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|---|---|---|
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| 0000860413-23-000087-index.html | 2023-05-05 16:52:20 | |
| 0000860413-23-000087.txt | 2023-05-05 16:52:20 | |
 0000860413-23-000087-xbrl.zip | 630886 | 2023-05-05 16:52:20 |
| fibk-20230331.htm | 5355937 | 2023-05-05 16:52:20 |
| fibk-20230331.xsd | 87819 | 2023-05-05 16:52:20 |
| fibk-20230331xex311.htm | 10314 | 2023-05-05 16:52:20 |
| fibk-20230331xex312.htm | 10464 | 2023-05-05 16:52:20 |
| fibk-20230331xex32.htm | 4169 | 2023-05-05 16:52:20 |
| fibk-20230331_cal.xml | 164643 | 2023-05-05 16:52:20 |
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| fibk-20230331_htm.xml | 6731141 | 2023-05-05 16:52:20 |
| fibk-20230331_lab.xml | 1166911 | 2023-05-05 16:52:20 |
| fibk-20230331_pre.xml | 948521 | 2023-05-05 16:52:20 |
| FilingSummary.xml | 52444 | 2023-05-05 16:52:20 |
| Financial_Report.xlsx | 222955 | 2023-05-05 16:52:20 |
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| report.css | 2767 | 2023-05-05 16:52:20 |
| Show.js | 1085 | 2023-05-05 16:52:20 |