XML 27 R57.htm IDEA: XBRL DOCUMENT
v2.4.1.9

Allowance for Loan Losses and Credit Quality of Loans, Allowance for Loan Losses (Details) (USD $) | 12 Months Ended
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Dec. 31, 2014 | Dec. 31, 2013 | Dec. 31, 2012
Changes in allowance for loan losses by portfolio segment [Roll Forward] |  |  |
Balance, beginning of period | $ 69,434,000 us-gaap_FinancingReceivableAllowanceForCreditLosses | $ 69,334,000 us-gaap_FinancingReceivableAllowanceForCreditLosses | $ 71,334,000 us-gaap_FinancingReceivableAllowanceForCreditLosses
Charge-offs | (27,473,000)us-gaap_FinancingReceivableAllowanceForCreditLossesWriteOffs | (27,689,000)us-gaap_FinancingReceivableAllowanceForCreditLossesWriteOffs | (26,504,000)us-gaap_FinancingReceivableAllowanceForCreditLossesWriteOffs
Recoveries | 4,859,000 us-gaap_FinancingReceivableAllowanceForCreditLossesRecovery | 5,365,000 us-gaap_FinancingReceivableAllowanceForCreditLossesRecovery | 4,235,000 us-gaap_FinancingReceivableAllowanceForCreditLossesRecovery
Provision | 19,539,000 us-gaap_ProvisionForLoanLeaseAndOtherLosses | 22,424,000 us-gaap_ProvisionForLoanLeaseAndOtherLosses | 20,269,000 us-gaap_ProvisionForLoanLeaseAndOtherLosses
Balance, end of period | 66,359,000 us-gaap_FinancingReceivableAllowanceForCreditLosses | 69,434,000 us-gaap_FinancingReceivableAllowanceForCreditLosses | 69,334,000 us-gaap_FinancingReceivableAllowanceForCreditLosses
Allowance for loan losses and recorded investment by portfolio segment [Abstract] |  |  |
Allowance for loan losses | 66,359,000 us-gaap_FinancingReceivableAllowanceForCreditLosses | 69,434,000 us-gaap_FinancingReceivableAllowanceForCreditLosses | 69,334,000 us-gaap_FinancingReceivableAllowanceForCreditLosses
Allowance for loans individually evaluated for impairment | 1,100,000 us-gaap_FinancingReceivableAllowanceForCreditLossesIndividuallyEvaluatedForImpairment1 | 715,000 us-gaap_FinancingReceivableAllowanceForCreditLossesIndividuallyEvaluatedForImpairment1 |
Allowance for loans collectively evaluated for impairment | 65,259,000 us-gaap_FinancingReceivableAllowanceForCreditLossesCollectivelyEvaluatedForImpairment | 68,719,000 us-gaap_FinancingReceivableAllowanceForCreditLossesCollectivelyEvaluatedForImpairment |
Ending balance of loans | 5,595,271,000 us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome | 5,406,795,000 us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome |
Commercial Loans [Member] |  |  |
Changes in allowance for loan losses by portfolio segment [Roll Forward] |  |  |
Balance, beginning of period | 35,090,000 us-gaap_FinancingReceivableAllowanceForCreditLosses / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialPortfolioSegmentMember | 35,624,000 us-gaap_FinancingReceivableAllowanceForCreditLosses / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialPortfolioSegmentMember | 38,831,000 us-gaap_FinancingReceivableAllowanceForCreditLosses / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialPortfolioSegmentMember
Charge-offs | (9,414,000)us-gaap_FinancingReceivableAllowanceForCreditLossesWriteOffs / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialPortfolioSegmentMember | (10,459,000)us-gaap_FinancingReceivableAllowanceForCreditLossesWriteOffs / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialPortfolioSegmentMember | (8,750,000)us-gaap_FinancingReceivableAllowanceForCreditLossesWriteOffs / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialPortfolioSegmentMember
Recoveries | 1,774,000 us-gaap_FinancingReceivableAllowanceForCreditLossesRecovery / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialPortfolioSegmentMember | 1,957,000 us-gaap_FinancingReceivableAllowanceForCreditLossesRecovery / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialPortfolioSegmentMember | 1,641,000 us-gaap_FinancingReceivableAllowanceForCreditLossesRecovery / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialPortfolioSegmentMember
Provision | 4,983,000 us-gaap_ProvisionForLoanLeaseAndOtherLosses / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialPortfolioSegmentMember | 7,968,000 us-gaap_ProvisionForLoanLeaseAndOtherLosses / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialPortfolioSegmentMember | 3,902,000 us-gaap_ProvisionForLoanLeaseAndOtherLosses / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialPortfolioSegmentMember
Balance, end of period | 32,433,000 us-gaap_FinancingReceivableAllowanceForCreditLosses / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialPortfolioSegmentMember | 35,090,000 us-gaap_FinancingReceivableAllowanceForCreditLosses / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialPortfolioSegmentMember | 35,624,000 us-gaap_FinancingReceivableAllowanceForCreditLosses / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialPortfolioSegmentMember
Allowance for loan losses and recorded investment by portfolio segment [Abstract] |  |  |
Allowance for loan losses | 32,433,000 us-gaap_FinancingReceivableAllowanceForCreditLosses / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialPortfolioSegmentMember | 35,090,000 us-gaap_FinancingReceivableAllowanceForCreditLosses / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialPortfolioSegmentMember | 35,624,000 us-gaap_FinancingReceivableAllowanceForCreditLosses / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialPortfolioSegmentMember
Allowance for loans individually evaluated for impairment | 1,100,000 us-gaap_FinancingReceivableAllowanceForCreditLossesIndividuallyEvaluatedForImpairment1 / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialPortfolioSegmentMember | 715,000 us-gaap_FinancingReceivableAllowanceForCreditLossesIndividuallyEvaluatedForImpairment1 / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialPortfolioSegmentMember |
Allowance for loans collectively evaluated for impairment | 31,333,000 us-gaap_FinancingReceivableAllowanceForCreditLossesCollectivelyEvaluatedForImpairment / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialPortfolioSegmentMember | 34,375,000 us-gaap_FinancingReceivableAllowanceForCreditLossesCollectivelyEvaluatedForImpairment / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialPortfolioSegmentMember |
Ending balance of loans | 2,473,702,000 us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialPortfolioSegmentMember | 2,392,621,000 us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialPortfolioSegmentMember |
Consumer Loans [Member] |  |  |
Changes in allowance for loan losses by portfolio segment [Roll Forward] |  |  |
Balance, beginning of period | 27,694,000 us-gaap_FinancingReceivableAllowanceForCreditLosses / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ConsumerPortfolioSegmentMember | 27,162,000 us-gaap_FinancingReceivableAllowanceForCreditLosses / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ConsumerPortfolioSegmentMember | 26,049,000 us-gaap_FinancingReceivableAllowanceForCreditLosses / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ConsumerPortfolioSegmentMember
Charge-offs | (16,642,000)us-gaap_FinancingReceivableAllowanceForCreditLossesWriteOffs / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ConsumerPortfolioSegmentMember | (15,459,000)us-gaap_FinancingReceivableAllowanceForCreditLossesWriteOffs / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ConsumerPortfolioSegmentMember | (15,848,000)us-gaap_FinancingReceivableAllowanceForCreditLossesWriteOffs / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ConsumerPortfolioSegmentMember
Recoveries | 2,800,000 us-gaap_FinancingReceivableAllowanceForCreditLossesRecovery / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ConsumerPortfolioSegmentMember | 3,136,000 us-gaap_FinancingReceivableAllowanceForCreditLossesRecovery / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ConsumerPortfolioSegmentMember | 2,556,000 us-gaap_FinancingReceivableAllowanceForCreditLossesRecovery / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ConsumerPortfolioSegmentMember
Provision | 12,868,000 us-gaap_ProvisionForLoanLeaseAndOtherLosses / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ConsumerPortfolioSegmentMember | 12,855,000 us-gaap_ProvisionForLoanLeaseAndOtherLosses / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ConsumerPortfolioSegmentMember | 14,405,000 us-gaap_ProvisionForLoanLeaseAndOtherLosses / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ConsumerPortfolioSegmentMember
Balance, end of period | 26,720,000 us-gaap_FinancingReceivableAllowanceForCreditLosses / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ConsumerPortfolioSegmentMember | 27,694,000 us-gaap_FinancingReceivableAllowanceForCreditLosses / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ConsumerPortfolioSegmentMember | 27,162,000 us-gaap_FinancingReceivableAllowanceForCreditLosses / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ConsumerPortfolioSegmentMember
Allowance for loan losses and recorded investment by portfolio segment [Abstract] |  |  |
Allowance for loan losses | 26,720,000 us-gaap_FinancingReceivableAllowanceForCreditLosses / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ConsumerPortfolioSegmentMember | 27,694,000 us-gaap_FinancingReceivableAllowanceForCreditLosses / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ConsumerPortfolioSegmentMember | 27,162,000 us-gaap_FinancingReceivableAllowanceForCreditLosses / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ConsumerPortfolioSegmentMember
Allowance for loans individually evaluated for impairment | 0 us-gaap_FinancingReceivableAllowanceForCreditLossesIndividuallyEvaluatedForImpairment1 / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ConsumerPortfolioSegmentMember | 0 us-gaap_FinancingReceivableAllowanceForCreditLossesIndividuallyEvaluatedForImpairment1 / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ConsumerPortfolioSegmentMember |
Allowance for loans collectively evaluated for impairment | 26,720,000 us-gaap_FinancingReceivableAllowanceForCreditLossesCollectivelyEvaluatedForImpairment / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ConsumerPortfolioSegmentMember | 27,694,000 us-gaap_FinancingReceivableAllowanceForCreditLossesCollectivelyEvaluatedForImpairment / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ConsumerPortfolioSegmentMember |
Ending balance of loans | 2,005,980,000 us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ConsumerPortfolioSegmentMember | 1,972,537,000 us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ConsumerPortfolioSegmentMember |
Residential Real Estate Mortgages [Member] |  |  |
Changes in allowance for loan losses by portfolio segment [Roll Forward] |  |  |
Balance, beginning of period | 6,520,000 us-gaap_FinancingReceivableAllowanceForCreditLosses / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ResidentialPortfolioSegmentMember | 6,252,000 us-gaap_FinancingReceivableAllowanceForCreditLosses / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ResidentialPortfolioSegmentMember | 6,249,000 us-gaap_FinancingReceivableAllowanceForCreditLosses / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ResidentialPortfolioSegmentMember
Charge-offs | (1,417,000)us-gaap_FinancingReceivableAllowanceForCreditLossesWriteOffs / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ResidentialPortfolioSegmentMember | (1,771,000)us-gaap_FinancingReceivableAllowanceForCreditLossesWriteOffs / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ResidentialPortfolioSegmentMember | (1,906,000)us-gaap_FinancingReceivableAllowanceForCreditLossesWriteOffs / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ResidentialPortfolioSegmentMember
Recoveries | 285,000 us-gaap_FinancingReceivableAllowanceForCreditLossesRecovery / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ResidentialPortfolioSegmentMember | 272,000 us-gaap_FinancingReceivableAllowanceForCreditLossesRecovery / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ResidentialPortfolioSegmentMember | 38,000 us-gaap_FinancingReceivableAllowanceForCreditLossesRecovery / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ResidentialPortfolioSegmentMember
Provision | 1,742,000 us-gaap_ProvisionForLoanLeaseAndOtherLosses / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ResidentialPortfolioSegmentMember | 1,767,000 us-gaap_ProvisionForLoanLeaseAndOtherLosses / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ResidentialPortfolioSegmentMember | 1,871,000 us-gaap_ProvisionForLoanLeaseAndOtherLosses / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ResidentialPortfolioSegmentMember
Balance, end of period | 7,130,000 us-gaap_FinancingReceivableAllowanceForCreditLosses / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ResidentialPortfolioSegmentMember | 6,520,000 us-gaap_FinancingReceivableAllowanceForCreditLosses / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ResidentialPortfolioSegmentMember | 6,252,000 us-gaap_FinancingReceivableAllowanceForCreditLosses / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ResidentialPortfolioSegmentMember
Allowance for loan losses and recorded investment by portfolio segment [Abstract] |  |  |
Allowance for loan losses | 7,130,000 us-gaap_FinancingReceivableAllowanceForCreditLosses / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ResidentialPortfolioSegmentMember | 6,520,000 us-gaap_FinancingReceivableAllowanceForCreditLosses / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ResidentialPortfolioSegmentMember | 6,252,000 us-gaap_FinancingReceivableAllowanceForCreditLosses / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ResidentialPortfolioSegmentMember
Allowance for loans individually evaluated for impairment | 0 us-gaap_FinancingReceivableAllowanceForCreditLossesIndividuallyEvaluatedForImpairment1 / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ResidentialPortfolioSegmentMember | 0 us-gaap_FinancingReceivableAllowanceForCreditLossesIndividuallyEvaluatedForImpairment1 / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ResidentialPortfolioSegmentMember |
Allowance for loans collectively evaluated for impairment | 7,130,000 us-gaap_FinancingReceivableAllowanceForCreditLossesCollectivelyEvaluatedForImpairment / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ResidentialPortfolioSegmentMember | 6,520,000 us-gaap_FinancingReceivableAllowanceForCreditLossesCollectivelyEvaluatedForImpairment / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ResidentialPortfolioSegmentMember |
Ending balance of loans | 1,115,589,000 us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ResidentialPortfolioSegmentMember | 1,041,637,000 us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ResidentialPortfolioSegmentMember |
Unallocated [Member] |  |  |
Changes in allowance for loan losses by portfolio segment [Roll Forward] |  |  |
Balance, beginning of period | 130,000 us-gaap_FinancingReceivableAllowanceForCreditLosses / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_UnallocatedFinancingReceivablesMember | 296,000 us-gaap_FinancingReceivableAllowanceForCreditLosses / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_UnallocatedFinancingReceivablesMember | 205,000 us-gaap_FinancingReceivableAllowanceForCreditLosses / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_UnallocatedFinancingReceivablesMember
Charge-offs | 0 us-gaap_FinancingReceivableAllowanceForCreditLossesWriteOffs / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_UnallocatedFinancingReceivablesMember | 0 us-gaap_FinancingReceivableAllowanceForCreditLossesWriteOffs / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_UnallocatedFinancingReceivablesMember | 0 us-gaap_FinancingReceivableAllowanceForCreditLossesWriteOffs / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_UnallocatedFinancingReceivablesMember
Recoveries | 0 us-gaap_FinancingReceivableAllowanceForCreditLossesRecovery / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_UnallocatedFinancingReceivablesMember | 0 us-gaap_FinancingReceivableAllowanceForCreditLossesRecovery / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_UnallocatedFinancingReceivablesMember | 0 us-gaap_FinancingReceivableAllowanceForCreditLossesRecovery / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_UnallocatedFinancingReceivablesMember
Provision | (54,000)us-gaap_ProvisionForLoanLeaseAndOtherLosses / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_UnallocatedFinancingReceivablesMember | (166,000)us-gaap_ProvisionForLoanLeaseAndOtherLosses / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_UnallocatedFinancingReceivablesMember | 91,000 us-gaap_ProvisionForLoanLeaseAndOtherLosses / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_UnallocatedFinancingReceivablesMember
Balance, end of period | 76,000 us-gaap_FinancingReceivableAllowanceForCreditLosses / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_UnallocatedFinancingReceivablesMember | 130,000 us-gaap_FinancingReceivableAllowanceForCreditLosses / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_UnallocatedFinancingReceivablesMember | 296,000 us-gaap_FinancingReceivableAllowanceForCreditLosses / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_UnallocatedFinancingReceivablesMember
Allowance for loan losses and recorded investment by portfolio segment [Abstract] |  |  |
Allowance for loan losses | 76,000 us-gaap_FinancingReceivableAllowanceForCreditLosses / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_UnallocatedFinancingReceivablesMember | 130,000 us-gaap_FinancingReceivableAllowanceForCreditLosses / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_UnallocatedFinancingReceivablesMember | 296,000 us-gaap_FinancingReceivableAllowanceForCreditLosses / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_UnallocatedFinancingReceivablesMember
Allowance for loans collectively evaluated for impairment | 76,000 us-gaap_FinancingReceivableAllowanceForCreditLossesCollectivelyEvaluatedForImpairment / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_UnallocatedFinancingReceivablesMember | 130,000 us-gaap_FinancingReceivableAllowanceForCreditLossesCollectivelyEvaluatedForImpairment / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_UnallocatedFinancingReceivablesMember |
Originated Loans [Member] |  |  |
Allowance for loan losses and recorded investment by portfolio segment [Abstract] |  |  |
Ending balance of loans | 4,847,937,000 us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome / nbtb_ClassOfFinancingReceivablesAxis = nbtb_OriginatedLoansMember | 4,476,403,000 us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome / nbtb_ClassOfFinancingReceivablesAxis = nbtb_OriginatedLoansMember |
Ending balance of loans individually evaluated for impairment | 20,121,000 us-gaap_FinancingReceivableIndividuallyEvaluatedForImpairment / nbtb_ClassOfFinancingReceivablesAxis = nbtb_OriginatedLoansMember | 21,380,000 us-gaap_FinancingReceivableIndividuallyEvaluatedForImpairment / nbtb_ClassOfFinancingReceivablesAxis = nbtb_OriginatedLoansMember |
Ending balance of loans collectively evaluated for impairment | 4,827,816,000 us-gaap_FinancingReceivableCollectivelyEvaluatedForImpairment / nbtb_ClassOfFinancingReceivablesAxis = nbtb_OriginatedLoansMember | 4,455,023,000 us-gaap_FinancingReceivableCollectivelyEvaluatedForImpairment / nbtb_ClassOfFinancingReceivablesAxis = nbtb_OriginatedLoansMember |
Originated Loans [Member] | Commercial Loans [Member] |  |  |
Allowance for loan losses and recorded investment by portfolio segment [Abstract] |  |  |
Ending balance of loans | 2,140,371,000 us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome / nbtb_ClassOfFinancingReceivablesAxis = nbtb_OriginatedLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialPortfolioSegmentMember | 1,990,232,000 us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome / nbtb_ClassOfFinancingReceivablesAxis = nbtb_OriginatedLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialPortfolioSegmentMember |
Ending balance of loans individually evaluated for impairment | 11,079,000 us-gaap_FinancingReceivableIndividuallyEvaluatedForImpairment / nbtb_ClassOfFinancingReceivablesAxis = nbtb_OriginatedLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialPortfolioSegmentMember | 16,120,000 us-gaap_FinancingReceivableIndividuallyEvaluatedForImpairment / nbtb_ClassOfFinancingReceivablesAxis = nbtb_OriginatedLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialPortfolioSegmentMember |
Ending balance of loans collectively evaluated for impairment | 2,129,292,000 us-gaap_FinancingReceivableCollectivelyEvaluatedForImpairment / nbtb_ClassOfFinancingReceivablesAxis = nbtb_OriginatedLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialPortfolioSegmentMember | 1,974,112,000 us-gaap_FinancingReceivableCollectivelyEvaluatedForImpairment / nbtb_ClassOfFinancingReceivablesAxis = nbtb_OriginatedLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialPortfolioSegmentMember |
Originated Loans [Member] | Consumer Loans [Member] |  |  |
Allowance for loan losses and recorded investment by portfolio segment [Abstract] |  |  |
Ending balance of loans | 1,858,724,000 us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome / nbtb_ClassOfFinancingReceivablesAxis = nbtb_OriginatedLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ConsumerPortfolioSegmentMember | 1,752,950,000 us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome / nbtb_ClassOfFinancingReceivablesAxis = nbtb_OriginatedLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ConsumerPortfolioSegmentMember |
Ending balance of loans individually evaluated for impairment | 5,498,000 us-gaap_FinancingReceivableIndividuallyEvaluatedForImpairment / nbtb_ClassOfFinancingReceivablesAxis = nbtb_OriginatedLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ConsumerPortfolioSegmentMember | 3,248,000 us-gaap_FinancingReceivableIndividuallyEvaluatedForImpairment / nbtb_ClassOfFinancingReceivablesAxis = nbtb_OriginatedLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ConsumerPortfolioSegmentMember |
Ending balance of loans collectively evaluated for impairment | 1,853,226,000 us-gaap_FinancingReceivableCollectivelyEvaluatedForImpairment / nbtb_ClassOfFinancingReceivablesAxis = nbtb_OriginatedLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ConsumerPortfolioSegmentMember | 1,749,702,000 us-gaap_FinancingReceivableCollectivelyEvaluatedForImpairment / nbtb_ClassOfFinancingReceivablesAxis = nbtb_OriginatedLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ConsumerPortfolioSegmentMember |
Originated Loans [Member] | Residential Real Estate Mortgages [Member] |  |  |
Allowance for loan losses and recorded investment by portfolio segment [Abstract] |  |  |
Ending balance of loans | 848,842,000 us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome / nbtb_ClassOfFinancingReceivablesAxis = nbtb_OriginatedLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ResidentialPortfolioSegmentMember | 733,221,000 us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome / nbtb_ClassOfFinancingReceivablesAxis = nbtb_OriginatedLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ResidentialPortfolioSegmentMember |
Ending balance of loans individually evaluated for impairment | 3,544,000 us-gaap_FinancingReceivableIndividuallyEvaluatedForImpairment / nbtb_ClassOfFinancingReceivablesAxis = nbtb_OriginatedLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ResidentialPortfolioSegmentMember | 2,012,000 us-gaap_FinancingReceivableIndividuallyEvaluatedForImpairment / nbtb_ClassOfFinancingReceivablesAxis = nbtb_OriginatedLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ResidentialPortfolioSegmentMember |
Ending balance of loans collectively evaluated for impairment | 845,298,000 us-gaap_FinancingReceivableCollectivelyEvaluatedForImpairment / nbtb_ClassOfFinancingReceivablesAxis = nbtb_OriginatedLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ResidentialPortfolioSegmentMember | 731,209,000 us-gaap_FinancingReceivableCollectivelyEvaluatedForImpairment / nbtb_ClassOfFinancingReceivablesAxis = nbtb_OriginatedLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ResidentialPortfolioSegmentMember |
Acquired Loans [Member] |  |  |
Changes in allowance for loan losses by portfolio segment [Roll Forward] |  |  |
Balance, beginning of period | 0 us-gaap_FinancingReceivableAllowanceForCreditLosses / nbtb_ClassOfFinancingReceivablesAxis = nbtb_AcquiredLoansMember |  |
Charge-offs | (4,800,000)us-gaap_FinancingReceivableAllowanceForCreditLossesWriteOffs / nbtb_ClassOfFinancingReceivablesAxis = nbtb_AcquiredLoansMember | (400,000)us-gaap_FinancingReceivableAllowanceForCreditLossesWriteOffs / nbtb_ClassOfFinancingReceivablesAxis = nbtb_AcquiredLoansMember |
Balance, end of period | 500 us-gaap_FinancingReceivableAllowanceForCreditLosses / nbtb_ClassOfFinancingReceivablesAxis = nbtb_AcquiredLoansMember | 0 us-gaap_FinancingReceivableAllowanceForCreditLosses / nbtb_ClassOfFinancingReceivablesAxis = nbtb_AcquiredLoansMember |
Allowance for loan losses and recorded investment by portfolio segment [Abstract] |  |  |
Allowance for loan losses | 500 us-gaap_FinancingReceivableAllowanceForCreditLosses / nbtb_ClassOfFinancingReceivablesAxis = nbtb_AcquiredLoansMember | 0 us-gaap_FinancingReceivableAllowanceForCreditLosses / nbtb_ClassOfFinancingReceivablesAxis = nbtb_AcquiredLoansMember |
Ending balance of loans | 747,334,000 us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome / nbtb_ClassOfFinancingReceivablesAxis = nbtb_AcquiredLoansMember | 930,392,000 us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome / nbtb_ClassOfFinancingReceivablesAxis = nbtb_AcquiredLoansMember |
Ending balance of loans individually evaluated for impairment | 5,675,000 us-gaap_FinancingReceivableIndividuallyEvaluatedForImpairment / nbtb_ClassOfFinancingReceivablesAxis = nbtb_AcquiredLoansMember | 10,060,000 us-gaap_FinancingReceivableIndividuallyEvaluatedForImpairment / nbtb_ClassOfFinancingReceivablesAxis = nbtb_AcquiredLoansMember |
Ending balance of loans collectively evaluated for impairment | 741,659,000 us-gaap_FinancingReceivableCollectivelyEvaluatedForImpairment / nbtb_ClassOfFinancingReceivablesAxis = nbtb_AcquiredLoansMember | 920,332,000 us-gaap_FinancingReceivableCollectivelyEvaluatedForImpairment / nbtb_ClassOfFinancingReceivablesAxis = nbtb_AcquiredLoansMember |
Acquired Loans [Member] | Commercial Loans [Member] |  |  |
Allowance for loan losses and recorded investment by portfolio segment [Abstract] |  |  |
Ending balance of loans | 333,331,000 us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome / nbtb_ClassOfFinancingReceivablesAxis = nbtb_AcquiredLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialPortfolioSegmentMember | 402,389,000 us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome / nbtb_ClassOfFinancingReceivablesAxis = nbtb_AcquiredLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialPortfolioSegmentMember |
Ending balance of loans individually evaluated for impairment | 5,675,000 us-gaap_FinancingReceivableIndividuallyEvaluatedForImpairment / nbtb_ClassOfFinancingReceivablesAxis = nbtb_AcquiredLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialPortfolioSegmentMember | 10,060,000 us-gaap_FinancingReceivableIndividuallyEvaluatedForImpairment / nbtb_ClassOfFinancingReceivablesAxis = nbtb_AcquiredLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialPortfolioSegmentMember |
Ending balance of loans collectively evaluated for impairment | 327,656,000 us-gaap_FinancingReceivableCollectivelyEvaluatedForImpairment / nbtb_ClassOfFinancingReceivablesAxis = nbtb_AcquiredLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialPortfolioSegmentMember | 392,329,000 us-gaap_FinancingReceivableCollectivelyEvaluatedForImpairment / nbtb_ClassOfFinancingReceivablesAxis = nbtb_AcquiredLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_CommercialPortfolioSegmentMember |
Acquired Loans [Member] | Consumer Loans [Member] |  |  |
Allowance for loan losses and recorded investment by portfolio segment [Abstract] |  |  |
Ending balance of loans | 147,256,000 us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome / nbtb_ClassOfFinancingReceivablesAxis = nbtb_AcquiredLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ConsumerPortfolioSegmentMember | 219,587,000 us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome / nbtb_ClassOfFinancingReceivablesAxis = nbtb_AcquiredLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ConsumerPortfolioSegmentMember |
Ending balance of loans individually evaluated for impairment | 0 us-gaap_FinancingReceivableIndividuallyEvaluatedForImpairment / nbtb_ClassOfFinancingReceivablesAxis = nbtb_AcquiredLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ConsumerPortfolioSegmentMember | 0 us-gaap_FinancingReceivableIndividuallyEvaluatedForImpairment / nbtb_ClassOfFinancingReceivablesAxis = nbtb_AcquiredLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ConsumerPortfolioSegmentMember |
Ending balance of loans collectively evaluated for impairment | 147,256,000 us-gaap_FinancingReceivableCollectivelyEvaluatedForImpairment / nbtb_ClassOfFinancingReceivablesAxis = nbtb_AcquiredLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ConsumerPortfolioSegmentMember | 219,587,000 us-gaap_FinancingReceivableCollectivelyEvaluatedForImpairment / nbtb_ClassOfFinancingReceivablesAxis = nbtb_AcquiredLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ConsumerPortfolioSegmentMember |
Acquired Loans [Member] | Residential Real Estate Mortgages [Member] |  |  |
Allowance for loan losses and recorded investment by portfolio segment [Abstract] |  |  |
Ending balance of loans | 266,747,000 us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome / nbtb_ClassOfFinancingReceivablesAxis = nbtb_AcquiredLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ResidentialPortfolioSegmentMember | 308,416,000 us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome / nbtb_ClassOfFinancingReceivablesAxis = nbtb_AcquiredLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ResidentialPortfolioSegmentMember |
Ending balance of loans individually evaluated for impairment | 0 us-gaap_FinancingReceivableIndividuallyEvaluatedForImpairment / nbtb_ClassOfFinancingReceivablesAxis = nbtb_AcquiredLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ResidentialPortfolioSegmentMember | 0 us-gaap_FinancingReceivableIndividuallyEvaluatedForImpairment / nbtb_ClassOfFinancingReceivablesAxis = nbtb_AcquiredLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ResidentialPortfolioSegmentMember |
Ending balance of loans collectively evaluated for impairment | $ 266,747,000 us-gaap_FinancingReceivableCollectivelyEvaluatedForImpairment / nbtb_ClassOfFinancingReceivablesAxis = nbtb_AcquiredLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ResidentialPortfolioSegmentMember | $ 308,416,000 us-gaap_FinancingReceivableCollectivelyEvaluatedForImpairment / nbtb_ClassOfFinancingReceivablesAxis = nbtb_AcquiredLoansMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ResidentialPortfolioSegmentMember |

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