Segment Information - Schedule of Operating Results by Segment (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Segment Reporting Information [Line Items]
Other Noninterest Expense	$ 187,991us-gaap_OtherNoninterestExpense	$ 181,214us-gaap_OtherNoninterestExpense	$ 181,014us-gaap_OtherNoninterestExpense
Net interest income (loss)	225,044us-gaap_InterestIncomeExpenseNet	221,025us-gaap_InterestIncomeExpenseNet	235,315us-gaap_InterestIncomeExpenseNet
Depreciation, Amortization and Accretion, Net	7,243	7,315	6,954
(Recovery of) provision for loan losses	(7,333)us-gaap_ProvisionForLoanAndLeaseLosses	3,415us-gaap_ProvisionForLoanAndLeaseLosses	35,419us-gaap_ProvisionForLoanAndLeaseLosses
Other income	75,549prk_OtherIncomeLossAndSecurityGains	73,277prk_OtherIncomeLossAndSecurityGains	92,403prk_OtherIncomeLossAndSecurityGains
Gain (Loss) on Sale of Investments	(1,158)us-gaap_GainLossOnSaleOfInvestments	0us-gaap_GainLossOnSaleOfInvestments	0us-gaap_GainLossOnSaleOfInvestments
Other expense	195,234us-gaap_NoninterestExpense	188,529us-gaap_NoninterestExpense	187,968us-gaap_NoninterestExpense
Income (loss) before taxes	112,692	102,358	104,331
Income taxes (benefit)	28,602us-gaap_IncomeTaxExpenseBenefit	25,131us-gaap_IncomeTaxExpenseBenefit	25,701us-gaap_IncomeTaxExpenseBenefit
Net income	84,090us-gaap_NetIncomeLoss	77,227us-gaap_NetIncomeLoss	78,630us-gaap_NetIncomeLoss
Assets	7,003,256us-gaap_Assets	6,638,347us-gaap_Assets	6,642,803us-gaap_Assets
Loans	4,829,682	4,620,505	4,450,322
Deposits	5,128,000us-gaap_Deposits	4,789,994us-gaap_Deposits	4,716,032us-gaap_Deposits
Totals For Reportable Segments [Member]
Segment Reporting Information [Line Items]
Other Noninterest Expense	179,991	173,694	174,429
Net interest income (loss)	227,056	218,197	230,573
Depreciation, Amortization and Accretion, Net	7,243	7,315	6,954
Income taxes (benefit)	33,389	27,957	27,506
Assets	6,996,513	6,643,994	6,656,933
Deposits	5,228,649	4,903,564	4,822,465
PNB
Segment Reporting Information [Line Items]
Net interest income (loss)	218,641	210,781	221,758
(Recovery of) provision for loan losses	3,517	14,039	16,678
Other income	69,384	70,841	70,739
Other expense	171,365	165,665	156,516
Income (loss) before taxes	113,143	101,918	119,303
Income taxes (benefit)	30,103	26,324	32,197
Net income	83,040	75,594	87,106
Assets	6,912,443	6,524,098	6,502,579
Loans	4,781,761	4,559,406	4,369,173
Deposits	5,222,766	4,896,405	4,814,107
GFSC
Segment Reporting Information [Line Items]
Net interest income (loss)	7,457	8,741	9,156
(Recovery of) provision for loan losses	1,544	1,175	859
Other income	(1)	11	0
Other expense	4,103	3,133	2,835
Income (loss) before taxes	1,809	4,444	5,462
Income taxes (benefit)	634	1,556	1,912
Net income	1,175	2,888	3,550
Assets	40,308	47,115	49,926
Loans	40,645	47,228	50,082
Deposits	5,883	7,159	8,358
SEPH
Segment Reporting Information [Line Items]
Net interest income (loss)	958	(1,325)	(341)
(Recovery of) provision for loan losses	(12,394)	(11,799)	17,882
Other income	5,991	1,956	21,431
Other expense	11,766	12,211	22,032
Income (loss) before taxes	7,577	219	(18,824)
Income taxes (benefit)	2,652	77	(6,603)
Net income	4,925	142	(12,221)
Assets	43,762	72,781	104,428
Loans	23,956	38,014	59,178
Deposits	0	0	0
All Other
Segment Reporting Information [Line Items]
Net interest income (loss)	(2,012)	2,828	4,742
(Recovery of) provision for loan losses	0	0	0
Other income	175	469	233
Other expense	8,000	7,520	6,585
Income (loss) before taxes	(9,837)	(4,223)	(1,610)
Income taxes (benefit)	(4,787)	(2,826)	(1,805)
Net income	(5,050)	(1,397)	195
Assets	6,743	(5,647)	(14,130)
Loans	(16,680)	(24,143)	(28,111)
Deposits	(100,649)	(113,570)	(106,433)
Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Other Noninterest Expense	0	0	0
Net interest income (loss)	3,708	8,659	8,558
Depreciation, Amortization and Accretion, Net	0	0	0
Income taxes (benefit)	0	0	0
Assets	(18,556)	(30,369)	(35,639)
Deposits	(100,649)	(113,570)	(106,433)
Parent Co Gfsc Totals Not Eliminated [Member]
Segment Reporting Information [Line Items]
Other Noninterest Expense	8,000	7,520	6,585
Net interest income (loss)	(5,720)	(5,831)	(3,816)
Depreciation, Amortization and Accretion, Net	0	0	0
Income taxes (benefit)	(4,787)	(2,826)	(1,805)
Assets	25,299	24,722	21,509
Deposits	$ 0	$ 0	$ 0

Other Income (Loss) and Security Gains

No definition available.

Name:	prk_OtherIncomeLossAndSecurityGains
Namespace Prefix:	prk_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Sum of the carrying amounts as of the balance sheet date of all assets that are recognized. Assets are probable future economic benefits obtained or controlled by an entity as a result of past transactions or events.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.18)

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 03

-Paragraph 12

-Article 7

Reference 4: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 18

-Article 5

+ Details

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

- Definition

The aggregate of all deposit liabilities held by the entity, including foreign and domestic, interest and noninterest bearing; may include demand deposits, saving deposits, Negotiable Order of Withdrawal (NOW) and time deposits among others.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 942

-SubTopic 210

-Section S99

-Paragraph 1

-Subparagraph (SX 210.9-03.12)

-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 03

-Paragraph 12

-Article 9

+ Details

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

- Definition

The aggregate net amount of depreciation, amortization, and accretion recognized during an accounting period. As a noncash item, the net amount is added back to net income when calculating cash provided by or used in operations using the indirect method.

+ References

+ Details

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

- Definition

The net realized gain (loss) on investments sold during the period, not including gains (losses) on securities separately or otherwise categorized as trading, available-for-sale, or held-to-maturity, which, for cash flow reporting, is a component of proceeds from investing activities.

+ References

+ Details

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

- Definition

Sum of operating profit and nonoperating income or expense before Income or Loss from equity method investments, income taxes, extraordinary items, and noncontrolling interest.

+ References

+ Details

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

- Definition

Amount of current income tax expense (benefit) and deferred income tax expense (benefit) pertaining to continuing operations.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 235

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.4-08.(h))

-URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 08

-Paragraph h

-Article 4

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Income Tax Expense (or Benefit)

-URI http://asc.fasb.org/extlink&oid=6515339

Reference 4: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 740

-SubTopic 10

-Section 50

-Paragraph 9

-Subparagraph (a),(b)

-URI http://asc.fasb.org/extlink&oid=6907707&loc=d3e32639-109319

+ Details

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

- Definition

The net amount of operating interest income (expense).

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 942

-SubTopic 225

-Section S99

-Paragraph 1

-Subparagraph (SX 210.9-04.10)

-URI http://asc.fasb.org/extlink&oid=6879574&loc=d3e536633-122882

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 04

-Paragraph 10

-Article 9

+ Details

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

- Definition

Amount before allowance of loans and leases held in portfolio, including but not limited to, commercial and consumer loans. Includes deferred interest and fees, undisbursed portion of loan balance, unamortized costs and premiums and discounts from face amounts. Excludes loans and leases covered under loss sharing agreements.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 310

-SubTopic 10

-Section 45

-Paragraph 2

-URI http://asc.fasb.org/extlink&oid=28367877&loc=d3e4428-111522

+ Details

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

- Definition

The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 45

-Paragraph 28

-URI http://asc.fasb.org/extlink&oid=31042434&loc=d3e3602-108585

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 260

-SubTopic 10

-Section 50

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=6371337&loc=d3e3550-109257

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Other Comprehensive Income

-URI http://asc.fasb.org/extlink&oid=6519514

Reference 4: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Net Income

-URI http://asc.fasb.org/extlink&oid=6518256

Reference 5: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 944

-SubTopic 225

-Section S99

-Paragraph 1

-Subparagraph (SX 210.7-04.19)

-URI http://asc.fasb.org/extlink&oid=6879464&loc=d3e573970-122913

Reference 6: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 225

-SubTopic 10

-Section S99

-Paragraph 2

-Subparagraph (SX 210.5-03.18)

-URI http://asc.fasb.org/extlink&oid=26872669&loc=d3e20235-122688

Reference 7: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 944

-SubTopic 225

-Section S99

-Paragraph 1

-Subparagraph (SX 210.7-04.22)

-URI http://asc.fasb.org/extlink&oid=6879464&loc=d3e573970-122913

Reference 8: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 03

-Paragraph 19

-Article 5

Reference 9: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 04

-Paragraph 20

-Article 9

+ Details

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

- Definition

Total aggregate amount of all noninterest expense.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 942

-SubTopic 225

-Section S99

-Paragraph 1

-Subparagraph (SX 210.9-04.14)

-URI http://asc.fasb.org/extlink&oid=6879574&loc=d3e536633-122882

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 04

-Paragraph 14

-Article 9

+ Details

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

- Definition

Other noninterest expenses that are not separately presented in any other noninterest expense category.

+ References

+ Details

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

- Definition

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

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 45

-Paragraph 28

-Subparagraph (a)

-URI http://asc.fasb.org/extlink&oid=31042434&loc=d3e3602-108585

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 04

-Paragraph 11

-Article 9

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 942

-SubTopic 225

-Section S99

-Paragraph 1

-Subparagraph (SX 210.9-04.11)

-URI http://asc.fasb.org/extlink&oid=6879574&loc=d3e536633-122882

Reference 4: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 310

-SubTopic 10

-Section 50

-Paragraph 11B

-Subparagraph (c)(2)

-URI http://asc.fasb.org/extlink&oid=35738203&loc=SL6953423-111524

+ Details

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

- Details

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

- Details

Name:	us-gaap_StatementBusinessSegmentsAxis=prk_GfscMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_StatementBusinessSegmentsAxis=prk_ParentCoGfscTotalsNotEliminatedMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_StatementBusinessSegmentsAxis=prk_SegmentOneMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_StatementBusinessSegmentsAxis=prk_SephMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_StatementBusinessSegmentsAxis=prk_TotalsForReportableSegmentsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_StatementBusinessSegmentsAxis=us-gaap_AllOtherSegmentsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_StatementBusinessSegmentsAxis=us-gaap_IntersegmentEliminationMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: