ratio (as a percent) |  | 12.27%us-gaap_TierOneLeverageCapitalToAverageAssets | 12.33%us-gaap_TierOneLeverageCapitalToAverageAssets |
Tier 1 Capital (to Risk Weighted Assets), Actual Ratio (as a percent) |  | 17.83%us-gaap_TierOneRiskBasedCapitalToRiskWeightedAssets | 19.34%us-gaap_TierOneRiskBasedCapitalToRiskWeightedAssets |
Total Capital (to Risk Weighted Assets), Actual Ratio (as a percent) | 4.50%us-gaap_CapitalToRiskWeightedAssets | 18.67%us-gaap_CapitalToRiskWeightedAssets | 20.24%us-gaap_CapitalToRiskWeightedAssets |
Total Capital (to Risk Weighted Assets), For Capital Adequacy Purposes Ratio (as a percent) | 2.50%us-gaap_CapitalRequiredForCapitalAdequacyToRiskWeightedAssets |  |  |
Term of mandatory compliance | 4 years |  |  |
Percentage of capital securities issued by trust qualifying as Tier I capital, maximum |  | 25.00%iboc_MaximumPercentageOfCapitalSecuritiesIssuedByTrustQualifyingAsTierOneCapital |  |
Percentage of capital securities issued by trust qualifying as Tier II capital, minimum |  | 25.00%iboc_MinimumPercentageOfCapitalSecuritiesIssuedByTrustQualifyingAsTierTwoCapital |  |
Capital securities issued by the trust, qualifying as Tier I capital |  | $ 175,416,000 iboc_CapitalSecuritiesIssuedByTrustQualifyingAsTierOneCapital |  |
Minimum |  |  |  |
Common Equity Tier 1 ("CET1") ratio |  | 7.00%iboc_CommonEquityTierOneRatio / us-gaap_RangeAxis = us-gaap_MinimumMember |  |
Tier 1 Capital (to Risk Weighted Assets), Actual Ratio (as a percent) |  |  |  | 4.00%us-gaap_TierOneRiskBasedCapitalToRiskWeightedAssets / us-gaap_RangeAxis = us-gaap_MinimumMember
Forecast |  |  |  |
Total Capital (to Risk Weighted Assets), For Capital Adequacy Purposes Ratio (as a percent) |  | 0.625%us-gaap_CapitalRequiredForCapitalAdequacyToRiskWeightedAssets / us-gaap_StatementScenarioAxis = us-gaap_ScenarioForecastMember |  |

X
- Definition Represents capital securities issued by trust that is qualified as Tier I capital as on the reporting date. + References No definition available. + Details
Name: | iboc_CapitalSecuritiesIssuedByTrustQualifyingAsTierOneCapital
Namespace Prefix: | iboc_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Represents information pertaining to Common Equity Tier 1 ("CET1")ratio. + References No definition available. + Details
Name: | iboc_CommonEquityTierOneRatio
Namespace Prefix: | iboc_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition Period representing the new rule of mandatory compliance. + References No definition available. + Details
Name: | iboc_MandatoryComplianceTerm
Namespace Prefix: | iboc_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- Definition Represents the maximum percentage of capital securities issued by the trust qualifying as Tier I capital on an aggregate basis. + References No definition available. + Details
Name: | iboc_MaximumPercentageOfCapitalSecuritiesIssuedByTrustQualifyingAsTierOneCapital
Namespace Prefix: | iboc_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Represents the minimum percentage of capital securities issued by the trust qualifying as Tier II capital on an aggregate basis. + References No definition available. + Details
Name: | iboc_MinimumPercentageOfCapitalSecuritiesIssuedByTrustQualifyingAsTierTwoCapital
Namespace Prefix: | iboc_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition The minimum Total risk based capital ratio (total capital divided by risk weighted assets) required for capital adequacy purposes under the regulatory framework for prompt corrective action. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 505 -Section 50 -Paragraph 1H -Subparagraph (c)(2) -URI http://asc.fasb.org/extlink&oid=35709795&loc=d3e65071-112826 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 505 -Section 50 -Paragraph 1 -Subparagraph (c)(1) -URI http://asc.fasb.org/extlink&oid=35709795&loc=SL5958568-112826 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 505 -Section 50 -Paragraph 1B -URI http://asc.fasb.org/extlink&oid=35709795&loc=SL5958570-112826 + Details
Name: | us-gaap_CapitalRequiredForCapitalAdequacyToRiskWeightedAssets
Namespace Prefix: | us-gaap_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition Total Capital divided by risk weighted assets as defined in the regulations. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 505 -Section 50 -Paragraph 1H -Subparagraph (c)(2) -URI http://asc.fasb.org/extlink&oid=35709795&loc=d3e65071-112826 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 505 -Section 50 -Paragraph 1 -Subparagraph (c)(1) -URI http://asc.fasb.org/extlink&oid=35709795&loc=SL5958568-112826 + Details
Name: | us-gaap_CapitalToRiskWeightedAssets
Namespace Prefix: | us-gaap_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition Tier 1 Leverage Capital divided by average assets as defined in the regulations. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 505 -Section 50 -Paragraph 1H -Subparagraph (c)(2) -URI http://asc.fasb.org/extlink&oid=35709795&loc=d3e65071-112826 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 505 -Section 50 -Paragraph 1 -Subparagraph (c)(1) -URI http://asc.fasb.org/extlink&oid=35709795&loc=SL5958568-112826 + Details
Name: | us-gaap_TierOneLeverageCapitalToAverageAssets
Namespace Prefix: | us-gaap_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition Tier 1 capital divided by risk weighted assets as defined by regulations. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 505 -Section 50 -Paragraph 1H -Subparagraph (c)(2) -URI http://asc.fasb.org/extlink&oid=35709795&loc=d3e65071-112826 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 505 -Section 50 -Paragraph 1 -Subparagraph (c)(1) -URI http://asc.fasb.org/extlink&oid=35709795&loc=SL5958568-112826 + Details
Name: | us-gaap_TierOneRiskBasedCapitalToRiskWeightedAssets
Namespace Prefix: | us-gaap_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- Details
Name: | us-gaap_RangeAxis=us-gaap_MinimumMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_StatementScenarioAxis=us-gaap_ScenarioForecastMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |