XML 88 R72.htm IDEA: XBRL DOCUMENT
v3.25.4

Deposits (Scheduled Maturities) (Details) - USD ($) $ in Thousands | Dec. 31, 2025 | Dec. 31, 2024
--- | --- | ---
Scheduled maturities of time deposits |  |
2026 | $ 3,072,855 |
2027 | 94,969 |
2028 | 25,054 |
2029 | 8,139 |
2030 | 302 |
Thereafter | 1 |
Total time, certificates of deposit | 3,201,320 | $ 2,899,543
Time Deposits 250,000 or exceed | 1,702,199 | $ 1,494,267
Scheduled maturities of time deposits in amounts of $100,000 or more |  |
Due within 3 months or less | 1,132,341 |
Due after 3 months and within 6 months | 854,833 |
Due after 6 months and within 12 months | 469,068 |
Due after 12 months | 89,429 |
Total | $ 2,545,671 |

X
- Definition The aggregate amount of domestic and foreign time deposit liabilities (including certificates of deposits, individual retirement accounts and open accounts) or exceed the FDIC insurance limit of $250,000. + References No definition available. + Details
Name: | iboc_TimeDeposits250000OrExceedFdicInsurance
Namespace Prefix: | iboc_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- References No definition available. + Details
Name: | us-gaap_ContractualMaturitiesTimeDeposits100000OrMoreAbstract
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Amount of time deposit liabilities, including certificates of deposit, in denominations of $100,000 or more, maturing after twelve months from the balance sheet date. + References No definition available. + Details
Name: | us-gaap_ContractualMaturitiesTimeDeposits100000OrMoreAfter12Months
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, in denominations of $100,000 or more, maturing within six to twelve months after the balance sheet date. + References No definition available. + Details
Name: | us-gaap_ContractualMaturitiesTimeDeposits100000OrMoreSixMonthsThrough12Months
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, in denominations of $100,000 or more, maturing within three months or fewer from the balance sheet date. + References No definition available. + Details
Name: | us-gaap_ContractualMaturitiesTimeDeposits100000OrMoreThreeMonthsOrLess
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, in denominations of $100,000 or more, maturing within three to six months after the balance sheet date. + References No definition available. + Details
Name: | us-gaap_ContractualMaturitiesTimeDeposits100000OrMoreThreeMonthsThroughSixMonths
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Amount of time deposit maturing after fifth fiscal year following current fiscal year. Time deposit includes, but is not limited to, certificate of deposit. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach). + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Name Accounting Standards Codification -Section 50 -Paragraph 1 -SubTopic 10 -Topic 470 -Publisher FASB -URI https://asc.fasb.org/1943274/2147481544/470-10-50-1 + Details
Name: | us-gaap_TimeDepositMaturitiesAfterYearFive
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Amount of time deposit maturing in fifth fiscal year following current fiscal year. Time deposit includes, but is not limited to, certificate of deposit. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach). + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Name Accounting Standards Codification -Section 50 -Paragraph 1 -SubTopic 10 -Topic 470 -Publisher FASB -URI https://asc.fasb.org/1943274/2147481544/470-10-50-1 + Details
Name: | us-gaap_TimeDepositMaturitiesYearFive
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Amount of time deposit maturing in fourth fiscal year following current fiscal year. Time deposit includes, but is not limited to, certificate of deposit. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach). + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Name Accounting Standards Codification -Section 50 -Paragraph 1 -SubTopic 10 -Topic 470 -Publisher FASB -URI https://asc.fasb.org/1943274/2147481544/470-10-50-1 + Details
Name: | us-gaap_TimeDepositMaturitiesYearFour
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Amount of time deposit maturing in next fiscal year following current fiscal year. Time deposit includes, but is not limited to, certificate of deposit. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach). + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Name Accounting Standards Codification -Section 50 -Paragraph 1 -SubTopic 10 -Topic 470 -Publisher FASB -URI https://asc.fasb.org/1943274/2147481544/470-10-50-1 + Details
Name: | us-gaap_TimeDepositMaturitiesYearOne
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Amount of time deposit maturing in third fiscal year following current fiscal year. Time deposit includes, but is not limited to, certificate of deposit. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach). + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Name Accounting Standards Codification -Section 50 -Paragraph 1 -SubTopic 10 -Topic 470 -Publisher FASB -URI https://asc.fasb.org/1943274/2147481544/470-10-50-1 + Details
Name: | us-gaap_TimeDepositMaturitiesYearThree
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Amount of time deposit maturing in second fiscal year following current fiscal year. Time deposit includes, but is not limited to, certificate of deposit. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach). + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Name Accounting Standards Codification -Section 50 -Paragraph 1 -SubTopic 10 -Topic 470 -Publisher FASB -URI https://asc.fasb.org/1943274/2147481544/470-10-50-1 + Details
Name: | us-gaap_TimeDepositMaturitiesYearTwo
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://fasb.org/us-gaap/role/ref/legacyRef -Name Accounting Standards Codification -Section 50 -Paragraph 1 -SubTopic 405 -Topic 942 -Publisher FASB -URI https://asc.fasb.org/1943274/2147478353/942-405-50-1 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Topic 942 -SubTopic 210 -Name Accounting Standards Codification -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-03(12)) -Publisher FASB -URI https://asc.fasb.org/1943274/2147478546/942-210-S99-1 + Details
Name: | us-gaap_TimeDeposits
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, in denominations of $100,000 or more. + References No definition available. + Details
Name: | us-gaap_TimeDeposits100000OrMore
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

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