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| 0000860413-13-000003-index.html | 2013-02-28 19:06:05 | |
| 0000860413-13-000003.txt | 2013-02-28 19:06:05 | |
 0000860413-13-000003-xbrl.zip | 546635 | 2013-02-28 19:06:05 |
| fibk-20121231.xml | 5721357 | 2013-02-28 19:06:05 |
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| fibk-20211231xex32.htm | 8428 | 2013-02-28 19:06:05 |
| FilingSummary.xml | 54610 | 2013-02-28 19:06:05 |
| Financial_Report.xls | 4514272 | 2013-02-28 19:06:05 |
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| report.css | 2721 | 2013-02-28 19:06:05 |
| Show.js | 6423 | 2013-02-28 19:06:05 |