XML 68 R58.htm IDEA: XBRL DOCUMENT
v3.21.2

Loans (Recorded Investment by Loan Class in Current and Nonaccrual Loans) (Details) - USD ($) $ in Thousands | Sep. 30, 2021 | Dec. 31, 2020
--- | --- | ---
Financing Receivable, Recorded Investment, Past Due [Line Items] |  |
Total Loans | $ 3,609,791 | $ 3,557,908
Investment securities, nonaccrual | 6,675 | 9,286
Nonaccrual with no allowance | 5,597 | 8,616
30 to 59 Days Past Due [Member] |  |
Financing Receivable, Recorded Investment, Past Due [Line Items] |  |
Total Loans | 16,943 | 6,209
60 to 89 Days Past Due [Member] |  |
Financing Receivable, Recorded Investment, Past Due [Line Items] |  |
Total Loans | 1,003 | 1,554
Greater than 90 Days [Member] |  |
Financing Receivable, Recorded Investment, Past Due [Line Items] |  |
Total Loans | 1 | 231
Total Past Due [Member] |  |
Financing Receivable, Recorded Investment, Past Due [Line Items] |  |
Total Loans | 17,947 | 7,994
Current [Member] |  |
Financing Receivable, Recorded Investment, Past Due [Line Items] |  |
Total Loans | 3,585,169 | 3,540,628
Commercial Business [Member] |  |
Financing Receivable, Recorded Investment, Past Due [Line Items] |  |
Total Loans | 689,819 | 798,409
Investment securities, nonaccrual | 1,046 | 1,975
Nonaccrual with no allowance | 498 | 1,502
Commercial Business [Member] | 30 to 59 Days Past Due [Member] |  |
Financing Receivable, Recorded Investment, Past Due [Line Items] |  |
Total Loans | 11,489 | 264
Commercial Business [Member] | 60 to 89 Days Past Due [Member] |  |
Financing Receivable, Recorded Investment, Past Due [Line Items] |  |
Total Loans |  | 87
Commercial Business [Member] | Greater than 90 Days [Member] |  |
Financing Receivable, Recorded Investment, Past Due [Line Items] |  |
Total Loans |  |
Commercial Business [Member] | Total Past Due [Member] |  |
Financing Receivable, Recorded Investment, Past Due [Line Items] |  |
Total Loans | 11,489 | 351
Commercial Business [Member] | Current [Member] |  |
Financing Receivable, Recorded Investment, Past Due [Line Items] |  |
Total Loans | 677,284 | 796,083
Commercial Mortgage [Member] |  |
Financing Receivable, Recorded Investment, Past Due [Line Items] |  |
Total Loans | 1,350,932 | 1,256,525
Investment securities, nonaccrual | 874 | 2,906
Nonaccrual with no allowance | 344 | 2,709
Commercial Mortgage [Member] | 30 to 59 Days Past Due [Member] |  |
Financing Receivable, Recorded Investment, Past Due [Line Items] |  |
Total Loans | 272 | 822
Commercial Mortgage [Member] | 60 to 89 Days Past Due [Member] |  |
Financing Receivable, Recorded Investment, Past Due [Line Items] |  |
Total Loans |  | 26
Commercial Mortgage [Member] | Greater than 90 Days [Member] |  |
Financing Receivable, Recorded Investment, Past Due [Line Items] |  |
Total Loans |  |
Commercial Mortgage [Member] | Total Past Due [Member] |  |
Financing Receivable, Recorded Investment, Past Due [Line Items] |  |
Total Loans | 272 | 848
Commercial Mortgage [Member] | Current [Member] |  |
Financing Receivable, Recorded Investment, Past Due [Line Items] |  |
Total Loans | 1,349,786 | 1,252,771
Residential Real Estate Loans [Member] |  |
Financing Receivable, Recorded Investment, Past Due [Line Items] |  |
Total Loans | 570,435 | 586,537
Investment securities, nonaccrual | 2,457 | 2,587
Nonaccrual with no allowance | 2,457 | 2,587
Residential Real Estate Loans [Member] | 30 to 59 Days Past Due [Member] |  |
Financing Receivable, Recorded Investment, Past Due [Line Items] |  |
Total Loans | 543 | 984
Residential Real Estate Loans [Member] | 60 to 89 Days Past Due [Member] |  |
Financing Receivable, Recorded Investment, Past Due [Line Items] |  |
Total Loans | 80 | 60
Residential Real Estate Loans [Member] | Greater than 90 Days [Member] |  |
Financing Receivable, Recorded Investment, Past Due [Line Items] |  |
Total Loans |  |
Residential Real Estate Loans [Member] | Total Past Due [Member] |  |
Financing Receivable, Recorded Investment, Past Due [Line Items] |  |
Total Loans | 623 | 1,044
Residential Real Estate Loans [Member] | Current [Member] |  |
Financing Receivable, Recorded Investment, Past Due [Line Items] |  |
Total Loans | 567,355 | 582,906
Residential Real Estate Lines [Member] |  |
Financing Receivable, Recorded Investment, Past Due [Line Items] |  |
Total Loans | 76,214 | 86,708
Investment securities, nonaccrual | 192 | 323
Nonaccrual with no allowance | 192 | 323
Residential Real Estate Lines [Member] | 30 to 59 Days Past Due [Member] |  |
Financing Receivable, Recorded Investment, Past Due [Line Items] |  |
Total Loans | 55 | 40
Residential Real Estate Lines [Member] | 60 to 89 Days Past Due [Member] |  |
Financing Receivable, Recorded Investment, Past Due [Line Items] |  |
Total Loans |  | 15
Residential Real Estate Lines [Member] | Greater than 90 Days [Member] |  |
Financing Receivable, Recorded Investment, Past Due [Line Items] |  |
Total Loans |  |
Residential Real Estate Lines [Member] | Total Past Due [Member] |  |
Financing Receivable, Recorded Investment, Past Due [Line Items] |  |
Total Loans | 79 | 55
Residential Real Estate Lines [Member] | Current [Member] |  |
Financing Receivable, Recorded Investment, Past Due [Line Items] |  |
Total Loans | 75,943 | 86,330
Consumer Indirect [Member] |  |
Financing Receivable, Recorded Investment, Past Due [Line Items] |  |
Total Loans | 907,185 | 812,816
Investment securities, nonaccrual | 2,104 | 1,495
Nonaccrual with no allowance | 2,104 | 1,495
Consumer Indirect [Member] | 30 to 59 Days Past Due [Member] |  |
Financing Receivable, Recorded Investment, Past Due [Line Items] |  |
Total Loans | 4,499 | 3,966
Consumer Indirect [Member] | 60 to 89 Days Past Due [Member] |  |
Financing Receivable, Recorded Investment, Past Due [Line Items] |  |
Total Loans | 899 | 1,348
Consumer Indirect [Member] | Greater than 90 Days [Member] |  |
Financing Receivable, Recorded Investment, Past Due [Line Items] |  |
Total Loans |  |
Consumer Indirect [Member] | Total Past Due [Member] |  |
Financing Receivable, Recorded Investment, Past Due [Line Items] |  |
Total Loans | 5,398 | 5,314
Consumer Indirect [Member] | Current [Member] |  |
Financing Receivable, Recorded Investment, Past Due [Line Items] |  |
Total Loans | 899,683 | 806,007
Other Consumer [Member] |  |
Financing Receivable, Recorded Investment, Past Due [Line Items] |  |
Total Loans | 15,206 | 16,913
Investment securities, nonaccrual | 2 |
Nonaccrual with no allowance | 2 |
Other Consumer [Member] | 30 to 59 Days Past Due [Member] |  |
Financing Receivable, Recorded Investment, Past Due [Line Items] |  |
Total Loans | 85 | 133
Other Consumer [Member] | 60 to 89 Days Past Due [Member] |  |
Financing Receivable, Recorded Investment, Past Due [Line Items] |  |
Total Loans | 0 | 18
Other Consumer [Member] | Greater than 90 Days [Member] |  |
Financing Receivable, Recorded Investment, Past Due [Line Items] |  |
Total Loans | 1 | 231
Other Consumer [Member] | Total Past Due [Member] |  |
Financing Receivable, Recorded Investment, Past Due [Line Items] |  |
Total Loans | 86 | 382
Other Consumer [Member] | Current [Member] |  |
Financing Receivable, Recorded Investment, Past Due [Line Items] |  |
Total Loans | $ 15,118 | $ 16,531

X
- Definition Amount of financing receivable on nonaccrual status with no allowance for credit loss. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 20 -Section 50 -Paragraph 16 -Subparagraph (d) -URI http://asc.fasb.org/extlink&oid=124255953&loc=SL82919258-210447 + Details
Name: | us-gaap_FinancingReceivableNonaccrualNoAllowance
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amount of financing receivable on nonaccrual status. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 7 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=123577603&loc=d3e5111-111524 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 20 -Section 50 -Paragraph 16 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=124255953&loc=SL82919258-210447 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Publisher SEC -Name Regulation S-K (SK) -Number 229 -Section 1405 -Paragraph (a) -Subparagraph (3) Reference 4: http://www.xbrl.org/2003/role/disclosureRef -Publisher SEC -Name Regulation S-K (SK) -Number 229 -Section 1405 -Paragraph (a) -Subparagraph (2) + Details
Name: | us-gaap_FinancingReceivableRecordedInvestmentNonaccrualStatus
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. + References No definition available. + Details
Name: | us-gaap_FinancingReceivableRecordedInvestmentPastDueLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Amount, before allowance for credit loss, of financing receivable. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 7A -URI http://asc.fasb.org/extlink&oid=123577603&loc=SL6953401-111524 Reference 2: http://www.xbrl.org/2003/role/exampleRef -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 20 -Section 55 -Paragraph 79 -URI http://asc.fasb.org/extlink&oid=124267575&loc=SL82922352-210448 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 20 -Section 50 -Paragraph 14 -URI http://asc.fasb.org/extlink&oid=124255953&loc=SL82919253-210447 Reference 4: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 20 -Section 45 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=124255206&loc=SL82895884-210446 Reference 5: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 20 -Section 50 -Paragraph 5 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=124255953&loc=SL82919230-210447 Reference 6: http://www.xbrl.org/2003/role/exampleRef -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 20 -Section 55 -Paragraph 80 -URI http://asc.fasb.org/extlink&oid=124267575&loc=SL82922355-210448 Reference 7: http://www.xbrl.org/2003/role/disclosureRef -Publisher SEC -Name Regulation S-K (SK) -Number 229 -Section 1405 -Paragraph (a) -Subparagraph (1) Reference 8: http://www.xbrl.org/2003/role/disclosureRef -Publisher SEC -Name Regulation S-K (SK) -Number 229 -Section 1405 -Paragraph (a) -Subparagraph (2) Reference 9: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher SEC -Name Regulation S-K (SK) -Number 229 -Section 1404 -Paragraph (a) + Details
Name: | us-gaap_NotesReceivableGross
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Details
Name: | us-gaap_FinancingReceivablesPeriodPastDueAxis=us-gaap_FinancingReceivables30To59DaysPastDueMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancingReceivablesPeriodPastDueAxis=us-gaap_FinancingReceivables60To89DaysPastDueMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancingReceivablesPeriodPastDueAxis=us-gaap_FinancingReceivablesEqualToGreaterThan90DaysPastDueMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancingReceivablesPeriodPastDueAxis=us-gaap_FinancialAssetPastDueMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancingReceivablesPeriodPastDueAxis=us-gaap_FinancialAssetNotPastDueMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=fisi_CommercialAndIndustrialMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=us-gaap_CommercialRealEstateMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=us-gaap_ResidentialMortgageMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=us-gaap_HomeEquityMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=fisi_ConsumerIndirectMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=us-gaap_ConsumerPortfolioSegmentMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |