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Junior Subordinated Interest Deferrable Debentures (Tables) | 3 Months Ended
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Mar. 31, 2019
Junior Subordinated Interest Deferrable Debentures |
Junior subordinated deferrable interest debentures, major types of business trusts |
|  | 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 |  | 6.13 | % | LIBOR | + | 3.45 |  | November 2032 |  | February 2008 |
Trust VIII |  |  | 25,774 |  | Quarterly |  | 5.84 | % | LIBOR | + | 3.05 |  | October 2033 |  | October 2008 |
Trust IX |  |  | 41,238 |  | Quarterly |  | 4.42 | % | LIBOR | + | 1.62 |  | October 2036 |  | October 2011 |
Trust X |  |  | 21,021 |  | Quarterly |  | 4.39 | % | LIBOR | + | 1.65 |  | February 2037 |  | February 2012 |
Trust XI |  |  | 25,990 |  | Quarterly |  | 4.42 | % | LIBOR | + | 1.62 |  | July 2037 |  | July 2012 |
Trust XII |  |  | 20,619 |  | Quarterly |  | 4.08 | % | LIBOR | + | 1.45 |  | September 2037 |  | September 2012 |
|  | $ | 160,416 |  |  |  |  |  |  |  |  |  |  |  |  |
The Capital and Common Securities may be redeemed in whole or in part on any interest payment date after the Optional Redemption Date.

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