Parent Directory| Name | Size | Last Modified |
|---|---|---|
 0000860413-25-000045-index-headers.html | 2025-04-08 16:03:39 | |
| 0000860413-25-000045-index.html | 2025-04-08 16:03:39 | |
| 0000860413-25-000045.txt | 2025-04-08 16:03:39 | |
 0000860413-25-000045-xbrl.zip | 8625369 | 2025-04-08 16:03:39 |
| fibk-20250408.htm | 4003078 | 2025-04-08 16:03:39 |
| fibk-20250408.xsd | 4893 | 2025-04-08 16:03:39 |
| fibk-20250408_def.xml | 7546 | 2025-04-08 16:03:39 |
 fibk-20250408_g1.jpg | 48081 | 2025-04-08 16:03:39 |
 fibk-20250408_g10.gif | 145471 | 2025-04-08 16:03:39 |
 fibk-20250408_g11.gif | 271078 | 2025-04-08 16:03:39 |
 fibk-20250408_g12.jpg | 642561 | 2025-04-08 16:03:39 |
 fibk-20250408_g13.jpg | 930389 | 2025-04-08 16:03:39 |
 fibk-20250408_g14.jpg | 87612 | 2025-04-08 16:03:39 |
 fibk-20250408_g15.jpg | 557615 | 2025-04-08 16:03:39 |
 fibk-20250408_g16.jpg | 146890 | 2025-04-08 16:03:39 |
 fibk-20250408_g17.jpg | 156881 | 2025-04-08 16:03:39 |
 fibk-20250408_g18.jpg | 138498 | 2025-04-08 16:03:39 |
 fibk-20250408_g19.jpg | 142877 | 2025-04-08 16:03:39 |
 fibk-20250408_g2.jpg | 2035675 | 2025-04-08 16:03:39 |
 fibk-20250408_g20.jpg | 139568 | 2025-04-08 16:03:39 |
 fibk-20250408_g21.jpg | 140784 | 2025-04-08 16:03:39 |
 fibk-20250408_g22.jpg | 145222 | 2025-04-08 16:03:39 |
 fibk-20250408_g23.jpg | 145574 | 2025-04-08 16:03:39 |
 fibk-20250408_g24.jpg | 150950 | 2025-04-08 16:03:39 |
 fibk-20250408_g25.jpg | 141305 | 2025-04-08 16:03:39 |
 fibk-20250408_g26.jpg | 142769 | 2025-04-08 16:03:39 |
 fibk-20250408_g27.jpg | 153867 | 2025-04-08 16:03:39 |
 fibk-20250408_g28.jpg | 162363 | 2025-04-08 16:03:39 |
 fibk-20250408_g29.jpg | 158292 | 2025-04-08 16:03:39 |
 fibk-20250408_g3.jpg | 7749 | 2025-04-08 16:03:39 |
 fibk-20250408_g30.jpg | 143952 | 2025-04-08 16:03:39 |
 fibk-20250408_g31.jpg | 170988 | 2025-04-08 16:03:39 |
 fibk-20250408_g32.jpg | 115749 | 2025-04-08 16:03:39 |
 fibk-20250408_g33.jpg | 170228 | 2025-04-08 16:03:39 |
 fibk-20250408_g34.jpg | 153115 | 2025-04-08 16:03:39 |
 fibk-20250408_g35.jpg | 165645 | 2025-04-08 16:03:39 |
 fibk-20250408_g36.jpg | 160064 | 2025-04-08 16:03:39 |
 fibk-20250408_g37.jpg | 165844 | 2025-04-08 16:03:39 |
 fibk-20250408_g38.jpg | 343661 | 2025-04-08 16:03:39 |
 fibk-20250408_g39.gif | 24433 | 2025-04-08 16:03:39 |
 fibk-20250408_g4.jpg | 30698 | 2025-04-08 16:03:39 |
 fibk-20250408_g40.gif | 30323 | 2025-04-08 16:03:39 |
 fibk-20250408_g41.gif | 84835 | 2025-04-08 16:03:39 |
 fibk-20250408_g42.gif | 77775 | 2025-04-08 16:03:39 |
 fibk-20250408_g43.gif | 79447 | 2025-04-08 16:03:39 |
 fibk-20250408_g44.jpg | 136046 | 2025-04-08 16:03:39 |
 fibk-20250408_g45.jpg | 257823 | 2025-04-08 16:03:39 |
 fibk-20250408_g46.jpg | 185341 | 2025-04-08 16:03:39 |
 fibk-20250408_g47.jpg | 78001 | 2025-04-08 16:03:39 |
 fibk-20250408_g5.jpg | 19606 | 2025-04-08 16:03:39 |
 fibk-20250408_g6.jpg | 27808 | 2025-04-08 16:03:39 |
 fibk-20250408_g7.jpg | 623891 | 2025-04-08 16:03:39 |
 fibk-20250408_g8.gif | 72696 | 2025-04-08 16:03:39 |
 fibk-20250408_g9.gif | 63037 | 2025-04-08 16:03:39 |
| fibk-20250408_htm.xml | 226120 | 2025-04-08 16:03:39 |
| fibk-20250408_lab.xml | 10712 | 2025-04-08 16:03:39 |
| fibk-20250408_pre.xml | 6181 | 2025-04-08 16:03:39 |
| FilingSummary.xml | 5186 | 2025-04-08 16:03:39 |
| MetaLinks.json | 200370 | 2025-04-08 16:03:39 |
| R1.htm | 10841 | 2025-04-08 16:03:39 |
| R2.htm | 260908 | 2025-04-08 16:03:39 |
| R3.htm | 7603 | 2025-04-08 16:03:39 |
| R4.htm | 4370 | 2025-04-08 16:03:39 |
| report.css | 2767 | 2025-04-08 16:03:39 |
| Show.js | 1085 | 2025-04-08 16:03:39 |