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| 0000860413-24-000118.txt | 2024-08-02 11:56:02 | |
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| fibk-20240630.htm | 4206785 | 2024-08-02 11:56:02 |
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| fibk-20240630xex32.htm | 4069 | 2024-08-02 11:56:02 |
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