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| 0000860413-20-000126-index.html | 2020-05-11 12:20:23 | |
| 0000860413-20-000126.txt | 2020-05-11 12:20:23 | |
 0000860413-20-000126-xbrl.zip | 452068 | 2020-05-11 12:20:23 |
| fibk-20200331.xsd | 67800 | 2020-05-11 12:20:23 |
| fibk-20200331x10q.htm | 4250184 | 2020-05-11 12:20:23 |
| fibk-20200331x10q_htm.xml | 5337008 | 2020-05-11 12:20:23 |
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| fibk-20200331_cal.xml | 189110 | 2020-05-11 12:20:23 |
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| fibk-20200331_pre.xml | 692410 | 2020-05-11 12:20:23 |
| FilingSummary.xml | 44295 | 2020-05-11 12:20:23 |
| Financial_Report.xlsx | 139990 | 2020-05-11 12:20:23 |
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