XML 17 R54.htm IDEA: XBRL DOCUMENT
v2.4.1.9

LOANS, Amount of Loans by Credit Quality Category (Details) (USD $) In Thousands, unless otherwise specified | Dec. 31, 2014 | Dec. 31, 2013
--- | --- | ---
Financing Receivable, Recorded Investment [Line Items] |  |
Loans | $ 4,236,206 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount | $ 4,109,083 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount
Business Lending [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Loans | 1,262,484 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / cbu_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivable2Axis = us-gaap_CommercialLoanMember | 1,260,364 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / cbu_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivable2Axis = us-gaap_CommercialLoanMember
Legacy Loan [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Loans | 3,963,398 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / cbu_FinancingReceivableRecordedInvestmentByTypeOfFinancingReceivableAxis = cbu_LegacyLoanMember | 3,771,875 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / cbu_FinancingReceivableRecordedInvestmentByTypeOfFinancingReceivableAxis = cbu_LegacyLoanMember
Legacy Loan [Member] | Business Lending [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Loans | 1,124,594 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / cbu_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivable2Axis = us-gaap_CommercialLoanMember / cbu_FinancingReceivableRecordedInvestmentByTypeOfFinancingReceivableAxis = cbu_LegacyLoanMember | 1,086,025 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / cbu_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivable2Axis = us-gaap_CommercialLoanMember / cbu_FinancingReceivableRecordedInvestmentByTypeOfFinancingReceivableAxis = cbu_LegacyLoanMember
Legacy Loan [Member] | All Other Loans [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Loans | 2,838,804 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / cbu_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivable2Axis = cbu_ExcludingBusinessLendingLoansMember / cbu_FinancingReceivableRecordedInvestmentByTypeOfFinancingReceivableAxis = cbu_LegacyLoanMember | 2,685,850 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / cbu_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivable2Axis = cbu_ExcludingBusinessLendingLoansMember / cbu_FinancingReceivableRecordedInvestmentByTypeOfFinancingReceivableAxis = cbu_LegacyLoanMember
Acquired Loans [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Loans | 272,808 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / cbu_FinancingReceivableRecordedInvestmentByTypeOfFinancingReceivableAxis = cbu_AcquiredLoansMember | 337,208 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / cbu_FinancingReceivableRecordedInvestmentByTypeOfFinancingReceivableAxis = cbu_AcquiredLoansMember
Acquired Loans [Member] | Business Lending [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Loans | 137,890 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / cbu_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivable2Axis = us-gaap_CommercialLoanMember / cbu_FinancingReceivableRecordedInvestmentByTypeOfFinancingReceivableAxis = cbu_AcquiredLoansMember | 174,339 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / cbu_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivable2Axis = us-gaap_CommercialLoanMember / cbu_FinancingReceivableRecordedInvestmentByTypeOfFinancingReceivableAxis = cbu_AcquiredLoansMember
Acquired Loans [Member] | All Other Loans [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Loans | 134,918 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / cbu_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivable2Axis = cbu_ExcludingBusinessLendingLoansMember / cbu_FinancingReceivableRecordedInvestmentByTypeOfFinancingReceivableAxis = cbu_AcquiredLoansMember | 162,869 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / cbu_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivable2Axis = cbu_ExcludingBusinessLendingLoansMember / cbu_FinancingReceivableRecordedInvestmentByTypeOfFinancingReceivableAxis = cbu_AcquiredLoansMember
Pass [Member] | Business Lending [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Loans | 1,043,470 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / cbu_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivable2Axis = us-gaap_CommercialLoanMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_PassMember | 1,025,156 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / cbu_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivable2Axis = us-gaap_CommercialLoanMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_PassMember
Pass [Member] | Legacy Loan [Member] | Business Lending [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Loans | 949,960 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / cbu_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivable2Axis = us-gaap_CommercialLoanMember / cbu_FinancingReceivableRecordedInvestmentByTypeOfFinancingReceivableAxis = cbu_LegacyLoanMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_PassMember | 908,885 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / cbu_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivable2Axis = us-gaap_CommercialLoanMember / cbu_FinancingReceivableRecordedInvestmentByTypeOfFinancingReceivableAxis = cbu_LegacyLoanMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_PassMember
Pass [Member] | Acquired Loans [Member] | Business Lending [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Loans | 93,510 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / cbu_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivable2Axis = us-gaap_CommercialLoanMember / cbu_FinancingReceivableRecordedInvestmentByTypeOfFinancingReceivableAxis = cbu_AcquiredLoansMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_PassMember | 116,271 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / cbu_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivable2Axis = us-gaap_CommercialLoanMember / cbu_FinancingReceivableRecordedInvestmentByTypeOfFinancingReceivableAxis = cbu_AcquiredLoansMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_PassMember
Special Mention [Member] | Business Lending [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Loans | 121,214 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / cbu_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivable2Axis = us-gaap_CommercialLoanMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_SpecialMentionMember | 117,864 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / cbu_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivable2Axis = us-gaap_CommercialLoanMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_SpecialMentionMember
Special Mention [Member] | Legacy Loan [Member] | Business Lending [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Loans | 103,176 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / cbu_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivable2Axis = us-gaap_CommercialLoanMember / cbu_FinancingReceivableRecordedInvestmentByTypeOfFinancingReceivableAxis = cbu_LegacyLoanMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_SpecialMentionMember | 93,600 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / cbu_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivable2Axis = us-gaap_CommercialLoanMember / cbu_FinancingReceivableRecordedInvestmentByTypeOfFinancingReceivableAxis = cbu_LegacyLoanMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_SpecialMentionMember
Special Mention [Member] | Acquired Loans [Member] | Business Lending [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Loans | 18,038 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / cbu_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivable2Axis = us-gaap_CommercialLoanMember / cbu_FinancingReceivableRecordedInvestmentByTypeOfFinancingReceivableAxis = cbu_AcquiredLoansMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_SpecialMentionMember | 24,264 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / cbu_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivable2Axis = us-gaap_CommercialLoanMember / cbu_FinancingReceivableRecordedInvestmentByTypeOfFinancingReceivableAxis = cbu_AcquiredLoansMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_SpecialMentionMember
Classified [Member] | Business Lending [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Loans | 92,488 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / cbu_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivable2Axis = us-gaap_CommercialLoanMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_SubstandardMember | 110,093 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / cbu_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivable2Axis = us-gaap_CommercialLoanMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_SubstandardMember
Classified [Member] | Legacy Loan [Member] | Business Lending [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Loans | 71,458 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / cbu_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivable2Axis = us-gaap_CommercialLoanMember / cbu_FinancingReceivableRecordedInvestmentByTypeOfFinancingReceivableAxis = cbu_LegacyLoanMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_SubstandardMember | 83,379 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / cbu_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivable2Axis = us-gaap_CommercialLoanMember / cbu_FinancingReceivableRecordedInvestmentByTypeOfFinancingReceivableAxis = cbu_LegacyLoanMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_SubstandardMember
Classified [Member] | Acquired Loans [Member] | Business Lending [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Loans | 21,030 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / cbu_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivable2Axis = us-gaap_CommercialLoanMember / cbu_FinancingReceivableRecordedInvestmentByTypeOfFinancingReceivableAxis = cbu_AcquiredLoansMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_SubstandardMember | 26,714 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / cbu_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivable2Axis = us-gaap_CommercialLoanMember / cbu_FinancingReceivableRecordedInvestmentByTypeOfFinancingReceivableAxis = cbu_AcquiredLoansMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_SubstandardMember
Doubtful [Member] | Business Lending [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Loans | 0 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / cbu_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivable2Axis = us-gaap_CommercialLoanMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_DoubtfulMember | 161 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / cbu_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivable2Axis = us-gaap_CommercialLoanMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_DoubtfulMember
Doubtful [Member] | Legacy Loan [Member] | Business Lending [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Loans | 0 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / cbu_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivable2Axis = us-gaap_CommercialLoanMember / cbu_FinancingReceivableRecordedInvestmentByTypeOfFinancingReceivableAxis = cbu_LegacyLoanMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_DoubtfulMember | 161 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / cbu_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivable2Axis = us-gaap_CommercialLoanMember / cbu_FinancingReceivableRecordedInvestmentByTypeOfFinancingReceivableAxis = cbu_LegacyLoanMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_DoubtfulMember
Doubtful [Member] | Acquired Loans [Member] | Business Lending [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Loans | 0 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / cbu_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivable2Axis = us-gaap_CommercialLoanMember / cbu_FinancingReceivableRecordedInvestmentByTypeOfFinancingReceivableAxis = cbu_AcquiredLoansMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_DoubtfulMember | 0 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / cbu_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivable2Axis = us-gaap_CommercialLoanMember / cbu_FinancingReceivableRecordedInvestmentByTypeOfFinancingReceivableAxis = cbu_AcquiredLoansMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_DoubtfulMember
Acquired Impaired [Member] | Business Lending [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Loans | 5,312 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / cbu_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivable2Axis = us-gaap_CommercialLoanMember / us-gaap_InternalCreditAssessmentAxis = cbu_PurchasedImpairedMember | 7,090 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / cbu_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivable2Axis = us-gaap_CommercialLoanMember / us-gaap_InternalCreditAssessmentAxis = cbu_PurchasedImpairedMember
Acquired Impaired [Member] | Legacy Loan [Member] | Business Lending [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Loans | 0 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / cbu_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivable2Axis = us-gaap_CommercialLoanMember / cbu_FinancingReceivableRecordedInvestmentByTypeOfFinancingReceivableAxis = cbu_LegacyLoanMember / us-gaap_InternalCreditAssessmentAxis = cbu_PurchasedImpairedMember | 0 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / cbu_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivable2Axis = us-gaap_CommercialLoanMember / cbu_FinancingReceivableRecordedInvestmentByTypeOfFinancingReceivableAxis = cbu_LegacyLoanMember / us-gaap_InternalCreditAssessmentAxis = cbu_PurchasedImpairedMember
Acquired Impaired [Member] | Acquired Loans [Member] | Business Lending [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Loans | 5,312 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / cbu_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivable2Axis = us-gaap_CommercialLoanMember / cbu_FinancingReceivableRecordedInvestmentByTypeOfFinancingReceivableAxis = cbu_AcquiredLoansMember / us-gaap_InternalCreditAssessmentAxis = cbu_PurchasedImpairedMember | 7,090 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / cbu_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivable2Axis = us-gaap_CommercialLoanMember / cbu_FinancingReceivableRecordedInvestmentByTypeOfFinancingReceivableAxis = cbu_AcquiredLoansMember / us-gaap_InternalCreditAssessmentAxis = cbu_PurchasedImpairedMember
Performing [Member] | Legacy Loan [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Loans | 2,820,941 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / cbu_FinancingReceivableRecordedInvestmentByTypeOfFinancingReceivableAxis = cbu_LegacyLoanMember / us-gaap_InternalCreditAssessmentAxis = cbu_PerformingFinancingReceivable1Member | 2,670,614 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / cbu_FinancingReceivableRecordedInvestmentByTypeOfFinancingReceivableAxis = cbu_LegacyLoanMember / us-gaap_InternalCreditAssessmentAxis = cbu_PerformingFinancingReceivable1Member
Performing [Member] | Acquired Loans [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Loans | 132,074 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / cbu_FinancingReceivableRecordedInvestmentByTypeOfFinancingReceivableAxis = cbu_AcquiredLoansMember / us-gaap_InternalCreditAssessmentAxis = cbu_PerformingFinancingReceivable1Member | 160,796 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / cbu_FinancingReceivableRecordedInvestmentByTypeOfFinancingReceivableAxis = cbu_AcquiredLoansMember / us-gaap_InternalCreditAssessmentAxis = cbu_PerformingFinancingReceivable1Member
Nonperforming [Member] | Legacy Loan [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Loans | 17,863 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / cbu_FinancingReceivableRecordedInvestmentByTypeOfFinancingReceivableAxis = cbu_LegacyLoanMember / us-gaap_InternalCreditAssessmentAxis = cbu_NonperformingFinancingReceivable1Member | 15,236 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / cbu_FinancingReceivableRecordedInvestmentByTypeOfFinancingReceivableAxis = cbu_LegacyLoanMember / us-gaap_InternalCreditAssessmentAxis = cbu_NonperformingFinancingReceivable1Member
Nonperforming [Member] | Acquired Loans [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Loans | 2,844 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / cbu_FinancingReceivableRecordedInvestmentByTypeOfFinancingReceivableAxis = cbu_AcquiredLoansMember / us-gaap_InternalCreditAssessmentAxis = cbu_NonperformingFinancingReceivable1Member | 2,073 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / cbu_FinancingReceivableRecordedInvestmentByTypeOfFinancingReceivableAxis = cbu_AcquiredLoansMember / us-gaap_InternalCreditAssessmentAxis = cbu_NonperformingFinancingReceivable1Member
Consumer Mortgage [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Loans | 1,613,384 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ResidentialMortgageMember | 1,582,058 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ResidentialMortgageMember
Consumer Mortgage [Member] | Legacy Loan [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Loans | 1,544,401 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ResidentialMortgageMember / cbu_FinancingReceivableRecordedInvestmentByTypeOfFinancingReceivableAxis = cbu_LegacyLoanMember | 1,502,259 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ResidentialMortgageMember / cbu_FinancingReceivableRecordedInvestmentByTypeOfFinancingReceivableAxis = cbu_LegacyLoanMember
Consumer Mortgage [Member] | Acquired Loans [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Loans | 68,983 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ResidentialMortgageMember / cbu_FinancingReceivableRecordedInvestmentByTypeOfFinancingReceivableAxis = cbu_AcquiredLoansMember | 79,799 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ResidentialMortgageMember / cbu_FinancingReceivableRecordedInvestmentByTypeOfFinancingReceivableAxis = cbu_AcquiredLoansMember
Consumer Mortgage [Member] | Performing [Member] | Legacy Loan [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Loans | 1,529,035 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ResidentialMortgageMember / cbu_FinancingReceivableRecordedInvestmentByTypeOfFinancingReceivableAxis = cbu_LegacyLoanMember / us-gaap_InternalCreditAssessmentAxis = cbu_PerformingFinancingReceivable1Member | 1,489,909 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ResidentialMortgageMember / cbu_FinancingReceivableRecordedInvestmentByTypeOfFinancingReceivableAxis = cbu_LegacyLoanMember / us-gaap_InternalCreditAssessmentAxis = cbu_PerformingFinancingReceivable1Member
Consumer Mortgage [Member] | Performing [Member] | Acquired Loans [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Loans | 66,629 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ResidentialMortgageMember / cbu_FinancingReceivableRecordedInvestmentByTypeOfFinancingReceivableAxis = cbu_AcquiredLoansMember / us-gaap_InternalCreditAssessmentAxis = cbu_PerformingFinancingReceivable1Member | 78,251 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ResidentialMortgageMember / cbu_FinancingReceivableRecordedInvestmentByTypeOfFinancingReceivableAxis = cbu_AcquiredLoansMember / us-gaap_InternalCreditAssessmentAxis = cbu_PerformingFinancingReceivable1Member
Consumer Mortgage [Member] | Nonperforming [Member] | Legacy Loan [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Loans | 15,366 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ResidentialMortgageMember / cbu_FinancingReceivableRecordedInvestmentByTypeOfFinancingReceivableAxis = cbu_LegacyLoanMember / us-gaap_InternalCreditAssessmentAxis = cbu_NonperformingFinancingReceivable1Member | 12,350 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ResidentialMortgageMember / cbu_FinancingReceivableRecordedInvestmentByTypeOfFinancingReceivableAxis = cbu_LegacyLoanMember / us-gaap_InternalCreditAssessmentAxis = cbu_NonperformingFinancingReceivable1Member
Consumer Mortgage [Member] | Nonperforming [Member] | Acquired Loans [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Loans | 2,354 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ResidentialMortgageMember / cbu_FinancingReceivableRecordedInvestmentByTypeOfFinancingReceivableAxis = cbu_AcquiredLoansMember / us-gaap_InternalCreditAssessmentAxis = cbu_NonperformingFinancingReceivable1Member | 1,548 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ResidentialMortgageMember / cbu_FinancingReceivableRecordedInvestmentByTypeOfFinancingReceivableAxis = cbu_AcquiredLoansMember / us-gaap_InternalCreditAssessmentAxis = cbu_NonperformingFinancingReceivable1Member
Consumer Indirect [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Loans | 833,968 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = cbu_ConsumerInstallmentIndirectMember | 740,002 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = cbu_ConsumerInstallmentIndirectMember
Consumer Indirect [Member] | Legacy Loan [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Loans | 832,745 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = cbu_ConsumerInstallmentIndirectMember / cbu_FinancingReceivableRecordedInvestmentByTypeOfFinancingReceivableAxis = cbu_LegacyLoanMember | 736,277 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = cbu_ConsumerInstallmentIndirectMember / cbu_FinancingReceivableRecordedInvestmentByTypeOfFinancingReceivableAxis = cbu_LegacyLoanMember
Consumer Indirect [Member] | Acquired Loans [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Loans | 1,223 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = cbu_ConsumerInstallmentIndirectMember / cbu_FinancingReceivableRecordedInvestmentByTypeOfFinancingReceivableAxis = cbu_AcquiredLoansMember | 3,725 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = cbu_ConsumerInstallmentIndirectMember / cbu_FinancingReceivableRecordedInvestmentByTypeOfFinancingReceivableAxis = cbu_AcquiredLoansMember
Consumer Indirect [Member] | Performing [Member] | Legacy Loan [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Loans | 832,653 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = cbu_ConsumerInstallmentIndirectMember / cbu_FinancingReceivableRecordedInvestmentByTypeOfFinancingReceivableAxis = cbu_LegacyLoanMember / us-gaap_InternalCreditAssessmentAxis = cbu_PerformingFinancingReceivable1Member | 735,525 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = cbu_ConsumerInstallmentIndirectMember / cbu_FinancingReceivableRecordedInvestmentByTypeOfFinancingReceivableAxis = cbu_LegacyLoanMember / us-gaap_InternalCreditAssessmentAxis = cbu_PerformingFinancingReceivable1Member
Consumer Indirect [Member] | Performing [Member] | Acquired Loans [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Loans | 1,223 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = cbu_ConsumerInstallmentIndirectMember / cbu_FinancingReceivableRecordedInvestmentByTypeOfFinancingReceivableAxis = cbu_AcquiredLoansMember / us-gaap_InternalCreditAssessmentAxis = cbu_PerformingFinancingReceivable1Member | 3,708 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = cbu_ConsumerInstallmentIndirectMember / cbu_FinancingReceivableRecordedInvestmentByTypeOfFinancingReceivableAxis = cbu_AcquiredLoansMember / us-gaap_InternalCreditAssessmentAxis = cbu_PerformingFinancingReceivable1Member
Consumer Indirect [Member] | Nonperforming [Member] | Legacy Loan [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Loans | 92 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = cbu_ConsumerInstallmentIndirectMember / cbu_FinancingReceivableRecordedInvestmentByTypeOfFinancingReceivableAxis = cbu_LegacyLoanMember / us-gaap_InternalCreditAssessmentAxis = cbu_NonperformingFinancingReceivable1Member | 752 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = cbu_ConsumerInstallmentIndirectMember / cbu_FinancingReceivableRecordedInvestmentByTypeOfFinancingReceivableAxis = cbu_LegacyLoanMember / us-gaap_InternalCreditAssessmentAxis = cbu_NonperformingFinancingReceivable1Member
Consumer Indirect [Member] | Nonperforming [Member] | Acquired Loans [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Loans | 0 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = cbu_ConsumerInstallmentIndirectMember / cbu_FinancingReceivableRecordedInvestmentByTypeOfFinancingReceivableAxis = cbu_AcquiredLoansMember / us-gaap_InternalCreditAssessmentAxis = cbu_NonperformingFinancingReceivable1Member | 17 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = cbu_ConsumerInstallmentIndirectMember / cbu_FinancingReceivableRecordedInvestmentByTypeOfFinancingReceivableAxis = cbu_AcquiredLoansMember / us-gaap_InternalCreditAssessmentAxis = cbu_NonperformingFinancingReceivable1Member
Consumer Direct [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Loans | 184,028 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = cbu_ConsumerInstallmentDirectMember | 180,139 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = cbu_ConsumerInstallmentDirectMember
Consumer Direct [Member] | Legacy Loan [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Loans | 178,585 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = cbu_ConsumerInstallmentDirectMember / cbu_FinancingReceivableRecordedInvestmentByTypeOfFinancingReceivableAxis = cbu_LegacyLoanMember | 171,404 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = cbu_ConsumerInstallmentDirectMember / cbu_FinancingReceivableRecordedInvestmentByTypeOfFinancingReceivableAxis = cbu_LegacyLoanMember
Consumer Direct [Member] | Acquired Loans [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Loans | 5,443 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = cbu_ConsumerInstallmentDirectMember / cbu_FinancingReceivableRecordedInvestmentByTypeOfFinancingReceivableAxis = cbu_AcquiredLoansMember | 8,735 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = cbu_ConsumerInstallmentDirectMember / cbu_FinancingReceivableRecordedInvestmentByTypeOfFinancingReceivableAxis = cbu_AcquiredLoansMember
Consumer Direct [Member] | Performing [Member] | Legacy Loan [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Loans | 178,547 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = cbu_ConsumerInstallmentDirectMember / cbu_FinancingReceivableRecordedInvestmentByTypeOfFinancingReceivableAxis = cbu_LegacyLoanMember / us-gaap_InternalCreditAssessmentAxis = cbu_PerformingFinancingReceivable1Member | 171,310 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = cbu_ConsumerInstallmentDirectMember / cbu_FinancingReceivableRecordedInvestmentByTypeOfFinancingReceivableAxis = cbu_LegacyLoanMember / us-gaap_InternalCreditAssessmentAxis = cbu_PerformingFinancingReceivable1Member
Consumer Direct [Member] | Performing [Member] | Acquired Loans [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Loans | 5,425 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = cbu_ConsumerInstallmentDirectMember / cbu_FinancingReceivableRecordedInvestmentByTypeOfFinancingReceivableAxis = cbu_AcquiredLoansMember / us-gaap_InternalCreditAssessmentAxis = cbu_PerformingFinancingReceivable1Member | 8,708 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = cbu_ConsumerInstallmentDirectMember / cbu_FinancingReceivableRecordedInvestmentByTypeOfFinancingReceivableAxis = cbu_AcquiredLoansMember / us-gaap_InternalCreditAssessmentAxis = cbu_PerformingFinancingReceivable1Member
Consumer Direct [Member] | Nonperforming [Member] | Legacy Loan [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Loans | 38 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = cbu_ConsumerInstallmentDirectMember / cbu_FinancingReceivableRecordedInvestmentByTypeOfFinancingReceivableAxis = cbu_LegacyLoanMember / us-gaap_InternalCreditAssessmentAxis = cbu_NonperformingFinancingReceivable1Member | 94 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = cbu_ConsumerInstallmentDirectMember / cbu_FinancingReceivableRecordedInvestmentByTypeOfFinancingReceivableAxis = cbu_LegacyLoanMember / us-gaap_InternalCreditAssessmentAxis = cbu_NonperformingFinancingReceivable1Member
Consumer Direct [Member] | Nonperforming [Member] | Acquired Loans [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Loans | 18 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = cbu_ConsumerInstallmentDirectMember / cbu_FinancingReceivableRecordedInvestmentByTypeOfFinancingReceivableAxis = cbu_AcquiredLoansMember / us-gaap_InternalCreditAssessmentAxis = cbu_NonperformingFinancingReceivable1Member | 27 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = cbu_ConsumerInstallmentDirectMember / cbu_FinancingReceivableRecordedInvestmentByTypeOfFinancingReceivableAxis = cbu_AcquiredLoansMember / us-gaap_InternalCreditAssessmentAxis = cbu_NonperformingFinancingReceivable1Member
Home Equity [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Loans | 342,342 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = cbu_HomeEquityReceivablesMember | 346,520 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = cbu_HomeEquityReceivablesMember
Home Equity [Member] | Legacy Loan [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Loans | 283,073 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = cbu_HomeEquityReceivablesMember / cbu_FinancingReceivableRecordedInvestmentByTypeOfFinancingReceivableAxis = cbu_LegacyLoanMember | 275,910 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = cbu_HomeEquityReceivablesMember / cbu_FinancingReceivableRecordedInvestmentByTypeOfFinancingReceivableAxis = cbu_LegacyLoanMember
Home Equity [Member] | Acquired Loans [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Loans | 59,269 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = cbu_HomeEquityReceivablesMember / cbu_FinancingReceivableRecordedInvestmentByTypeOfFinancingReceivableAxis = cbu_AcquiredLoansMember | 70,610 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = cbu_HomeEquityReceivablesMember / cbu_FinancingReceivableRecordedInvestmentByTypeOfFinancingReceivableAxis = cbu_AcquiredLoansMember
Home Equity [Member] | Performing [Member] | Legacy Loan [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Loans | 280,706 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = cbu_HomeEquityReceivablesMember / cbu_FinancingReceivableRecordedInvestmentByTypeOfFinancingReceivableAxis = cbu_LegacyLoanMember / us-gaap_InternalCreditAssessmentAxis = cbu_PerformingFinancingReceivable1Member | 273,870 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = cbu_HomeEquityReceivablesMember / cbu_FinancingReceivableRecordedInvestmentByTypeOfFinancingReceivableAxis = cbu_LegacyLoanMember / us-gaap_InternalCreditAssessmentAxis = cbu_PerformingFinancingReceivable1Member
Home Equity [Member] | Performing [Member] | Acquired Loans [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Loans | 58,797 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = cbu_HomeEquityReceivablesMember / cbu_FinancingReceivableRecordedInvestmentByTypeOfFinancingReceivableAxis = cbu_AcquiredLoansMember / us-gaap_InternalCreditAssessmentAxis = cbu_PerformingFinancingReceivable1Member | 70,129 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = cbu_HomeEquityReceivablesMember / cbu_FinancingReceivableRecordedInvestmentByTypeOfFinancingReceivableAxis = cbu_AcquiredLoansMember / us-gaap_InternalCreditAssessmentAxis = cbu_PerformingFinancingReceivable1Member
Home Equity [Member] | Nonperforming [Member] | Legacy Loan [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Loans | 2,367 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = cbu_HomeEquityReceivablesMember / cbu_FinancingReceivableRecordedInvestmentByTypeOfFinancingReceivableAxis = cbu_LegacyLoanMember / us-gaap_InternalCreditAssessmentAxis = cbu_NonperformingFinancingReceivable1Member | 2,040 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = cbu_HomeEquityReceivablesMember / cbu_FinancingReceivableRecordedInvestmentByTypeOfFinancingReceivableAxis = cbu_LegacyLoanMember / us-gaap_InternalCreditAssessmentAxis = cbu_NonperformingFinancingReceivable1Member
Home Equity [Member] | Nonperforming [Member] | Acquired Loans [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Loans | $ 472 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = cbu_HomeEquityReceivablesMember / cbu_FinancingReceivableRecordedInvestmentByTypeOfFinancingReceivableAxis = cbu_AcquiredLoansMember / us-gaap_InternalCreditAssessmentAxis = cbu_NonperformingFinancingReceivable1Member | $ 481 us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = cbu_HomeEquityReceivablesMember / cbu_FinancingReceivableRecordedInvestmentByTypeOfFinancingReceivableAxis = cbu_AcquiredLoansMember / us-gaap_InternalCreditAssessmentAxis = cbu_NonperformingFinancingReceivable1Member

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