XML 49 R34.htm IDEA: XBRL DOCUMENT
v2.4.1.9

Allowance for Loan Losses and Credit Quality of Loans, Impaired Loans (Details) (USD $) | 3 Months Ended |
--- | --- | ---
Mar. 31, 2015 | Mar. 31, 2014 | Dec. 31, 2014
Allowance for Loan Losses and Credit Quality of Loans [Abstract] |  |  |
Minimum balance for classified loans to be evaluated individually for impairment | $ 500,000 nbtb_FinancingReceivableClassifiedGradingMinimumBalanceForIndividuallyEvaluatedForImpairment |  |
With an allowance recorded [Abstract] |  |  |
Recorded investment balance (book) | 32,717,000 us-gaap_ImpairedFinancingReceivableRecordedInvestment |  | 25,796,000 us-gaap_ImpairedFinancingReceivableRecordedInvestment
Unpaid principal balance (legal) | 39,371,000 us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalance |  | 32,290,000 us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalance
Related allowance | 2,950,000 us-gaap_ImpairedFinancingReceivableRelatedAllowance |  | 1,100,000 us-gaap_ImpairedFinancingReceivableRelatedAllowance
Average recorded investment | 33,026,000 us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment | 32,294,000 us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment |
Interest income recognized accrual | 183,000 us-gaap_ImpairedFinancingReceivableInterestIncomeAccrualMethod | 132,000 us-gaap_ImpairedFinancingReceivableInterestIncomeAccrualMethod |
Originated Loans [Member] |  |  |
With no allowance recorded [Abstract] |  |  |
Recorded investment balance (book) | 18,068,000 us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceRecordedInvestment / nbtb_ClassOfFinancingReceivablesAxis = nbtb_OriginatedLoansMember |  | 17,358,000 us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceRecordedInvestment / nbtb_ClassOfFinancingReceivablesAxis = nbtb_OriginatedLoansMember
Unpaid principal balance (legal) | 19,540,000 us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceUnpaidPrincipalBalance / nbtb_ClassOfFinancingReceivablesAxis = nbtb_OriginatedLoansMember |  | 19,181,000 us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceUnpaidPrincipalBalance / nbtb_ClassOfFinancingReceivablesAxis = nbtb_OriginatedLoansMember
With an allowance recorded [Abstract] |  |  |
Recorded investment balance (book) | 4,877,000 us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceRecordedInvestment / nbtb_ClassOfFinancingReceivablesAxis = nbtb_OriginatedLoansMember |  | 2,763,000 us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceRecordedInvestment / nbtb_ClassOfFinancingReceivablesAxis = nbtb_OriginatedLoansMember
Unpaid principal balance (legal) | 6,725,000 us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceUnpaidPrincipalBalance / nbtb_ClassOfFinancingReceivablesAxis = nbtb_OriginatedLoansMember |  | 4,611,000 us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceUnpaidPrincipalBalance / nbtb_ClassOfFinancingReceivablesAxis = nbtb_OriginatedLoansMember
Related allowance | 1,100,000 us-gaap_ImpairedFinancingReceivableRelatedAllowance / nbtb_ClassOfFinancingReceivablesAxis = nbtb_OriginatedLoansMember |  | 600,000 us-gaap_ImpairedFinancingReceivableRelatedAllowance / nbtb_ClassOfFinancingReceivablesAxis = nbtb_OriginatedLoansMember
Average recorded investment | 23,007,000 us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment / nbtb_ClassOfFinancingReceivablesAxis = nbtb_OriginatedLoansMember | 22,334,000 us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment / nbtb_ClassOfFinancingReceivablesAxis = nbtb_OriginatedLoansMember |
Interest income recognized accrual | 183,000 us-gaap_ImpairedFinancingReceivableInterestIncomeAccrualMethod / nbtb_ClassOfFinancingReceivablesAxis = nbtb_OriginatedLoansMember | 132,000 us-gaap_ImpairedFinancingReceivableInterestIncomeAccrualMethod / nbtb_ClassOfFinancingReceivablesAxis = nbtb_OriginatedLoansMember |
Originated Loans [Member] | Commercial Loans [Member] |  |  |
With no allowance recorded [Abstract] |  |  |
Recorded investment balance (book) | 7,376,000 us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceRecordedInvestment / nbtb_ClassOfFinancingReceivablesAxis = nbtb_OriginatedLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialPortfolioSegmentMember |  | 8,316,000 us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceRecordedInvestment / nbtb_ClassOfFinancingReceivablesAxis = nbtb_OriginatedLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialPortfolioSegmentMember
Unpaid principal balance (legal) | 7,713,000 us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceUnpaidPrincipalBalance / nbtb_ClassOfFinancingReceivablesAxis = nbtb_OriginatedLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialPortfolioSegmentMember |  | 9,189,000 us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceUnpaidPrincipalBalance / nbtb_ClassOfFinancingReceivablesAxis = nbtb_OriginatedLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialPortfolioSegmentMember
Originated Loans [Member] | Commercial [Member] |  |  |
With no allowance recorded [Abstract] |  |  |
Recorded investment balance (book) | 1,628,000 us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceRecordedInvestment / nbtb_ClassOfFinancingReceivablesAxis = nbtb_OriginatedLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = nbtb_CommercialFinancingReceivableMember |  | 1,748,000 us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceRecordedInvestment / nbtb_ClassOfFinancingReceivablesAxis = nbtb_OriginatedLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = nbtb_CommercialFinancingReceivableMember
Unpaid principal balance (legal) | 1,781,000 us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceUnpaidPrincipalBalance / nbtb_ClassOfFinancingReceivablesAxis = nbtb_OriginatedLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = nbtb_CommercialFinancingReceivableMember |  | 1,901,000 us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceUnpaidPrincipalBalance / nbtb_ClassOfFinancingReceivablesAxis = nbtb_OriginatedLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = nbtb_CommercialFinancingReceivableMember
With an allowance recorded [Abstract] |  |  |
Average recorded investment | 1,689,000 us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment / nbtb_ClassOfFinancingReceivablesAxis = nbtb_OriginatedLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = nbtb_CommercialFinancingReceivableMember | 2,038,000 us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment / nbtb_ClassOfFinancingReceivablesAxis = nbtb_OriginatedLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = nbtb_CommercialFinancingReceivableMember |
Interest income recognized accrual | 25,000 us-gaap_ImpairedFinancingReceivableInterestIncomeAccrualMethod / nbtb_ClassOfFinancingReceivablesAxis = nbtb_OriginatedLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = nbtb_CommercialFinancingReceivableMember | 0 us-gaap_ImpairedFinancingReceivableInterestIncomeAccrualMethod / nbtb_ClassOfFinancingReceivablesAxis = nbtb_OriginatedLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = nbtb_CommercialFinancingReceivableMember |
Originated Loans [Member] | Commercial Real Estate [Member] |  |  |
With no allowance recorded [Abstract] |  |  |
Recorded investment balance (book) | 4,227,000 us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceRecordedInvestment / nbtb_ClassOfFinancingReceivablesAxis = nbtb_OriginatedLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialRealEstateOtherReceivableMember |  | 4,505,000 us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceRecordedInvestment / nbtb_ClassOfFinancingReceivablesAxis = nbtb_OriginatedLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialRealEstateOtherReceivableMember
Unpaid principal balance (legal) | 4,238,000 us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceUnpaidPrincipalBalance / nbtb_ClassOfFinancingReceivablesAxis = nbtb_OriginatedLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialRealEstateOtherReceivableMember |  | 4,520,000 us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceUnpaidPrincipalBalance / nbtb_ClassOfFinancingReceivablesAxis = nbtb_OriginatedLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialRealEstateOtherReceivableMember
With an allowance recorded [Abstract] |  |  |
Average recorded investment | 9,125,000 us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment / nbtb_ClassOfFinancingReceivablesAxis = nbtb_OriginatedLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialRealEstateOtherReceivableMember | 11,553,000 us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment / nbtb_ClassOfFinancingReceivablesAxis = nbtb_OriginatedLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialRealEstateOtherReceivableMember |
Interest income recognized accrual | 41,000 us-gaap_ImpairedFinancingReceivableInterestIncomeAccrualMethod / nbtb_ClassOfFinancingReceivablesAxis = nbtb_OriginatedLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialRealEstateOtherReceivableMember | 42,000 us-gaap_ImpairedFinancingReceivableInterestIncomeAccrualMethod / nbtb_ClassOfFinancingReceivablesAxis = nbtb_OriginatedLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialRealEstateOtherReceivableMember |
Originated Loans [Member] | Agricultural [Member] |  |  |
With no allowance recorded [Abstract] |  |  |
Recorded investment balance (book) | 19,000 us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceRecordedInvestment / nbtb_ClassOfFinancingReceivablesAxis = nbtb_OriginatedLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = nbtb_AgriculturalFinancingReceivableMember |  | 20,000 us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceRecordedInvestment / nbtb_ClassOfFinancingReceivablesAxis = nbtb_OriginatedLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = nbtb_AgriculturalFinancingReceivableMember
Unpaid principal balance (legal) | 25,000 us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceUnpaidPrincipalBalance / nbtb_ClassOfFinancingReceivablesAxis = nbtb_OriginatedLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = nbtb_AgriculturalFinancingReceivableMember |  | 26,000 us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceUnpaidPrincipalBalance / nbtb_ClassOfFinancingReceivablesAxis = nbtb_OriginatedLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = nbtb_AgriculturalFinancingReceivableMember
With an allowance recorded [Abstract] |  |  |
Average recorded investment | 20,000 us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment / nbtb_ClassOfFinancingReceivablesAxis = nbtb_OriginatedLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = nbtb_AgriculturalFinancingReceivableMember | 125,000 us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment / nbtb_ClassOfFinancingReceivablesAxis = nbtb_OriginatedLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = nbtb_AgriculturalFinancingReceivableMember |
Interest income recognized accrual | 0 us-gaap_ImpairedFinancingReceivableInterestIncomeAccrualMethod / nbtb_ClassOfFinancingReceivablesAxis = nbtb_OriginatedLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = nbtb_AgriculturalFinancingReceivableMember | 0 us-gaap_ImpairedFinancingReceivableInterestIncomeAccrualMethod / nbtb_ClassOfFinancingReceivablesAxis = nbtb_OriginatedLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = nbtb_AgriculturalFinancingReceivableMember |
Originated Loans [Member] | Agricultural Real Estate [Member] |  |  |
With no allowance recorded [Abstract] |  |  |
Recorded investment balance (book) | 633,000 us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceRecordedInvestment / nbtb_ClassOfFinancingReceivablesAxis = nbtb_OriginatedLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = nbtb_AgriculturalRealEstateFinancingReceivableMember |  | 1,147,000 us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceRecordedInvestment / nbtb_ClassOfFinancingReceivablesAxis = nbtb_OriginatedLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = nbtb_AgriculturalRealEstateFinancingReceivableMember
Unpaid principal balance (legal) | 759,000 us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceUnpaidPrincipalBalance / nbtb_ClassOfFinancingReceivablesAxis = nbtb_OriginatedLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = nbtb_AgriculturalRealEstateFinancingReceivableMember |  | 1,441,000 us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceUnpaidPrincipalBalance / nbtb_ClassOfFinancingReceivablesAxis = nbtb_OriginatedLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = nbtb_AgriculturalRealEstateFinancingReceivableMember
With an allowance recorded [Abstract] |  |  |
Average recorded investment | 636,000 us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment / nbtb_ClassOfFinancingReceivablesAxis = nbtb_OriginatedLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = nbtb_AgriculturalRealEstateFinancingReceivableMember | 1,424,000 us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment / nbtb_ClassOfFinancingReceivablesAxis = nbtb_OriginatedLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = nbtb_AgriculturalRealEstateFinancingReceivableMember |
Interest income recognized accrual | 11,000 us-gaap_ImpairedFinancingReceivableInterestIncomeAccrualMethod / nbtb_ClassOfFinancingReceivablesAxis = nbtb_OriginatedLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = nbtb_AgriculturalRealEstateFinancingReceivableMember | 12,000 us-gaap_ImpairedFinancingReceivableInterestIncomeAccrualMethod / nbtb_ClassOfFinancingReceivablesAxis = nbtb_OriginatedLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = nbtb_AgriculturalRealEstateFinancingReceivableMember |
Originated Loans [Member] | Business Banking [Member] |  |  |
With no allowance recorded [Abstract] |  |  |
Recorded investment balance (book) | 869,000 us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceRecordedInvestment / nbtb_ClassOfFinancingReceivablesAxis = nbtb_OriginatedLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = nbtb_SmallBusinessFinancingReceivableMember |  | 896,000 us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceRecordedInvestment / nbtb_ClassOfFinancingReceivablesAxis = nbtb_OriginatedLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = nbtb_SmallBusinessFinancingReceivableMember
Unpaid principal balance (legal) | 910,000 us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceUnpaidPrincipalBalance / nbtb_ClassOfFinancingReceivablesAxis = nbtb_OriginatedLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = nbtb_SmallBusinessFinancingReceivableMember |  | 1,301,000 us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceUnpaidPrincipalBalance / nbtb_ClassOfFinancingReceivablesAxis = nbtb_OriginatedLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = nbtb_SmallBusinessFinancingReceivableMember
With an allowance recorded [Abstract] |  |  |
Average recorded investment | 873,000 us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment / nbtb_ClassOfFinancingReceivablesAxis = nbtb_OriginatedLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = nbtb_SmallBusinessFinancingReceivableMember | 185,000 us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment / nbtb_ClassOfFinancingReceivablesAxis = nbtb_OriginatedLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = nbtb_SmallBusinessFinancingReceivableMember |
Interest income recognized accrual | 4,000 us-gaap_ImpairedFinancingReceivableInterestIncomeAccrualMethod / nbtb_ClassOfFinancingReceivablesAxis = nbtb_OriginatedLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = nbtb_SmallBusinessFinancingReceivableMember | 12,000 us-gaap_ImpairedFinancingReceivableInterestIncomeAccrualMethod / nbtb_ClassOfFinancingReceivablesAxis = nbtb_OriginatedLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = nbtb_SmallBusinessFinancingReceivableMember |
Originated Loans [Member] | Consumer Loans [Member] |  |  |
With no allowance recorded [Abstract] |  |  |
Recorded investment balance (book) | 6,423,000 us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceRecordedInvestment / nbtb_ClassOfFinancingReceivablesAxis = nbtb_OriginatedLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ConsumerPortfolioSegmentMember |  | 5,498,000 us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceRecordedInvestment / nbtb_ClassOfFinancingReceivablesAxis = nbtb_OriginatedLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ConsumerPortfolioSegmentMember
Unpaid principal balance (legal) | 7,085,000 us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceUnpaidPrincipalBalance / nbtb_ClassOfFinancingReceivablesAxis = nbtb_OriginatedLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ConsumerPortfolioSegmentMember |  | 6,033,000 us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceUnpaidPrincipalBalance / nbtb_ClassOfFinancingReceivablesAxis = nbtb_OriginatedLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ConsumerPortfolioSegmentMember
Originated Loans [Member] | Indirect [Member] |  |  |
With no allowance recorded [Abstract] |  |  |
Recorded investment balance (book) | 17,000 us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceRecordedInvestment / nbtb_ClassOfFinancingReceivablesAxis = nbtb_OriginatedLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = nbtb_IndirectFinancingReceivableMember |  | 0 us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceRecordedInvestment / nbtb_ClassOfFinancingReceivablesAxis = nbtb_OriginatedLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = nbtb_IndirectFinancingReceivableMember
Unpaid principal balance (legal) | 26,000 us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceUnpaidPrincipalBalance / nbtb_ClassOfFinancingReceivablesAxis = nbtb_OriginatedLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = nbtb_IndirectFinancingReceivableMember |  | 0 us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceUnpaidPrincipalBalance / nbtb_ClassOfFinancingReceivablesAxis = nbtb_OriginatedLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = nbtb_IndirectFinancingReceivableMember
With an allowance recorded [Abstract] |  |  |
Average recorded investment | 9,000 us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment / nbtb_ClassOfFinancingReceivablesAxis = nbtb_OriginatedLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = nbtb_IndirectFinancingReceivableMember | 0 us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment / nbtb_ClassOfFinancingReceivablesAxis = nbtb_OriginatedLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = nbtb_IndirectFinancingReceivableMember |
Interest income recognized accrual | 0 us-gaap_ImpairedFinancingReceivableInterestIncomeAccrualMethod / nbtb_ClassOfFinancingReceivablesAxis = nbtb_OriginatedLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = nbtb_IndirectFinancingReceivableMember | 0 us-gaap_ImpairedFinancingReceivableInterestIncomeAccrualMethod / nbtb_ClassOfFinancingReceivablesAxis = nbtb_OriginatedLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = nbtb_IndirectFinancingReceivableMember |
Originated Loans [Member] | Home Equity [Member] |  |  |
With no allowance recorded [Abstract] |  |  |
Recorded investment balance (book) | 6,403,000 us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceRecordedInvestment / nbtb_ClassOfFinancingReceivablesAxis = nbtb_OriginatedLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_HomeEquityMember |  | 5,498,000 us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceRecordedInvestment / nbtb_ClassOfFinancingReceivablesAxis = nbtb_OriginatedLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_HomeEquityMember
Unpaid principal balance (legal) | 7,056,000 us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceUnpaidPrincipalBalance / nbtb_ClassOfFinancingReceivablesAxis = nbtb_OriginatedLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_HomeEquityMember |  | 6,033,000 us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceUnpaidPrincipalBalance / nbtb_ClassOfFinancingReceivablesAxis = nbtb_OriginatedLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_HomeEquityMember
With an allowance recorded [Abstract] |  |  |
Average recorded investment | 6,388,000 us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment / nbtb_ClassOfFinancingReceivablesAxis = nbtb_OriginatedLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_HomeEquityMember | 4,282,000 us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment / nbtb_ClassOfFinancingReceivablesAxis = nbtb_OriginatedLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_HomeEquityMember |
Interest income recognized accrual | 72,000 us-gaap_ImpairedFinancingReceivableInterestIncomeAccrualMethod / nbtb_ClassOfFinancingReceivablesAxis = nbtb_OriginatedLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_HomeEquityMember | 43,000 us-gaap_ImpairedFinancingReceivableInterestIncomeAccrualMethod / nbtb_ClassOfFinancingReceivablesAxis = nbtb_OriginatedLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_HomeEquityMember |
Originated Loans [Member] | Direct [Member] |  |  |
With no allowance recorded [Abstract] |  |  |
Recorded investment balance (book) | 3,000 us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceRecordedInvestment / nbtb_ClassOfFinancingReceivablesAxis = nbtb_OriginatedLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = nbtb_DirectFinancingReceivableMember |  | 0 us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceRecordedInvestment / nbtb_ClassOfFinancingReceivablesAxis = nbtb_OriginatedLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = nbtb_DirectFinancingReceivableMember
Unpaid principal balance (legal) | 3,000 us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceUnpaidPrincipalBalance / nbtb_ClassOfFinancingReceivablesAxis = nbtb_OriginatedLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = nbtb_DirectFinancingReceivableMember |  | 0 us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceUnpaidPrincipalBalance / nbtb_ClassOfFinancingReceivablesAxis = nbtb_OriginatedLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = nbtb_DirectFinancingReceivableMember
With an allowance recorded [Abstract] |  |  |
Average recorded investment | 2,000 us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment / nbtb_ClassOfFinancingReceivablesAxis = nbtb_OriginatedLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = nbtb_DirectFinancingReceivableMember | 0 us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment / nbtb_ClassOfFinancingReceivablesAxis = nbtb_OriginatedLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = nbtb_DirectFinancingReceivableMember |
Interest income recognized accrual | 0 us-gaap_ImpairedFinancingReceivableInterestIncomeAccrualMethod / nbtb_ClassOfFinancingReceivablesAxis = nbtb_OriginatedLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = nbtb_DirectFinancingReceivableMember | 0 us-gaap_ImpairedFinancingReceivableInterestIncomeAccrualMethod / nbtb_ClassOfFinancingReceivablesAxis = nbtb_OriginatedLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = nbtb_DirectFinancingReceivableMember |
Originated Loans [Member] | Residential Real Estate Mortgages [Member] |  |  |
With no allowance recorded [Abstract] |  |  |
Recorded investment balance (book) | 4,269,000 us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceRecordedInvestment / nbtb_ClassOfFinancingReceivablesAxis = nbtb_OriginatedLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ResidentialPortfolioSegmentMember |  | 3,544,000 us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceRecordedInvestment / nbtb_ClassOfFinancingReceivablesAxis = nbtb_OriginatedLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ResidentialPortfolioSegmentMember
Unpaid principal balance (legal) | 4,742,000 us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceUnpaidPrincipalBalance / nbtb_ClassOfFinancingReceivablesAxis = nbtb_OriginatedLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ResidentialPortfolioSegmentMember |  | 3,959,000 us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceUnpaidPrincipalBalance / nbtb_ClassOfFinancingReceivablesAxis = nbtb_OriginatedLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ResidentialPortfolioSegmentMember
With an allowance recorded [Abstract] |  |  |
Average recorded investment | 4,265,000 us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment / nbtb_ClassOfFinancingReceivablesAxis = nbtb_OriginatedLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ResidentialPortfolioSegmentMember | 2,727,000 us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment / nbtb_ClassOfFinancingReceivablesAxis = nbtb_OriginatedLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ResidentialPortfolioSegmentMember |
Interest income recognized accrual | 30,000 us-gaap_ImpairedFinancingReceivableInterestIncomeAccrualMethod / nbtb_ClassOfFinancingReceivablesAxis = nbtb_OriginatedLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ResidentialPortfolioSegmentMember | 23,000 us-gaap_ImpairedFinancingReceivableInterestIncomeAccrualMethod / nbtb_ClassOfFinancingReceivablesAxis = nbtb_OriginatedLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ResidentialPortfolioSegmentMember |
Acquired Loans [Member] |  |  |
With an allowance recorded [Abstract] |  |  |
Average recorded investment | 10,019,000 us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment / nbtb_ClassOfFinancingReceivablesAxis = nbtb_AcquiredLoansMember | 9,960,000 us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment / nbtb_ClassOfFinancingReceivablesAxis = nbtb_AcquiredLoansMember |
Interest income recognized accrual | 0 us-gaap_ImpairedFinancingReceivableInterestIncomeAccrualMethod / nbtb_ClassOfFinancingReceivablesAxis = nbtb_AcquiredLoansMember | 0 us-gaap_ImpairedFinancingReceivableInterestIncomeAccrualMethod / nbtb_ClassOfFinancingReceivablesAxis = nbtb_AcquiredLoansMember |
Acquired Loans [Member] | Commercial Loans [Member] |  |  |
With an allowance recorded [Abstract] |  |  |
Recorded investment balance (book) | 3,837,000 us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceRecordedInvestment / nbtb_ClassOfFinancingReceivablesAxis = nbtb_AcquiredLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialPortfolioSegmentMember |  | 3,009,000 us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceRecordedInvestment / nbtb_ClassOfFinancingReceivablesAxis = nbtb_AcquiredLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialPortfolioSegmentMember
Unpaid principal balance (legal) | 5,997,000 us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceUnpaidPrincipalBalance / nbtb_ClassOfFinancingReceivablesAxis = nbtb_AcquiredLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialPortfolioSegmentMember |  | 4,668,000 us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceUnpaidPrincipalBalance / nbtb_ClassOfFinancingReceivablesAxis = nbtb_AcquiredLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialPortfolioSegmentMember
Related allowance | 1,850,000 us-gaap_ImpairedFinancingReceivableRelatedAllowance / nbtb_ClassOfFinancingReceivablesAxis = nbtb_AcquiredLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialPortfolioSegmentMember |  | 500,000 us-gaap_ImpairedFinancingReceivableRelatedAllowance / nbtb_ClassOfFinancingReceivablesAxis = nbtb_AcquiredLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialPortfolioSegmentMember
Acquired Loans [Member] | Commercial [Member] |  |  |
With an allowance recorded [Abstract] |  |  |
Recorded investment balance (book) | 2,508,000 us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceRecordedInvestment / nbtb_ClassOfFinancingReceivablesAxis = nbtb_AcquiredLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = nbtb_CommercialFinancingReceivableMember |  | 3,009,000 us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceRecordedInvestment / nbtb_ClassOfFinancingReceivablesAxis = nbtb_AcquiredLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = nbtb_CommercialFinancingReceivableMember
Unpaid principal balance (legal) | 4,668,000 us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceUnpaidPrincipalBalance / nbtb_ClassOfFinancingReceivablesAxis = nbtb_AcquiredLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = nbtb_CommercialFinancingReceivableMember |  | 4,668,000 us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceUnpaidPrincipalBalance / nbtb_ClassOfFinancingReceivablesAxis = nbtb_AcquiredLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = nbtb_CommercialFinancingReceivableMember
Related allowance | 1,000,000 us-gaap_ImpairedFinancingReceivableRelatedAllowance / nbtb_ClassOfFinancingReceivablesAxis = nbtb_AcquiredLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = nbtb_CommercialFinancingReceivableMember |  | 500,000 us-gaap_ImpairedFinancingReceivableRelatedAllowance / nbtb_ClassOfFinancingReceivablesAxis = nbtb_AcquiredLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = nbtb_CommercialFinancingReceivableMember
Average recorded investment | 2,883,000 us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment / nbtb_ClassOfFinancingReceivablesAxis = nbtb_AcquiredLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = nbtb_CommercialFinancingReceivableMember | 6,436,000 us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment / nbtb_ClassOfFinancingReceivablesAxis = nbtb_AcquiredLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = nbtb_CommercialFinancingReceivableMember |
Interest income recognized accrual | 0 us-gaap_ImpairedFinancingReceivableInterestIncomeAccrualMethod / nbtb_ClassOfFinancingReceivablesAxis = nbtb_AcquiredLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = nbtb_CommercialFinancingReceivableMember | 0 us-gaap_ImpairedFinancingReceivableInterestIncomeAccrualMethod / nbtb_ClassOfFinancingReceivablesAxis = nbtb_AcquiredLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = nbtb_CommercialFinancingReceivableMember |
Acquired Loans [Member] | Commercial Real Estate [Member] |  |  |
With no allowance recorded [Abstract] |  |  |
Recorded investment balance (book) | 5,935,000 us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceRecordedInvestment / nbtb_ClassOfFinancingReceivablesAxis = nbtb_AcquiredLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialRealEstateOtherReceivableMember |  | 2,666,000 us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceRecordedInvestment / nbtb_ClassOfFinancingReceivablesAxis = nbtb_AcquiredLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialRealEstateOtherReceivableMember
Unpaid principal balance (legal) | 7,109,000 us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceUnpaidPrincipalBalance / nbtb_ClassOfFinancingReceivablesAxis = nbtb_AcquiredLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialRealEstateOtherReceivableMember |  | 3,830,000 us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceUnpaidPrincipalBalance / nbtb_ClassOfFinancingReceivablesAxis = nbtb_AcquiredLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialRealEstateOtherReceivableMember
With an allowance recorded [Abstract] |  |  |
Recorded investment balance (book) | 1,329,000 us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceRecordedInvestment / nbtb_ClassOfFinancingReceivablesAxis = nbtb_AcquiredLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialRealEstateOtherReceivableMember |  | 0 us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceRecordedInvestment / nbtb_ClassOfFinancingReceivablesAxis = nbtb_AcquiredLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialRealEstateOtherReceivableMember
Unpaid principal balance (legal) | 1,329,000 us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceUnpaidPrincipalBalance / nbtb_ClassOfFinancingReceivablesAxis = nbtb_AcquiredLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialRealEstateOtherReceivableMember |  | 0 us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceUnpaidPrincipalBalance / nbtb_ClassOfFinancingReceivablesAxis = nbtb_AcquiredLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialRealEstateOtherReceivableMember
Related allowance | 850,000 us-gaap_ImpairedFinancingReceivableRelatedAllowance / nbtb_ClassOfFinancingReceivablesAxis = nbtb_AcquiredLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialRealEstateOtherReceivableMember |  | 0 us-gaap_ImpairedFinancingReceivableRelatedAllowance / nbtb_ClassOfFinancingReceivablesAxis = nbtb_AcquiredLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialRealEstateOtherReceivableMember
Average recorded investment | 7,136,000 us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment / nbtb_ClassOfFinancingReceivablesAxis = nbtb_AcquiredLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialRealEstateOtherReceivableMember | 3,524,000 us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment / nbtb_ClassOfFinancingReceivablesAxis = nbtb_AcquiredLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialRealEstateOtherReceivableMember |
Interest income recognized accrual | $ 0 us-gaap_ImpairedFinancingReceivableInterestIncomeAccrualMethod / nbtb_ClassOfFinancingReceivablesAxis = nbtb_AcquiredLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialRealEstateOtherReceivableMember | $ 0 us-gaap_ImpairedFinancingReceivableInterestIncomeAccrualMethod / nbtb_ClassOfFinancingReceivablesAxis = nbtb_AcquiredLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialRealEstateOtherReceivableMember |

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