Ratio of allowance for credit losses to total loans.

No definition available.

Name:	cbu_AllowanceForCreditLossesToTotalLoansRatio
Namespace Prefix:	cbu_
Data Type:	xbrli:pureItemType
Balance Type:	na
Period Type:	instant

- Definition

Amount of increase in allowance for credit loss on financing receivable from acquisition.

+ References

No definition available.

+ Details

Name:	cbu_FinancingReceivableAllowanceForCreditLossAcquisition
Namespace Prefix:	cbu_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Increase (Decrease) in allowance for credit losses to total loans ratio over prior year end.

+ References

No definition available.

+ Details

Name:	cbu_IncreaseDecreaseInAllowanceForCreditLossesToTotalLoansRatioOverPriorYearEnd
Namespace Prefix:	cbu_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Increase (Decrease) in allowance for credit losses to total loans ratio over the same quarter in prior year.

+ References

No definition available.

+ Details

Name:	cbu_IncreaseDecreaseInAllowanceForCreditLossesToTotalLoansRatioOverTheSameQuarterInPriorYear
Namespace Prefix:	cbu_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of acquisition of off-balance sheet credit exposure which had previously been fully or partially written-off. Excludes off-balance sheet credit exposure accounted for as insurance and instrument accounted for under derivatives and hedging.

+ References

No definition available.

+ Details

Name:	cbu_OffBalanceSheetCreditLossLiabilityAcquisition
Namespace Prefix:	cbu_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Amount that has been written off for expected credit loss for off-balance sheet credit exposure. Excludes off-balance sheet credit exposure accounted for as insurance and instrument accounted for under derivatives and hedging.

+ References

No definition available.

+ Details

Name:	cbu_OffBalanceSheetCreditLossLiabilityChargeOffs
Namespace Prefix:	cbu_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Amount of recovery of off-balance sheet credit exposure which had previously been fully or partially written-off. Excludes off-balance sheet credit exposure accounted for as insurance and instrument accounted for under derivatives and hedging.

+ References

No definition available.

+ Details

Name:	cbu_OffBalanceSheetCreditLossLiabilityRecovery
Namespace Prefix:	cbu_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Percentage of peak unemployment due to decrease in economic activity.

+ References

No definition available.

+ Details

Name:	cbu_PercentageOfUnemployment
Namespace Prefix:	cbu_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of expense related loan transactions, lease transactions, credit loss from transactions other than loan and lease transactions, and other loss, excluding acquisition-related provision for credit losses based on assessment of uncollectability from the counterparty to reduce the account to their net realizable value.

+ References

No definition available.

+ Details

Name:	cbu_ProvisionForLoanLeaseAndOtherLossesExcludingAcquisitionRelatedProvisionForCreditLosses
Namespace Prefix:	cbu_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- References

No definition available.

+ Details

Name:	us-gaap_AllowanceForCreditLossAbstract
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of recovery of loans and lease receivables which had previously been fully or partially written-off as bad debts.

+ References

+ Details

Name:	us-gaap_AllowanceForLoanAndLeaseLossRecoveryOfBadDebts
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Amount of addition to allowance reserve for credit loss arising from purchase of loan and lease portfolios.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 15
-URI http://asc.fasb.org/extlink&oid=121611835&loc=d3e5212-111524

+ Details

Name:	us-gaap_AllowanceForLoanAndLeaseLossesLoansAcquired
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

+ References

No definition available.

+ Details

Name:	us-gaap_AllowanceForLoanAndLeaseLossesRollForward
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of loans and leases that have been written off from both loan receivables and allowance reserve for credit loss.

+ References

+ Details

Name:	us-gaap_AllowanceForLoanAndLeaseLossesWriteOffs
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Amount of allowance for credit loss on financing receivable. Excludes allowance for financing receivable covered under loss sharing agreement.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 11B
-Subparagraph (c)(1)
-URI http://asc.fasb.org/extlink&oid=121611835&loc=SL6953423-111524

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03(7)(2))
-URI http://asc.fasb.org/extlink&oid=120398452&loc=d3e534808-122878

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 20
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=121599878&loc=SL82895884-210446

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 20
-Section 50
-Paragraph 13
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=121599337&loc=SL82919249-210447

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 20
-Section 50
-Paragraph 13
-Subparagraph (f)
-URI http://asc.fasb.org/extlink&oid=121599337&loc=SL82919249-210447

+ Details

Name:	us-gaap_FinancingReceivableAllowanceForCreditLosses
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of increase in allowance for credit loss on financing receivable from recovery.

+ References

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 20
-Section 55
-Paragraph 79
-URI http://asc.fasb.org/extlink&oid=121647567&loc=SL82922352-210448

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 20
-Section 50
-Paragraph 13
-Subparagraph (e)
-URI http://asc.fasb.org/extlink&oid=121599337&loc=SL82919249-210447

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 11B
-Subparagraph (c)(4)
-URI http://asc.fasb.org/extlink&oid=121611835&loc=SL6953423-111524

+ Details

Name:	us-gaap_FinancingReceivableAllowanceForCreditLossesRecovery
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

+ References

No definition available.

+ Details

Name:	us-gaap_FinancingReceivableAllowanceForCreditLossesRollForward
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of writeoff of financing receivable, charged against allowance for credit loss.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 20
-Section 50
-Paragraph 13
-Subparagraph (d)
-URI http://asc.fasb.org/extlink&oid=121599337&loc=SL82919249-210447

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 11B
-Subparagraph (c)(3)
-URI http://asc.fasb.org/extlink&oid=121611835&loc=SL6953423-111524

Reference 3: http://www.xbrl.org/2003/role/exampleRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 20
-Section 55
-Paragraph 79
-URI http://asc.fasb.org/extlink&oid=121647567&loc=SL82922352-210448

+ Details

Name:	us-gaap_FinancingReceivableAllowanceForCreditLossesWriteOffs
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Amount of allowance to cover probable credit losses on loans and leases. Includes carryover of or adjustments to the allowance for loan losses in connection with business combinations. Excludes allowance for loans and leases covered under loss sharing agreements.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 11B
-Subparagraph (g)
-URI http://asc.fasb.org/extlink&oid=121611835&loc=SL6953423-111524

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 30
-Section 50
-Paragraph 2
-Subparagraph (b)(1)(ii)
-URI http://asc.fasb.org/extlink&oid=121614798&loc=d3e15032-111544

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 11B
-Subparagraph (c)(1)
-URI http://asc.fasb.org/extlink&oid=121611835&loc=SL6953423-111524

Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section S99
-Paragraph 4
-Subparagraph (SAB Topic 6.L.1)
-URI http://asc.fasb.org/extlink&oid=27010918&loc=d3e74567-122707

+ Details

Name:	us-gaap_LoansAndLeasesReceivableAllowance
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of expected credit loss for credit exposure on off-balance-sheet commitment, including but not limited to, loan commitment, standby letter of credit, financial guarantee not accounted for as insurance. Excludes off-balance sheet credit exposure accounted for as insurance and instrument accounted for under derivatives and hedging.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 460
-SubTopic 10
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=121611286&loc=d3e11927-110247

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 20
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=121599878&loc=SL82919202-210446

+ Details

Name:	us-gaap_OffBalanceSheetCreditLossLiability
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of expense (reversal of expense) for expected credit loss for off-balance sheet credit exposure. Excludes off-balance sheet credit exposure accounted for as insurance and instrument accounted for under derivatives and hedging.

+ References

+ Details

Name:	us-gaap_OffBalanceSheetCreditLossLiabilityCreditLossExpenseReversal
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- References

No definition available.

+ Details

Name:	us-gaap_OffBalanceSheetCreditLossLiabilityRollforward
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of expense related to estimated loss from loan and lease transactions.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=121586364&loc=d3e3602-108585

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 220
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-04.11)
-URI http://asc.fasb.org/extlink&oid=120399700&loc=SL114874048-224260

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 11B
-Subparagraph (c)(2)
-URI http://asc.fasb.org/extlink&oid=121611835&loc=SL6953423-111524

+ Details

Name:	us-gaap_ProvisionForLoanAndLeaseLosses
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Details

Name:	srt_StatementScenarioAxis=srt_ScenarioForecastMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_RangeAxis=srt_MinimumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_UnusualOrInfrequentItemAxis=us-gaap_NaturalDisastersAndOtherCasualtyEventsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_RangeAxis=srt_MaximumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_AdjustmentsForNewAccountingPronouncementsAxis=us-gaap_AccountingStandardsUpdate201613Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_CumulativeEffectPeriodOfAdoptionAxis=srt_CumulativeEffectPeriodOfAdoptionAdjustmentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_CreditLossStatusAxis=cbu_AcquiredImpairedLoansMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_CreditLossStatusAxis=us-gaap_FinancialAssetAcquiredWithCreditDeteriorationMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivablePortfolioSegmentAxis=us-gaap_CommercialPortfolioSegmentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=us-gaap_CommercialLoanMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivablePortfolioSegmentAxis=us-gaap_ResidentialPortfolioSegmentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=us-gaap_ResidentialMortgageMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivablePortfolioSegmentAxis=us-gaap_ConsumerPortfolioSegmentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=cbu_ConsumerInstallmentIndirectMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=cbu_ConsumerInstallmentDirectMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=cbu_HomeEquityReceivablesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivablePortfolioSegmentAxis=us-gaap_UnallocatedFinancingReceivablesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

LOANS, Allowance for Credit Losses (Details) $ in Thousands	3 Months Ended			6 Months Ended
LOANS, Allowance for Credit Losses (Details) $ in Thousands	Sep. 30, 2021	Jun. 30, 2020 USD ($)	Jun. 30, 2019 USD ($)	Jun. 30, 2020 USD ($)	Jun. 30, 2019 USD ($)
Allowance for credit losses - loans [Roll Forward]
Beginning balance		$ 55,652	$ 49,107	$ 49,911	$ 49,284
Charge-offs		(2,094)	(2,871)		(6,772)
Recoveries		1,184	1,674		2,976
Steuben acquisition		3,662
Provision		6,033	1,400		3,822
Ending balance		64,437	49,310	64,437	49,310
Liabilities for off-balance-sheet credit exposures [Roll Forward]
Beginning balance		845		0
Charge-offs		0
Recoveries		0
Steuben acquisition		67
Provision		540
Ending balance		1,452		1,452
Total allowance for credit losses [Roll Forward]
Beginning balance		56,497		49,911
Charge-offs		(2,094)
Recoveries		1,184
Steuben acquisition		3,729
Provision		6,573
Ending balance		$ 65,889		$ 65,889
Allowance for Credit Losses [Abstract]
Allowance for credit losses to total loans ratio		0.0086		0.0086
Increase in allowance for credit losses to total loans ratio over the same quarter in prior year				800.00%
Increase in allowance for credit losses to total loans ratio over the prior year end				0.14%
Forecast [Member] \| Minimum [Member] \| COVID-19 [Member]
Allowance for Credit Losses [Abstract]
Percentage of peak unemployment	9.00%
Forecast [Member] \| Maximum [Member] \| COVID-19 [Member]
Allowance for Credit Losses [Abstract]
Percentage of peak unemployment	12.00%
Topic ASC 326 [Member]
Allowance for credit losses - loans [Roll Forward]
Beginning balance				$ 51,268
Charge-offs				(5,141)
Recoveries				2,681
Steuben acquisition				3,662
Provision				11,967
Ending balance		$ 64,437		64,437
Liabilities for off-balance-sheet credit exposures [Roll Forward]
Beginning balance				1,185
Charge-offs				0
Recoveries				0
Steuben acquisition				67
Provision				200
Ending balance		1,452		1,452
Total allowance for credit losses [Roll Forward]
Beginning balance				52,453
Charge-offs				(5,141)
Recoveries				2,681
Steuben acquisition				3,729
Provision				12,167
Ending balance		65,889		65,889
Topic ASC 326 [Member] \| Cumulative Effect, Period of Adoption, Adjustment [Member]
Allowance for credit losses - loans [Roll Forward]
Beginning balance				1,357
Liabilities for off-balance-sheet credit exposures [Roll Forward]
Beginning balance				1,185
Total allowance for credit losses [Roll Forward]
Beginning balance				2,542
Purchased Credit Impaired [Member]
Allowance for credit losses - loans [Roll Forward]
Beginning balance			155	163	33
Charge-offs			0		0
Recoveries			0		0
Provision			0		122
Ending balance			155		155
Purchased Credit Impaired [Member] \| Topic ASC 326 [Member]
Allowance for credit losses - loans [Roll Forward]
Beginning balance				0
Charge-offs				0
Recoveries				0
Steuben acquisition				0
Provision				0
Ending balance		0		0
Purchased Credit Impaired [Member] \| Topic ASC 326 [Member] \| Cumulative Effect, Period of Adoption, Adjustment [Member]
Allowance for credit losses - loans [Roll Forward]
Beginning balance				(163)
Purchased Credit Deteriorated [Member]
Allowance for credit losses - loans [Roll Forward]
Beginning balance		3,046		0
Charge-offs		0
Recoveries		48
Steuben acquisition		528
Provision		(61)
Ending balance		3,561		3,561
Purchased Credit Deteriorated [Member] \| Topic ASC 326 [Member]
Allowance for credit losses - loans [Roll Forward]
Beginning balance				3,072
Charge-offs				0
Recoveries				48
Steuben acquisition				528
Provision				(87)
Ending balance		3,561		3,561
Purchased Credit Deteriorated [Member] \| Topic ASC 326 [Member] \| Cumulative Effect, Period of Adoption, Adjustment [Member]
Allowance for credit losses - loans [Roll Forward]
Beginning balance				3,072
Commercial Portfolio Segment [Member] \| Business Lending [Member]
Allowance for credit losses - loans [Roll Forward]
Beginning balance		19,489	18,271	19,426	18,522
Charge-offs		(7)	(253)		(1,469)
Recoveries		84	169		303
Steuben acquisition		2,483
Provision		2,155	(418)		413
Ending balance		24,204	17,769	24,204	17,769
Commercial Portfolio Segment [Member] \| Business Lending [Member] \| Topic ASC 326 [Member]
Allowance for credit losses - loans [Roll Forward]
Beginning balance				19,714
Charge-offs				(183)
Recoveries				222
Steuben acquisition				2,483
Provision				1,968
Ending balance		24,204		24,204
Commercial Portfolio Segment [Member] \| Business Lending [Member] \| Topic ASC 326 [Member] \| Cumulative Effect, Period of Adoption, Adjustment [Member]
Allowance for credit losses - loans [Roll Forward]
Beginning balance				288
Residential Portfolio Segment [Member] \| Consumer Mortgage [Member]
Allowance for credit losses - loans [Roll Forward]
Beginning balance		12,430	10,317	10,269	10,124
Charge-offs		(234)	(587)		(840)
Recoveries		36	14		36
Steuben acquisition		146
Provision		710	1,019		1,443
Ending balance		13,088	10,763	13,088	10,763
Residential Portfolio Segment [Member] \| Consumer Mortgage [Member] \| Topic ASC 326 [Member]
Allowance for credit losses - loans [Roll Forward]
Beginning balance				9,218
Charge-offs				(420)
Recoveries				44
Steuben acquisition				146
Provision				4,100
Ending balance		13,088		13,088
Residential Portfolio Segment [Member] \| Consumer Mortgage [Member] \| Topic ASC 326 [Member] \| Cumulative Effect, Period of Adoption, Adjustment [Member]
Allowance for credit losses - loans [Roll Forward]
Beginning balance				(1,051)
Consumer Portfolio Segment [Member] \| Consumer Indirect [Member]
Allowance for credit losses - loans [Roll Forward]
Beginning balance		13,694	14,251	13,712	14,366
Charge-offs		(1,431)	(1,482)		(3,305)
Recoveries		833	1,239		2,201
Steuben acquisition		183
Provision		2,587	337		1,083
Ending balance		15,866	14,345	15,866	14,345
Consumer Portfolio Segment [Member] \| Consumer Indirect [Member] \| Topic ASC 326 [Member]
Allowance for credit losses - loans [Roll Forward]
Beginning balance				12,715
Charge-offs				(3,510)
Recoveries				1,996
Steuben acquisition				183
Provision				4,482
Ending balance		15,866		15,866
Consumer Portfolio Segment [Member] \| Consumer Indirect [Member] \| Topic ASC 326 [Member] \| Cumulative Effect, Period of Adoption, Adjustment [Member]
Allowance for credit losses - loans [Roll Forward]
Beginning balance				(997)
Consumer Portfolio Segment [Member] \| Consumer Direct [Member]
Allowance for credit losses - loans [Roll Forward]
Beginning balance		3,737	3,056	3,255	3,095
Charge-offs		(341)	(445)		(980)
Recoveries		171	221		400
Steuben acquisition		87
Provision		374	352		669
Ending balance		4,028	3,184	4,028	3,184
Consumer Portfolio Segment [Member] \| Consumer Direct [Member] \| Topic ASC 326 [Member]
Allowance for credit losses - loans [Roll Forward]
Beginning balance				2,612
Charge-offs				(874)
Recoveries				353
Steuben acquisition				87
Provision				1,850
Ending balance		4,028		4,028
Consumer Portfolio Segment [Member] \| Consumer Direct [Member] \| Topic ASC 326 [Member] \| Cumulative Effect, Period of Adoption, Adjustment [Member]
Allowance for credit losses - loans [Roll Forward]
Beginning balance				(643)
Consumer Portfolio Segment [Member] \| Home Equity [Member]
Allowance for credit losses - loans [Roll Forward]
Beginning balance		2,484	2,067	2,129	2,144
Charge-offs		(81)	(104)		(178)
Recoveries		12	31		36
Steuben acquisition		235
Provision		40	109		101
Ending balance		2,690	2,103	2,690	2,103
Consumer Portfolio Segment [Member] \| Home Equity [Member] \| Topic ASC 326 [Member]
Allowance for credit losses - loans [Roll Forward]
Beginning balance				2,937
Charge-offs				(154)
Recoveries				18
Steuben acquisition				235
Provision				(346)
Ending balance		2,690		2,690
Consumer Portfolio Segment [Member] \| Home Equity [Member] \| Topic ASC 326 [Member] \| Cumulative Effect, Period of Adoption, Adjustment [Member]
Allowance for credit losses - loans [Roll Forward]
Beginning balance				808
Unallocated Financing Receivables [Member]
Allowance for credit losses - loans [Roll Forward]
Beginning balance		772	990	957	1,000
Charge-offs		0	0		0
Recoveries		0	0		0
Steuben acquisition		0
Provision		228	1		(9)
Ending balance		1,000	$ 991	1,000	$ 991
Unallocated Financing Receivables [Member] \| Topic ASC 326 [Member]
Allowance for credit losses - loans [Roll Forward]
Beginning balance				1,000
Charge-offs				0
Recoveries				0
Steuben acquisition				0
Provision				0
Ending balance		$ 1,000		1,000
Unallocated Financing Receivables [Member] \| Topic ASC 326 [Member] \| Cumulative Effect, Period of Adoption, Adjustment [Member]
Allowance for credit losses - loans [Roll Forward]
Beginning balance				$ 43