XML 77 R60.htm IDEA: XBRL DOCUMENT v2.4.1.9
Allowance for Loan Losses and Credit Quality of Loans, Credit Quality by Loan Class (Details) (USD $)
In Thousands, unless otherwise specified
Dec. 31, 2014
Dec. 31, 2013
Originated Loans [Member] | Commercial Credit Exposure [Member]    
Financing Receivable, Recorded Investment [Line Items]    
Financing Receivable $ 1,741,936us-gaap_NotesReceivableNet
/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis
= us-gaap_CommercialPortfolioSegmentMember
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= nbtb_OriginatedLoansMember		 $ 1,652,553us-gaap_NotesReceivableNet
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= us-gaap_CommercialPortfolioSegmentMember
/ nbtb_ClassOfFinancingReceivablesAxis
= nbtb_OriginatedLoansMember
Originated Loans [Member] | Commercial Credit Exposure [Member] | Pass [Member]    
Financing Receivable, Recorded Investment [Line Items]    
Financing Receivable 1,648,664us-gaap_NotesReceivableNet
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= us-gaap_CommercialPortfolioSegmentMember
/ nbtb_ClassOfFinancingReceivablesAxis
= nbtb_OriginatedLoansMember
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= us-gaap_PassMember		 1,547,669us-gaap_NotesReceivableNet
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= us-gaap_CommercialPortfolioSegmentMember
/ nbtb_ClassOfFinancingReceivablesAxis
= nbtb_OriginatedLoansMember
/ us-gaap_InternalCreditAssessmentAxis
= us-gaap_PassMember
Originated Loans [Member] | Commercial Credit Exposure [Member] | Special Mention [Member]    
Financing Receivable, Recorded Investment [Line Items]    
Financing Receivable 23,680us-gaap_NotesReceivableNet
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= us-gaap_CommercialPortfolioSegmentMember
/ nbtb_ClassOfFinancingReceivablesAxis
= nbtb_OriginatedLoansMember
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= us-gaap_SpecialMentionMember		 40,037us-gaap_NotesReceivableNet
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= us-gaap_CommercialPortfolioSegmentMember
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= nbtb_OriginatedLoansMember
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= us-gaap_SpecialMentionMember
Originated Loans [Member] | Commercial Credit Exposure [Member] | Substandard [Member]    
Financing Receivable, Recorded Investment [Line Items]    
Financing Receivable 69,584us-gaap_NotesReceivableNet
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= us-gaap_CommercialPortfolioSegmentMember
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= nbtb_OriginatedLoansMember
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= us-gaap_SubstandardMember		 64,835us-gaap_NotesReceivableNet
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= us-gaap_CommercialPortfolioSegmentMember
/ nbtb_ClassOfFinancingReceivablesAxis
= nbtb_OriginatedLoansMember
/ us-gaap_InternalCreditAssessmentAxis
= us-gaap_SubstandardMember
Originated Loans [Member] | Commercial Credit Exposure [Member] | Doubtful [Member]    
Financing Receivable, Recorded Investment [Line Items]    
Financing Receivable 8us-gaap_NotesReceivableNet
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= us-gaap_CommercialPortfolioSegmentMember
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= nbtb_OriginatedLoansMember
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= nbtb_OriginatedLoansMember
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= us-gaap_DoubtfulMember
Originated Loans [Member] | Commercial Credit Exposure [Member] | Commercial [Member]    
Financing Receivable, Recorded Investment [Line Items]    
Financing Receivable 615,147us-gaap_NotesReceivableNet
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= us-gaap_CommercialPortfolioSegmentMember
/ nbtb_ClassOfFinancingReceivablesAxis
= nbtb_OriginatedLoansMember
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= nbtb_CommercialFinancingReceivableMember		 616,423us-gaap_NotesReceivableNet
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= nbtb_CommercialFinancingReceivableMember
Originated Loans [Member] | Commercial Credit Exposure [Member] | Commercial [Member] | Pass [Member]    
Financing Receivable, Recorded Investment [Line Items]    
Financing Receivable 570,884us-gaap_NotesReceivableNet
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= us-gaap_CommercialPortfolioSegmentMember
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= nbtb_CommercialFinancingReceivableMember
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= us-gaap_CommercialPortfolioSegmentMember
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= nbtb_CommercialFinancingReceivableMember
/ us-gaap_InternalCreditAssessmentAxis
= us-gaap_PassMember
Originated Loans [Member] | Commercial Credit Exposure [Member] | Commercial [Member] | Special Mention [Member]    
Financing Receivable, Recorded Investment [Line Items]    
Financing Receivable 6,022us-gaap_NotesReceivableNet
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= us-gaap_CommercialPortfolioSegmentMember
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= nbtb_CommercialFinancingReceivableMember
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= us-gaap_SpecialMentionMember		 16,836us-gaap_NotesReceivableNet
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= us-gaap_CommercialPortfolioSegmentMember
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Originated Loans [Member] | Commercial Credit Exposure [Member] | Commercial [Member] | Substandard [Member]    
Financing Receivable, Recorded Investment [Line Items]    
Financing Receivable 38,241us-gaap_NotesReceivableNet
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Originated Loans [Member] | Commercial Credit Exposure [Member] | Commercial [Member] | Doubtful [Member]    
Financing Receivable, Recorded Investment [Line Items]    
Financing Receivable 0us-gaap_NotesReceivableNet
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= us-gaap_DoubtfulMember
Originated Loans [Member] | Commercial Credit Exposure [Member] | Commercial Real Estate [Member]    
Financing Receivable, Recorded Investment [Line Items]    
Financing Receivable 1,068,868us-gaap_NotesReceivableNet
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= us-gaap_CommercialPortfolioSegmentMember
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Originated Loans [Member] | Commercial Credit Exposure [Member] | Commercial Real Estate [Member] | Pass [Member]    
Financing Receivable, Recorded Investment [Line Items]    
Financing Receivable 1,023,856us-gaap_NotesReceivableNet
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= us-gaap_PassMember
Originated Loans [Member] | Commercial Credit Exposure [Member] | Commercial Real Estate [Member] | Special Mention [Member]    
Financing Receivable, Recorded Investment [Line Items]    
Financing Receivable 17,341us-gaap_NotesReceivableNet
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= us-gaap_CommercialPortfolioSegmentMember
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Originated Loans [Member] | Commercial Credit Exposure [Member] | Commercial Real Estate [Member] | Substandard [Member]    
Financing Receivable, Recorded Investment [Line Items]    
Financing Receivable 27,671us-gaap_NotesReceivableNet
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Originated Loans [Member] | Commercial Credit Exposure [Member] | Commercial Real Estate [Member] | Doubtful [Member]    
Financing Receivable, Recorded Investment [Line Items]    
Financing Receivable 0us-gaap_NotesReceivableNet
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Originated Loans [Member] | Commercial Credit Exposure [Member] | Agricultural [Member]    
Financing Receivable, Recorded Investment [Line Items]    
Financing Receivable 32,947us-gaap_NotesReceivableNet
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Originated Loans [Member] | Commercial Credit Exposure [Member] | Agricultural [Member] | Pass [Member]    
Financing Receivable, Recorded Investment [Line Items]    
Financing Receivable 30,481us-gaap_NotesReceivableNet
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Originated Loans [Member] | Commercial Credit Exposure [Member] | Agricultural [Member] | Special Mention [Member]    
Financing Receivable, Recorded Investment [Line Items]    
Financing Receivable 275us-gaap_NotesReceivableNet
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Originated Loans [Member] | Commercial Credit Exposure [Member] | Agricultural [Member] | Substandard [Member]    
Financing Receivable, Recorded Investment [Line Items]    
Financing Receivable 2,183us-gaap_NotesReceivableNet
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Originated Loans [Member] | Commercial Credit Exposure [Member] | Agricultural [Member] | Doubtful [Member]    
Financing Receivable, Recorded Investment [Line Items]    
Financing Receivable 8us-gaap_NotesReceivableNet
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Originated Loans [Member] | Commercial Credit Exposure [Member] | Agricultural Real Estate [Member]    
Financing Receivable, Recorded Investment [Line Items]    
Financing Receivable 24,974us-gaap_NotesReceivableNet
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Originated Loans [Member] | Commercial Credit Exposure [Member] | Agricultural Real Estate [Member] | Pass [Member]    
Financing Receivable, Recorded Investment [Line Items]    
Financing Receivable 23,443us-gaap_NotesReceivableNet
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Originated Loans [Member] | Commercial Credit Exposure [Member] | Agricultural Real Estate [Member] | Special Mention [Member]    
Financing Receivable, Recorded Investment [Line Items]    
Financing Receivable 42us-gaap_NotesReceivableNet
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Originated Loans [Member] | Commercial Credit Exposure [Member] | Agricultural Real Estate [Member] | Substandard [Member]    
Financing Receivable, Recorded Investment [Line Items]    
Financing Receivable 1,489us-gaap_NotesReceivableNet
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Originated Loans [Member] | Commercial Credit Exposure [Member] | Agricultural Real Estate [Member] | Doubtful [Member]    
Financing Receivable, Recorded Investment [Line Items]    
Financing Receivable 0us-gaap_NotesReceivableNet
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Originated Loans [Member] | Business Banking Credit Exposure [Member]    
Financing Receivable, Recorded Investment [Line Items]    
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Financing Receivable, Recorded Investment [Line Items]    
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Financing Receivable, Recorded Investment [Line Items]    
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Financing Receivable, Recorded Investment [Line Items]    
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Financing Receivable, Recorded Investment [Line Items]    
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Financing Receivable, Recorded Investment [Line Items]    
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Financing Receivable, Recorded Investment [Line Items]    
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Financing Receivable, Recorded Investment [Line Items]    
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Financing Receivable, Recorded Investment [Line Items]    
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Originated Loans [Member] | Consumer Credit Exposure [Member] | Indirect [Member]    
Financing Receivable, Recorded Investment [Line Items]    
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Financing Receivable, Recorded Investment [Line Items]    
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Originated Loans [Member] | Consumer Credit Exposure [Member] | Indirect [Member] | Nonperforming [Member]    
Financing Receivable, Recorded Investment [Line Items]    
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Financing Receivable, Recorded Investment [Line Items]    
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Originated Loans [Member] | Consumer Credit Exposure [Member] | Home Equity Member] | Nonperforming [Member]    
Financing Receivable, Recorded Investment [Line Items]    
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Originated Loans [Member] | Consumer Credit Exposure [Member] | Direct [Member]    
Financing Receivable, Recorded Investment [Line Items]    
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Originated Loans [Member] | Consumer Credit Exposure [Member] | Direct [Member] | Performing [Member]    
Financing Receivable, Recorded Investment [Line Items]    
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Financing Receivable, Recorded Investment [Line Items]    
Financing Receivable 136us-gaap_NotesReceivableNet
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Originated Loans [Member] | Residential Mortgage Credit Exposure [Member]    
Financing Receivable, Recorded Investment [Line Items]    
Financing Receivable 848,842us-gaap_NotesReceivableNet
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Originated Loans [Member] | Residential Mortgage Credit Exposure [Member] | Performing [Member]    
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Originated Loans [Member] | Residential Mortgage Credit Exposure [Member] | Nonperforming [Member]    
Financing Receivable, Recorded Investment [Line Items]    
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Originated Loans [Member] | Residential Mortgage Credit Exposure [Member] | Residential Mortgage [Member]    
Financing Receivable, Recorded Investment [Line Items]    
Financing Receivable 848,842us-gaap_NotesReceivableNet
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Originated Loans [Member] | Residential Mortgage Credit Exposure [Member] | Residential Mortgage [Member] | Performing [Member]    
Financing Receivable, Recorded Investment [Line Items]    
Financing Receivable 838,816us-gaap_NotesReceivableNet
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Originated Loans [Member] | Residential Mortgage Credit Exposure [Member] | Residential Mortgage [Member] | Nonperforming [Member]    
Financing Receivable, Recorded Investment [Line Items]    
Financing Receivable 10,026us-gaap_NotesReceivableNet
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Acquired Loans [Member] | Commercial Credit Exposure [Member]    
Financing Receivable, Recorded Investment [Line Items]    
Financing Receivable 275,152us-gaap_NotesReceivableNet
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Acquired Loans [Member] | Commercial Credit Exposure [Member] | Pass [Member]    
Financing Receivable, Recorded Investment [Line Items]    
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Acquired Loans [Member] | Commercial Credit Exposure [Member] | Special Mention [Member]    
Financing Receivable, Recorded Investment [Line Items]    
Financing Receivable 5,486us-gaap_NotesReceivableNet
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Acquired Loans [Member] | Commercial Credit Exposure [Member] | Substandard [Member]    
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