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| 0000860413-20-000236-index.html | 2020-11-04 13:14:38 | |
| 0000860413-20-000236.txt | 2020-11-04 13:14:38 | |
 0000860413-20-000236-xbrl.zip | 575440 | 2020-11-04 13:14:38 |
| fibk-20200930.htm | 4747907 | 2020-11-04 13:14:38 |
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| fibk-20200930xex311.htm | 10311 | 2020-11-04 13:14:38 |
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| report.css | 2767 | 2020-11-04 13:14:38 |
| Show.js | 1085 | 2020-11-04 13:14:38 |