Accounting Policies (Policies)	3 Months Ended
Mar. 31, 2019
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation The unaudited condensed consolidated financial statements (“financial statements”) include the accounts of Glatfelter and its wholly-owned subsidiaries. All intercompany balances and transactions have been eliminated. We prepared these financial statements in accordance with accounting principles generally accepted in the United States of America (“generally accepted accounting principles” or “GAAP”) and pursuant to the rules and regulations of the Securities and Exchange Commission pertaining to interim financial statements. In our opinion, the financial statements reflect all normal, recurring adjustments needed to present fairly our results for the interim periods. When preparing these financial statements, we have assumed you have read the audited consolidated financial statements included in our 2018 Annual Report on Form 10-K.
Discontinued Operations	Discontinued Operations The results of operations for our Specialty Papers Business Unit have been classified as discontinued operations for all periods presented in the condensed consolidated statements of income.
Accounting Estimates	Accounting Estimates The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosures of contingencies as of the balance sheet date and the reported amounts of revenues and expenses during the reporting period. Management believes the estimates and assumptions used in the preparation of these financial statements are reasonable, based upon currently available facts and known circumstances, but recognizes actual results may differ from those estimates and assumptions.
Recently Issued Accounting Pronouncements	Recently Issued Accounting Pronouncements In February 2016, the FASB issued ASU No. 2016-02, Leases (Topic 842) (“ASU 842”). This ASU requires organizations to recognize on its balance sheet the assets and liabilities for the rights and obligations created by leases. We adopted ASU 842 as of January 1, 2019 and elected to follow a modified retrospective method which permitted us to adopt the standard without restating previously reported periods. As a result of adopting ASU 842, we recorded a right of use asset and corresponding lease obligation of approximately $14.1 million. Refer to Note 14 “Leases” for additional information. In August 2017, the FASB issued ASU No. 2017-12, "Derivatives and Hedging (Topic 815), Targeted Improvements to Accounting for Hedging Activities" (“ASU No. 2017-12”), which simplifies the application of hedge accounting and more closely aligns hedge accounting with an entity’s risk management strategies. ASU No. 2017-12 also amends the manner in which hedge effectiveness may be performed and changes the presentation of hedge ineffectiveness in the financial statements. We adopted ASU No. 2017-12 effective January 1, 2019 but it had an insignificant effect on our results of operations and financial position. In June 2016, the FASB issued ASU No. 2016-13 “Financial Instruments—Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments” that changes the impairment model for most financial instruments, including trade receivables from an incurred loss method to a new forward-looking approach, based on expected losses. Under the new guidance, an allowance is recognized based on an estimate of expected credit losses. This standard is effective for us in the first quarter of 2020 and must be adopted using a modified retrospective approach. We are currently assessing the impact this standard may have on our results of operations and financial position.

Discontinued Operations The results of operations for our Specialty Papers Business Unit have been classified as discontinued operations for all periods presented in the condensed consolidated statements of income.

Recently Issued Accounting Pronouncements

Recently Issued Accounting Pronouncements In February 2016, the FASB issued ASU No. 2016-02, Leases (Topic 842) (“ASU 842”). This ASU requires organizations to recognize on its balance sheet the assets and liabilities for the rights and obligations created by leases. We adopted ASU 842 as of January 1, 2019 and elected to follow a modified retrospective method which permitted us to adopt the standard without restating previously reported periods. As a result of adopting ASU 842, we recorded a right of use asset and corresponding lease obligation of approximately $14.1 million. Refer to Note 14 “Leases” for additional information.

In August 2017, the FASB issued ASU No. 2017-12, "Derivatives and Hedging (Topic 815), Targeted Improvements to Accounting for Hedging Activities" (“ASU No. 2017-12”), which simplifies the application of hedge accounting and more closely aligns hedge accounting with an entity’s risk management strategies. ASU No. 2017-12 also amends the manner in which hedge effectiveness may be performed and changes the presentation of hedge ineffectiveness in the financial statements. We adopted ASU No. 2017-12 effective January 1, 2019 but it had an insignificant effect on our results of operations and financial position.

In June 2016, the FASB issued ASU No. 2016-13 “Financial Instruments—Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments” that changes the impairment model for most financial instruments, including trade receivables from an incurred loss method to a new forward-looking approach, based on expected losses. Under the new guidance, an allowance is recognized based on an estimate of expected credit losses. This standard is effective for us in the first quarter of 2020 and must be adopted using a modified retrospective approach. We are currently assessing the impact this standard may have on our results of operations and financial position.