XML 30 R35.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 | Mar. 31, 2015 | Dec. 31, 2014
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Originated Loans [Member] | Commercial Credit Exposure [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Financing Receivable | $ 1,760,672 us-gaap_NotesReceivableNet / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_CommercialPortfolioSegmentMember / nbtb_ClassOfFinancingReceivablesAxis = nbtb_OriginatedLoansMember | $ 1,741,936 us-gaap_NotesReceivableNet / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_CommercialPortfolioSegmentMember / nbtb_ClassOfFinancingReceivablesAxis = nbtb_OriginatedLoansMember
Originated Loans [Member] | Commercial Credit Exposure [Member] | Pass [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Financing Receivable | 1,674,082 us-gaap_NotesReceivableNet / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_CommercialPortfolioSegmentMember / nbtb_ClassOfFinancingReceivablesAxis = nbtb_OriginatedLoansMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_PassMember | 1,648,664 us-gaap_NotesReceivableNet / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = 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 | 35,812 us-gaap_NotesReceivableNet / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_CommercialPortfolioSegmentMember / nbtb_ClassOfFinancingReceivablesAxis = nbtb_OriginatedLoansMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_SpecialMentionMember | 23,680 us-gaap_NotesReceivableNet / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_CommercialPortfolioSegmentMember / nbtb_ClassOfFinancingReceivablesAxis = nbtb_OriginatedLoansMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_SpecialMentionMember
Originated Loans [Member] | Commercial Credit Exposure [Member] | Substandard [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Financing Receivable | 50,770 us-gaap_NotesReceivableNet / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_CommercialPortfolioSegmentMember / nbtb_ClassOfFinancingReceivablesAxis = nbtb_OriginatedLoansMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_SubstandardMember | 69,584 us-gaap_NotesReceivableNet / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = 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 | 8 us-gaap_NotesReceivableNet / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_CommercialPortfolioSegmentMember / nbtb_ClassOfFinancingReceivablesAxis = nbtb_OriginatedLoansMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_DoubtfulMember | 8 us-gaap_NotesReceivableNet / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_CommercialPortfolioSegmentMember / nbtb_ClassOfFinancingReceivablesAxis = nbtb_OriginatedLoansMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_DoubtfulMember
Originated Loans [Member] | Commercial Credit Exposure [Member] | Commercial [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Financing Receivable | 621,513 us-gaap_NotesReceivableNet / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_CommercialPortfolioSegmentMember / nbtb_ClassOfFinancingReceivablesAxis = nbtb_OriginatedLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = nbtb_CommercialFinancingReceivableMember | 615,147 us-gaap_NotesReceivableNet / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_CommercialPortfolioSegmentMember / nbtb_ClassOfFinancingReceivablesAxis = nbtb_OriginatedLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = nbtb_CommercialFinancingReceivableMember
Originated Loans [Member] | Commercial Credit Exposure [Member] | Commercial [Member] | Pass [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Financing Receivable | 584,916 us-gaap_NotesReceivableNet / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_CommercialPortfolioSegmentMember / nbtb_ClassOfFinancingReceivablesAxis = nbtb_OriginatedLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = nbtb_CommercialFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_PassMember | 570,884 us-gaap_NotesReceivableNet / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_CommercialPortfolioSegmentMember / nbtb_ClassOfFinancingReceivablesAxis = nbtb_OriginatedLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = 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 | 15,872 us-gaap_NotesReceivableNet / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_CommercialPortfolioSegmentMember / nbtb_ClassOfFinancingReceivablesAxis = nbtb_OriginatedLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = nbtb_CommercialFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_SpecialMentionMember | 6,022 us-gaap_NotesReceivableNet / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_CommercialPortfolioSegmentMember / nbtb_ClassOfFinancingReceivablesAxis = nbtb_OriginatedLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = nbtb_CommercialFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_SpecialMentionMember
Originated Loans [Member] | Commercial Credit Exposure [Member] | Commercial [Member] | Substandard [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Financing Receivable | 20,725 us-gaap_NotesReceivableNet / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_CommercialPortfolioSegmentMember / nbtb_ClassOfFinancingReceivablesAxis = nbtb_OriginatedLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = nbtb_CommercialFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_SubstandardMember | 38,241 us-gaap_NotesReceivableNet / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_CommercialPortfolioSegmentMember / nbtb_ClassOfFinancingReceivablesAxis = nbtb_OriginatedLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = nbtb_CommercialFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_SubstandardMember
Originated Loans [Member] | Commercial Credit Exposure [Member] | Commercial [Member] | Doubtful [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Financing Receivable | 0 us-gaap_NotesReceivableNet / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_CommercialPortfolioSegmentMember / nbtb_ClassOfFinancingReceivablesAxis = nbtb_OriginatedLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = nbtb_CommercialFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_DoubtfulMember | 0 us-gaap_NotesReceivableNet / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_CommercialPortfolioSegmentMember / nbtb_ClassOfFinancingReceivablesAxis = nbtb_OriginatedLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = nbtb_CommercialFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_DoubtfulMember
Originated Loans [Member] | Commercial Credit Exposure [Member] | Commercial Real Estate [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Financing Receivable | 1,082,619 us-gaap_NotesReceivableNet / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_CommercialPortfolioSegmentMember / nbtb_ClassOfFinancingReceivablesAxis = nbtb_OriginatedLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialRealEstateOtherReceivableMember | 1,068,868 us-gaap_NotesReceivableNet / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_CommercialPortfolioSegmentMember / nbtb_ClassOfFinancingReceivablesAxis = nbtb_OriginatedLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialRealEstateOtherReceivableMember
Originated Loans [Member] | Commercial Credit Exposure [Member] | Commercial Real Estate [Member] | Pass [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Financing Receivable | 1,036,469 us-gaap_NotesReceivableNet / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_CommercialPortfolioSegmentMember / nbtb_ClassOfFinancingReceivablesAxis = nbtb_OriginatedLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialRealEstateOtherReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_PassMember | 1,023,856 us-gaap_NotesReceivableNet / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_CommercialPortfolioSegmentMember / nbtb_ClassOfFinancingReceivablesAxis = nbtb_OriginatedLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialRealEstateOtherReceivableMember / us-gaap_InternalCreditAssessmentAxis = 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 | 19,820 us-gaap_NotesReceivableNet / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_CommercialPortfolioSegmentMember / nbtb_ClassOfFinancingReceivablesAxis = nbtb_OriginatedLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialRealEstateOtherReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_SpecialMentionMember | 17,341 us-gaap_NotesReceivableNet / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_CommercialPortfolioSegmentMember / nbtb_ClassOfFinancingReceivablesAxis = nbtb_OriginatedLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialRealEstateOtherReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_SpecialMentionMember
Originated Loans [Member] | Commercial Credit Exposure [Member] | Commercial Real Estate [Member] | Substandard [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Financing Receivable | 26,330 us-gaap_NotesReceivableNet / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_CommercialPortfolioSegmentMember / nbtb_ClassOfFinancingReceivablesAxis = nbtb_OriginatedLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialRealEstateOtherReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_SubstandardMember | 27,671 us-gaap_NotesReceivableNet / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_CommercialPortfolioSegmentMember / nbtb_ClassOfFinancingReceivablesAxis = nbtb_OriginatedLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialRealEstateOtherReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_SubstandardMember
Originated Loans [Member] | Commercial Credit Exposure [Member] | Commercial Real Estate [Member] | Doubtful [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Financing Receivable | 0 us-gaap_NotesReceivableNet / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_CommercialPortfolioSegmentMember / nbtb_ClassOfFinancingReceivablesAxis = nbtb_OriginatedLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialRealEstateOtherReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_DoubtfulMember | 0 us-gaap_NotesReceivableNet / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_CommercialPortfolioSegmentMember / nbtb_ClassOfFinancingReceivablesAxis = nbtb_OriginatedLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialRealEstateOtherReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_DoubtfulMember
Originated Loans [Member] | Commercial Credit Exposure [Member] | Agricultural [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Financing Receivable | 32,009 us-gaap_NotesReceivableNet / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_CommercialPortfolioSegmentMember / nbtb_ClassOfFinancingReceivablesAxis = nbtb_OriginatedLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = nbtb_AgriculturalFinancingReceivableMember | 32,947 us-gaap_NotesReceivableNet / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_CommercialPortfolioSegmentMember / nbtb_ClassOfFinancingReceivablesAxis = nbtb_OriginatedLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = nbtb_AgriculturalFinancingReceivableMember
Originated Loans [Member] | Commercial Credit Exposure [Member] | Agricultural [Member] | Pass [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Financing Receivable | 29,781 us-gaap_NotesReceivableNet / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_CommercialPortfolioSegmentMember / nbtb_ClassOfFinancingReceivablesAxis = nbtb_OriginatedLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = nbtb_AgriculturalFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_PassMember | 30,481 us-gaap_NotesReceivableNet / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_CommercialPortfolioSegmentMember / nbtb_ClassOfFinancingReceivablesAxis = nbtb_OriginatedLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = nbtb_AgriculturalFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_PassMember
Originated Loans [Member] | Commercial Credit Exposure [Member] | Agricultural [Member] | Special Mention [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Financing Receivable | 117 us-gaap_NotesReceivableNet / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_CommercialPortfolioSegmentMember / nbtb_ClassOfFinancingReceivablesAxis = nbtb_OriginatedLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = nbtb_AgriculturalFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_SpecialMentionMember | 275 us-gaap_NotesReceivableNet / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_CommercialPortfolioSegmentMember / nbtb_ClassOfFinancingReceivablesAxis = nbtb_OriginatedLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = nbtb_AgriculturalFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_SpecialMentionMember
Originated Loans [Member] | Commercial Credit Exposure [Member] | Agricultural [Member] | Substandard [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Financing Receivable | 2,103 us-gaap_NotesReceivableNet / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_CommercialPortfolioSegmentMember / nbtb_ClassOfFinancingReceivablesAxis = nbtb_OriginatedLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = nbtb_AgriculturalFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_SubstandardMember | 2,183 us-gaap_NotesReceivableNet / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_CommercialPortfolioSegmentMember / nbtb_ClassOfFinancingReceivablesAxis = nbtb_OriginatedLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = nbtb_AgriculturalFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_SubstandardMember
Originated Loans [Member] | Commercial Credit Exposure [Member] | Agricultural [Member] | Doubtful [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Financing Receivable | 8 us-gaap_NotesReceivableNet / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_CommercialPortfolioSegmentMember / nbtb_ClassOfFinancingReceivablesAxis = nbtb_OriginatedLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = nbtb_AgriculturalFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_DoubtfulMember | 8 us-gaap_NotesReceivableNet / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_CommercialPortfolioSegmentMember / nbtb_ClassOfFinancingReceivablesAxis = nbtb_OriginatedLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = nbtb_AgriculturalFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_DoubtfulMember
Originated Loans [Member] | Commercial Credit Exposure [Member] | Agricultural Real Estate [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Financing Receivable | 24,531 us-gaap_NotesReceivableNet / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_CommercialPortfolioSegmentMember / nbtb_ClassOfFinancingReceivablesAxis = nbtb_OriginatedLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = nbtb_AgriculturalRealEstateFinancingReceivableMember | 24,974 us-gaap_NotesReceivableNet / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_CommercialPortfolioSegmentMember / nbtb_ClassOfFinancingReceivablesAxis = nbtb_OriginatedLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = nbtb_AgriculturalRealEstateFinancingReceivableMember
Originated Loans [Member] | Commercial Credit Exposure [Member] | Agricultural Real Estate [Member] | Pass [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Financing Receivable | 22,916 us-gaap_NotesReceivableNet / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_CommercialPortfolioSegmentMember / nbtb_ClassOfFinancingReceivablesAxis = nbtb_OriginatedLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = nbtb_AgriculturalRealEstateFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_PassMember | 23,443 us-gaap_NotesReceivableNet / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_CommercialPortfolioSegmentMember / nbtb_ClassOfFinancingReceivablesAxis = nbtb_OriginatedLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = nbtb_AgriculturalRealEstateFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_PassMember
Originated Loans [Member] | Commercial Credit Exposure [Member] | Agricultural Real Estate [Member] | Special Mention [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Financing Receivable | 3 us-gaap_NotesReceivableNet / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_CommercialPortfolioSegmentMember / nbtb_ClassOfFinancingReceivablesAxis = nbtb_OriginatedLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = nbtb_AgriculturalRealEstateFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_SpecialMentionMember | 42 us-gaap_NotesReceivableNet / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_CommercialPortfolioSegmentMember / nbtb_ClassOfFinancingReceivablesAxis = nbtb_OriginatedLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = nbtb_AgriculturalRealEstateFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_SpecialMentionMember
Originated Loans [Member] | Commercial Credit Exposure [Member] | Agricultural Real Estate [Member] | Substandard [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Financing Receivable | 1,612 us-gaap_NotesReceivableNet / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_CommercialPortfolioSegmentMember / nbtb_ClassOfFinancingReceivablesAxis = nbtb_OriginatedLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = nbtb_AgriculturalRealEstateFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_SubstandardMember | 1,489 us-gaap_NotesReceivableNet / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_CommercialPortfolioSegmentMember / nbtb_ClassOfFinancingReceivablesAxis = nbtb_OriginatedLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = nbtb_AgriculturalRealEstateFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_SubstandardMember
Originated Loans [Member] | Commercial Credit Exposure [Member] | Agricultural Real Estate [Member] | Doubtful [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Financing Receivable | 0 us-gaap_NotesReceivableNet / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_CommercialPortfolioSegmentMember / nbtb_ClassOfFinancingReceivablesAxis = nbtb_OriginatedLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = nbtb_AgriculturalRealEstateFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_DoubtfulMember | 0 us-gaap_NotesReceivableNet / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_CommercialPortfolioSegmentMember / nbtb_ClassOfFinancingReceivablesAxis = nbtb_OriginatedLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = nbtb_AgriculturalRealEstateFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_DoubtfulMember
Originated Loans [Member] | Business Banking Credit Exposure [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Financing Receivable | 398,390 us-gaap_NotesReceivableNet / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = nbtb_BusinessBankingCreditExposureMember / nbtb_ClassOfFinancingReceivablesAxis = nbtb_OriginatedLoansMember | 398,435 us-gaap_NotesReceivableNet / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = nbtb_BusinessBankingCreditExposureMember / nbtb_ClassOfFinancingReceivablesAxis = nbtb_OriginatedLoansMember
Originated Loans [Member] | Business Banking Credit Exposure [Member] | Non-classified [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Financing Receivable | 379,306 us-gaap_NotesReceivableNet / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = nbtb_BusinessBankingCreditExposureMember / nbtb_ClassOfFinancingReceivablesAxis = nbtb_OriginatedLoansMember / us-gaap_InternalCreditAssessmentAxis = nbtb_NonClassifiedMember | 379,445 us-gaap_NotesReceivableNet / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = nbtb_BusinessBankingCreditExposureMember / nbtb_ClassOfFinancingReceivablesAxis = nbtb_OriginatedLoansMember / us-gaap_InternalCreditAssessmentAxis = nbtb_NonClassifiedMember
Originated Loans [Member] | Business Banking Credit Exposure [Member] | Classified [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Financing Receivable | 19,084 us-gaap_NotesReceivableNet / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = nbtb_BusinessBankingCreditExposureMember / nbtb_ClassOfFinancingReceivablesAxis = nbtb_OriginatedLoansMember / us-gaap_InternalCreditAssessmentAxis = nbtb_ClassifiedMember | 18,990 us-gaap_NotesReceivableNet / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = nbtb_BusinessBankingCreditExposureMember / nbtb_ClassOfFinancingReceivablesAxis = nbtb_OriginatedLoansMember / us-gaap_InternalCreditAssessmentAxis = nbtb_ClassifiedMember
Originated Loans [Member] | Business Banking Credit Exposure [Member] | Business Banking [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Financing Receivable | 398,390 us-gaap_NotesReceivableNet / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = nbtb_BusinessBankingCreditExposureMember / nbtb_ClassOfFinancingReceivablesAxis = nbtb_OriginatedLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = nbtb_SmallBusinessFinancingReceivableMember | 398,435 us-gaap_NotesReceivableNet / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = nbtb_BusinessBankingCreditExposureMember / nbtb_ClassOfFinancingReceivablesAxis = nbtb_OriginatedLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = nbtb_SmallBusinessFinancingReceivableMember
Originated Loans [Member] | Business Banking Credit Exposure [Member] | Business Banking [Member] | Non-classified [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Financing Receivable | 379,306 us-gaap_NotesReceivableNet / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = nbtb_BusinessBankingCreditExposureMember / nbtb_ClassOfFinancingReceivablesAxis = nbtb_OriginatedLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = nbtb_SmallBusinessFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = nbtb_NonClassifiedMember | 379,445 us-gaap_NotesReceivableNet / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = nbtb_BusinessBankingCreditExposureMember / nbtb_ClassOfFinancingReceivablesAxis = nbtb_OriginatedLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = nbtb_SmallBusinessFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = nbtb_NonClassifiedMember
Originated Loans [Member] | Business Banking Credit Exposure [Member] | Business Banking [Member] | Classified [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Financing Receivable | 19,084 us-gaap_NotesReceivableNet / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = nbtb_BusinessBankingCreditExposureMember / nbtb_ClassOfFinancingReceivablesAxis = nbtb_OriginatedLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = nbtb_SmallBusinessFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = nbtb_ClassifiedMember | 18,990 us-gaap_NotesReceivableNet / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = nbtb_BusinessBankingCreditExposureMember / nbtb_ClassOfFinancingReceivablesAxis = nbtb_OriginatedLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = nbtb_SmallBusinessFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = nbtb_ClassifiedMember
Originated Loans [Member] | Consumer Credit Exposure [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Financing Receivable | 1,880,448 us-gaap_NotesReceivableNet / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_ConsumerPortfolioSegmentMember / nbtb_ClassOfFinancingReceivablesAxis = nbtb_OriginatedLoansMember | 1,858,724 us-gaap_NotesReceivableNet / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_ConsumerPortfolioSegmentMember / nbtb_ClassOfFinancingReceivablesAxis = nbtb_OriginatedLoansMember
Originated Loans [Member] | Consumer Credit Exposure [Member] | Performing [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Financing Receivable | 1,869,874 us-gaap_NotesReceivableNet / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_ConsumerPortfolioSegmentMember / nbtb_ClassOfFinancingReceivablesAxis = nbtb_OriginatedLoansMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_PerformingFinancingReceivableMember | 1,847,216 us-gaap_NotesReceivableNet / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_ConsumerPortfolioSegmentMember / nbtb_ClassOfFinancingReceivablesAxis = nbtb_OriginatedLoansMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_PerformingFinancingReceivableMember
Originated Loans [Member] | Consumer Credit Exposure [Member] | Nonperforming [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Financing Receivable | 10,574 us-gaap_NotesReceivableNet / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_ConsumerPortfolioSegmentMember / nbtb_ClassOfFinancingReceivablesAxis = nbtb_OriginatedLoansMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_NonperformingFinancingReceivableMember | 11,508 us-gaap_NotesReceivableNet / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_ConsumerPortfolioSegmentMember / nbtb_ClassOfFinancingReceivablesAxis = nbtb_OriginatedLoansMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_NonperformingFinancingReceivableMember
Originated Loans [Member] | Consumer Credit Exposure [Member] | Indirect [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Financing Receivable | 1,345,573 us-gaap_NotesReceivableNet / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_ConsumerPortfolioSegmentMember / nbtb_ClassOfFinancingReceivablesAxis = nbtb_OriginatedLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = nbtb_IndirectFinancingReceivableMember | 1,310,050 us-gaap_NotesReceivableNet / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_ConsumerPortfolioSegmentMember / nbtb_ClassOfFinancingReceivablesAxis = nbtb_OriginatedLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = nbtb_IndirectFinancingReceivableMember
Originated Loans [Member] | Consumer Credit Exposure [Member] | Indirect [Member] | Performing [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Financing Receivable | 1,341,795 us-gaap_NotesReceivableNet / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_ConsumerPortfolioSegmentMember / nbtb_ClassOfFinancingReceivablesAxis = nbtb_OriginatedLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = nbtb_IndirectFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_PerformingFinancingReceivableMember | 1,306,095 us-gaap_NotesReceivableNet / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_ConsumerPortfolioSegmentMember / nbtb_ClassOfFinancingReceivablesAxis = nbtb_OriginatedLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = nbtb_IndirectFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_PerformingFinancingReceivableMember
Originated Loans [Member] | Consumer Credit Exposure [Member] | Indirect [Member] | Nonperforming [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Financing Receivable | 3,778 us-gaap_NotesReceivableNet / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_ConsumerPortfolioSegmentMember / nbtb_ClassOfFinancingReceivablesAxis = nbtb_OriginatedLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = nbtb_IndirectFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_NonperformingFinancingReceivableMember | 3,955 us-gaap_NotesReceivableNet / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_ConsumerPortfolioSegmentMember / nbtb_ClassOfFinancingReceivablesAxis = nbtb_OriginatedLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = nbtb_IndirectFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_NonperformingFinancingReceivableMember
Originated Loans [Member] | Consumer Credit Exposure [Member] | Home Equity Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Financing Receivable | 481,295 us-gaap_NotesReceivableNet / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_ConsumerPortfolioSegmentMember / nbtb_ClassOfFinancingReceivablesAxis = nbtb_OriginatedLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = nbtb_HomeEquityFinancingReceivablesMember | 492,880 us-gaap_NotesReceivableNet / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_ConsumerPortfolioSegmentMember / nbtb_ClassOfFinancingReceivablesAxis = nbtb_OriginatedLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = nbtb_HomeEquityFinancingReceivablesMember
Originated Loans [Member] | Consumer Credit Exposure [Member] | Home Equity Member] | Performing [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Financing Receivable | 474,651 us-gaap_NotesReceivableNet / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_ConsumerPortfolioSegmentMember / nbtb_ClassOfFinancingReceivablesAxis = nbtb_OriginatedLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = nbtb_HomeEquityFinancingReceivablesMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_PerformingFinancingReceivableMember | 485,463 us-gaap_NotesReceivableNet / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_ConsumerPortfolioSegmentMember / nbtb_ClassOfFinancingReceivablesAxis = nbtb_OriginatedLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = nbtb_HomeEquityFinancingReceivablesMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_PerformingFinancingReceivableMember
Originated Loans [Member] | Consumer Credit Exposure [Member] | Home Equity Member] | Nonperforming [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Financing Receivable | 6,644 us-gaap_NotesReceivableNet / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_ConsumerPortfolioSegmentMember / nbtb_ClassOfFinancingReceivablesAxis = nbtb_OriginatedLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = nbtb_HomeEquityFinancingReceivablesMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_NonperformingFinancingReceivableMember | 7,417 us-gaap_NotesReceivableNet / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_ConsumerPortfolioSegmentMember / nbtb_ClassOfFinancingReceivablesAxis = nbtb_OriginatedLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = nbtb_HomeEquityFinancingReceivablesMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_NonperformingFinancingReceivableMember
Originated Loans [Member] | Consumer Credit Exposure [Member] | Direct [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Financing Receivable | 53,580 us-gaap_NotesReceivableNet / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_ConsumerPortfolioSegmentMember / nbtb_ClassOfFinancingReceivablesAxis = nbtb_OriginatedLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = nbtb_DirectFinancingReceivableMemberMember | 55,794 us-gaap_NotesReceivableNet / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_ConsumerPortfolioSegmentMember / nbtb_ClassOfFinancingReceivablesAxis = nbtb_OriginatedLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = nbtb_DirectFinancingReceivableMemberMember
Originated Loans [Member] | Consumer Credit Exposure [Member] | Direct [Member] | Performing [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Financing Receivable | 53,428 us-gaap_NotesReceivableNet / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_ConsumerPortfolioSegmentMember / nbtb_ClassOfFinancingReceivablesAxis = nbtb_OriginatedLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = nbtb_DirectFinancingReceivableMemberMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_PerformingFinancingReceivableMember | 55,658 us-gaap_NotesReceivableNet / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_ConsumerPortfolioSegmentMember / nbtb_ClassOfFinancingReceivablesAxis = nbtb_OriginatedLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = nbtb_DirectFinancingReceivableMemberMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_PerformingFinancingReceivableMember
Originated Loans [Member] | Consumer Credit Exposure [Member] | Direct [Member] | Nonperforming [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Financing Receivable | 152 us-gaap_NotesReceivableNet / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_ConsumerPortfolioSegmentMember / nbtb_ClassOfFinancingReceivablesAxis = nbtb_OriginatedLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = nbtb_DirectFinancingReceivableMemberMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_NonperformingFinancingReceivableMember | 136 us-gaap_NotesReceivableNet / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_ConsumerPortfolioSegmentMember / nbtb_ClassOfFinancingReceivablesAxis = nbtb_OriginatedLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = nbtb_DirectFinancingReceivableMemberMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_NonperformingFinancingReceivableMember
Originated Loans [Member] | Residential Mortgage Credit Exposure [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Financing Receivable | 864,743 us-gaap_NotesReceivableNet / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_ResidentialPortfolioSegmentMember / nbtb_ClassOfFinancingReceivablesAxis = nbtb_OriginatedLoansMember | 848,842 us-gaap_NotesReceivableNet / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_ResidentialPortfolioSegmentMember / nbtb_ClassOfFinancingReceivablesAxis = nbtb_OriginatedLoansMember
Originated Loans [Member] | Residential Mortgage Credit Exposure [Member] | Performing [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Financing Receivable | 856,970 us-gaap_NotesReceivableNet / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_ResidentialPortfolioSegmentMember / nbtb_ClassOfFinancingReceivablesAxis = nbtb_OriginatedLoansMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_PerformingFinancingReceivableMember | 838,816 us-gaap_NotesReceivableNet / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_ResidentialPortfolioSegmentMember / nbtb_ClassOfFinancingReceivablesAxis = nbtb_OriginatedLoansMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_PerformingFinancingReceivableMember
Originated Loans [Member] | Residential Mortgage Credit Exposure [Member] | Nonperforming [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Financing Receivable | 7,773 us-gaap_NotesReceivableNet / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_ResidentialPortfolioSegmentMember / nbtb_ClassOfFinancingReceivablesAxis = nbtb_OriginatedLoansMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_NonperformingFinancingReceivableMember | 10,026 us-gaap_NotesReceivableNet / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_ResidentialPortfolioSegmentMember / nbtb_ClassOfFinancingReceivablesAxis = nbtb_OriginatedLoansMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_NonperformingFinancingReceivableMember
Originated Loans [Member] | Residential Mortgage Credit Exposure [Member] | Residential Mortgage [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Financing Receivable | 864,743 us-gaap_NotesReceivableNet / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_ResidentialPortfolioSegmentMember / nbtb_ClassOfFinancingReceivablesAxis = nbtb_OriginatedLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ResidentialMortgageMember | 848,842 us-gaap_NotesReceivableNet / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_ResidentialPortfolioSegmentMember / nbtb_ClassOfFinancingReceivablesAxis = nbtb_OriginatedLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ResidentialMortgageMember
Originated Loans [Member] | Residential Mortgage Credit Exposure [Member] | Residential Mortgage [Member] | Performing [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Financing Receivable | 856,970 us-gaap_NotesReceivableNet / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_ResidentialPortfolioSegmentMember / nbtb_ClassOfFinancingReceivablesAxis = nbtb_OriginatedLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ResidentialMortgageMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_PerformingFinancingReceivableMember | 838,816 us-gaap_NotesReceivableNet / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_ResidentialPortfolioSegmentMember / nbtb_ClassOfFinancingReceivablesAxis = nbtb_OriginatedLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ResidentialMortgageMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_PerformingFinancingReceivableMember
Originated Loans [Member] | Residential Mortgage Credit Exposure [Member] | Residential Mortgage [Member] | Nonperforming [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Financing Receivable | 7,773 us-gaap_NotesReceivableNet / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_ResidentialPortfolioSegmentMember / nbtb_ClassOfFinancingReceivablesAxis = nbtb_OriginatedLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ResidentialMortgageMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_NonperformingFinancingReceivableMember | 10,026 us-gaap_NotesReceivableNet / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_ResidentialPortfolioSegmentMember / nbtb_ClassOfFinancingReceivablesAxis = nbtb_OriginatedLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ResidentialMortgageMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_NonperformingFinancingReceivableMember
Acquired Loans [Member] | Commercial Credit Exposure [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Financing Receivable | 270,334 us-gaap_NotesReceivableNet / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_CommercialPortfolioSegmentMember / nbtb_ClassOfFinancingReceivablesAxis = nbtb_AcquiredLoansMember | 275,152 us-gaap_NotesReceivableNet / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_CommercialPortfolioSegmentMember / nbtb_ClassOfFinancingReceivablesAxis = nbtb_AcquiredLoansMember
Acquired Loans [Member] | Commercial Credit Exposure [Member] | Pass [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Financing Receivable | 246,181 us-gaap_NotesReceivableNet / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_CommercialPortfolioSegmentMember / nbtb_ClassOfFinancingReceivablesAxis = nbtb_AcquiredLoansMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_PassMember | 249,666 us-gaap_NotesReceivableNet / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_CommercialPortfolioSegmentMember / nbtb_ClassOfFinancingReceivablesAxis = nbtb_AcquiredLoansMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_PassMember
Acquired Loans [Member] | Commercial Credit Exposure [Member] | Special Mention [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Financing Receivable | 5,282 us-gaap_NotesReceivableNet / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_CommercialPortfolioSegmentMember / nbtb_ClassOfFinancingReceivablesAxis = nbtb_AcquiredLoansMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_SpecialMentionMember | 5,486 us-gaap_NotesReceivableNet / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_CommercialPortfolioSegmentMember / nbtb_ClassOfFinancingReceivablesAxis = nbtb_AcquiredLoansMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_SpecialMentionMember
Acquired Loans [Member] | Commercial Credit Exposure [Member] | Substandard [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Financing Receivable | 18,871 us-gaap_NotesReceivableNet / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_CommercialPortfolioSegmentMember / nbtb_ClassOfFinancingReceivablesAxis = nbtb_AcquiredLoansMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_SubstandardMember | 20,000 us-gaap_NotesReceivableNet / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_CommercialPortfolioSegmentMember / nbtb_ClassOfFinancingReceivablesAxis = nbtb_AcquiredLoansMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_SubstandardMember
Acquired Loans [Member] | Commercial Credit Exposure [Member] | Commercial [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Financing Receivable | 72,569 us-gaap_NotesReceivableNet / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_CommercialPortfolioSegmentMember / nbtb_ClassOfFinancingReceivablesAxis = nbtb_AcquiredLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = nbtb_CommercialFinancingReceivableMember | 75,264 us-gaap_NotesReceivableNet / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_CommercialPortfolioSegmentMember / nbtb_ClassOfFinancingReceivablesAxis = nbtb_AcquiredLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = nbtb_CommercialFinancingReceivableMember
Acquired Loans [Member] | Commercial Credit Exposure [Member] | Commercial [Member] | Pass [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Financing Receivable | 64,904 us-gaap_NotesReceivableNet / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_CommercialPortfolioSegmentMember / nbtb_ClassOfFinancingReceivablesAxis = nbtb_AcquiredLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = nbtb_CommercialFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_PassMember | 63,630 us-gaap_NotesReceivableNet / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_CommercialPortfolioSegmentMember / nbtb_ClassOfFinancingReceivablesAxis = nbtb_AcquiredLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = nbtb_CommercialFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_PassMember
Acquired Loans [Member] | Commercial Credit Exposure [Member] | Commercial [Member] | Special Mention [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Financing Receivable | 2,662 us-gaap_NotesReceivableNet / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_CommercialPortfolioSegmentMember / nbtb_ClassOfFinancingReceivablesAxis = nbtb_AcquiredLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = nbtb_CommercialFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_SpecialMentionMember | 2,840 us-gaap_NotesReceivableNet / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_CommercialPortfolioSegmentMember / nbtb_ClassOfFinancingReceivablesAxis = nbtb_AcquiredLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = nbtb_CommercialFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_SpecialMentionMember
Acquired Loans [Member] | Commercial Credit Exposure [Member] | Commercial [Member] | Substandard [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Financing Receivable | 5,003 us-gaap_NotesReceivableNet / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_CommercialPortfolioSegmentMember / nbtb_ClassOfFinancingReceivablesAxis = nbtb_AcquiredLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = nbtb_CommercialFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_SubstandardMember | 8,794 us-gaap_NotesReceivableNet / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_CommercialPortfolioSegmentMember / nbtb_ClassOfFinancingReceivablesAxis = nbtb_AcquiredLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = nbtb_CommercialFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_SubstandardMember
Acquired Loans [Member] | Commercial Credit Exposure [Member] | Commercial Real Estate [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Financing Receivable | 197,765 us-gaap_NotesReceivableNet / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_CommercialPortfolioSegmentMember / nbtb_ClassOfFinancingReceivablesAxis = nbtb_AcquiredLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialRealEstateOtherReceivableMember | 199,888 us-gaap_NotesReceivableNet / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_CommercialPortfolioSegmentMember / nbtb_ClassOfFinancingReceivablesAxis = nbtb_AcquiredLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialRealEstateOtherReceivableMember
Acquired Loans [Member] | Commercial Credit Exposure [Member] | Commercial Real Estate [Member] | Pass [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Financing Receivable | 181,277 us-gaap_NotesReceivableNet / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_CommercialPortfolioSegmentMember / nbtb_ClassOfFinancingReceivablesAxis = nbtb_AcquiredLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialRealEstateOtherReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_PassMember | 186,036 us-gaap_NotesReceivableNet / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_CommercialPortfolioSegmentMember / nbtb_ClassOfFinancingReceivablesAxis = nbtb_AcquiredLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialRealEstateOtherReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_PassMember
Acquired Loans [Member] | Commercial Credit Exposure [Member] | Commercial Real Estate [Member] | Special Mention [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Financing Receivable | 2,620 us-gaap_NotesReceivableNet / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_CommercialPortfolioSegmentMember / nbtb_ClassOfFinancingReceivablesAxis = nbtb_AcquiredLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialRealEstateOtherReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_SpecialMentionMember | 2,646 us-gaap_NotesReceivableNet / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_CommercialPortfolioSegmentMember / nbtb_ClassOfFinancingReceivablesAxis = nbtb_AcquiredLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialRealEstateOtherReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_SpecialMentionMember
Acquired Loans [Member] | Commercial Credit Exposure [Member] | Commercial Real Estate [Member] | Substandard [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Financing Receivable | 13,868 us-gaap_NotesReceivableNet / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_CommercialPortfolioSegmentMember / nbtb_ClassOfFinancingReceivablesAxis = nbtb_AcquiredLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialRealEstateOtherReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_SubstandardMember | 11,206 us-gaap_NotesReceivableNet / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_CommercialPortfolioSegmentMember / nbtb_ClassOfFinancingReceivablesAxis = nbtb_AcquiredLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialRealEstateOtherReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_SubstandardMember
Acquired Loans [Member] | Business Banking Credit Exposure [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Financing Receivable | 54,904 us-gaap_NotesReceivableNet / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = nbtb_BusinessBankingCreditExposureMember / nbtb_ClassOfFinancingReceivablesAxis = nbtb_AcquiredLoansMember | 58,179 us-gaap_NotesReceivableNet / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = nbtb_BusinessBankingCreditExposureMember / nbtb_ClassOfFinancingReceivablesAxis = nbtb_AcquiredLoansMember
Acquired Loans [Member] | Business Banking Credit Exposure [Member] | Non-classified [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Financing Receivable | 50,222 us-gaap_NotesReceivableNet / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = nbtb_BusinessBankingCreditExposureMember / nbtb_ClassOfFinancingReceivablesAxis = nbtb_AcquiredLoansMember / us-gaap_InternalCreditAssessmentAxis = nbtb_NonClassifiedMember | 53,264 us-gaap_NotesReceivableNet / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = nbtb_BusinessBankingCreditExposureMember / nbtb_ClassOfFinancingReceivablesAxis = nbtb_AcquiredLoansMember / us-gaap_InternalCreditAssessmentAxis = nbtb_NonClassifiedMember
Acquired Loans [Member] | Business Banking Credit Exposure [Member] | Classified [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Financing Receivable | 4,682 us-gaap_NotesReceivableNet / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = nbtb_BusinessBankingCreditExposureMember / nbtb_ClassOfFinancingReceivablesAxis = nbtb_AcquiredLoansMember / us-gaap_InternalCreditAssessmentAxis = nbtb_ClassifiedMember | 4,915 us-gaap_NotesReceivableNet / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = nbtb_BusinessBankingCreditExposureMember / nbtb_ClassOfFinancingReceivablesAxis = nbtb_AcquiredLoansMember / us-gaap_InternalCreditAssessmentAxis = nbtb_ClassifiedMember
Acquired Loans [Member] | Business Banking Credit Exposure [Member] | Business Banking [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Financing Receivable | 54,904 us-gaap_NotesReceivableNet / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = nbtb_BusinessBankingCreditExposureMember / nbtb_ClassOfFinancingReceivablesAxis = nbtb_AcquiredLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = nbtb_SmallBusinessFinancingReceivableMember | 58,179 us-gaap_NotesReceivableNet / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = nbtb_BusinessBankingCreditExposureMember / nbtb_ClassOfFinancingReceivablesAxis = nbtb_AcquiredLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = nbtb_SmallBusinessFinancingReceivableMember
Acquired Loans [Member] | Business Banking Credit Exposure [Member] | Business Banking [Member] | Non-classified [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Financing Receivable | 50,222 us-gaap_NotesReceivableNet / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = nbtb_BusinessBankingCreditExposureMember / nbtb_ClassOfFinancingReceivablesAxis = nbtb_AcquiredLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = nbtb_SmallBusinessFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = nbtb_NonClassifiedMember | 53,264 us-gaap_NotesReceivableNet / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = nbtb_BusinessBankingCreditExposureMember / nbtb_ClassOfFinancingReceivablesAxis = nbtb_AcquiredLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = nbtb_SmallBusinessFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = nbtb_NonClassifiedMember
Acquired Loans [Member] | Business Banking Credit Exposure [Member] | Business Banking [Member] | Classified [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Financing Receivable | 4,682 us-gaap_NotesReceivableNet / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = nbtb_BusinessBankingCreditExposureMember / nbtb_ClassOfFinancingReceivablesAxis = nbtb_AcquiredLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = nbtb_SmallBusinessFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = nbtb_ClassifiedMember | 4,915 us-gaap_NotesReceivableNet / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = nbtb_BusinessBankingCreditExposureMember / nbtb_ClassOfFinancingReceivablesAxis = nbtb_AcquiredLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = nbtb_SmallBusinessFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = nbtb_ClassifiedMember
Acquired Loans [Member] | Consumer Credit Exposure [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Financing Receivable | 132,675 us-gaap_NotesReceivableNet / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_ConsumerPortfolioSegmentMember / nbtb_ClassOfFinancingReceivablesAxis = nbtb_AcquiredLoansMember | 147,256 us-gaap_NotesReceivableNet / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_ConsumerPortfolioSegmentMember / nbtb_ClassOfFinancingReceivablesAxis = nbtb_AcquiredLoansMember
Acquired Loans [Member] | Consumer Credit Exposure [Member] | Performing [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Financing Receivable | 132,033 us-gaap_NotesReceivableNet / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_ConsumerPortfolioSegmentMember / nbtb_ClassOfFinancingReceivablesAxis = nbtb_AcquiredLoansMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_PerformingFinancingReceivableMember | 146,494 us-gaap_NotesReceivableNet / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_ConsumerPortfolioSegmentMember / nbtb_ClassOfFinancingReceivablesAxis = nbtb_AcquiredLoansMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_PerformingFinancingReceivableMember
Acquired Loans [Member] | Consumer Credit Exposure [Member] | Nonperforming [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Financing Receivable | 642 us-gaap_NotesReceivableNet / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_ConsumerPortfolioSegmentMember / nbtb_ClassOfFinancingReceivablesAxis = nbtb_AcquiredLoansMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_NonperformingFinancingReceivableMember | 762 us-gaap_NotesReceivableNet / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_ConsumerPortfolioSegmentMember / nbtb_ClassOfFinancingReceivablesAxis = nbtb_AcquiredLoansMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_NonperformingFinancingReceivableMember
Acquired Loans [Member] | Consumer Credit Exposure [Member] | Indirect [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Financing Receivable | 54,147 us-gaap_NotesReceivableNet / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_ConsumerPortfolioSegmentMember / nbtb_ClassOfFinancingReceivablesAxis = nbtb_AcquiredLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = nbtb_IndirectFinancingReceivableMember | 65,223 us-gaap_NotesReceivableNet / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_ConsumerPortfolioSegmentMember / nbtb_ClassOfFinancingReceivablesAxis = nbtb_AcquiredLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = nbtb_IndirectFinancingReceivableMember
Acquired Loans [Member] | Consumer Credit Exposure [Member] | Indirect [Member] | Performing [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Financing Receivable | 53,964 us-gaap_NotesReceivableNet / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_ConsumerPortfolioSegmentMember / nbtb_ClassOfFinancingReceivablesAxis = nbtb_AcquiredLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = nbtb_IndirectFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_PerformingFinancingReceivableMember | 65,063 us-gaap_NotesReceivableNet / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_ConsumerPortfolioSegmentMember / nbtb_ClassOfFinancingReceivablesAxis = nbtb_AcquiredLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = nbtb_IndirectFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_PerformingFinancingReceivableMember
Acquired Loans [Member] | Consumer Credit Exposure [Member] | Indirect [Member] | Nonperforming [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Financing Receivable | 183 us-gaap_NotesReceivableNet / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_ConsumerPortfolioSegmentMember / nbtb_ClassOfFinancingReceivablesAxis = nbtb_AcquiredLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = nbtb_IndirectFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_NonperformingFinancingReceivableMember | 160 us-gaap_NotesReceivableNet / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_ConsumerPortfolioSegmentMember / nbtb_ClassOfFinancingReceivablesAxis = nbtb_AcquiredLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = nbtb_IndirectFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_NonperformingFinancingReceivableMember
Acquired Loans [Member] | Consumer Credit Exposure [Member] | Home Equity Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Financing Receivable | 73,718 us-gaap_NotesReceivableNet / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_ConsumerPortfolioSegmentMember / nbtb_ClassOfFinancingReceivablesAxis = nbtb_AcquiredLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = nbtb_HomeEquityFinancingReceivablesMember | 76,716 us-gaap_NotesReceivableNet / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_ConsumerPortfolioSegmentMember / nbtb_ClassOfFinancingReceivablesAxis = nbtb_AcquiredLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = nbtb_HomeEquityFinancingReceivablesMember
Acquired Loans [Member] | Consumer Credit Exposure [Member] | Home Equity Member] | Performing [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Financing Receivable | 73,291 us-gaap_NotesReceivableNet / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_ConsumerPortfolioSegmentMember / nbtb_ClassOfFinancingReceivablesAxis = nbtb_AcquiredLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = nbtb_HomeEquityFinancingReceivablesMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_PerformingFinancingReceivableMember | 76,154 us-gaap_NotesReceivableNet / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_ConsumerPortfolioSegmentMember / nbtb_ClassOfFinancingReceivablesAxis = nbtb_AcquiredLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = nbtb_HomeEquityFinancingReceivablesMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_PerformingFinancingReceivableMember
Acquired Loans [Member] | Consumer Credit Exposure [Member] | Home Equity Member] | Nonperforming [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Financing Receivable | 427 us-gaap_NotesReceivableNet / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_ConsumerPortfolioSegmentMember / nbtb_ClassOfFinancingReceivablesAxis = nbtb_AcquiredLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = nbtb_HomeEquityFinancingReceivablesMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_NonperformingFinancingReceivableMember | 562 us-gaap_NotesReceivableNet / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_ConsumerPortfolioSegmentMember / nbtb_ClassOfFinancingReceivablesAxis = nbtb_AcquiredLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = nbtb_HomeEquityFinancingReceivablesMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_NonperformingFinancingReceivableMember
Acquired Loans [Member] | Consumer Credit Exposure [Member] | Direct [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Financing Receivable | 4,810 us-gaap_NotesReceivableNet / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_ConsumerPortfolioSegmentMember / nbtb_ClassOfFinancingReceivablesAxis = nbtb_AcquiredLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = nbtb_DirectFinancingReceivableMemberMember | 5,317 us-gaap_NotesReceivableNet / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_ConsumerPortfolioSegmentMember / nbtb_ClassOfFinancingReceivablesAxis = nbtb_AcquiredLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = nbtb_DirectFinancingReceivableMemberMember
Acquired Loans [Member] | Consumer Credit Exposure [Member] | Direct [Member] | Performing [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Financing Receivable | 4,778 us-gaap_NotesReceivableNet / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_ConsumerPortfolioSegmentMember / nbtb_ClassOfFinancingReceivablesAxis = nbtb_AcquiredLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = nbtb_DirectFinancingReceivableMemberMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_PerformingFinancingReceivableMember | 5,277 us-gaap_NotesReceivableNet / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_ConsumerPortfolioSegmentMember / nbtb_ClassOfFinancingReceivablesAxis = nbtb_AcquiredLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = nbtb_DirectFinancingReceivableMemberMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_PerformingFinancingReceivableMember
Acquired Loans [Member] | Consumer Credit Exposure [Member] | Direct [Member] | Nonperforming [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Financing Receivable | 32 us-gaap_NotesReceivableNet / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_ConsumerPortfolioSegmentMember / nbtb_ClassOfFinancingReceivablesAxis = nbtb_AcquiredLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = nbtb_DirectFinancingReceivableMemberMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_NonperformingFinancingReceivableMember | 40 us-gaap_NotesReceivableNet / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_ConsumerPortfolioSegmentMember / nbtb_ClassOfFinancingReceivablesAxis = nbtb_AcquiredLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = nbtb_DirectFinancingReceivableMemberMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_NonperformingFinancingReceivableMember
Acquired Loans [Member] | Residential Mortgage Credit Exposure [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Financing Receivable | 260,857 us-gaap_NotesReceivableNet / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_ResidentialPortfolioSegmentMember / nbtb_ClassOfFinancingReceivablesAxis = nbtb_AcquiredLoansMember | 266,747 us-gaap_NotesReceivableNet / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_ResidentialPortfolioSegmentMember / nbtb_ClassOfFinancingReceivablesAxis = nbtb_AcquiredLoansMember
Acquired Loans [Member] | Residential Mortgage Credit Exposure [Member] | Performing [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Financing Receivable | 257,756 us-gaap_NotesReceivableNet / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_ResidentialPortfolioSegmentMember / nbtb_ClassOfFinancingReceivablesAxis = nbtb_AcquiredLoansMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_PerformingFinancingReceivableMember | 262,883 us-gaap_NotesReceivableNet / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_ResidentialPortfolioSegmentMember / nbtb_ClassOfFinancingReceivablesAxis = nbtb_AcquiredLoansMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_PerformingFinancingReceivableMember
Acquired Loans [Member] | Residential Mortgage Credit Exposure [Member] | Nonperforming [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Financing Receivable | 3,101 us-gaap_NotesReceivableNet / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_ResidentialPortfolioSegmentMember / nbtb_ClassOfFinancingReceivablesAxis = nbtb_AcquiredLoansMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_NonperformingFinancingReceivableMember | 3,864 us-gaap_NotesReceivableNet / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_ResidentialPortfolioSegmentMember / nbtb_ClassOfFinancingReceivablesAxis = nbtb_AcquiredLoansMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_NonperformingFinancingReceivableMember
Acquired Loans [Member] | Residential Mortgage Credit Exposure [Member] | Residential Mortgage [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Financing Receivable | 260,857 us-gaap_NotesReceivableNet / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_ResidentialPortfolioSegmentMember / nbtb_ClassOfFinancingReceivablesAxis = nbtb_AcquiredLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ResidentialMortgageMember | 266,747 us-gaap_NotesReceivableNet / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_ResidentialPortfolioSegmentMember / nbtb_ClassOfFinancingReceivablesAxis = nbtb_AcquiredLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ResidentialMortgageMember
Acquired Loans [Member] | Residential Mortgage Credit Exposure [Member] | Residential Mortgage [Member] | Performing [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Financing Receivable | 257,756 us-gaap_NotesReceivableNet / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_ResidentialPortfolioSegmentMember / nbtb_ClassOfFinancingReceivablesAxis = nbtb_AcquiredLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ResidentialMortgageMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_PerformingFinancingReceivableMember | 262,883 us-gaap_NotesReceivableNet / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_ResidentialPortfolioSegmentMember / nbtb_ClassOfFinancingReceivablesAxis = nbtb_AcquiredLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ResidentialMortgageMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_PerformingFinancingReceivableMember
Acquired Loans [Member] | Residential Mortgage Credit Exposure [Member] | Residential Mortgage [Member] | Nonperforming [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Financing Receivable | $ 3,101 us-gaap_NotesReceivableNet / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_ResidentialPortfolioSegmentMember / nbtb_ClassOfFinancingReceivablesAxis = nbtb_AcquiredLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ResidentialMortgageMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_NonperformingFinancingReceivableMember | $ 3,864 us-gaap_NotesReceivableNet / us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis = us-gaap_ResidentialPortfolioSegmentMember / nbtb_ClassOfFinancingReceivablesAxis = nbtb_AcquiredLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ResidentialMortgageMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_NonperformingFinancingReceivableMember

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- Definition Net amount of the investment in a contractual right to receive money on demand or on fixed or determinable dates that is recognized as an asset in the creditor's statement of financial position. Examples include, but are not limited to, credit card receivables, notes receivable and receivables relating to lessor's rights to payments from leases other than operating leases that have been recorded as assets. Excludes trade accounts receivable with contractual maturity of one year or less and arose from the sale of goods or services. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.3) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 02 -Paragraph 3 -Article 5 + Details
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