XML 72 R59.htm IDEA: XBRL DOCUMENT
v3.3.1.900

Investment Securities (Investments' Gross Unrealized Losses And Fair Value) (Details) - USD ($) $ in Thousands | Dec. 31, 2015 | Dec. 31, 2014
--- | --- | ---
Investment [Line Items] |  |
Securities available for sale, Less than 12 months, Fair Value | $ 232,913 | $ 51,852
Securities available for sale, Less than 12 months, Unrealized Losses | 3,312 | 116
Securities available for sale, 12 months or longer, Fair Value | 35,864 | 207,942
Securities available for sale, 12 months or longer, Unrealized Losses | 513 | 5,699
Securities available for sale, Fair Value, Total | 268,777 | 259,794
Securities available for sale, Unrealized Losses, Total | 3,825 | 5,815
Securities held to maturity, Less than 12 months, Fair Value | 167,386 |
Securities held to maturity, Less than 12 months, Unrealized Losses | 2,281 |
Securities held to maturity, Fair Value, Total | 167,386 |
Securities held to maturity, Unrealized Losses, Total | 2,281 | 120
Total Securities, Less than 12 months, Fair Value | 400,299 | 69,888
Total Securities, Less than 12 months, Unrealized Losses | 5,593 | 236
Total Securities, 12 months or longer, Fair Value | 35,864 | 207,942
Total Securities, 12 months or longer, Unrealized Losses | 513 | 5,699
Total Securities, Fair Value | 436,163 | 277,830
Total Securities, Unrealized Losses | 6,106 | 5,935
U.S. Government Agencies And Government Sponsored Enterprises [Member] |  |
Investment [Line Items] |  |
Securities available for sale, Less than 12 months, Fair Value | 82,298 | 34,995
Securities available for sale, Less than 12 months, Unrealized Losses | 735 | 77
Securities available for sale, 12 months or longer, Fair Value | 26,302 | 41,070
Securities available for sale, 12 months or longer, Unrealized Losses | 314 | 898
Securities available for sale, Fair Value, Total | 108,600 | 76,065
Securities available for sale, Unrealized Losses, Total | 1,049 | 975
State And Political Subdivisions [Member] |  |
Investment [Line Items] |  |
Securities held to maturity, Less than 12 months, Fair Value | 3,075 | 18,036
Securities held to maturity, Less than 12 months, Unrealized Losses | 4 | 120
Securities held to maturity, Fair Value, Total | 3,075 | 18,036
Securities held to maturity, Unrealized Losses, Total | 4 | 120
Collateralized Mortgage Obligations [Member] | Federal National Mortgage Association [Member] |  |
Investment [Line Items] |  |
Securities available for sale, Less than 12 months, Fair Value | 7,778 | 11,228
Securities available for sale, Less than 12 months, Unrealized Losses | 154 | 24
Securities available for sale, 12 months or longer, Fair Value |  | 25,644
Securities available for sale, 12 months or longer, Unrealized Losses |  | 920
Securities available for sale, Fair Value, Total | 7,778 | 36,872
Securities available for sale, Unrealized Losses, Total | 154 | 944
Securities held to maturity, Less than 12 months, Fair Value | 55,973 |
Securities held to maturity, Less than 12 months, Unrealized Losses | 818 |
Securities held to maturity, Fair Value, Total | 55,973 |
Securities held to maturity, Unrealized Losses, Total | 818 |
Collateralized Mortgage Obligations [Member] | Federal Home Loan Mortgage Corporation [Member] |  |
Investment [Line Items] |  |
Securities available for sale, Less than 12 months, Fair Value | 4,998 |
Securities available for sale, Less than 12 months, Unrealized Losses | 91 |
Securities available for sale, 12 months or longer, Fair Value |  | 76,126
Securities available for sale, 12 months or longer, Unrealized Losses |  | 2,585
Securities available for sale, Fair Value, Total | 4,998 | 76,126
Securities available for sale, Unrealized Losses, Total | 91 | 2,585
Securities held to maturity, Less than 12 months, Fair Value | 79,323 |
Securities held to maturity, Less than 12 months, Unrealized Losses | 1,120 |
Securities held to maturity, Fair Value, Total | 79,323 |
Securities held to maturity, Unrealized Losses, Total | 1,120 |
Collateralized Mortgage Obligations [Member] | Government National Mortgage Association [Member] |  |
Investment [Line Items] |  |
Securities available for sale, 12 months or longer, Fair Value |  | 2,510
Securities available for sale, 12 months or longer, Unrealized Losses |  | 40
Securities available for sale, Fair Value, Total |  | 2,510
Securities available for sale, Unrealized Losses, Total |  | 40
Securities held to maturity, Less than 12 months, Fair Value | 14,559 |
Securities held to maturity, Less than 12 months, Unrealized Losses | 101 |
Securities held to maturity, Fair Value, Total | 14,559 |
Securities held to maturity, Unrealized Losses, Total | 101 |
Mortgage-Backed Securities [Member] |  |
Investment [Line Items] |  |
Securities available for sale, Less than 12 months, Fair Value | 150,615 | 16,857
Securities available for sale, Less than 12 months, Unrealized Losses | 2,577 | 39
Securities available for sale, 12 months or longer, Fair Value | 9,562 | 166,872
Securities available for sale, 12 months or longer, Unrealized Losses | 199 | 4,801
Securities available for sale, Fair Value, Total | 160,177 | 183,729
Securities available for sale, Unrealized Losses, Total | 2,776 | 4,840
Securities held to maturity, Less than 12 months, Fair Value | 164,311 |
Securities held to maturity, Less than 12 months, Unrealized Losses | 2,277 |
Securities held to maturity, Fair Value, Total | 164,311 |
Securities held to maturity, Unrealized Losses, Total | 2,277 |
Mortgage-Backed Securities [Member] | Federal National Mortgage Association [Member] |  |
Investment [Line Items] |  |
Securities available for sale, Less than 12 months, Fair Value | 123,774 | 2,242
Securities available for sale, Less than 12 months, Unrealized Losses | 2,134 | 8
Securities available for sale, 12 months or longer, Fair Value | 9,562 | 62,592
Securities available for sale, 12 months or longer, Unrealized Losses | 199 | 1,256
Securities available for sale, Fair Value, Total | 133,336 | 64,834
Securities available for sale, Unrealized Losses, Total | 2,333 | 1,264
Securities held to maturity, Less than 12 months, Fair Value | 5,666 |
Securities held to maturity, Less than 12 months, Unrealized Losses | 79 |
Securities held to maturity, Fair Value, Total | 5,666 |
Securities held to maturity, Unrealized Losses, Total | 79 |
Mortgage-Backed Securities [Member] | Federal Home Loan Mortgage Corporation [Member] |  |
Investment [Line Items] |  |
Securities available for sale, Less than 12 months, Fair Value | 12,660 | 3,387
Securities available for sale, Less than 12 months, Unrealized Losses | 194 | 7
Securities available for sale, Fair Value, Total | 12,660 | 3,387
Securities available for sale, Unrealized Losses, Total | 194 | $ 7
Mortgage-Backed Securities [Member] | Government National Mortgage Association [Member] |  |
Investment [Line Items] |  |
Securities available for sale, Less than 12 months, Fair Value | 1,405 |
Securities available for sale, Less than 12 months, Unrealized Losses | 4 |
Securities available for sale, Fair Value, Total | 1,405 |
Securities available for sale, Unrealized Losses, Total | 4 |
Securities held to maturity, Less than 12 months, Fair Value | 8,790 |
Securities held to maturity, Less than 12 months, Unrealized Losses | 159 |
Securities held to maturity, Fair Value, Total | 8,790 |
Securities held to maturity, Unrealized Losses, Total | $ 159 |

X
- Definition Amount of accumulated pre-tax unrealized loss on securities classified as available-for-sale that have been in a loss position for twelve months or longer impacting investments. + References No definition available. + Details
Name: | fisi_AvailableForSaleSecuritiesContinuousUnrealizedLossPosition12MonthsOrLongerAggregateLossesAccumulatedInInvestments
Namespace Prefix: | fisi_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Amount of accumulated pre-tax unrealized loss on securities classified as available-for-sale impacting investments. + References No definition available. + Details
Name: | fisi_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionAggregateLossesAccumulatedInInvestments
Namespace Prefix: | fisi_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Amount of accumulated pre-tax unrealized loss on investments in available-for-sale securities that have been in a loss position for less than twelve months impacting investments. + References No definition available. + Details
Name: | fisi_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThan12MonthsAggregateLossesAccumulatedInInvestments
Namespace Prefix: | fisi_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Amount of accumulated pre-tax unrealized loss on securities. + References No definition available. + Details
Name: | fisi_InvestmentSecuritiesAccumulatedUnrecognizedHoldingLoss
Namespace Prefix: | fisi_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Amount of accumulated pre-tax unrealized loss on securities that have been in a loss position for twelve months or longer. + References No definition available. + Details
Name: | fisi_InvestmentSecuritiesContinuousUnrealizedLossPosition12MonthsOrLongerAccumulatedLoss
Namespace Prefix: | fisi_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition This item represents the fair value of securities which are in an unrealized loss position. + References No definition available. + Details
Name: | fisi_InvestmentSecuritiesContinuousUnrealizedLossPositionFairValue
Namespace Prefix: | fisi_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amount of accumulated pre-tax unrealized loss on investments in securities that have been in a loss position for less than twelve months. + References No definition available. + Details
Name: | fisi_InvestmentSecuritiesContinuousUnrealizedLossPositionLessThan12MonthsAccumulatedLoss
Namespace Prefix: | fisi_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition This item represents the fair value of securities that have been in a continuous unrealized loss position for less than twelve months. + References No definition available. + Details
Name: | fisi_InvestmentSecuritiesContinuousUnrealizedLossPositionLessThanTwelveMonthsFairValue
Namespace Prefix: | fisi_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition This item represents the fair value of securities that have been in a continuous unrealized loss position for twelve months or longer. + References No definition available. + Details
Name: | fisi_InvestmentSecuritiesContinuousUnrealizedLossPositionTwelveMonthsOrLongerFairValue
Namespace Prefix: | fisi_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

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

X
- Definition This item represents the aggregate fair value of investments in debt and equity securities in an unrealized loss position which are categorized neither as held-to-maturity nor trading securities. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 6 -Subparagraph (a)(1) -URI http://asc.fasb.org/extlink&oid=27724398&loc=d3e27290-111563 + Details
Name: | us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionFairValue
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition This item represents the aggregate fair value of investments in debt and equity securities categorized neither as held-to-maturity nor trading securities that have been in a continuous unrealized loss position for less than twelve months. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 7 -URI http://asc.fasb.org/extlink&oid=27724398&loc=d3e27337-111563 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 6 -Subparagraph (a)(1) -URI http://asc.fasb.org/extlink&oid=27724398&loc=d3e27290-111563 + Details
Name: | us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThanTwelveMonthsFairValue
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition This item represents the aggregate fair value of investments in debt and equity securities categorized neither as held-to-maturity nor trading securities that have been in a continuous unrealized loss position for twelve months or longer. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 6 -Subparagraph (a)(1) -URI http://asc.fasb.org/extlink&oid=27724398&loc=d3e27290-111563 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 7 -URI http://asc.fasb.org/extlink&oid=27724398&loc=d3e27337-111563 + Details
Name: | us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionTwelveMonthsOrLongerFairValue
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amount of accumulated unrealized loss on investments in debt securities classified as held-to-maturity. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 5 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=27724398&loc=d3e27232-111563 + Details
Name: | us-gaap_HeldToMaturitySecuritiesAccumulatedUnrecognizedHoldingLoss
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition This item represents the fair value of securities categorized as held-to-maturity which are in an unrealized loss position. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 6 -Subparagraph (a)(1) -URI http://asc.fasb.org/extlink&oid=27724398&loc=d3e27290-111563 + Details
Name: | us-gaap_HeldToMaturitySecuritiesContinuousUnrealizedLossPositionFairValue
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amount of accumulated unrealized loss on investments in debt securities classified as held-to-maturity that have been in a continuous loss position for less than twelve months. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 7 -URI http://asc.fasb.org/extlink&oid=27724398&loc=d3e27337-111563 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 6 -Subparagraph (a)(2) -URI http://asc.fasb.org/extlink&oid=27724398&loc=d3e27290-111563 + Details
Name: | us-gaap_HeldToMaturitySecuritiesContinuousUnrealizedLossPositionLessThan12MonthsAccumulatedLoss
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition This item represents the fair value of securities categorized as held-to-maturity that have been in a continuous unrealized loss position for less than twelve months. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 6 -Subparagraph (a)(1) -URI http://asc.fasb.org/extlink&oid=27724398&loc=d3e27290-111563 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 7 -URI http://asc.fasb.org/extlink&oid=27724398&loc=d3e27337-111563 + Details
Name: | us-gaap_HeldToMaturitySecuritiesContinuousUnrealizedLossPositionLessThanTwelveMonthsFairValue
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Details
Name: | us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis=us-gaap_USGovernmentSponsoredEnterprisesDebtSecuritiesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis=us-gaap_USStatesAndPoliticalSubdivisionsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis=us-gaap_CollateralizedMortgageObligationsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_InvestmentTypeAxis=us-gaap_FederalNationalMortgageAssociationCertificatesAndObligationsFNMAMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_InvestmentTypeAxis=us-gaap_FederalHomeLoanMortgageCorporationCertificatesAndObligationsFHLMCMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_InvestmentTypeAxis=us-gaap_GovernmentNationalMortgageAssociationCertificatesAndObligationsGNMAMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis=us-gaap_MortgageBackedSecuritiesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |