XML 41 R30.htm IDEA: XBRL DOCUMENT
v3.7.0.1

Fair Value Measurements (Other Assumptions) (Details) - USD ($) | Mar. 31, 2017 | Dec. 31, 2016
--- | --- | ---
Deposits |  |
Carrying amount of time deposits | $ 2,222,643,000 | $ 2,248,310,000
Significant Unobservable Inputs (Level 3) |  |
Loans |  |
Carrying amount of fixed rate performing loans | 1,398,641,000 | 1,411,272,000
Estimated fair value of fixed rate performing loans | 1,360,095,000 | 1,375,807,000
Deposits |  |
Carrying amount of time deposits | 2,222,643,000 | 2,248,310,000
Estimated fair value of time deposits | 2,222,058,000 | 2,247,648,000
Securities Sold Under Repurchase Agreements |  |
Carrying amount of long-term repurchase agreements | 100,000,000 | 300,000,000
Estimated fair value of long-term repurchase agreements | $ 97,269,000 | $ 289,324,000

X
- Definition Represents the portion of fixed rate performing loans valued at fair value by the entity whether such amount is presented as a separate caption or as a parenthetical disclosure. Fixed rate loan represents loans charging borrowers fixed rates of interest. + References No definition available. + Details
Name: | iboc_LoansReceivableWithFixedRateOfInterestFairValueDisclosure
Namespace Prefix: | iboc_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition The carrying value as of the balance sheet date of securities that an institution sells and agrees to repurchase under a long term agreement (the identical or substantially the same securities) as a seller-borrower at a specified date for a specified price, also known as a repurchase agreement. + References No definition available. + Details
Name: | iboc_SecuritiesSoldUnderLongTermAgreementsToRepurchase
Namespace Prefix: | iboc_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Represents the portion of time deposits valued at fair value by the entity whether such amount is presented as a separate caption or as a parenthetical disclosure. Time deposits include certificates of deposits, individual retirement accounts and open accounts. + References No definition available. + Details
Name: | iboc_TimeDepositsFairValueDisclosure
Namespace Prefix: | iboc_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- References No definition available. + Details
Name: | us-gaap_DepositsAbstract
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- References No definition available. + Details
Name: | us-gaap_FederalFundsPurchasedAndSecuritiesSoldUnderAgreementsToRepurchaseAbstract
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- References No definition available. + Details
Name: | us-gaap_LoansAndLeasesReceivableNetReportedAmountAbstract
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Amount of loan with fixed rate of interest. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 45 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=65884687&loc=d3e4428-111522 + Details
Name: | us-gaap_LoansReceivableWithFixedRatesOfInterest1
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Fair value portion of securities that an entity sells and agrees to repurchase at a specified date for a specified price. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 825 -SubTopic 10 -Section 50 -Paragraph 10 -URI http://asc.fasb.org/extlink&oid=73719730&loc=d3e13433-108611 + Details
Name: | us-gaap_SecuritiesLoanedOrSoldUnderAgreementsToRepurchaseFairValueDisclosure
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Amount of time deposit liabilities, including certificates of deposit. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 405 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=50488274&loc=d3e64164-112818 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-03.12) -URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Industry Guide -Number 3 -Section V -Paragraph D-E + Details
Name: | us-gaap_TimeDeposits
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Details
Name: | us-gaap_FairValueByFairValueHierarchyLevelAxis=us-gaap_FairValueInputsLevel3Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |