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|---|---|---|
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| 0000860413-21-000198-index.html | 2021-08-06 14:55:18 | |
| 0000860413-21-000198.txt | 2021-08-06 14:55:18 | |
 0000860413-21-000198-xbrl.zip | 515632 | 2021-08-06 14:55:18 |
| fibk-20210630.htm | 4574627 | 2021-08-06 14:55:18 |
| fibk-20210630.xsd | 50473 | 2021-08-06 14:55:18 |
| fibk-20210630xex311.htm | 10317 | 2021-08-06 14:55:18 |
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| fibk-20210630xex32.htm | 4171 | 2021-08-06 14:55:18 |
| fibk-20210630_cal.xml | 161682 | 2021-08-06 14:55:18 |
| fibk-20210630_def.xml | 499956 | 2021-08-06 14:55:18 |
| fibk-20210630_htm.xml | 4879614 | 2021-08-06 14:55:18 |
| fibk-20210630_lab.xml | 931370 | 2021-08-06 14:55:18 |
| fibk-20210630_pre.xml | 684980 | 2021-08-06 14:55:18 |
| FilingSummary.xml | 35504 | 2021-08-06 14:55:18 |
| Financial_Report.xlsx | 137119 | 2021-08-06 14:55:18 |
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| report.css | 2767 | 2021-08-06 14:55:18 |
| Show.js | 1085 | 2021-08-06 14:55:18 |