Adoption of New Accounting Pronouncements and Issued Not Yet Effective Accounting Standards Adoption of New Accounting Pronouncements (Policies)	12 Months Ended
Dec. 31, 2017
Accounting Changes and Error Corrections [Abstract]
New Accounting Pronouncements, Policy [Policy Text Block]	Adoption of New Accounting Pronouncements and Issued Not Yet Effective Accounting Standards The following is a summary of new accounting pronouncements, new laws impacting Park's consolidated financial statements, and issued not yet effective accounting standards: Adoption of New Accounting Pronouncements ASU 2016-09 - Compensation - Stock Compensation (Topic 718): Improvements to Employee Share-Based Payment Accounting: In March 2016, FASB issued ASU 2016-09 - Compensation - Stock Compensation (Topic 718): Improvements to Employee Share-Based Payment Accounting. This ASU provides simplification for several aspects of accounting for share-based payment transactions, including the income tax consequences, classification of awards as either equity or liabilities, and classification on the statement of cash flows. The new guidance is effective for annual reporting periods and interim reporting periods within those annual periods, beginning after December 15, 2016. Early adoption was permitted. The adoption of this guidance on January 1, 2017 did not have a material impact on Park's consolidated financial statements. ASU 2017-01 – Business Combinations (Topic 805): Clarifying the Definition of a Business: In January 2017, the FASB issued ASU 2017-01, Business Combinations (Topic 805): Clarifying the Definition of a Business. This ASU clarifies the definition of a business with the objective of adding guidance to assist entities with evaluating whether transactions should be accounted for as acquisitions (or disposals) of assets or businesses. The new guidance is effective for annual reporting periods and interim reporting periods within those annual periods, beginning after December 15, 2017. Early adoption is permitted. The early adoption of this guidance on October 1, 2017 did not have a material impact on Park's consolidated financial statements. Park will apply this guidance to all future transactions. ASU 2017-04 - Intangibles - Goodwill and Other (Topic 350): Simplifying the Test for Goodwill Impairment: In January 2017, the FASB issued ASU 2017-04, Intangibles - Goodwill and Other (Topic 350): Simplifying the Test for Goodwill Impairment. This ASU eliminates Step 2 from the goodwill impairment test. Instead, under the new guidance, an entity should perform its annual goodwill impairment test by comparing the fair value of a reporting unit with its carrying amount. An impairment charge would be recognized for the amount by which the carrying amount exceeds the reporting unit's fair value. The new guidance is effective for annual reporting periods, and interim reporting periods within those annual periods, beginning after December 15, 2019. Early adoption is permitted for interim or annual goodwill impairment tests performed on testing dates after January 1, 2017. The early adoption of this guidance with Park's April 1, 2017 annual goodwill impairment test did not have an impact on Park's consolidated financial statements. Issued Not Yet Effective Accounting Standards ASU 2014-09 - Revenue from Contracts with Customers (Topic 606): In May 2014, the FASB issued ASU 2014-09, Revenue from Contracts with Customers (Topic 606). This ASU creates a new topic, Topic 606, to provide guidance on revenue recognition for entities that enter into contracts with customers to transfer goods or services or enter into contracts for the transfer of nonfinancial assets. The core principle of the guidance is that an entity should recognize revenue to depict the transfer of promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services. Additional disclosures are required to provide quantitative and qualitative information regarding the nature, amount, timing, and uncertainty of revenue and cash flows arising from contracts with customers. The new guidance is effective for annual reporting periods, and interim reporting periods within those annual periods, beginning after December 15, 2017. The adoption of this guidance on January 1, 2018 did not have a material impact on Park's consolidated financial statements. However, the adoption of this standard will result in additional disclosures beginning with the first quarter 2018 Form 10-Q. ASU 2016-01 - Financial Instruments - Overall (Subtopic 825-10): Recognition and Measurement of Financial Assets and Financial Liabilities. In January 2016, the FASB issued ASU 2016-01 - Financial Instruments - Overall (Subtopic 825-10): Recognition and Measurement of Financial Assets and Financial Liabilities. Changes to the current U.S. GAAP model primarily affect the accounting for equity investments, financial liabilities under the fair value option, and the presentation and disclosure requirements for financial instruments. In addition, this ASU clarifies guidance related to the valuation allowance assessment when recognizing deferred tax assets resulting from unrealized losses on AFS securities. The new guidance is effective for annual reporting periods and interim reporting periods within those annual periods, beginning after December 15, 2017. The adoption of this guidance on January 1, 2018 did not have a material impact on Park's consolidated financial statements, but will impact the fair value disclosures in Note 25 beginning with the first quarter 2018 Form 10-Q. ASU 2016-02 - Leases (Topic 842): In February 2016, the FASB issued ASU 2016-02 - Leases (Topic 842). This ASU will require all organizations that lease assets to recognize on the balance sheet the assets and liabilities for the rights and obligations created by those leases. Additional qualitative and quantitative disclosures will be required so that users can understand more about the nature of an entity’s leasing activities. The new guidance is effective for annual reporting periods and interim reporting periods within those annual periods, beginning after December 15, 2018. Early adoption is permitted. Management is currently analyzing data on leased assets. The adoption of this guidance is expected to increase both assets and liabilities, but is not expected to have a material impact on Park's consolidated statement of income. ASU 2016-13 - Financial Instruments - Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments: In June 2016, FASB issued ASU 2016-13 - Financial Instruments - Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments. The new guidance replaces the incurred loss model with an expected loss model, which is referred to as the current expected credit loss ("CECL") model. The CECL model is applicable to the measurement of credit losses on financial assets measured at amortized cost, including loan receivables, HTM debt securities, and reinsurance receivables. It also applies to off-balance sheet credit exposures not accounted for as insurance (loan commitments, standby letters of credit, financial guarantees, and other similar instruments) and net investments in leases recognized by a lessor. The CECL model requires an entity to estimate credit losses over the life of an asset or off-balance sheet exposure. The new guidance is effective for annual reporting periods and interim reporting periods within those annual periods, beginning after December 15, 2019. Early adoption is permitted for annual reporting periods and interim reporting periods within those annual periods, beginning after December 15, 2018. Management is currently evaluating the impact of the adoption of this guidance on Park's consolidated financial statements. We anticipate that the adoption of the CECL model will result in a material increase to Park's allowance for loan losses. Management has established a committee to oversee the implementation of the CECL model and is currently in the process of implementing a software solution to assist in the adoption of this ASU. Management plans to run our current allowance model and a CECL model concurrently for 12 months prior to the adoption of this guidance on January 1, 2020. ASU 2016-15 - Statement of Cash Flows (Topic 203): Classification of Certain Cash Receipts and Cash Payments (a consensus of the Emerging Issues Task Force): In August 2016, the FASB issued ASU 2016-15, Statement of Cash Flows (Topic 203): Classification of Certain Cash Receipts and Cash Payments (a consensus of the Emerging Issues Task Force). This ASU provides guidance on eight specific cash flow issues where current GAAP is either unclear or does not include specific guidance. The new guidance is effective for annual reporting periods, and interim reporting periods within those annual periods, beginning after December 15, 2017. As such transactions arise, management will utilize the updated guidance within Park’s consolidated statements of cash flows. ASU 2017-07 - Compensation - Retirement Benefits (Topic 715): Improving the Presentation of Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost: In March 2017, the FASB issued ASU 2017-07 - Compensation - Retirement Benefits (Topic 715): Improving the Presentation of Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost. This ASU requires that an employer report the service cost component in the same line item or items as other compensation costs arising from services rendered by the pertinent employees during the period. The other components of net benefit cost are required to be presented in the income statement separately from the service cost component. The new guidance is effective for annual reporting periods, and interim reporting periods within those annual periods, beginning after December 15, 2017. The adoption of this guidance on January 1, 2018 did not have a material impact on Park's consolidated financial statements. ASU 2017-08 - Receivables - Nonrefundable Fees and Other Costs (Subtopic 310-20): Premium Amortization on Purchased Callable Debt Securities: In March 2017, the FASB issued ASU 2017-08 - Receivables - Nonrefundable Fees and Other Costs (Subtopic 310-20): Premium Amortization on Purchased Callable Debt Securities. This ASU amends the amortization period for certain purchased callable debt securities held at a premium. It shortens the amortization period for the premium to the earliest call date. Under current U.S. GAAP, premiums on callable debt securities generally are amortized to the maturity date. The new guidance is effective for annual reporting periods, and interim reporting periods within those annual periods, beginning after December 15, 2018. Early adoption is permitted for interim or annual periods. The adoption of this guidance is not expected to have a material impact on Park's consolidated financial statements. ASU 2017-09 - Compensation - Stock Compensation (Topic 718): Scope of Modification Accounting: In May 2017, the FASB issued ASU 2017-09 - Compensation - Stock Compensation (Topic 718): Scope of Modification Accounting. This ASU amends the guidance concerning which changes to the terms or conditions of a share-based payment award require an entity to apply modification accounting in Topic 718. The new guidance is effective for annual reporting periods, and interim reporting periods within those annual periods, beginning after December 15, 2017. The adoption of this guidance on January 1, 2018 did not impact Park's consolidated financial statements. ASU 2017-12 - Derivatives and Hedging (Topic 815): Targeted Improvements to Accounting for Hedging Activities: In August 2017, the FASB issued ASU 2017-12 - Derivatives and Hedging (Topic 815): Targeted Improvements to Accounting for Hedging Activities. This ASU amends the current guidance with the objective of improving the financial reporting of hedging relationships to better portray the economic results of an entity's risk management activities in its financial statements. In addition, this ASU amends the current guidance to simplify the application of the hedge accounting guidance. The new guidance is effective for annual reporting periods, and interim reporting periods within those annual periods, beginning after December 15, 2018. Early adoption is permitted for interim or annual periods. The adoption of this guidance is not expected to have a material impact on Park's consolidated financial statements. Park is considering the early adoption of this guidance. ASU 2018-02 - Income Statement - Reporting Comprehensive Income (Topic 220): Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income: In February 2018, the FASB issued ASU 2018-02 - Income Statement - Reporting Comprehensive Income (Topic 220): Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income. This ASU allows a reclassification from accumulated other comprehensive income to retained earnings for stranded tax effects, resulting from the newly - enacted federal corporate income tax rate. The amount of the reclassification is the difference between the historical federal corporate income tax rate and the newly - enacted 21% federal corporate income tax rate. The guidance is effective for annual reporting periods, and interim reporting periods within those annual periods, beginning after December 15, 2018. Early adoption is permitted for interim or annual periods. The early adoption of this guidance on January 1, 2018 resulted in a $3.8 million increase to Park's accumulated other comprehensive loss and a $3.8 million increase to retained earnings, which will be reflected in Park's first quarter 2018 Consolidated Balance Sheet.

Adoption of New Accounting Pronouncements and Issued Not Yet Effective Accounting Standards

The following is a summary of new accounting pronouncements, new laws impacting Park's consolidated financial statements, and issued not yet effective accounting standards:

Adoption of New Accounting Pronouncements

ASU 2016-09 - Compensation - Stock Compensation (Topic 718): Improvements to Employee Share-Based Payment Accounting: In March 2016, FASB issued ASU 2016-09 - Compensation - Stock Compensation (Topic 718): Improvements to Employee Share-Based Payment Accounting. This ASU provides simplification for several aspects of accounting for share-based payment transactions, including the income tax consequences, classification of awards as either equity or liabilities, and classification on the statement of cash flows. The new guidance is effective for annual reporting periods and interim reporting periods within those annual periods, beginning after December 15, 2016. Early adoption was permitted. The adoption of this guidance on January 1, 2017 did not have a material impact on Park's consolidated financial statements.

ASU 2017-01 – Business Combinations (Topic 805): Clarifying the Definition of a Business: In January 2017, the FASB issued ASU 2017-01, Business Combinations (Topic 805): Clarifying the Definition of a Business. This ASU clarifies the definition of a business with the objective of adding guidance to assist entities with evaluating whether transactions should be accounted for as acquisitions (or disposals) of assets or businesses. The new guidance is effective for annual reporting periods and interim reporting periods within those annual periods, beginning after December 15, 2017. Early adoption is permitted. The early adoption of this guidance on October 1, 2017 did not have a material impact on Park's consolidated financial statements. Park will apply this guidance to all future transactions.

ASU 2017-04 - Intangibles - Goodwill and Other (Topic 350): Simplifying the Test for Goodwill Impairment: In January 2017, the FASB issued ASU 2017-04, Intangibles - Goodwill and Other (Topic 350): Simplifying the Test for Goodwill Impairment. This ASU eliminates Step 2 from the goodwill impairment test. Instead, under the new guidance, an entity should perform its annual goodwill impairment test by comparing the fair value of a reporting unit with its carrying amount. An impairment charge would be recognized for the amount by which the carrying amount exceeds the reporting unit's fair value. The new guidance is effective for annual reporting periods, and interim reporting periods within those annual periods, beginning after December 15, 2019. Early adoption is permitted for interim or annual goodwill impairment tests performed on testing dates after January 1, 2017. The early adoption of this guidance with Park's April 1, 2017 annual goodwill impairment test did not have an impact on Park's consolidated financial statements.

Issued Not Yet Effective Accounting Standards

ASU 2014-09 - Revenue from Contracts with Customers (Topic 606): In May 2014, the FASB issued ASU 2014-09, Revenue from Contracts with Customers (Topic 606). This ASU creates a new topic, Topic 606, to provide guidance on revenue recognition for entities that enter into contracts with customers to transfer goods or services or enter into contracts for the transfer of nonfinancial assets. The core principle of the guidance is that an entity should recognize revenue to depict the transfer of promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services. Additional disclosures are required to provide quantitative and qualitative information regarding the nature, amount, timing, and uncertainty of revenue and cash flows arising from contracts with customers. The new guidance is effective for annual reporting periods, and interim reporting periods within those annual periods, beginning after December 15, 2017. The adoption of this guidance on January 1, 2018 did not have a material impact on Park's consolidated financial statements. However, the adoption of this standard will result in additional disclosures beginning with the first quarter 2018 Form 10-Q.

ASU 2016-01 - Financial Instruments - Overall (Subtopic 825-10): Recognition and Measurement of Financial Assets and Financial Liabilities. In January 2016, the FASB issued ASU 2016-01 - Financial Instruments - Overall (Subtopic 825-10): Recognition and Measurement of Financial Assets and Financial Liabilities. Changes to the current U.S. GAAP model primarily affect the accounting for equity investments, financial liabilities under the fair value option, and the presentation and disclosure requirements for financial instruments. In addition, this ASU clarifies guidance related to the valuation allowance assessment when recognizing deferred tax assets resulting from unrealized losses on AFS securities. The new guidance is effective for annual reporting periods and interim reporting periods within those annual periods, beginning after December 15, 2017. The adoption of this guidance on January 1, 2018 did not have a material impact on Park's consolidated financial statements, but will impact the fair value disclosures in Note 25 beginning with the first quarter 2018 Form 10-Q.

ASU 2016-02 - Leases (Topic 842): In February 2016, the FASB issued ASU 2016-02 - Leases (Topic 842). This ASU will require all organizations that lease assets to recognize on the balance sheet the assets and liabilities for the rights and obligations created by those leases. Additional qualitative and quantitative disclosures will be required so that users can understand more about the nature of an entity’s leasing activities. The new guidance is effective for annual reporting periods and interim reporting periods within those annual periods, beginning after December 15, 2018. Early adoption is permitted. Management is currently analyzing data on leased assets. The adoption of this guidance is expected to increase both assets and liabilities, but is not expected to have a material impact on Park's consolidated statement of income.

ASU 2016-13 - Financial Instruments - Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments: In June 2016, FASB issued ASU 2016-13 - Financial Instruments - Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments. The new guidance replaces the incurred loss model with an expected loss model, which is referred to as the current expected credit loss ("CECL") model. The CECL model is applicable to the measurement of credit losses on financial assets measured at amortized cost, including loan receivables, HTM debt securities, and reinsurance receivables. It also applies to off-balance sheet credit exposures not accounted for as insurance (loan commitments, standby letters of credit, financial guarantees, and other similar instruments) and net investments in leases recognized by a lessor. The CECL model requires an entity to estimate credit losses over the life of an asset or off-balance sheet exposure. The new guidance is effective for annual reporting periods and interim reporting periods within those annual periods, beginning after December 15, 2019. Early adoption is permitted for annual reporting periods and interim reporting periods within those annual periods, beginning after December 15, 2018.

Management is currently evaluating the impact of the adoption of this guidance on Park's consolidated financial statements. We anticipate that the adoption of the CECL model will result in a material increase to Park's allowance for loan losses. Management has established a committee to oversee the implementation of the CECL model and is currently in the process of implementing a software solution to assist in the adoption of this ASU. Management plans to run our current allowance model and a CECL model concurrently for 12 months prior to the adoption of this guidance on January 1, 2020.

ASU 2016-15 - Statement of Cash Flows (Topic 203): Classification of Certain Cash Receipts and Cash Payments (a consensus of the Emerging Issues Task Force): In August 2016, the FASB issued ASU 2016-15, Statement of Cash Flows (Topic 203): Classification of Certain Cash Receipts and Cash Payments (a consensus of the Emerging Issues Task Force). This ASU provides guidance on eight specific cash flow issues where current GAAP is either unclear or does not include specific guidance. The new guidance is effective for annual reporting periods, and interim reporting periods within those annual periods, beginning after December 15, 2017. As such transactions arise, management will utilize the updated guidance within Park’s consolidated statements of cash flows.

ASU 2017-07 - Compensation - Retirement Benefits (Topic 715): Improving the Presentation of Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost: In March 2017, the FASB issued ASU 2017-07 - Compensation - Retirement Benefits (Topic 715): Improving the Presentation of Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost. This ASU requires that an employer report the service cost component in the same line item or items as other compensation costs arising from services rendered by the pertinent employees during the period. The other components of net benefit cost are required to be presented in the income statement separately from the service cost component. The new guidance is effective for annual reporting periods, and interim reporting periods within those annual periods, beginning after December 15, 2017. The adoption of this guidance on January 1, 2018 did not have a material impact on Park's consolidated financial statements.

ASU 2017-08 - Receivables - Nonrefundable Fees and Other Costs (Subtopic 310-20): Premium Amortization on Purchased Callable Debt Securities: In March 2017, the FASB issued ASU 2017-08 - Receivables - Nonrefundable Fees and Other Costs (Subtopic 310-20): Premium Amortization on Purchased Callable Debt Securities. This ASU amends the amortization period for certain purchased callable debt securities held at a premium. It shortens the amortization period for the premium to the earliest call date. Under current U.S. GAAP, premiums on callable debt securities generally are amortized to the maturity date. The new guidance is effective for annual reporting periods, and interim reporting periods within those annual periods, beginning after December 15, 2018. Early adoption is permitted for interim or annual periods. The adoption of this guidance is not expected to have a material impact on Park's consolidated financial statements.

ASU 2017-09 - Compensation - Stock Compensation (Topic 718): Scope of Modification Accounting: In May 2017, the FASB issued ASU 2017-09 - Compensation - Stock Compensation (Topic 718): Scope of Modification Accounting. This ASU amends the guidance concerning which changes to the terms or conditions of a share-based payment award require an entity to apply modification accounting in Topic 718. The new guidance is effective for annual reporting periods, and interim reporting periods within those annual periods, beginning after December 15, 2017. The adoption of this guidance on January 1, 2018 did not impact Park's consolidated financial statements.

ASU 2017-12 - Derivatives and Hedging (Topic 815): Targeted Improvements to Accounting for Hedging Activities: In August 2017, the FASB issued ASU 2017-12 - Derivatives and Hedging (Topic 815): Targeted Improvements to Accounting for Hedging Activities. This ASU amends the current guidance with the objective of improving the financial reporting of hedging relationships to better portray the economic results of an entity's risk management activities in its financial statements. In addition, this ASU amends the current guidance to simplify the application of the hedge accounting guidance. The new guidance is effective for annual reporting periods, and interim reporting periods within those annual periods, beginning after December 15, 2018. Early adoption is permitted for interim or annual periods. The adoption of this guidance is not expected to have a material impact on Park's consolidated financial statements. Park is considering the early adoption of this guidance.

ASU 2018-02 - Income Statement - Reporting Comprehensive Income (Topic 220): Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income: In February 2018, the FASB issued ASU 2018-02 - Income Statement - Reporting Comprehensive Income (Topic 220): Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income. This ASU allows a reclassification from accumulated other comprehensive income to retained earnings for stranded tax effects, resulting from the newly - enacted federal corporate income tax rate. The amount of the reclassification is the difference between the historical federal corporate income tax rate and the newly - enacted 21% federal corporate income tax rate. The guidance is effective for annual reporting periods, and interim reporting periods within those annual periods, beginning after December 15, 2018. Early adoption is permitted for interim or annual periods. The early adoption of this guidance on January 1, 2018 resulted in a $3.8 million increase to Park's accumulated other comprehensive loss and a $3.8 million increase to retained earnings, which will be reflected in Park's first quarter 2018 Consolidated Balance Sheet.