XML 60 R43.htm IDEA: XBRL DOCUMENT
v3.22.4

Deposits (Tables) | 12 Months Ended
--- | ---
Dec. 31, 2022
Deposits [Abstract] |
Summary of Deposits | A summary of deposits as of December 31 are as follows (in thousands):
|  | 2022 |  |  | 2021 |
Noninterest-bearing demand |  | $ | 1,139,214 |  |  | $ | 1,107,561 |
Interest-bearing demand |  |  | 863,822 |  |  |  | 864,528 |
Savings and money market |  |  | 1,643,516 |  |  |  | 1,933,047 |
Time deposits, due: |  |  |  |  |  |
Within one year |  |  | 1,238,202 |  |  |  | 880,892 |
One to two years |  |  | 35,046 |  |  |  | 23,572 |
Two to three years |  |  | 4,952 |  |  |  | 9,881 |
Three to four years |  |  | 3,386 |  |  |  | 6,485 |
Four to five years |  |  | 1,286 |  |  |  | 1,124 |
Thereafter |  |  | - |  |  |  | - |
Total time deposits |  |  | 1,282,872 |  |  |  | 921,954 |
Total deposits |  | $ | 4,929,424 |  |  | $ | 4,827,090 |
Interest Expense by Deposits Type | Interest expense by deposit type for the years ended December 31 is summarized as follows (in thousands):
|  | 2022 |  |  | 2021 |  |  | 2020 |
Interest-bearing demand |  | $ | 2,180 |  |  | $ | 1,156 |  |  | $ | 1,091 |
Savings and money market |  |  | 9,778 |  |  |  | 3,363 |  |  |  | 4,788 |
Time deposits |  |  | 11,036 |  |  |  | 3,599 |  |  |  | 11,943 |
Total interest expense on deposits |  | $ | 22,994 |  |  | $ | 8,118 |  |  | $ | 17,822 |

X
- Definition Interest Expense By Deposits Type [Table Text Block] + References No definition available. + Details
Name: | fisi_InterestExpenseByDepositsTypeTableTextBlock
Namespace Prefix: | fisi_
Data Type: | dtr-types:textBlockItemType
Balance Type: | na
Period Type: | duration

X
- Definition Tabular disclosure of type of deposit liability. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher SEC -Name Regulation S-K (SK) -Number 229 -Section 1406 -Paragraph (e) Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher SEC -Name Regulation S-K (SK) -Number 229 -Section 1406 -Paragraph (f) -Subparagraph (2)(i)(ii) Reference 3: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher SEC -Name Regulation S-K (SK) -Number 229 -Section 1406 -Paragraph (a) -Subparagraph (1) Reference 4: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher SEC -Name Regulation S-K (SK) -Number 229 -Section 1406 -Paragraph (f) -Subparagraph (1) Reference 5: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher SEC -Name Regulation S-K (SK) -Number 229 -Section 1406 -Paragraph (d) Reference 6: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher SEC -Name Regulation S-K (SK) -Number 229 -Section 1406 -Paragraph (f) -Subparagraph (2)(i) Reference 7: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher SEC -Name Regulation S-K (SK) -Number 229 -Section 1406 -Paragraph (f) -Subparagraph (2)(i)(iv) Reference 8: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher SEC -Name Regulation S-K (SK) -Number 229 -Section 1406 -Paragraph (a) -Subparagraph (5) Reference 9: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher SEC -Name Regulation S-K (SK) -Number 229 -Section 1406 -Paragraph (f) -Subparagraph (2)(i)(iii) Reference 10: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher SEC -Name Regulation S-K (SK) -Number 229 -Section 1406 -Paragraph (a) -Subparagraph (4) Reference 11: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher SEC -Name Regulation S-K (SK) -Number 229 -Section 1406 -Paragraph (f) -Subparagraph (2) Reference 12: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher SEC -Name Regulation S-K (SK) -Number 229 -Section 1406 -Paragraph (c) Reference 13: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher SEC -Name Regulation S-K (SK) -Number 229 -Section 1406 -Paragraph (a) -Subparagraph (2) Reference 14: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher SEC -Name Regulation S-K (SK) -Number 229 -Section 1406 -Paragraph (a) -Subparagraph (3) Reference 15: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher SEC -Name Regulation S-K (SK) -Number 229 -Section 1406 -Paragraph (a) + Details
Name: | us-gaap_DepositLiabilitiesTypeTableTextBlock
Namespace Prefix: | us-gaap_
Data Type: | dtr-types:textBlockItemType
Balance Type: | na
Period Type: | duration

X
- References No definition available. + Details
Name: | us-gaap_DepositsAbstract
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration