Parent Directory| Name | Size | Last Modified |
|---|---|---|
 0000950170-22-015551-index-headers.html | 2022-08-08 16:23:34 | |
| 0000950170-22-015551-index.html | 2022-08-08 16:23:34 | |
| 0000950170-22-015551.txt | 2022-08-08 16:23:34 | |
 0000950170-22-015551-xbrl.zip | 534270 | 2022-08-08 16:23:34 |
| FilingSummary.xml | 70987 | 2022-08-08 16:23:34 |
| Financial_Report.xlsx | 181546 | 2022-08-08 16:23:34 |
| fisi-20220630.htm | 10812155 | 2022-08-08 16:23:34 |
| fisi-20220630.xsd | 92301 | 2022-08-08 16:23:34 |
| fisi-20220630_cal.xml | 110554 | 2022-08-08 16:23:34 |
| fisi-20220630_def.xml | 425555 | 2022-08-08 16:23:34 |
| fisi-20220630_htm.xml | 11841053 | 2022-08-08 16:23:34 |
| fisi-20220630_lab.xml | 771506 | 2022-08-08 16:23:34 |
| fisi-20220630_pre.xml | 654934 | 2022-08-08 16:23:34 |
| fisi-ex31_1.htm | 18330 | 2022-08-08 16:23:34 |
| fisi-ex31_2.htm | 18301 | 2022-08-08 16:23:34 |
| fisi-ex32.htm | 26230 | 2022-08-08 16:23:34 |
| MetaLinks.json | 1111852 | 2022-08-08 16:23:34 |
| R1.htm | 52151 | 2022-08-08 16:23:34 |
| R10.htm | 9518 | 2022-08-08 16:23:34 |
| R11.htm | 66125 | 2022-08-08 16:23:34 |
| R12.htm | 129560 | 2022-08-08 16:23:34 |
| R13.htm | 804534 | 2022-08-08 16:23:34 |
| R14.htm | 1773733 | 2022-08-08 16:23:34 |
| R15.htm | 151446 | 2022-08-08 16:23:34 |
| R16.htm | 89286 | 2022-08-08 16:23:34 |
| R17.htm | 35660 | 2022-08-08 16:23:34 |
| R18.htm | 194330 | 2022-08-08 16:23:34 |
| R19.htm | 125659 | 2022-08-08 16:23:34 |
| R2.htm | 92739 | 2022-08-08 16:23:34 |
| R20.htm | 642699 | 2022-08-08 16:23:34 |
| R21.htm | 87192 | 2022-08-08 16:23:34 |
| R22.htm | 66790 | 2022-08-08 16:23:34 |
| R23.htm | 48590 | 2022-08-08 16:23:34 |
| R24.htm | 627888 | 2022-08-08 16:23:34 |
| R25.htm | 258774 | 2022-08-08 16:23:34 |
| R26.htm | 87064 | 2022-08-08 16:23:34 |
| R27.htm | 37351 | 2022-08-08 16:23:34 |
| R28.htm | 54843 | 2022-08-08 16:23:34 |
| R29.htm | 130320 | 2022-08-08 16:23:34 |
| R3.htm | 33725 | 2022-08-08 16:23:34 |
| R30.htm | 778726 | 2022-08-08 16:23:34 |
| R31.htm | 1744978 | 2022-08-08 16:23:34 |
| R32.htm | 148612 | 2022-08-08 16:23:34 |
| R33.htm | 87098 | 2022-08-08 16:23:34 |
| R34.htm | 34923 | 2022-08-08 16:23:34 |
| R35.htm | 182079 | 2022-08-08 16:23:34 |
| R36.htm | 119428 | 2022-08-08 16:23:34 |
| R37.htm | 641587 | 2022-08-08 16:23:34 |
| R38.htm | 79773 | 2022-08-08 16:23:34 |
| R39.htm | 60784 | 2022-08-08 16:23:34 |
| R4.htm | 130511 | 2022-08-08 16:23:34 |
| R40.htm | 36734 | 2022-08-08 16:23:34 |
| R41.htm | 605158 | 2022-08-08 16:23:34 |
| R42.htm | 253919 | 2022-08-08 16:23:34 |
| R43.htm | 45113 | 2022-08-08 16:23:34 |
| R44.htm | 18082 | 2022-08-08 16:23:34 |
| R45.htm | 11914 | 2022-08-08 16:23:34 |
| R46.htm | 27602 | 2022-08-08 16:23:34 |
| R47.htm | 12062 | 2022-08-08 16:23:34 |
| R48.htm | 38922 | 2022-08-08 16:23:34 |
| R49.htm | 10893 | 2022-08-08 16:23:34 |
| R5.htm | 33461 | 2022-08-08 16:23:34 |
| R50.htm | 66904 | 2022-08-08 16:23:34 |
| R51.htm | 53037 | 2022-08-08 16:23:34 |
| R52.htm | 9577 | 2022-08-08 16:23:34 |
| R53.htm | 58557 | 2022-08-08 16:23:34 |
| R54.htm | 58682 | 2022-08-08 16:23:34 |
| R55.htm | 31838 | 2022-08-08 16:23:34 |
| R56.htm | 50722 | 2022-08-08 16:23:34 |
| R57.htm | 73563 | 2022-08-08 16:23:34 |
| R58.htm | 15441 | 2022-08-08 16:23:34 |
| R59.htm | 63976 | 2022-08-08 16:23:34 |
| R6.htm | 90687 | 2022-08-08 16:23:34 |
| R60.htm | 71551 | 2022-08-08 16:23:34 |
| R61.htm | 39178 | 2022-08-08 16:23:34 |
| R62.htm | 12379 | 2022-08-08 16:23:34 |
| R63.htm | 15515 | 2022-08-08 16:23:34 |
| R64.htm | 19392 | 2022-08-08 16:23:34 |
| R65.htm | 21402 | 2022-08-08 16:23:34 |
| R66.htm | 3957 | 2022-08-08 16:23:34 |
| R67.htm | 8748 | 2022-08-08 16:23:34 |
| R68.htm | 12463 | 2022-08-08 16:23:34 |
| R69.htm | 13940 | 2022-08-08 16:23:34 |
| R7.htm | 11257 | 2022-08-08 16:23:34 |
| R70.htm | 15149 | 2022-08-08 16:23:34 |
| R71.htm | 14794 | 2022-08-08 16:23:34 |
| R72.htm | 19081 | 2022-08-08 16:23:34 |
| R73.htm | 38788 | 2022-08-08 16:23:34 |
| R74.htm | 7460 | 2022-08-08 16:23:34 |
| R75.htm | 15681 | 2022-08-08 16:23:34 |
| R76.htm | 31434 | 2022-08-08 16:23:34 |
| R77.htm | 12401 | 2022-08-08 16:23:34 |
| R78.htm | 58869 | 2022-08-08 16:23:34 |
| R79.htm | 38247 | 2022-08-08 16:23:34 |
| R8.htm | 94142 | 2022-08-08 16:23:34 |
| R80.htm | 69375 | 2022-08-08 16:23:34 |
| R81.htm | 8989 | 2022-08-08 16:23:34 |
| R82.htm | 29260 | 2022-08-08 16:23:34 |
| R83.htm | 23144 | 2022-08-08 16:23:34 |
| R84.htm | 9981 | 2022-08-08 16:23:34 |
| R85.htm | 21922 | 2022-08-08 16:23:34 |
| R86.htm | 5647 | 2022-08-08 16:23:34 |
| R87.htm | 9668 | 2022-08-08 16:23:34 |
| R88.htm | 7178 | 2022-08-08 16:23:34 |
| R89.htm | 15468 | 2022-08-08 16:23:34 |
| R9.htm | 78144 | 2022-08-08 16:23:34 |
| R90.htm | 78206 | 2022-08-08 16:23:34 |
| R91.htm | 14147 | 2022-08-08 16:23:34 |
| R92.htm | 30392 | 2022-08-08 16:23:34 |
| R93.htm | 71075 | 2022-08-08 16:23:34 |
| R94.htm | 4354 | 2022-08-08 16:23:34 |
| R95.htm | 24789 | 2022-08-08 16:23:34 |
| R96.htm | 44835 | 2022-08-08 16:23:34 |
| report.css | 2768 | 2022-08-08 16:23:34 |
| Show.js | 1086 | 2022-08-08 16:23:34 |