XML 59 R44.htm IDEA: XBRL DOCUMENT
v3.10.0.1

Junior Subordinated Interest Deferrable Debentures (Tables) | 12 Months Ended
--- | ---
Dec. 31, 2018
Junior Subordinated Interest Deferrable Debentures |
Junior subordinated deferrable interest debentures, major types of business trusts | The following table illustrates key information about each of the Debentures and their interest rates at December 31, 2018:
|  | Junior |  |  |  |  |  |  |  |  |  |  |  |  |
|  | Subordinated |  |  |  |  |  |  |  |  |  |  |  |  |
|  | Deferrable |  |  |  |  |  |  |  |  |  |  |  |  |
|  | Interest |  | Repricing |  | Interest |  | Interest |  |  |  | Optional |
|  | Debentures |  | Frequency |  | Rate |  | Rate Index(1) |  | Maturity Date |  | Redemption Date(1) |
|  | (Dollars in Thousands) |  |  |  |  |  |  |  |  |  |  |
Trust VI |  | $ | 25,774 |  | Quarterly |  | 6.07 | % | LIBOR | + | 3.45 |  | November 2032 |  | February 2008 |
Trust VIII |  |  | 25,774 |  | Quarterly |  | 5.49 | % | LIBOR | + | 3.05 |  | October 2033 |  | October 2008 |
Trust IX |  |  | 41,238 |  | Quarterly |  | 4.02 | % | LIBOR | + | 1.62 |  | October 2036 |  | October 2011 |
Trust X |  |  | 21,021 |  | Quarterly |  | 4.19 | % | LIBOR | + | 1.65 |  | February 2037 |  | February 2012 |
Trust XI |  |  | 25,990 |  | Quarterly |  | 4.02 | % | LIBOR | + | 1.62 |  | July 2037 |  | July 2012 |
Trust XII |  |  | 20,619 |  | Quarterly |  | 4.19 | % | LIBOR | + | 1.45 |  | September 2037 |  | September 2012 |
|  | $ | 160,416 |  |  |  |  |  |  |  |  |  |  |  |  |
| (1) |  | The Capital Securities may be redeemed in whole or in part on any interest payment date after the Optional Redemption Date.

X
- Definition Tabular disclosure of borrowings under junior subordinated debt agreements, including restrictive covenants, collateral, interest rates and due dates, amounts due by date and amount owed in total. + References No definition available. + Details
Name: | iboc_ScheduleOfJuniorSubordinatedBorrowingsTableTextBlock
Namespace Prefix: | iboc_
Data Type: | nonnum:textBlockItemType
Balance Type: | na
Period Type: | duration

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