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| 0000860413-22-000134.txt | 2022-05-09 13:14:33 | |
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| fibk-20220331.htm | 4953513 | 2022-05-09 13:14:33 |
| fibk-20220331.xsd | 80260 | 2022-05-09 13:14:33 |
| fibk-20220331xex311.htm | 10314 | 2022-05-09 13:14:33 |
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| fibk-20220331xex32.htm | 4169 | 2022-05-09 13:14:33 |
| fibk-20220331xex41_descxse.htm | 8709 | 2022-05-09 13:14:33 |
| fibk-20220331_cal.xml | 189665 | 2022-05-09 13:14:33 |
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| fibk-20220331_lab.xml | 1153957 | 2022-05-09 13:14:33 |
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| report.css | 2767 | 2022-05-09 13:14:33 |
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