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| 0000860413-19-000062-index.html | 2019-05-08 16:29:47 | |
| 0000860413-19-000062.txt | 2019-05-08 16:29:47 | |
 0000860413-19-000062-xbrl.zip | 403139 | 2019-05-08 16:29:47 |
| fibk-20190331.xml | 4630514 | 2019-05-08 16:29:47 |
| fibk-20190331.xsd | 72422 | 2019-05-08 16:29:47 |
| fibk-20190331x10q.htm | 2456315 | 2019-05-08 16:29:47 |
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| fibk-20190331xex32.htm | 4718 | 2019-05-08 16:29:47 |
| fibk-20190331_cal.xml | 188017 | 2019-05-08 16:29:47 |
| fibk-20190331_def.xml | 595154 | 2019-05-08 16:29:47 |
| fibk-20190331_lab.xml | 1135234 | 2019-05-08 16:29:47 |
| fibk-20190331_pre.xml | 751379 | 2019-05-08 16:29:47 |
| FilingSummary.xml | 44347 | 2019-05-08 16:29:47 |
| Financial_Report.xlsx | 119659 | 2019-05-08 16:29:47 |
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| report.css | 2767 | 2019-05-08 16:29:47 |
| Show.js | 1085 | 2019-05-08 16:29:47 |