XML 64 R83.htm IDEA: XBRL DOCUMENT v2.4.1.9
Regulatory Matters (Narrative) (Details) (USD $)
Dec. 31, 2014
Dec. 31, 2013
Preferred Equity [Member]    
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]    
Tier 1 capital $ 17,300,000us-gaap_TierOneRiskBasedCapital
/ us-gaap_StatementEquityComponentsAxis
= us-gaap_PreferredStockMember
 
Federal Reserve Bank Of New York [Member]    
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]    
Reserve requirement   $ 1,000,000us-gaap_RestrictedCashAndCashEquivalents
/ dei_LegalEntityAxis
= fisi_FederalReserveBankOfNewYorkMember