FAIR VALUE MEASUREMENTS AND FAIR VALUES OF FINANCIAL INSTRUMENTS - Assets Measured at Fair Value (Details) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
Assets Measured at Fair Value
Total, fair value	$ 532,913	$ 517,679
Impaired loans with a valuation allowance	6,528	6,540
Valuation allowance	(730)	(740)
Impaired loans, net	6,528	6,540
Interest rate swap agreements
Assets Measured at Fair Value
Fair value derivative asset	137	3,104
Fair value of the derivative liability	137	3,104
Obligations of the U.S. Treasury
Assets Measured at Fair Value
Total, fair value	36,494	24,912
Obligations of U.S. Government agencies
Assets Measured at Fair Value
Total, fair value	23,408	24,091
Bank holding company debt securities
Assets Measured at Fair Value
Total, fair value	24,043	17,987
Obligations Of States And Political Subdivisions Tax Exempt
Assets Measured at Fair Value
Total, fair value	143,633	148,028
Obligations Of States And Political Subdivisions Taxable
Assets Measured at Fair Value
Total, fair value	69,629	72,765
Residential Passthrough Securities
Assets Measured at Fair Value
Total, fair value	106,568	98,181
Residential Collateralized Mortgage Obligations
Assets Measured at Fair Value
Total, fair value	43,868	44,247
Commercial Mortgage Backed Securities
Assets Measured at Fair Value
Total, fair value	85,270	87,468
Recurring fair value measurements
Assets Measured at Fair Value
Total, fair value	532,913	517,679
Marketable equity security	926	971
Servicing rights	2,429	2,329
Total asset fair value measurements	536,405	524,083
Recurring fair value measurements \| Level 1
Assets Measured at Fair Value
Total, fair value	36,494	24,912
Marketable equity security	926	971
Servicing rights	0	0
Total asset fair value measurements	37,420	25,883
Recurring fair value measurements \| Level 2
Assets Measured at Fair Value
Total, fair value	496,419	492,767
Marketable equity security	0	0
Servicing rights	0	0
Total asset fair value measurements	496,556	495,871
Recurring fair value measurements \| Level 3
Assets Measured at Fair Value
Total, fair value	0	0
Marketable equity security	0	0
Servicing rights	2,429	2,329
Total asset fair value measurements	2,429	2,329
Recurring fair value measurements \| Interest rate swap agreements
Assets Measured at Fair Value
Fair value derivative asset	137	3,104
Fair value of the derivative liability	137	3,104
Recurring fair value measurements \| Interest rate swap agreements \| Level 1
Assets Measured at Fair Value
Fair value derivative asset	0	0
Fair value of the derivative liability	0	0
Recurring fair value measurements \| Interest rate swap agreements \| Level 2
Assets Measured at Fair Value
Fair value derivative asset	137	3,104
Fair value of the derivative liability	137	3,104
Recurring fair value measurements \| Interest rate swap agreements \| Level 3
Assets Measured at Fair Value
Fair value derivative asset	0	0
Fair value of the derivative liability	0	0
Recurring fair value measurements \| Obligations of the U.S. Treasury
Assets Measured at Fair Value
Total, fair value	36,494	24,912
Recurring fair value measurements \| Obligations of the U.S. Treasury \| Level 1
Assets Measured at Fair Value
Total, fair value	36,494	24,912
Recurring fair value measurements \| Obligations of the U.S. Treasury \| Level 2
Assets Measured at Fair Value
Total, fair value	0	0
Recurring fair value measurements \| Obligations of the U.S. Treasury \| Level 3
Assets Measured at Fair Value
Total, fair value	0	0
Recurring fair value measurements \| Obligations of U.S. Government agencies
Assets Measured at Fair Value
Total, fair value	23,408	24,091
Recurring fair value measurements \| Obligations of U.S. Government agencies \| Level 1
Assets Measured at Fair Value
Total, fair value	0	0
Recurring fair value measurements \| Obligations of U.S. Government agencies \| Level 2
Assets Measured at Fair Value
Total, fair value	23,408	24,091
Recurring fair value measurements \| Obligations of U.S. Government agencies \| Level 3
Assets Measured at Fair Value
Total, fair value	0	0
Recurring fair value measurements \| Bank holding company debt securities
Assets Measured at Fair Value
Total, fair value	24,043	17,987
Recurring fair value measurements \| Bank holding company debt securities \| Level 1
Assets Measured at Fair Value
Total, fair value	0	0
Recurring fair value measurements \| Bank holding company debt securities \| Level 2
Assets Measured at Fair Value
Total, fair value	24,043	17,987
Recurring fair value measurements \| Bank holding company debt securities \| Level 3
Assets Measured at Fair Value
Total, fair value	0	0
Recurring fair value measurements \| Obligations Of States And Political Subdivisions Tax Exempt
Assets Measured at Fair Value
Total, fair value	143,633	148,028
Recurring fair value measurements \| Obligations Of States And Political Subdivisions Tax Exempt \| Level 1
Assets Measured at Fair Value
Total, fair value	0	0
Recurring fair value measurements \| Obligations Of States And Political Subdivisions Tax Exempt \| Level 2
Assets Measured at Fair Value
Total, fair value	143,633	148,028
Recurring fair value measurements \| Obligations Of States And Political Subdivisions Tax Exempt \| Level 3
Assets Measured at Fair Value
Total, fair value	0	0
Recurring fair value measurements \| Obligations Of States And Political Subdivisions Taxable
Assets Measured at Fair Value
Total, fair value	69,629	72,765
Recurring fair value measurements \| Obligations Of States And Political Subdivisions Taxable \| Level 1
Assets Measured at Fair Value
Total, fair value	0	0
Recurring fair value measurements \| Obligations Of States And Political Subdivisions Taxable \| Level 2
Assets Measured at Fair Value
Total, fair value	69,629	72,765
Recurring fair value measurements \| Obligations Of States And Political Subdivisions Taxable \| Level 3
Assets Measured at Fair Value
Total, fair value	0	0
Recurring fair value measurements \| Residential Passthrough Securities
Assets Measured at Fair Value
Total, fair value	106,568	98,181
Recurring fair value measurements \| Residential Passthrough Securities \| Level 1
Assets Measured at Fair Value
Total, fair value	0	0
Recurring fair value measurements \| Residential Passthrough Securities \| Level 2
Assets Measured at Fair Value
Total, fair value	106,568	98,181
Recurring fair value measurements \| Residential Passthrough Securities \| Level 3
Assets Measured at Fair Value
Total, fair value	0	0
Recurring fair value measurements \| Residential Collateralized Mortgage Obligations
Assets Measured at Fair Value
Total, fair value	43,868	44,247
Recurring fair value measurements \| Residential Collateralized Mortgage Obligations \| Level 1
Assets Measured at Fair Value
Total, fair value	0	0
Recurring fair value measurements \| Residential Collateralized Mortgage Obligations \| Level 2
Assets Measured at Fair Value
Total, fair value	43,868	44,247
Recurring fair value measurements \| Residential Collateralized Mortgage Obligations \| Level 3
Assets Measured at Fair Value
Total, fair value	0	0
Recurring fair value measurements \| Commercial Mortgage Backed Securities
Assets Measured at Fair Value
Total, fair value	85,270	87,468
Recurring fair value measurements \| Commercial Mortgage Backed Securities \| Level 1
Assets Measured at Fair Value
Total, fair value	0	0
Recurring fair value measurements \| Commercial Mortgage Backed Securities \| Level 2
Assets Measured at Fair Value
Total, fair value	85,270	87,468
Recurring fair value measurements \| Commercial Mortgage Backed Securities \| Level 3
Assets Measured at Fair Value
Total, fair value	0	0
Nonrecurring fair value measurements
Assets Measured at Fair Value
Total asset fair value measurements	6,329	6,484
Impaired loans, net	5,798	5,800
Foreclosed assets held for sale	531	684
Nonrecurring fair value measurements \| Level 1
Assets Measured at Fair Value
Total asset fair value measurements	0	0
Impaired loans, net	0	0
Foreclosed assets held for sale	0	0
Nonrecurring fair value measurements \| Level 2
Assets Measured at Fair Value
Total asset fair value measurements	0	0
Impaired loans, net	0	0
Foreclosed assets held for sale	0	0
Nonrecurring fair value measurements \| Level 3
Assets Measured at Fair Value
Total asset fair value measurements	6,329	6,484
Impaired loans, net	5,798	5,800
Foreclosed assets held for sale	$ 531	$ 684

Fair value portion of probable future economic benefits obtained or controlled by an entity as a result of past transactions or events.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=123874694&loc=d3e19207-110258

+ Details

Name:	us-gaap_AssetsFairValueDisclosure
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03(6))
-URI http://asc.fasb.org/extlink&oid=120398452&loc=d3e534808-122878

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 30
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=124258926&loc=SL82898722-210454

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 45
-Paragraph 1
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=124260329&loc=d3e26610-111562

Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (aa)
-URI http://asc.fasb.org/extlink&oid=123581744&loc=d3e27161-111563

+ Details

Name:	us-gaap_AvailableForSaleSecuritiesDebtSecurities
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Fair value of liability associated with financial asset or other contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4B
-Subparagraph (a),(c)
-URI http://asc.fasb.org/extlink&oid=125515794&loc=SL5624163-113959

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 20
-Section 55
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=99393222&loc=SL20226003-175313

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 20
-Section 50
-Paragraph 3
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=51824906&loc=SL20225862-175312

+ Details

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

- Definition

Fair value, before effects of master netting arrangements, of a financial asset or other contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes assets elected not to be offset. Excludes assets not subject to a master netting arrangement.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 20
-Section 50
-Paragraph 3
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=51824906&loc=SL20225862-175312

Reference 2: http://www.xbrl.org/2003/role/exampleRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 20
-Section 55
-Paragraph 22
-URI http://asc.fasb.org/extlink&oid=99393222&loc=SL20226052-175313

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 20
-Section 55
-Paragraph 7
-URI http://asc.fasb.org/extlink&oid=99393222&loc=SL20226000-175313

Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 860
-SubTopic 20
-Section 50
-Paragraph 4D
-Subparagraph (c)(2)
-URI http://asc.fasb.org/extlink&oid=121570589&loc=SL51823488-111719

Reference 5: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4B
-Subparagraph (a),(c)
-URI http://asc.fasb.org/extlink&oid=125515794&loc=SL5624163-113959

+ Details

Name:	us-gaap_DerivativeFairValueOfDerivativeAsset
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount of investment in equity security measured at fair value with change in fair value recognized in net income (FV-NI).

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 45
-Paragraph 1A
-URI http://asc.fasb.org/extlink&oid=123594786&loc=SL75136599-209740

+ Details

Name:	us-gaap_EquitySecuritiesFvNiCurrentAndNoncurrent
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

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

- Definition

Amount of allowance for credit losses related to recorded investment.

+ 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
-Subparagraph (a)(3)
-URI http://asc.fasb.org/extlink&oid=123577603&loc=d3e5212-111524

+ Details

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

- Definition

Amount of investment in impaired financing receivables for which there is a related allowance for credit losses.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 14A
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=123577603&loc=SL6953550-111524

+ Details

Name:	us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceRecordedInvestment
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Unpaid principal balance of impaired financing receivables for which there is a related allowance for credit losses.

+ 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
-Subparagraph (a)(4)
-URI http://asc.fasb.org/extlink&oid=123577603&loc=d3e5212-111524

+ Details

Name:	us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceUnpaidPrincipalBalance
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Carrying amount as of the balance sheet date of land and buildings obtained through foreclosure proceedings or defeasance in full or partial satisfaction of a debt arrangement.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 11
-URI http://asc.fasb.org/extlink&oid=123577603&loc=d3e5162-111524

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 45
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=124259787&loc=d3e4437-111522

+ Details

Name:	us-gaap_RealEstateAcquiredThroughForeclosure
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Fair value of an asset representing net future revenue from contractually specified servicing fees, late charges, and other ancillary revenues, in excess of future costs related to servicing arrangements.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 860
-SubTopic 50
-Section 45
-Paragraph 2
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=6469459&loc=d3e122501-111745

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 860
-SubTopic 50
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6469459&loc=d3e122492-111745

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 860
-SubTopic 50
-Section 50
-Paragraph 3
-Subparagraph (a)(1)
-URI http://asc.fasb.org/extlink&oid=125521744&loc=d3e122625-111746

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 860
-SubTopic 50
-Section 45
-Paragraph 2
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=6469459&loc=d3e122501-111745

+ Details

Name:	us-gaap_ServicingAssetAtFairValueAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Details

Name:	us-gaap_DerivativeInstrumentRiskAxis=us-gaap_InterestRateSwapMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancialInstrumentAxis=cznc_U.s.TreasuryDebtSecuritiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancialInstrumentAxis=us-gaap_USGovernmentAgenciesDebtSecuritiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancialInstrumentAxis=cznc_BankHoldingCompanyDebtSecuritiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancialInstrumentAxis=cznc_ObligationsOfStatesAndPoliticalSubdivisionsTaxExemptMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancialInstrumentAxis=cznc_ObligationsOfStatesAndPoliticalSubdivisionsTaxableMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancialInstrumentAxis=cznc_ResidentialPassthroughSecuritiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancialInstrumentAxis=cznc_ResidentialCollateralizedMortgageObligationsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancialInstrumentAxis=us-gaap_CommercialMortgageBackedSecuritiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FairValueByMeasurementFrequencyAxis=us-gaap_FairValueMeasurementsRecurringMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FairValueByFairValueHierarchyLevelAxis=us-gaap_FairValueInputsLevel1Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FairValueByFairValueHierarchyLevelAxis=us-gaap_FairValueInputsLevel2Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FairValueByFairValueHierarchyLevelAxis=us-gaap_FairValueInputsLevel3Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FairValueByMeasurementFrequencyAxis=us-gaap_FairValueMeasurementsNonrecurringMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: