Fair Value (Assets And Liabilities Measured At Fair Value On A Recurring Basis) (Details) - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2019	Dec. 31, 2018
Other Equity Securities [Member]
Fair Value, Assets And Liabilities Measured On Recurring Basis [Line Items]
Investment securities	$ 1,769	$ 1,649
Other Equity Securities [Member] \| Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets And Liabilities Measured On Recurring Basis [Line Items]
Investment securities	1,336	1,225
Other Equity Securities [Member] \| Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets And Liabilities Measured On Recurring Basis [Line Items]
Investment securities	433	424
Other Equity Securities [Member] \| Fair Value, Measurements, Recurring [Member]
Fair Value, Assets And Liabilities Measured On Recurring Basis [Line Items]
Investments, Fair Value Disclosure	1,769	1,649
Other Equity Securities [Member] \| Fair Value, Measurements, Recurring [Member] \| Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets And Liabilities Measured On Recurring Basis [Line Items]
Investments, Fair Value Disclosure	1,336	1,225
Other Equity Securities [Member] \| Fair Value, Measurements, Recurring [Member] \| Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets And Liabilities Measured On Recurring Basis [Line Items]
Investments, Fair Value Disclosure	433	424
Swap [Member]
Fair Value, Assets And Liabilities Measured On Recurring Basis [Line Items]
Swap	226	226
Swap [Member] \| Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets And Liabilities Measured On Recurring Basis [Line Items]
Unrealized Gain (Loss) on Cash Flow Hedging Instruments	261
Swap [Member] \| Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets And Liabilities Measured On Recurring Basis [Line Items]
Swap	226	226
Swap [Member] \| Fair Value, Measurements, Recurring [Member]
Fair Value, Assets And Liabilities Measured On Recurring Basis [Line Items]
Swap	226	226
Swap [Member] \| Fair Value, Measurements, Recurring [Member] \| Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets And Liabilities Measured On Recurring Basis [Line Items]
Swap	226	226
Cash and Cash Equivalents, Fair Value Disclosure	187,479	167,214
Mortgage loans held for sale	4,300	4,200
Investment securities	1,357,610	1,354,843
Loans Held-for-sale, Fair Value Disclosure	4,276	4,158
Impaired Loan Fair Value	5,462	6,399
Other Assets, Fair Value Disclosure	5,622,367	5,570,136
Loans Receivable, Fair Value Disclosure	5,632,280	5,580,780
Time deposits	985,542	1,044,620
Other Liabilities, Fair Value Disclosure	2,633	1,267
Deposits, Fair Value Disclosure	988,175	1,045,887
Short Term Borrowings Fair Value	212,569	221,966
Long-term debt	377,428	400,203
Subordinated Debt Obligations, Fair Value Disclosure	12,791	12,959
Unrealized Gain (Loss) on Cash Flow Hedging Instruments	261
Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets And Liabilities Measured On Recurring Basis [Line Items]
Cash and Cash Equivalents, Fair Value Disclosure	187,479	167,214
Mortgage IRLCs	0	0
Other Liabilities, Fair Value Disclosure	2,633	1,267
Deposits, Fair Value Disclosure	2,633	1,267
Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets And Liabilities Measured On Recurring Basis [Line Items]
Mortgage IRLCs	175	87
Investment securities	1,357,610	1,354,843
Loans Held-for-sale, Fair Value Disclosure	4,276	4,158
Loans Receivable, Fair Value Disclosure	4,451	4,245
Time deposits	985,542	1,044,620
Deposits, Fair Value Disclosure	985,542	1,044,620
Short Term Borrowings Fair Value	212,569	221,966
Long-term debt	377,428	400,203
Subordinated Debt Obligations, Fair Value Disclosure	12,791	12,959
Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets And Liabilities Measured On Recurring Basis [Line Items]
Mortgage IRLCs	0	0
Impaired Loan Fair Value	5,462	6,399
Other Assets, Fair Value Disclosure	5,622,367	5,570,136
Loans Receivable, Fair Value Disclosure	5,627,829	5,576,535
Fair Value, Measurements, Recurring [Member]
Fair Value, Assets And Liabilities Measured On Recurring Basis [Line Items]
Mortgage loans held for sale	4,276	4,158
Mortgage IRLCs	175	87
Fair Value, Measurements, Recurring [Member] \| Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets And Liabilities Measured On Recurring Basis [Line Items]
Mortgage loans held for sale	4,276	4,158
Mortgage IRLCs	175	87
Reported Value Measurement [Member] \| Other Equity Securities [Member]
Fair Value, Assets And Liabilities Measured On Recurring Basis [Line Items]
Investment securities	1,769	1,649
Reported Value Measurement [Member] \| Swap [Member]
Fair Value, Assets And Liabilities Measured On Recurring Basis [Line Items]
Swap	226	226
Reported Value Measurement [Member]
Fair Value, Assets And Liabilities Measured On Recurring Basis [Line Items]
Cash and Cash Equivalents, Fair Value Disclosure	187,479	167,214
Mortgage IRLCs	175	87
Investment securities	1,349,149	1,355,229
Loans Held-for-sale, Fair Value Disclosure	4,276	4,158
Impaired Loan Fair Value	5,462	6,399
Other Assets, Fair Value Disclosure	5,677,479	5,629,976
Loans Receivable, Fair Value Disclosure	5,687,392	5,640,620
Time deposits	982,983	1,043,177
Other Liabilities, Fair Value Disclosure	2,633	1,267
Deposits, Fair Value Disclosure	985,616	1,044,444
Short Term Borrowings Fair Value	212,569	221,966
Long-term debt	375,000	400,000
Subordinated Debt Obligations, Fair Value Disclosure	$ 15,000	$ 15,000

Fair Value, Assets And Liabilities Measured On Recurring Basis [Line Items]

No definition available.

Name:	prk_FairValueAssetsAndLiabilitiesMeasuredOnRecurringBasisLineItems
Namespace Prefix:	prk_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Impaired Loan Fair Value

+ References

No definition available.

+ Details

Name:	prk_ImpairedLoanFairValue
Namespace Prefix:	prk_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Short Term Borrowings Fair Value

+ References

No definition available.

+ Details

Name:	prk_ShortTermBorrowingsFairValue
Namespace Prefix:	prk_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Time Deposits Fair Value

+ References

No definition available.

+ Details

Name:	prk_TimeDepositsFairValue
Namespace Prefix:	prk_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Fair value portion of currency on hand as well as demand deposits with banks or financial institutions. Includes other kinds of accounts that have the general characteristics of demand deposits. Also includes short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates.

+ References

No definition available.

+ Details

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

- Definition

Fair value portion of deposit liabilities held by the entity, including, but not limited to, foreign and domestic, interest and noninterest bearing, demand deposits, saving deposits, negotiable orders of withdrawal (NOW) and time deposits.

+ References

No definition available.

+ Details

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

- Definition

Fair value, after the 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 not subject to a master netting arrangement and not elected to be offset.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 20
-Section 55
-Paragraph 10
-URI http://asc.fasb.org/extlink&oid=99393222&loc=SL20226008-175313

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 50
-Paragraph 10
-URI http://asc.fasb.org/extlink&oid=109250915&loc=d3e13433-108611

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 (c)
-URI http://asc.fasb.org/extlink&oid=51824906&loc=SL20225862-175312

+ Details

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

- Definition

Fair value, after the effects of master netting arrangements, of a financial liability or 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 liabilities not subject to a master netting arrangement and not elected to be offset.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 20
-Section 50
-Paragraph 3
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=51824906&loc=SL20225862-175312

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 50
-Paragraph 10
-URI http://asc.fasb.org/extlink&oid=109250915&loc=d3e13433-108611

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 20
-Section 55
-Paragraph 10
-URI http://asc.fasb.org/extlink&oid=99393222&loc=SL20226008-175313

+ Details

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

- Definition

Fair value of subordinated debt obligations including, but not limited to, subordinated loan, subordinated bond, subordinated debenture or junior debt.

+ References

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 (b)
-URI http://asc.fasb.org/extlink&oid=99377789&loc=d3e19207-110258

Reference 2: 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=99377789&loc=d3e19207-110258

+ Details

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

- Definition

Value of the investment at close of period. For schedules of investments that are categorized, the value would be aggregated by category. For investment in and advances to affiliates, if operations of any controlled companies are different in character from those of the company, group such affiliates within divisions and by type of activities.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 946
-SubTopic 210
-Section 50
-Paragraph 6
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=99383244&loc=d3e12121-115841

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 946
-SubTopic 320
-Section S99
-Paragraph 4
-Subparagraph (SX 210.12-12C.Column C.7)
-URI http://asc.fasb.org/extlink&oid=50485924&loc=d3e611225-123010

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 946
-SubTopic 320
-Section S99
-Paragraph 6
-Subparagraph (SX 210.12-14.Column E.2,3)
-URI http://asc.fasb.org/extlink&oid=50485924&loc=d3e611322-123010

Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 946
-SubTopic 320
-Section S99
-Paragraph 1
-Subparagraph (SX 210.12-12.Column C.3,4)
-URI http://asc.fasb.org/extlink&oid=50485924&loc=d3e611133-123010

Reference 5: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 946
-SubTopic 320
-Section S99
-Paragraph 5
-Subparagraph (SX 210.12-13.Column C.6)
-URI http://asc.fasb.org/extlink&oid=50485924&loc=d3e611282-123010

+ Details

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

- Definition

Fair value portion of investment securities, including, but not limited to, marketable securities, derivative financial instruments, and investments accounted for under the equity method.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=99377789&loc=d3e19207-110258

+ Details

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

- Definition

Fair value portion of loans held-for-sale including, but not limited to, mortgage loans and finance receivables.

+ References

No definition available.

+ Details

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

- Definition

Fair value portion of loan receivable, including, but not limited to, mortgage loans held for investment, finance receivables held for investment, policy loans on insurance contracts.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-URI http://asc.fasb.org/subtopic&trid=2196772

+ Details

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

- Definition

The fair value amount of long-term debt whether such amount is presented as a separate caption or as a parenthetical disclosure. Additionally, this element may be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements. The element may be used in both the balance sheet and disclosure in the same submission.

+ References

No definition available.

+ Details

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

- Definition

Fair value portion of mortgage loans held-for-sale.

+ References

No definition available.

+ Details

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

- Definition

Fair value portion of other assets.

+ References

No definition available.

+ Details

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

- Definition

Fair value portion of other liabilities.

+ References

No definition available.

+ Details

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

- Definition

Amount of unrealized gain (loss) related to derivatives designated as cash flow hedging instruments, recorded in results of operations to the extent that the cash flow hedge is determined to be ineffective.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4C
-Subparagraph (d)(1)
-URI http://asc.fasb.org/extlink&oid=109980867&loc=SL5624171-113959

+ Details

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

- Details

Name:	us-gaap_FinancialInstrumentAxis=us-gaap_EquitySecuritiesMember
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_FairValueInputsLevel3Member
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_FinancialInstrumentAxis=us-gaap_SwapMember
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_FairValueByMeasurementBasisAxis=us-gaap_CarryingReportedAmountFairValueDisclosureMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: