Magnera (MAGN) 10-Q 4 May 21 2021 Q1 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	3 Months Ended
	Mar. 31, 2021	Apr. 23, 2021
Cover [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Mar. 31, 2021
Document Fiscal Year Focus	2021
Document Fiscal Period Focus	Q1
Trading Symbol	GLT
Entity Registrant Name	Glatfelter Corporation
Entity Central Index Key	0000041719
Current Fiscal Year End Date	--12-31
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Current Reporting Status	Yes
Entity Shell Company	false
Entity Small Business	false
Entity Emerging Growth Company	false
Entity File Number	1-03560
Entity Tax Identification Number	23-0628360
Entity Address, Address Line One	4350 Congress Street
Entity Address, Address Line Two	Suite 600
Entity Address, City or Town	Charlotte
Entity Address, State or Province	NC
Entity Address, Postal Zip Code	28209
City Area Code	704
Entity Incorporation, State or Country Code	PA
Title of 12(b) Security	Common Stock
Document Transition Report	false
Document Quarterly Report	true
Security Exchange Name	NYSE
Local Phone Number	885-2555
Entity Common Stock, Shares Outstanding		44,451,658

Condensed Consolidated Statemen

Condensed Consolidated Statements of Income - USD ($) shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Income Statement [Abstract]
Net sales	$ 225,674	$ 231,560
Type of Revenue [Extensible List]	Product [Member]	Product [Member]
Costs of products sold	$ 186,378	$ 194,685
Type of Cost, Good or Service [Extensible List]	Product [Member]	Product [Member]
Gross profit	$ 39,296	$ 36,875
Selling, general and administrative expenses	22,827	24,594
Gains on dispositions of plant, equipment and timberlands, net	(850)
Operating income	17,319	12,281
Non-operating income (expense)
Interest expense	(1,531)	(1,778)
Interest income	20	264
Other, net	(224)	(753)
Total non-operating expense	(1,735)	(2,267)
Income from continuing operations before income taxes	15,584	10,014
Income tax provision	7,190	2,608
Net income	$ 8,394	$ 7,406
Basic earnings per share
Income from continuing operations	$ 0.19	$ 0.17
Basic earnings per share	0.19	0.17
Diluted earnings per share
Income from continuing operations	0.19	0.17
Diluted earnings per share	$ 0.19	$ 0.17
Weighted average shares outstanding
Basic	44,450	44,275
Diluted	44,869	44,530

Condensed Consolidated Statem_2

Condensed Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Statement Of Income And Comprehensive Income [Abstract]
Net income	$ 8,394	$ 7,406
Foreign currency translation adjustments	(13,193)	(13,903)
Net change in:
Deferred gains (losses) on cash flow hedges, net of taxes of $(1,301) and $401, respectively	3,261	(1,317)
Unrecognized retirement obligations, net of taxes of $(73) and $51, respectively	92	(101)
Other comprehensive loss	(9,840)	(15,321)
Comprehensive loss	$ (1,446)	$ (7,915)

Condensed Consolidated Statem_3

Condensed Consolidated Statements of Comprehensive Income (Parenthetical) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Statement Of Income And Comprehensive Income [Abstract]
Taxes on deferred gains (losses) on cash flow hedges	$ (1,301)	$ 401
Taxes on unrecognized retirement obligations	$ (73)	$ 51

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Assets
Cash and cash equivalents	$ 87,366	$ 99,581
Accounts receivable, net	126,507	122,817
Inventories	203,333	196,230
Prepaid expenses and other current assets	45,844	34,297
Total current assets	463,050	452,925
Plant, equipment and timberlands, net	523,428	543,267
Goodwill	157,341	164,369
Intangible assets, net	76,182	81,835
Other assets	47,878	44,485
Total assets	1,267,879	1,286,881
Liabilities and Shareholders' Equity
Current portion of long-term debt	23,942	25,057
Short-term debt	11,725
Accounts payable	115,456	127,505
Dividends payable	6,001	5,988
Environmental liabilities	3,600	3,700
Other current liabilities	75,005	71,093
Total current liabilities	235,729	233,343
Long-term debt	271,079	288,464
Deferred income taxes	75,387	77,131
Other long-term liabilities	114,623	110,011
Total liabilities	696,818	708,949
Commitments and contingencies
Shareholders’ equity
Common stock	544	544
Capital in excess of par value	62,576	63,261
Retained earnings	725,756	723,365
Accumulated other comprehensive loss	(68,493)	(58,653)
Shareholders' equity before treasury stock	720,383	728,517
Less cost of common stock in treasury	(149,322)	(150,585)
Total shareholders’ equity	571,061	577,932
Total liabilities and shareholders’ equity	$ 1,267,879	$ 1,286,881

Condensed Consolidated Statem_4

Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Operating activities
Net income	$ 8,394	$ 7,406
Adjustments to reconcile to net cash used by continuing operations:
Depreciation, depletion and amortization	13,733	15,402
Amortization of debt issue costs and original issue discount	153	147
Deferred income tax benefit	(410)	(2,612)
Gains on dispositions of plant, equipment and timberlands, net	(850)
Share-based compensation	1,208	1,085
Change in operating assets and liabilities
Accounts receivable	(7,002)	(7,203)
Inventories	(13,248)	(3,688)
Prepaid and other current assets	167	(2,315)
Accounts payable	(7,460)	(11,605)
Accruals and other current liabilities	(3,447)	(2,931)
Other	2,716	711
Net cash used by operating activities from continuing operations	(6,046)	(5,603)
Investing activities
Expenditures for purchases of plant, equipment and timberlands	(5,379)	(7,014)
Proceeds from disposals of plant, equipment and timberlands, net	876
Other	(100)
Net cash used by investing activities from continuing operations	(4,603)	(7,014)
Financing activities
Proceeds from short-term debt	11,725
Net borrowings under revolving credit facility	1,151	2,452
Payments of borrowing costs	(35)
Repayment of term loans	(6,136)	(3,089)
Payments of dividends	(5,990)	(5,752)
Payments related to share-based compensation awards and other	(536)	(458)
Net cash provided (used) by financing activities from continuing operations	179	(6,847)
Effect of exchange rate changes on cash	(2,213)	(937)
Net decrease in cash, cash equivalents and restricted cash	(12,683)	(20,401)
Decrease in cash, cash equivalents and restricted cash from discontinued operations	(78)	(316)
Cash, cash equivalents and restricted cash at the beginning of period	111,665	126,201
Cash, cash equivalents and restricted cash at the end of period	98,904	105,484
Less: restricted cash in Prepaid expenses and other current assets	(2,000)	(1,259)
Less: restricted cash in Other assets	(9,538)
Cash and cash equivalents at the end of period	87,366	104,225
Cash paid for:
Interest	1,408	1,443
Income taxes, net	$ 3,493	$ 3,446

Statements of Shareholders' Equ

Statements of Shareholders' Equity - USD ($) $ in Thousands	Total	Common Stock [Member]	Capital in Excess of Par Value [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Loss [Member]	Treasury Stock [Member]
Beginning Balance at Dec. 31, 2019	$ 555,959	$ 544	$ 59,900	$ 725,795	$ (77,896)	$ (152,384)
Net income	7,406			7,406
Other comprehensive loss	(15,321)				(15,321)
Comprehensive loss	(7,915)
Cash dividends declared	(5,761)			(5,761)
Share-based compensation expense	1,085		1,085
Delivery of treasury shares
RSUs and PSAs	(406)		(1,213)			807
Employee stock options exercised — net	(52)		(149)			97
Ending Balance at Mar. 31, 2020	542,910	544	59,623	727,440	(93,217)	(151,480)
Beginning Balance at Dec. 31, 2020	577,932	544	63,261	723,365	(58,653)	(150,585)
Net income	8,394			8,394
Other comprehensive loss	(9,840)				(9,840)
Comprehensive loss	(1,446)
Cash dividends declared	(6,003)			(6,003)
Share-based compensation expense	1,208		1,208
Delivery of treasury shares
RSUs and PSAs	(630)		(1,893)			1,263
Ending Balance at Mar. 31, 2021	$ 571,061	$ 544	$ 62,576	$ 725,756	$ (68,493)	$ (149,322)

Statements of Shareholders' E_2

Statements of Shareholders' Equity (Parenthetical) - $ / shares	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Retained Earnings [Member]
Per share amount of cash dividends declared	$ 0.135	$ 0.13

Organization

Organization	3 Months Ended
	Mar. 31, 2021
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Organization	1. ORGANIZATION Glatfelter Corporation and subsidiaries (“Glatfelter”) is a leading global supplier of engineered materials. Our high-quality, innovative and customizable solutions are found in tea and single-serve coffee filtration, personal hygiene and packaging products as well as home improvement and industrial applications. We are headquartered in Charlotte, NC, and operate facilities in the United States, Canada, Germany, France, the United Kingdom and the Philippines. We have sales and distribution offices in the United States, Europe, Russia, Italy, and China. Our products are marketed worldwide, either directly to customers or through brokers and agents. The terms “we,” “us,” “our,” “the Company,” or “Glatfelter,” refer to Glatfelter Corporation and subsidiaries unless the context indicates otherwise.

Accounting Policies

Accounting Policies	3 Months Ended
	Mar. 31, 2021
Accounting Policies [Abstract]
Accounting Policies	2. ACCOUNTING POLICIES 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 2020 Annual Report on Form 10-K. Discontinued Operations The results of operations and cash flows of our former Specialty Papers business have been classified as discontinued operations for all periods presented in the condensed consolidated statements of income. 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 In December 2019, the Financial Accounting Standards Board issued Accounting Standards Update No. 2019-12, Income Taxes (Topic 740): Simplifying the Accounting for Income Taxes (“ASU No. 2019-12”) . The update eliminates, clarifies, and modifies certain guidance related to the accounting for income taxes. We adopted ASU No. 2019-12 effective January 1, 2021 and it did not have a material impact on our financial statements.

Pending Acquisition

Pending Acquisition	3 Months Ended
	Mar. 31, 2021
Business Combinations [Abstract]
Pending Acquisition	3. PENDING ACQUISITION On January 5, 2021, we signed a definitive agreement to purchase Georgia-Pacific's U.S. nonwovens business ("G-P") for $175 million, subject to customary post-closing purchase price adjustments. This business includes the Mount Holly, NC manufacturing facility with annual production capacity of approximately 37,000 metric tons and an R&D center and pilot line for nonwovens product development in Memphis, TN. G-P had annual net sales of approximately $100 million in 2020. The waiting period for regulatory review expired, satisfying one of the conditions to the closing of the proposed acquisition, which remains subject to other customary closing conditions. The transaction is expected to close by mid-May 2021. The acquisition will be financed through a combination of cash on hand and borrowings under our revolving credit facility. Upon completion of the acquisition, the acquired business will be operated as part of our Airlaid Materials reporting segment.

Revenue

Revenue	3 Months Ended
	Mar. 31, 2021
Disaggregation Of Revenue [Abstract]
Revenue	4. REVENUE The following tables set forth disaggregated information pertaining to our net sales: Three months ended March 31 In thousands 2021 2020 Composite Fibers Food & beverage $ 76,953 $ 71,458 Wallcovering 22,629 19,893 Technical specialties 23,495 20,007 Composite laminates 9,809 9,763 Metallized 8,363 11,590 141,249 132,711 Airlaid Materials Feminine hygiene 47,641 50,096 Specialty wipes 15,916 17,212 Tabletop 6,863 15,052 Adult incontinence 4,678 6,145 Home care 3,923 5,212 Other 5,404 5,132 84,425 98,849 $ 225,674 $ 231,560 Three months ended March 31 In thousands 2021 2020 Composite Fibers Europe, Middle East and Africa $ 86,945 $ 79,586 Americas 31,841 32,721 Asia Pacific 22,463 20,404 141,249 132,711 Airlaid Materials Europe, Middle East and Africa 45,072 52,720 Americas 37,485 44,386 Asia Pacific 1,868 1,743 84,425 98,849 $ 225,674 $ 231,560

Gain on Dispositions of Plant,

Gain on Dispositions of Plant, Equipment and Timberlands	3 Months Ended
	Mar. 31, 2021
Property Plant And Equipment [Abstract]
Gain on Dispositions of Plant, Equipment and Timberlands	5 . GAINS ON DISPOSITION OF PLANT, EQUIPMENT AND TIMBERLANDS The following table sets forth sales of timberlands and other assets completed during the first three months of 2021. There were no such sales in the first three months of 2020: Dollars in thousands Acres Proceeds Gain 2021 Timberlands 358 $ 876 $ 850 Other n/a — — Total $ 876 $ 850

Discontinued Operations

Discontinued Operations	3 Months Ended
	Mar. 31, 2021
Discontinued Operations And Disposal Groups [Abstract]
Discontinued Operations	6 . DISCONTINUED OPERATIONS On October 31, 2018, we completed the previously announced sale of our Specialty Papers business on a cash free and debt free basis to Pixelle Specialty Solutions LLC, an affiliate of Lindsay Goldberg (the “Purchaser”) for $360 million. The following table sets forth a summary of cash flows from discontinued operations which is included in the condensed consolidated statements of cash flows: Three months ended March 31 In thousands 2021 2020 Net cash used by operating activities $ (78 ) $ (316 ) Net cash used by investing activities — — Net cash provided by financing activities — — Change in cash and cash equivalents from discontinued operations $ (78 ) $ (316 )

Earnings Per Share

Earnings Per Share	3 Months Ended
	Mar. 31, 2021
Earnings Per Share [Abstract]
Earnings Per Share	7 . EARNINGS PER SHARE The following table sets forth the details of basic and diluted earnings per share (“EPS”) from continuing operations: Three months ended March 31 In thousands, except per share 2021 2020 Income from continuing operations $ 8,394 $ 7,406 Weighted average common shares outstanding used in basic EPS 44,450 44,275 Effect of dilutive SOSARs, PSAs and RSUs 419 255 Weighted average common shares outstanding and common share equivalents used in diluted EPS 44,869 44,530 Earnings per share from continuing operations Basic $ 0.19 $ 0.17 Diluted 0.19 0.17 The following table sets forth potential common shares outstanding that were not included in the computation of diluted EPS for the periods indicated, because their effect would be anti-dilutive: March 31 In thousands 2021 2020 Three months ended 1,082 1,231

Accumulated Other Comprehensive

Accumulated Other Comprehensive Income	3 Months Ended
	Mar. 31, 2021
Equity [Abstract]
Accumulated Other Comprehensive Income	8 . ACCUMULATED OTHER COMPREHENSIVE INCOME The following table sets forth details of the changes in accumulated other comprehensive income (losses) for the three months ended March 31, 2021 and 2020. In thousands Currency translation adjustments Unrealized gain (loss) on cash flow hedges Change in pensions Change in other postretirement defined benefit plans Total Balance at January 1, 2021 $ (42,525 ) $ (2,496 ) $ (12,844 ) $ (788 ) $ (58,653 ) Other comprehensive income (loss) before reclassifications (net of tax) (13,193 ) 3,274 — — (9,919 ) Amounts reclassified from accumulated other comprehensive income (net of tax) — (13 ) 138 (46 ) 79 Net current period other comprehensive income (loss) (13,193 ) 3,261 138 (46 ) (9,840 ) Balance at March 31, 2021 $ (55,718 ) $ 765 $ (12,706 ) $ (834 ) $ (68,493 ) Balance at January 1, 2020 $ (76,346 ) $ 4,316 $ (7,253 ) $ 1,387 $ (77,896 ) Other comprehensive income (loss) before reclassifications (net of tax) (13,903 ) 283 — — (13,620 ) Amounts reclassified from accumulated other comprehensive income (net of tax) — (1,600 ) 148 (249 ) (1,701 ) Net current period other comprehensive income (loss) (13,903 ) (1,317 ) 148 (249 ) (15,321 ) Balance at March 31, 2020 $ (90,249 ) $ 2,999 $ (7,105 ) $ 1,138 $ (93,217 ) Reclassifications out of accumulated other comprehensive income and into the condensed consolidated statements of income were as follows: Three months ended March 31 In thousands 2021 2020 Description Line Item in Statements of Income Cash flow hedges (Note 17) (Gains) losses on cash flow hedges $ 24 $ (2,182 ) Costs of products sold Tax expense (benefit) (51 ) 582 Income tax provision Net of tax (27 ) (1,600 ) Loss on interest rate swaps 21 — Interest expense Tax benefit (7 ) — Income tax provision Net of tax 14 — Total cash flow hedges (13 ) (1,600 ) Retirement plan obligations (Note 10) Amortization of deferred benefit pension plans Prior service costs 12 12 Other, net Actuarial losses 199 160 Other, net 211 172 Tax benefit (73 ) (24 ) Income tax provision Net of tax 138 148 Amortization of deferred benefit other plans Prior service costs (58 ) (116 ) Other, net Actuarial gains 12 (209 ) Other, net (46 ) (325 ) Tax expense — 76 Income tax provision Net of tax (46 ) (249 ) Total reclassifications, net of tax $ 79 $ (1,701 )

Stock-Based Compensation

Stock-Based Compensation	3 Months Ended
	Mar. 31, 2021
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Stock-Based Compensation	9. STOCK-BASED The P. H. Glatfelter Amended and Restated Long-Term Incentive Plan (the “LTIP”) provides for the issuance of Glatfelter common stock to eligible participants in the form of restricted stock units, restricted stock awards, non-qualified stock options, performance shares, incentive stock options and performance units. Pursuant to terms of the LTIP, we have issued to eligible participants restricted stock units (“RSUs”), performance share awards (“PSAs”) and stock only stock appreciation rights. In 2021, we issued awards of RSUs and PSAs under our LTIP. Approximately 40% of fair value of the awards granted in 2021 were RSUs, which vest based on the passage of time, generally over a three-year period or in certain instances the RSUs were issued with five-year cliff vesting. In addition, some awards vest over one year or less depending upon the retirement eligibility of the grantees in the LTIP. The remaining 60% of the fair value of the awards granted in 2021 were PSAs. The PSAs awarded in 2021 vest based on either the achievement of a cumulative financial performance target covering a two-year period followed by an additional one-year service period or based on the three-year total shareholder return relative to a broad market index. The performance measures include a minimum, target and maximum performance level providing the grantees an opportunity to receive more or less shares than targeted depending on actual financial performance. For RSUs, the grant date fair value of the awards, or the closing price per common share on the date of the award, is used to determine the amount of expense to be recognized over the applicable service period. For PSAs, the grant date fair value is estimated using a lattice model. The significant inputs include the stock price, volatility, dividend yield, and risk-free rate of return. Settlement of RSUs and PSAs will be made in shares of our common stock currently held in treasury. The following table summarizes RSU and PSA activity during periods indicated: Units 2021 2020 Balance at January 1, 1,071,652 896,463 Granted 287,805 294,315 Forfeited (90,355 ) (17,455 ) Shares delivered (123,038 ) (78,509 ) Balance at March 31, 1,146,064 1,094,814 The amount granted in 2021 and 2020 includes 161,453 and 168,663, respectively, of PSAs exclusive of reinvested dividends. The following table sets forth aggregate RSU and PSA compensation expense included in continuing operations for the periods indicated: March 31 In thousands 2021 2020 Three months ended $ 1,208 $ 1,085 Stock Only Stock Appreciation Rights (“SOSARs”) Under terms of the SOSAR, a recipient receives the right to a payment in the form of shares of common stock equal to the difference, if any, in the fair market value of one share of common stock at the time of exercising the SOSAR and the exercise price. The SOSARs vest ratably over a three-year The following table sets forth information related to outstanding SOSARS: 2021 2020 SOSARS Shares Wtd Avg Exercise Price Shares Wtd Avg Exercise Price Outstanding at January 1, 1,082,413 $ 20.40 1,291,947 $ 20.05 Granted — — — — Exercised — — (44,710 ) 12.94 Canceled / forfeited — — (2,841 ) 17.27 Outstanding at March 31, 1,082,413 $ 20.40 1,244,396 $ 20.31

Retirement Plans and Other Post

Retirement Plans and Other Post-Retirement Benefits	3 Months Ended
	Mar. 31, 2021
Compensation And Retirement Disclosure [Abstract]
Retirement Plans and Other Post-Retirement Benefits	1 0 . RETIREMENT PLANS AND OTHER POST-RETIREMENT BENEFITS The following tables provide information with respect to the net periodic costs of our pension and post-retirement medical benefit plans included in continuing operations. Three months ended March 31 In thousands 2021 2020 Pension Benefits Service cost $ — $ 44 Interest cost 250 301 Amortization of prior service cost 12 12 Amortization of actuarial loss 199 160 Total net periodic benefit expense $ 461 $ 517 Other Benefits Service cost $ 7 $ 7 Interest cost 32 46 Amortization of prior service credit (58 ) (116 ) Amortization of actuarial loss (gain) 12 (209 ) Total net periodic benefit income $ (7 ) $ (272 )

Income Taxes

Income Taxes	3 Months Ended
	Mar. 31, 2021
Income Tax Disclosure [Abstract]
Income Taxes	1 1 . INCOME TAXES Income taxes are recognized for the amount of taxes payable or refundable for the current year and deferred tax liabilities and assets for the future tax consequences of events that have been recognized in our condensed consolidated financial statements or tax returns. The effects of income taxes are measured based on enacted tax laws and rates. For the three months ended March 31, 2021, we had pretax income of $15.6 million and income tax expense of $7.2 million. The effective income tax rate for the period ended March 31, 2021, was unfavorably impacted primarily by $4.5 million in operating losses in the U.S. which generated no tax benefit and a $0.5 million impact attributable to a local income tax rate increase in Germany. For the three months ended March 31, 2021, we recorded a decrease in our valuation allowance of $1.0 million against our net deferred tax assets. In assessing the need for a valuation allowance, management considers all available positive and negative evidence in its analysis. Based on this analysis, we recorded a valuation allowance for the portion of deferred tax assets where the weight of the evidence indicated it is more likely than not that the deferred assets will not be realized. As of March 31, 2021 and December 31, 2020, we had $47.2 million and $46.3 million, respectively, of gross unrecognized tax benefits. As of March 31, 2021, if such benefits were to be recognized, approximately $36.7 million would be recorded as a component of income tax expense, thereby affecting our effective tax rate. We, or one of our subsidiaries, file income tax returns with the United States Internal Revenue Service, as well as various state and foreign authorities. The following table summarizes, by major jurisdiction, tax years that remain subject to examination: Open Tax Years Jurisdiction Examinations not yet initiated Examinations in progress United States Federal 2014 - 2015; 2017 - 2020 N/A State 2016 - 2020 2015 - 2018 Canada (1) 2013 - 2018; 2020 2019 Germany (1) 2016 - 2020 N/A France 2018 - 2020 N/A United Kingdom 2019 - 2020 N/A Philippines 2019 - 2020 2018 (1) includes provincial or similar local jurisdictions, as applicable The amount of income taxes we pay is subject to ongoing audits by federal, state and foreign tax authorities, which often result in proposed assessments. Management performs a comprehensive review of its global tax positions on a quarterly basis and accrues amounts for uncertain tax positions. Based on these reviews and the result of discussions and resolutions of matters with certain tax authorities and the closure of tax years subject to tax audit, reserves are adjusted as necessary. However, future results may include favorable or unfavorable adjustments to our estimated tax liabilities in the period the assessments are determined or resolved or as such statutes are closed. Due to potential for resolution of federal, state and foreign examinations, and the lapse of various statutes of limitation, it is reasonably possible our gross unrecognized tax benefits balance may decrease within the next twelve months by a range of zero to $6.3 million. Substantially all of this range relates to tax positions taken in the U.S. We recognize interest and penalties related to uncertain tax positions as income tax expense. The following table summarizes information included in continuing operations related to interest on uncertain tax positions: Three months ended March 31 In millions 2021 2020 Interest expense (income) $ 0.2 $ 0.1 March 31 December 31 2021 2020 Accrued interest payable $ 2.0 $ 1.8

Inventories

Inventories	3 Months Ended
	Mar. 31, 2021
Inventory Disclosure [Abstract]
Inventories	1 2 . INVENTORIES Inventories, net of reserves, were as follows: March 31 December 31 In thousands 2021 2020 Raw materials $ 57,700 $ 55,466 In-process and finished 101,830 97,109 Supplies 43,803 43,655 Total $ 203,333 $ 196,230

Leases

Leases	3 Months Ended
	Mar. 31, 2021
Leases [Abstract]
Leases	13 . LEASES We enter into a variety of arrangements in which we are the lessee for the use of automobiles, forklifts and other production equipment, production facilities, warehouses and office space. We determine if an arrangement contains a lease at inception. All our lease arrangements are operating leases and are recorded in the condensed consolidated balance sheet under the caption “Other assets” and the lease obligation is under “Other current liabilities” and “Other long-term liabilities.” We currently do not have any finance leases. Operating lease right of use (“ROU”) assets and operating lease liabilities are recognized based on the present value of the future minimum lease payments over the lease term at commencement date. ROU assets also include any initial direct costs incurred and any lease payments made at or before the lease commencement date, less lease incentives received. We use our incremental borrowing rate based on information available at the commencement date in determining the lease liabilities as our leases generally do not provide an implicit rate. Lease terms may include options to extend or terminate when we are reasonably certain that the option will be exercised. Lease expense is recognized on a straight-line basis over the lease term. The following table sets forth information related to our leases as of the periods indicated. March 31 December 31 Dollars in thousands 2021 2020 Right of use asset $ 15,605 $ 11,789 Weighted average discount rate 2.95 % 2.94 % Weighted average remaining maturity (months) 89 66 The following table sets for operating lease expense for the periods indicated: March 31 In thousands 2021 2020 Three months ended 1,347 1,442 The following table sets forth required future minimum lease payments for the years indicated: In thousands 2021 $ 3,518 2022 3,475 2023 2,039 2024 1,537 2025 1,278 Thereafter 7,440

Short-Term Debt

Short-Term Debt	3 Months Ended
	Mar. 31, 2021
Debt Disclosure [Abstract]
Short-Term Debt	1 4 . SHORT-TERM DEBT On March 30, 2021, through Glatfelter Gernsbach GmbH, a wholly-owned subsidiary, we borrowed $11.7 million from Commerzbank AG, a German financial institution. The non-amortizing borrowing bears a fixed-interest rate of 0.75% per annum and the loan matures on March 29, 2022. The proceeds were used for general purposes.

Long-Term Debt

Long-Term Debt	3 Months Ended
	Mar. 31, 2021
Debt Disclosure [Abstract]
Long-Term Debt	1 5 . LONG-TERM DEBT Long-term debt is summarized as follows: March 31 December 31 In thousands 2021 2020 Revolving credit facility, due Feb. 2024 $ 36,531 $ 36,813 Term loan, due Feb. 2024 235,379 249,715 2.40% Term Loan, due Jun. 2022 2,094 2,629 2.05% Term Loan, due Mar. 2023 12,516 14,737 1.30% Term Loan, due Jun. 2023 3,769 4,382 1.55% Term Loan, due Sep. 2025 6,466 7,143 Total long-term debt 296,755 315,419 Less current portion (23,942 ) (25,057 ) Unamortized deferred issuance costs (1,734 ) (1,898 ) Long-term debt, net of current portion $ 271,079 $ 288,464 On February 8, 2019, we entered into an amended and restated $400 million Revolving Credit Facility and a €220 million Term Loan with a consortium of banks (together, the “Credit Agreement”). The proceeds of the Term Loan due Feb. 2024 were used to redeem in its entirety the 5.375% Notes. The principal amount of the Term Loan amortizes in consecutive quarterly installments of principal, with each such quarterly installment to be in an amount equal to 1.25% of the Term Loan funded, commencing on July 1, 2019 and continuing quarterly thereafter. For all U.S. dollar denominated borrowings under the Revolving Credit Facility, the borrowing rate is, at our option, either, (a) the bank’s base rate which is equal to the greater of i) the prime rate; ii) the federal funds rate plus 50 basis points; or iii) the Euro-rate plus 100 basis points plus an applicable spread over either i), ii) or iii) ranging from 12.5 basis points to 100 basis points based on the Company’s leverage ratio and its corporate credit ratings determined by Standard & Poor’s Rating Services and Moody’s Investor Service, Inc. (the “Corporate Credit Rating”); or (b) the Euro-rate plus an applicable margin ranging from 112.5 basis points to 200 basis points based on the Company’s leverage ratio and the Corporate Credit Rating. For non-US dollar denominated borrowings, the borrowing rate is, at our option, based on (b) above or for Euro denominated borrowings, the Euro Interbank Offering Rate (“EURIBOR”) plus an applicable margin ranging from 112.5 basis points to 200 basis points based on the Company’s leverage ratio and the Corporate Credit Rating. The Credit Agreement contains a number of customary covenants for financings of this type that, among other things, restrict our ability to dispose of or create liens on assets, incur additional indebtedness, repay other indebtedness, limits certain intercompany financing arrangements, make acquisitions and engage in mergers or consolidations. We are also required to comply with specified financial tests and ratios including: i) maximum net debt to EBITDA ratio (the “leverage ratio”); and ii) a consolidated EBITDA to interest expense ratio. The most restrictive of our covenants is a maximum leverage ratio of 4.0x provided that such ratio increases to 4.5x during the period of four fiscal quarters immediately following a material acquisition. As of March 31, 2021, the leverage ratio, as calculated in accordance with the definition in our Credit Agreement, was 1.8x. A breach of these requirements would give rise to certain remedies under the Revolving Credit Facility, among which are the termination of the agreement and accelerated repayment of the outstanding borrowings plus accrued and unpaid interest under the Credit Agreement. All remaining principal outstanding and accrued interest under the Credit Agreement will be due and payable on February 8, 2024. Glatfelter Gernsbach GmbH (“Gernsbach”), a wholly-owned subsidiary of ours, entered into a series of borrowing agreements with IKB Deutsche Industriebank AG, Düsseldorf (“IKB”) as summarized below: Amounts in thousands Original Principal Interest Rate Maturity Borrowing date Apr. 11, 2013 € 42,700 2.05 % Mar. 2023 Sep. 4, 2014 10,000 2.40 % Jun. 2022 Oct. 10, 2015 2,608 1.55 % Sep. 2025 Apr. 26, 2016 10,000 1.30 % Jun. 2023 May 4, 2016 7,195 1.55 % Sep. 2025 Each of the borrowings require quarterly repayments of principal and interest and provide for representations, warranties and covenants customary for financings of these types. The financial covenants contained in each of the IKB loans, which relate to the minimum ratio of consolidated EBITDA to consolidated interest expense and the maximum ratio of consolidated total net debt to consolidated adjusted EBITDA, are calculated by reference to our Credit Agreement. Glatfelter Corporation guarantees all debt obligations of its subsidiaries. All such obligations are recorded in these condensed consolidated financial statements. Letters of credit issued to us by certain financial institutions totaled $7.3 million as of March 31, 2021 and December 31, 2020. The letters of credit, which reduce amounts available under our Revolving Credit Facility, primarily provide financial assurances for the benefit of certain state workers compensation insurance agencies in conjunction with our self-insurance program and for performance of certain remediation activity related to the Fox River matter. We bear the credit risk on this amount to the extent that we do not comply with the provisions of certain agreements. No amounts are outstanding under the letters of credit.

Fair Value of Financial Instrum

Fair Value of Financial Instruments	3 Months Ended
	Mar. 31, 2021
Fair Value Disclosures [Abstract]
Fair Value of Financial Instruments	1 6 . FAIR VALUE OF FINANCIAL INSTRUMENTS The amounts reported on the condensed consolidated balance sheets for cash and cash equivalents, accounts receivable, accounts payable and short-term debt approximate their respective fair value. The following table sets forth carrying value and fair value of long-term debt: March 31, 2021 December 31, 2020 In thousands Carrying Value Fair Value Carrying Value Fair Value Variable rate debt $ 36,531 $ 36,531 $ 36,813 $ 36,813 Term loan, due Feb. 2024 235,379 235,379 249,715 249,715 2.40% Term Loan 2,094 2,116 2,629 2,651 2.05% Term Loan 12,516 12,669 14,737 14,873 1.30% Term Loan 3,769 3,784 4,382 4,384 1.55% Term Loan 6,466 6,544 7,143 7,210 Total $ 296,755 $ 297,023 $ 315,419 $ 315,646 The values set forth above are based on observable inputs and other relevant market data (Level 2). The fair value of financial derivatives is set forth below in Note 17.

Financial Derivatives and Hedgi

Financial Derivatives and Hedging Activities	3 Months Ended
	Mar. 31, 2021
Derivative Instruments And Hedging Activities Disclosure [Abstract]
Financial Derivatives and Hedging Activities	1 7 . FINANCIAL DERIVATIVES AND HEDGING ACTIVITIES As part of our overall risk management practices, we enter into financial derivatives primarily designed to either i) hedge foreign currency risks associated with forecasted transactions (“cash flow hedges”); ii) mitigate the impact that changes in currency exchange rates have on intercompany financing transactions and foreign currency denominated receivables and payables (“foreign currency hedges”); or iii) convert variable-interest-rate debt to fixed rates. Derivatives Designated as Hedging Instruments - Cash Flow Hedges We use currency forward contracts as cash flow hedges to manage our exposure to fluctuations in the currency exchange rates on certain forecasted production costs. Currency forward contracts involve fixing the exchange for delivery of a specified amount of foreign currency on a specified date. As of March 31, 2021, the maturity of currency forward contracts ranged from one month to 18 months. We designate certain currency forward contracts as cash flow hedges of forecasted raw material purchases, certain production costs or capital expenditures with exposure to changes in foreign currency exchange rates. Changes in the fair value of derivatives designated and that qualify as cash flow hedges of foreign exchange risk is deferred as a component of accumulated other comprehensive income in the accompanying condensed consolidated balance sheets. With respect to hedges of forecasted raw material purchases or production costs, the amount deferred is subsequently reclassified into costs of products sold in the period that inventory produced using the hedged transaction affects earnings. For hedged capital expenditures, deferred gains or losses are reclassified and included in the historical cost of the capital asset and subsequently affect earnings as depreciation is recognized. We had the following outstanding derivatives that were used to hedge foreign exchange risks associated with forecasted transactions and designated as hedging instruments: In thousands March 31, 2021 December 31, 2020 Derivative Sell/Buy - sell notional Philippine Peso / Euro — 18,522 Euro / British Pound 17,219 18,638 U.S. Dollar / Euro — 1,041 Canadian Dollar / U.S. Dollar — 70 Sell/Buy - buy notional Euro / Philippine Peso 1,003,403 853,686 British Pound / Philippine Peso 1,006,093 1,081,791 Euro / U.S. Dollar 72,770 69,324 U.S. Dollar / Canadian Dollar 34,707 34,847 In October 2019, we entered into a €180 million notional value floating-to-fixed interest rate swap agreement with certain financial institutions. Under the terms of the swap, we will pay a fixed interest rate of the applicable margin plus 0.0395% on €180 million of the underlying variable rate term loan. We will receive the greater of 0.00% or EURIBOR. Derivatives Designated as Hedging Instruments – Net Investment Hedge The €220 million Term Loan discussed in Note 15 – “ Long-Term Debt” is designated as a net investment hedge of our Euro functional currency foreign subsidiaries. During the first three months of 2021, we recognized a pre-tax gain of $11.0 million and in the same period of 2020 a pre-tax gain of $5.9 million on the remeasurement of the term loan from changes in currency exchange rates. Such amounts are recorded as a component of Other Comprehensive Income (Loss). Derivatives Not Designated as Hedging Instruments - Foreign Currency Hedges We also entered into forward foreign exchange contracts to mitigate the impact changes in currency exchange rates have on balance sheet monetary assets and liabilities. None of these contracts are designated as hedges for financial accounting purposes and, accordingly, changes in value of the foreign exchange forward contracts and in the offsetting underlying on-balance-sheet transactions are reflected in the accompanying condensed consolidated statements of income under the caption “Other, net.” The following sets forth derivatives used to mitigate the impact changes in currency exchange rates have on balance sheet monetary assets and liabilities: In thousands March 31, 2021 December 31, 2020 Derivative Sell/Buy - sell notional U.S. Dollar / British Pound 25,850 25,250 U.S. Dollar / Euro 250 — Euro / British Pound 500 600 British Pound / Euro 2,200 1,900 Sell/Buy - buy notional Euro / U.S. Dollar — 7,500 These contracts have maturities of one month from the date originally entered into. Fair Value Measurements The following table summarizes the fair values of derivative instruments for the period indicated and the line items in the accompanying condensed consolidated balance sheets where the instruments are recorded: In thousands March 31, 2021 December 31, 2020 March 31, 2021 December 31, 2020 Prepaid Expenses and Other Other Balance sheet caption Current Assets Current Liabilities Designated as hedging: Forward foreign currency exchange contracts $ 1,876 $ 577 $ 406 $ 4,342 Interest rate swap — — 108 136 Not designated as hedging: Forward foreign currency exchange contracts $ 66 $ 456 $ 349 $ 118 The amounts set forth in the table above represent the net asset or liability giving effect to rights of offset with each counterparty. The effect of netting the amounts presented above did not have a material effect on our consolidated financial position. The fair value hierarchy consists of three broad levels, which gives the highest priority to unadjusted quoted prices in active markets for identical assets or liabilities (Level 1) and the lowest priority to unobservable inputs (Level 3). The fair values of the foreign exchange forward contracts are considered to be Level 2. Foreign currency forward contracts are valued using foreign currency forward and interest rate curves. The fair value of each contract is determined by comparing the contract rate to the forward rate and discounting to present value. Contracts in a gain position are recorded in the condensed consolidated balance sheets under the caption “Prepaid expenses and other current assets” and the value of contracts in a loss position is recorded under the caption “Other current liabilities.” The following table summarizes the amount of income or (loss) from derivative instruments recognized in our results of operations for the periods indicated and the line items in the accompanying condensed consolidated statements of income where the results are recorded: Three months ended March 31 In thousands 2021 2020 Designated as hedging: Forward foreign currency exchange contracts: Cost of products sold $ (24 ) $ 2,182 Interest expense 21 — Not designated as hedging: Forward foreign currency exchange contracts: Other – net $ 270 $ (619 ) The impact of activity not designated as hedging was substantially all offset by the remeasurement of the underlying on-balance-sheet item. A rollforward of fair value amounts recorded as a component of accumulated other comprehensive income (loss), before taxes, is as follows: In thousands 2021 2020 Balance at January 1, $ (3,460 ) $ 5,859 Deferred gains (losses) on cash flow hedges 4,558 463 Reclassified to earnings 3 (2,182 ) Balance at March 31, $ 1,101 $ 4,140 We expect substantially all of the amounts recorded as a component of accumulated other comprehensive income will be recorded in results of operations within the next 12 to 18 months and the amount ultimately recognized will vary depending on actual market rates. Credit risk related to derivative activity arises in the event the counterparty fails to meet its obligations to us. This exposure is generally limited to the amounts, if any, by which the counterparty’s obligations exceed our obligation to them. Our policy is to enter into contracts only with financial institutions which meet certain minimum credit ratings.

Commitments, Contingencies and

Commitments, Contingencies and Legal Proceedings	3 Months Ended
	Mar. 31, 2021
Commitments And Contingencies Disclosure [Abstract]
Commitments, Contingencies and Legal Proceedings	18 . COMMITMENTS, CONTINGENCIES AND LEGAL PROCEEDINGS Fox River - Neenah, Wisconsin Background We have previously reported that we face liabilities associated with environmental claims arising out of the presence of polychlorinated biphenyls (“PCBs”) in sediments in the lower Fox River, on which our former Neenah facility was located, and in the Bay of Green Bay, Wisconsin (collectively, the “Site”). Since the early 1990s, the United States, the State of Wisconsin and two Indian tribes (collectively, the “Governments”) have pursued a cleanup of a 39-mile stretch of river from Little Lake Butte des Morts into Green Bay and natural resource damages (“NRDs”). The United States originally notified several entities that they were potentially responsible parties (“PRPs”); however, after giving effect to settlements reached with the Governments, the remaining PRPs exposed to continuing obligations to implement the remainder of the cleanup consist of us, Georgia-Pacific Consumer Products, L.P. (“Georgia-Pacific”) and NCR Corporation. The United States Environmental Protection Agency (“EPA”) has divided the Site into five “operable units”, including the most upstream portion of the Site on which our facility was located (“OU1”) and four downstream reaches of the river and bay (“OU2-5”). Over the past several years, we and certain other PRPs implemented and completed all remedial actions pursuant to applicable consent decrees or a Unilateral Administrative Order. In January 2019, we reached an agreement with the United States, the State of Wisconsin, and Georgia-Pacific to resolve all remaining claims among those parties. Under the Glatfelter consent decree, we are primarily responsible for long-term monitoring and maintenance in OU2-OU4a and for reimbursement of government oversight costs paid after October 2018. Finally, we remain responsible for our obligation to continue long-term monitoring and maintenance under our OU1 consent decree. Cost estimates Our remaining obligations under the OU1 consent decree consist of long-term monitoring and maintenance. Furthermore, we are primarily responsible for long term monitoring and maintenance in OU2-OU4a over a period of at least 30 years. The monitoring activities consist of, among others, testing fish tissue, sampling water quality and sediment, and inspections of the engineered caps. In 2018, we entered into a fixed-price, 30-year agreement with a third party for the performance of all of our monitoring and maintenance obligations in OU1 through OU4a with limited exceptions, such as, for extraordinary amounts of cap maintenance or replacement. Our obligation under this agreement is included in our total reserve for the Site. We are obligated to make the regular payments under that fixed-price contract until the remaining amount due is less than the OU1 escrow account balance. We are permitted to pay for this contract using the remaining balance of the escrow account established by us and WTM I Company (“WTM I”) another PRP, under the OU1 consent decree during any period that the balance in the escrow account exceeds the amount due under our fixed-price contract. As of March 31, 2021, the balance in the escrow is less than amounts due under the fixed-price contract by approximately $1.6 million. Our obligation to pay this difference is secured by a letter of credit At March 31, 2021, the escrow account balance totaled $8.9 million which is included in the condensed consolidated balance sheet under the caption “Other assets.” Under the consent decree, we are responsible for reimbursement of government oversight costs paid from October 2018 and later over approximately the next 30 years. We anticipate that oversight costs will decline as activities at the site transition from remediation to long-term monitoring and maintenance. Reserves for the Site Our reserve for past and future government oversight costs and long-term monitoring and maintenance is set forth below: Three months ended March 31 In thousands 2021 2020 Balance at January 1, $ 18,455 $ 21,870 Payments (420 ) (131 ) Accretion 51 52 Balance at March 31, $ 18,086 $ 21,791 The payments set forth above represent amounts due under the long-term monitoring and maintenance agreement. With respect to our total reserve for the Fox River, $3.6 million is recorded in the accompanying March 31, 2021 condensed consolidated balance sheet under the caption “Environmental liabilities” and the remaining $14.5 million is recorded under the caption “Other long-term liabilities.” Range of Reasonably Possible Outcomes Based on our analysis of all available information, including but not limited to decisions of the courts, official documents such as records of decision, discussions with legal counsel, cost estimates for future monitoring and maintenance and other post-remediation costs to be performed at the Site, we do not believe that our costs associated with the Fox River matter could exceed the aggregate amounts accrued by a material amount.

Segment Information

Segment Information	3 Months Ended
	Mar. 31, 2021
Segment Reporting [Abstract]
Segment Information	19 . SEGMENT INFORMATION The following tables set forth financial and other information by segment for the period indicated: Three months ended March 31 Other and Dollars in thousands Composite Fibers Airlaid Materials Unallocated Total 2021 2020 2021 2020 2021 2020 2021 2020 Net sales $ 141,249 $ 132,711 $ 84,425 $ 98,849 $ — $ — $ 225,674 $ 231,560 Cost of products sold 114,267 106,985 72,585 82,246 (474 ) 5,454 186,378 194,685 Gross profit (loss) 26,982 25,726 11,840 16,603 474 (5,454 ) 39,296 36,875 SG&A 10,917 10,624 4,643 4,581 7,267 9,389 22,827 24,594 Gains on dispositions of plant, equipment and timberlands, net — — — — (850 ) - (850 ) - Total operating income (loss) 16,065 15,102 7,197 12,022 (5,943 ) (14,843 ) 17,319 12,281 Non-operating expense — — — — (1,735 ) (2,267 ) (1,735 ) (2,267 ) Income (loss) before income taxes $ 16,065 $ 15,102 $ 7,197 $ 12,022 $ (7,678 ) $ (17,110 ) $ 15,584 $ 10,014 Supplementary Data Net tons sold 34,140 35,983 28,864 35,039 — — 63,004 71,022 Depreciation, depletion and amortization ($ in thousands) (1) $ 6,981 $ 6,466 $ 5,848 $ 5,451 $ 904 $ 3,485 $ 13,733 $ 15,402 Capital expenditures 2,773 3,956 1,739 2,103 867 955 5,379 7,014 (1) The amount presented in 2020 in the Other and unallocated column represents accelerated depreciation incurred in connection with the restructuring of our metallized operations. Segments Results of individual operating segments are presented based on our management accounting practices and management structure. There is no comprehensive, authoritative body of guidance for management accounting equivalent to accounting principles generally accepted in the United States of America; therefore, the financial results of individual segments are not necessarily comparable with similar information for any other company. The management accounting process uses assumptions and allocations to measure performance of the segments. Methodologies are refined from time to time as management accounting practices are enhanced and businesses change. The costs incurred by support areas not directly aligned with the segment are allocated primarily based on an estimated utilization of support area services or are included in “Other and Unallocated” in the table set forth above. Management evaluates results of operations of the operating segments before certain corporate level costs and the effects of certain gains or losses not considered to be related to the core business operations. Management believes that this is a more meaningful representation of the operating performance of its core businesses, the profitability of the segments and the extent of cash flow generated from these core operations. Such amounts are presented under the caption “Other and Unallocated.” In the evaluation of operating segments results, management does not use any measures of total assets. This presentation is aligned with the management and operating structure of our company. It is also on this basis that the Company’s performance is evaluated internally and by the Company’s Board of Directors.

Accounting Policies (Policies)

Accounting Policies (Policies)	3 Months Ended
	Mar. 31, 2021
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 2020 Annual Report on Form 10-K.
Discontinued Operations	Discontinued Operations The results of operations and cash flows of our former Specialty Papers business 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 December 2019, the Financial Accounting Standards Board issued Accounting Standards Update No. 2019-12, Income Taxes (Topic 740): Simplifying the Accounting for Income Taxes (“ASU No. 2019-12”) . The update eliminates, clarifies, and modifies certain guidance related to the accounting for income taxes. We adopted ASU No. 2019-12 effective January 1, 2021 and it did not have a material impact on our financial statements.

Revenue (Tables)

Revenue (Tables)	3 Months Ended
	Mar. 31, 2021
Disaggregation Of Revenue [Abstract]
Summary of Disaggregated Information Pertaining to Net Sales	The following tables set forth disaggregated information pertaining to our net sales: Three months ended March 31 In thousands 2021 2020 Composite Fibers Food & beverage $ 76,953 $ 71,458 Wallcovering 22,629 19,893 Technical specialties 23,495 20,007 Composite laminates 9,809 9,763 Metallized 8,363 11,590 141,249 132,711 Airlaid Materials Feminine hygiene 47,641 50,096 Specialty wipes 15,916 17,212 Tabletop 6,863 15,052 Adult incontinence 4,678 6,145 Home care 3,923 5,212 Other 5,404 5,132 84,425 98,849 $ 225,674 $ 231,560 Three months ended March 31 In thousands 2021 2020 Composite Fibers Europe, Middle East and Africa $ 86,945 $ 79,586 Americas 31,841 32,721 Asia Pacific 22,463 20,404 141,249 132,711 Airlaid Materials Europe, Middle East and Africa 45,072 52,720 Americas 37,485 44,386 Asia Pacific 1,868 1,743 84,425 98,849 $ 225,674 $ 231,560

Gain on Dispositions of Plant_2

Gain on Dispositions of Plant, Equipment and Timberlands (Tables)	3 Months Ended
	Mar. 31, 2021
Property Plant And Equipment [Abstract]
Summary for Sale of Timberlands and Other Assets	The following table sets forth sales of timberlands and other assets completed during the first three months of 2021. There were no such sales in the first three months of 2020: Dollars in thousands Acres Proceeds Gain 2021 Timberlands 358 $ 876 $ 850 Other n/a — — Total $ 876 $ 850

Discontinued Operations (Tables

Discontinued Operations (Tables)	3 Months Ended
	Mar. 31, 2021
Discontinued Operations And Disposal Groups [Abstract]
Summary of Cash Flows from Discontinued Operations Included in Condensed Consolidated Statements of Cash Flows	The following table sets forth a summary of cash flows from discontinued operations which is included in the condensed consolidated statements of cash flows: Three months ended March 31 In thousands 2021 2020 Net cash used by operating activities $ (78 ) $ (316 ) Net cash used by investing activities — — Net cash provided by financing activities — — Change in cash and cash equivalents from discontinued operations $ (78 ) $ (316 )

Earnings Per Share (Tables)

Earnings Per Share (Tables)	3 Months Ended
	Mar. 31, 2021
Earnings Per Share [Abstract]
Details of Basic and Diluted Earnings Per Share (EPS) from Continuing Operations	The following table sets forth the details of basic and diluted earnings per share (“EPS”) from continuing operations: Three months ended March 31 In thousands, except per share 2021 2020 Income from continuing operations $ 8,394 $ 7,406 Weighted average common shares outstanding used in basic EPS 44,450 44,275 Effect of dilutive SOSARs, PSAs and RSUs 419 255 Weighted average common shares outstanding and common share equivalents used in diluted EPS 44,869 44,530 Earnings per share from continuing operations Basic $ 0.19 $ 0.17 Diluted 0.19 0.17
Number of Potential Common Shares that have been Excluded from Computation of Diluted Earnings Per Share for Indicated Period Due to Their Anti-Dilutive Nature	The following table sets forth potential common shares outstanding that were not included in the computation of diluted EPS for the periods indicated, because their effect would be anti-dilutive: March 31 In thousands 2021 2020 Three months ended 1,082 1,231

Accumulated Other Comprehensi_2

Accumulated Other Comprehensive Income (Tables)	3 Months Ended
	Mar. 31, 2021
Equity [Abstract]
Schedule of Changes in Accumulated Other Comprehensive Income (Losses)	The following table sets forth details of the changes in accumulated other comprehensive income (losses) for the three months ended March 31, 2021 and 2020. In thousands Currency translation adjustments Unrealized gain (loss) on cash flow hedges Change in pensions Change in other postretirement defined benefit plans Total Balance at January 1, 2021 $ (42,525 ) $ (2,496 ) $ (12,844 ) $ (788 ) $ (58,653 ) Other comprehensive income (loss) before reclassifications (net of tax) (13,193 ) 3,274 — — (9,919 ) Amounts reclassified from accumulated other comprehensive income (net of tax) — (13 ) 138 (46 ) 79 Net current period other comprehensive income (loss) (13,193 ) 3,261 138 (46 ) (9,840 ) Balance at March 31, 2021 $ (55,718 ) $ 765 $ (12,706 ) $ (834 ) $ (68,493 ) Balance at January 1, 2020 $ (76,346 ) $ 4,316 $ (7,253 ) $ 1,387 $ (77,896 ) Other comprehensive income (loss) before reclassifications (net of tax) (13,903 ) 283 — — (13,620 ) Amounts reclassified from accumulated other comprehensive income (net of tax) — (1,600 ) 148 (249 ) (1,701 ) Net current period other comprehensive income (loss) (13,903 ) (1,317 ) 148 (249 ) (15,321 ) Balance at March 31, 2020 $ (90,249 ) $ 2,999 $ (7,105 ) $ 1,138 $ (93,217 )
Schedule of Amounts Reclassified from Accumulated Other Comprehensive Income and Into the Condensed Consolidated Statements of Income	Reclassifications out of accumulated other comprehensive income and into the condensed consolidated statements of income were as follows: Three months ended March 31 In thousands 2021 2020 Description Line Item in Statements of Income Cash flow hedges (Note 17) (Gains) losses on cash flow hedges $ 24 $ (2,182 ) Costs of products sold Tax expense (benefit) (51 ) 582 Income tax provision Net of tax (27 ) (1,600 ) Loss on interest rate swaps 21 — Interest expense Tax benefit (7 ) — Income tax provision Net of tax 14 — Total cash flow hedges (13 ) (1,600 ) Retirement plan obligations (Note 10) Amortization of deferred benefit pension plans Prior service costs 12 12 Other, net Actuarial losses 199 160 Other, net 211 172 Tax benefit (73 ) (24 ) Income tax provision Net of tax 138 148 Amortization of deferred benefit other plans Prior service costs (58 ) (116 ) Other, net Actuarial gains 12 (209 ) Other, net (46 ) (325 ) Tax expense — 76 Income tax provision Net of tax (46 ) (249 ) Total reclassifications, net of tax $ 79 $ (1,701 )

Stock-Based Compensation (Table

Stock-Based Compensation (Tables)	3 Months Ended
	Mar. 31, 2021
Restricted Stock Units (RSU) and Performance Share Awards (PSAs) [Member]
Summary of Share Based Compensation Activity	The following table summarizes RSU and PSA activity during periods indicated: Units 2021 2020 Balance at January 1, 1,071,652 896,463 Granted 287,805 294,315 Forfeited (90,355 ) (17,455 ) Shares delivered (123,038 ) (78,509 ) Balance at March 31, 1,146,064 1,094,814
Compensation Expense for Stock Option Activity Included in Continuing Operations	The following table sets forth aggregate RSU and PSA compensation expense included in continuing operations for the periods indicated: March 31 In thousands 2021 2020 Three months ended $ 1,208 $ 1,085
Stock Only Stock Appreciation Rights (SOSARs) [Member]
Summary of Share Based Compensation Activity	The following table sets forth information related to outstanding SOSARS: 2021 2020 SOSARS Shares Wtd Avg Exercise Price Shares Wtd Avg Exercise Price Outstanding at January 1, 1,082,413 $ 20.40 1,291,947 $ 20.05 Granted — — — — Exercised — — (44,710 ) 12.94 Canceled / forfeited — — (2,841 ) 17.27 Outstanding at March 31, 1,082,413 $ 20.40 1,244,396 $ 20.31

Retirement Plans and Other Po_2

Retirement Plans and Other Post-Retirement Benefits (Tables)	3 Months Ended
	Mar. 31, 2021
Compensation And Retirement Disclosure [Abstract]
Schedule of Net Periodic Costs of Pension and Post Retirement Medical Benefit Plans Included in Continuing Operations	The following tables provide information with respect to the net periodic costs of our pension and post-retirement medical benefit plans included in continuing operations. Three months ended March 31 In thousands 2021 2020 Pension Benefits Service cost $ — $ 44 Interest cost 250 301 Amortization of prior service cost 12 12 Amortization of actuarial loss 199 160 Total net periodic benefit expense $ 461 $ 517 Other Benefits Service cost $ 7 $ 7 Interest cost 32 46 Amortization of prior service credit (58 ) (116 ) Amortization of actuarial loss (gain) 12 (209 ) Total net periodic benefit income $ (7 ) $ (272 )

Income Taxes (Tables)

Income Taxes (Tables)	3 Months Ended
	Mar. 31, 2021
Income Tax Disclosure [Abstract]
Summary of Tax Years that Remain Subject to Examination by Major Jurisdiction	The following table summarizes, by major jurisdiction, tax years that remain subject to examination: Open Tax Years Jurisdiction Examinations not yet initiated Examinations in progress United States Federal 2014 - 2015; 2017 - 2020 N/A State 2016 - 2020 2015 - 2018 Canada (1) 2013 - 2018; 2020 2019 Germany (1) 2016 - 2020 N/A France 2018 - 2020 N/A United Kingdom 2019 - 2020 N/A Philippines 2019 - 2020 2018 (1) includes provincial or similar local jurisdictions, as applicable
Summary of Information Included in Continuing Operations Related to Interest on Uncertain Tax Positions	The following table summarizes information included in continuing operations related to interest on uncertain tax positions: Three months ended March 31 In millions 2021 2020 Interest expense (income) $ 0.2 $ 0.1 March 31 December 31 2021 2020 Accrued interest payable $ 2.0 $ 1.8

Inventories (Tables)

Inventories (Tables)	3 Months Ended
	Mar. 31, 2021
Inventory Disclosure [Abstract]
Inventories, Net of Reserves	Inventories, net of reserves, were as follows: March 31 December 31 In thousands 2021 2020 Raw materials $ 57,700 $ 55,466 In-process and finished 101,830 97,109 Supplies 43,803 43,655 Total $ 203,333 $ 196,230

Leases (Tables)

Leases (Tables)	3 Months Ended
	Mar. 31, 2021
Leases [Abstract]
Summary of Information Related to Leases	The following table sets forth information related to our leases as of the periods indicated. March 31 December 31 Dollars in thousands 2021 2020 Right of use asset $ 15,605 $ 11,789 Weighted average discount rate 2.95 % 2.94 % Weighted average remaining maturity (months) 89 66 The following table sets for operating lease expense for the periods indicated: March 31 In thousands 2021 2020 Three months ended 1,347 1,442
Summary of Future Minimum Lease Payments	The following table sets forth required future minimum lease payments for the years indicated: In thousands 2021 $ 3,518 2022 3,475 2023 2,039 2024 1,537 2025 1,278 Thereafter 7,440

Long-Term Debt (Tables)

Long-Term Debt (Tables)	3 Months Ended
	Mar. 31, 2021
Debt Disclosure [Abstract]
Summary of Long-Term Debt	Long-term debt is summarized as follows: March 31 December 31 In thousands 2021 2020 Revolving credit facility, due Feb. 2024 $ 36,531 $ 36,813 Term loan, due Feb. 2024 235,379 249,715 2.40% Term Loan, due Jun. 2022 2,094 2,629 2.05% Term Loan, due Mar. 2023 12,516 14,737 1.30% Term Loan, due Jun. 2023 3,769 4,382 1.55% Term Loan, due Sep. 2025 6,466 7,143 Total long-term debt 296,755 315,419 Less current portion (23,942 ) (25,057 ) Unamortized deferred issuance costs (1,734 ) (1,898 ) Long-term debt, net of current portion $ 271,079 $ 288,464
Summary of Debts Borrowed by Subsidiary	Glatfelter Gernsbach GmbH (“Gernsbach”), a wholly-owned subsidiary of ours, entered into a series of borrowing agreements with IKB Deutsche Industriebank AG, Düsseldorf (“IKB”) as summarized below: Amounts in thousands Original Principal Interest Rate Maturity Borrowing date Apr. 11, 2013 € 42,700 2.05 % Mar. 2023 Sep. 4, 2014 10,000 2.40 % Jun. 2022 Oct. 10, 2015 2,608 1.55 % Sep. 2025 Apr. 26, 2016 10,000 1.30 % Jun. 2023 May 4, 2016 7,195 1.55 % Sep. 2025

Fair Value of Financial Instr_2

Fair Value of Financial Instruments (Tables)	3 Months Ended
	Mar. 31, 2021
Fair Value Disclosures [Abstract]
Carrying Value and Fair Value of Long-Term Debt	The following table sets forth carrying value and fair value of long-term debt: March 31, 2021 December 31, 2020 In thousands Carrying Value Fair Value Carrying Value Fair Value Variable rate debt $ 36,531 $ 36,531 $ 36,813 $ 36,813 Term loan, due Feb. 2024 235,379 235,379 249,715 249,715 2.40% Term Loan 2,094 2,116 2,629 2,651 2.05% Term Loan 12,516 12,669 14,737 14,873 1.30% Term Loan 3,769 3,784 4,382 4,384 1.55% Term Loan 6,466 6,544 7,143 7,210 Total $ 296,755 $ 297,023 $ 315,419 $ 315,646

Financial Derivatives and Hed_2

Financial Derivatives and Hedging Activities (Tables)	3 Months Ended
	Mar. 31, 2021
Fair Values of Derivative Instruments	Fair Value Measurements The following table summarizes the fair values of derivative instruments for the period indicated and the line items in the accompanying condensed consolidated balance sheets where the instruments are recorded: In thousands March 31, 2021 December 31, 2020 March 31, 2021 December 31, 2020 Prepaid Expenses and Other Other Balance sheet caption Current Assets Current Liabilities Designated as hedging: Forward foreign currency exchange contracts $ 1,876 $ 577 $ 406 $ 4,342 Interest rate swap — — 108 136 Not designated as hedging: Forward foreign currency exchange contracts $ 66 $ 456 $ 349 $ 118
Income or (Loss) from Derivative Instruments Recognized in Results of Operations	The following table summarizes the amount of income or (loss) from derivative instruments recognized in our results of operations for the periods indicated and the line items in the accompanying condensed consolidated statements of income where the results are recorded: Three months ended March 31 In thousands 2021 2020 Designated as hedging: Forward foreign currency exchange contracts: Cost of products sold $ (24 ) $ 2,182 Interest expense 21 — Not designated as hedging: Forward foreign currency exchange contracts: Other – net $ 270 $ (619 )
Fair Value Amounts Recorded as Component of Accumulated Other Comprehensive Income (Loss) Before Taxes	A rollforward of fair value amounts recorded as a component of accumulated other comprehensive income (loss), before taxes, is as follows: In thousands 2021 2020 Balance at January 1, $ (3,460 ) $ 5,859 Deferred gains (losses) on cash flow hedges 4,558 463 Reclassified to earnings 3 (2,182 ) Balance at March 31, $ 1,101 $ 4,140
Designated as Hedging [Member]
Outstanding Derivatives Used to Hedge Foreign Exchange Risks	We had the following outstanding derivatives that were used to hedge foreign exchange risks associated with forecasted transactions and designated as hedging instruments: In thousands March 31, 2021 December 31, 2020 Derivative Sell/Buy - sell notional Philippine Peso / Euro — 18,522 Euro / British Pound 17,219 18,638 U.S. Dollar / Euro — 1,041 Canadian Dollar / U.S. Dollar — 70 Sell/Buy - buy notional Euro / Philippine Peso 1,003,403 853,686 British Pound / Philippine Peso 1,006,093 1,081,791 Euro / U.S. Dollar 72,770 69,324 U.S. Dollar / Canadian Dollar 34,707 34,847
Not Designated as Hedging [Member]
Outstanding Derivatives Used to Hedge Foreign Exchange Risks	The following sets forth derivatives used to mitigate the impact changes in currency exchange rates have on balance sheet monetary assets and liabilities: In thousands March 31, 2021 December 31, 2020 Derivative Sell/Buy - sell notional U.S. Dollar / British Pound 25,850 25,250 U.S. Dollar / Euro 250 — Euro / British Pound 500 600 British Pound / Euro 2,200 1,900 Sell/Buy - buy notional Euro / U.S. Dollar — 7,500

Commitments, Contingencies an_2

Commitments, Contingencies and Legal Proceedings (Tables)	3 Months Ended
	Mar. 31, 2021
Commitments And Contingencies Disclosure [Abstract]
Schedule of Reserves	Our reserve for past and future government oversight costs and long-term monitoring and maintenance is set forth below: Three months ended March 31 In thousands 2021 2020 Balance at January 1, $ 18,455 $ 21,870 Payments (420 ) (131 ) Accretion 51 52 Balance at March 31, $ 18,086 $ 21,791

Segment Information (Tables)

Segment Information (Tables)	3 Months Ended
	Mar. 31, 2021
Segment Reporting [Abstract]
Schedule of Financial and Other Information by Segment	The following tables set forth financial and other information by segment for the period indicated: Three months ended March 31 Other and Dollars in thousands Composite Fibers Airlaid Materials Unallocated Total 2021 2020 2021 2020 2021 2020 2021 2020 Net sales $ 141,249 $ 132,711 $ 84,425 $ 98,849 $ — $ — $ 225,674 $ 231,560 Cost of products sold 114,267 106,985 72,585 82,246 (474 ) 5,454 186,378 194,685 Gross profit (loss) 26,982 25,726 11,840 16,603 474 (5,454 ) 39,296 36,875 SG&A 10,917 10,624 4,643 4,581 7,267 9,389 22,827 24,594 Gains on dispositions of plant, equipment and timberlands, net — — — — (850 ) - (850 ) - Total operating income (loss) 16,065 15,102 7,197 12,022 (5,943 ) (14,843 ) 17,319 12,281 Non-operating expense — — — — (1,735 ) (2,267 ) (1,735 ) (2,267 ) Income (loss) before income taxes $ 16,065 $ 15,102 $ 7,197 $ 12,022 $ (7,678 ) $ (17,110 ) $ 15,584 $ 10,014 Supplementary Data Net tons sold 34,140 35,983 28,864 35,039 — — 63,004 71,022 Depreciation, depletion and amortization ($ in thousands) (1) $ 6,981 $ 6,466 $ 5,848 $ 5,451 $ 904 $ 3,485 $ 13,733 $ 15,402 Capital expenditures 2,773 3,956 1,739 2,103 867 955 5,379 7,014 (1) The amount presented in 2020 in the Other and unallocated column represents accelerated depreciation incurred in connection with the restructuring of our metallized operations.

Pending Acquisition - Additiona

Pending Acquisition - Additional Information (Details) - G-P U.S. Business [Member] $ in Millions	Jan. 05, 2021USD ($)t	Dec. 31, 2020USD ($)
Business Acquisition [Line Items]
Business acquisition purchase price	$ 175
Annual production capacity | t	37,000
Annual sales of acquiree		$ 100

Revenue - Summary of Disaggrega

Revenue - Summary of Disaggregated Information Pertaining to Net Sales (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Disaggregation Of Revenue [Line Items]
Net sales	$ 225,674	$ 231,560
Product [Member]
Disaggregation Of Revenue [Line Items]
Net sales	225,674	231,560
Composite Fibers [Member]
Disaggregation Of Revenue [Line Items]
Net sales	141,249	132,711
Composite Fibers [Member] | Europe, Middle East and Africa [Member]
Disaggregation Of Revenue [Line Items]
Net sales	86,945	79,586
Composite Fibers [Member] | Americas [Member]
Disaggregation Of Revenue [Line Items]
Net sales	31,841	32,721
Composite Fibers [Member] | Asia Pacific [Member]
Disaggregation Of Revenue [Line Items]
Net sales	22,463	20,404
Composite Fibers [Member] | Food & Beverage [Member]
Disaggregation Of Revenue [Line Items]
Net sales	76,953	71,458
Composite Fibers [Member] | Wallcovering [Member]
Disaggregation Of Revenue [Line Items]
Net sales	22,629	19,893
Composite Fibers [Member] | Technical Specialties [Member]
Disaggregation Of Revenue [Line Items]
Net sales	23,495	20,007
Composite Fibers [Member] | Composite Laminates [Member]
Disaggregation Of Revenue [Line Items]
Net sales	9,809	9,763
Composite Fibers [Member] | Metallized [Member]
Disaggregation Of Revenue [Line Items]
Net sales	8,363	11,590
Airlaid Materials [Member]
Disaggregation Of Revenue [Line Items]
Net sales	84,425	98,849
Airlaid Materials [Member] | Europe, Middle East and Africa [Member]
Disaggregation Of Revenue [Line Items]
Net sales	45,072	52,720
Airlaid Materials [Member] | Americas [Member]
Disaggregation Of Revenue [Line Items]
Net sales	37,485	44,386
Airlaid Materials [Member] | Asia Pacific [Member]
Disaggregation Of Revenue [Line Items]
Net sales	1,868	1,743
Airlaid Materials [Member] | Feminine Hygiene [Member]
Disaggregation Of Revenue [Line Items]
Net sales	47,641	50,096
Airlaid Materials [Member] | Specialty Wipes [Member]
Disaggregation Of Revenue [Line Items]
Net sales	15,916	17,212
Airlaid Materials [Member] | Tabletop [Member]
Disaggregation Of Revenue [Line Items]
Net sales	6,863	15,052
Airlaid Materials [Member] | Adult Incontinence [Member]
Disaggregation Of Revenue [Line Items]
Net sales	4,678	6,145
Airlaid Materials [Member] | Home Care [Member]
Disaggregation Of Revenue [Line Items]
Net sales	3,923	5,212
Airlaid Materials [Member] | Other [Member]
Disaggregation Of Revenue [Line Items]
Net sales	$ 5,404	$ 5,132

Gain on Dispositions of Plant_3

Gain on Dispositions of Plant, Equipment and Timberlands - Summary for Sale of Timberlands and Other Assets (Detail) $ in Thousands	3 Months Ended
	Mar. 31, 2021USD ($)a
Property, Plant and Equipment [Line Items]
Proceeds	$ 876
Gain	$ 850
Timberlands [Member]
Property, Plant and Equipment [Line Items]
Acres | a	358
Proceeds	$ 876
Gain	$ 850

Discontinued Operations - Addit

Discontinued Operations - Additional Information (Detail) $ in Millions	Oct. 31, 2018USD ($)
Specialty Papers [Member]
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items]
Selling price of business	$ 360

Discontinued Operations - Summa

Discontinued Operations - Summary of Cash Flows from Discontinued Operations Included in Condensed Consolidated Statements of Cash Flows (Detail) - Specialty Papers [Member] - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items]
Net cash used by operating activities	$ (78)	$ (316)
Change in cash and cash equivalents from discontinued operations	$ (78)	$ (316)

Earnings Per Share - Details of

Earnings Per Share - Details of Basic and Diluted Earnings Per Share (EPS) from Continuing Operations (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Earnings Per Share [Abstract]
Income from continuing operations	$ 8,394	$ 7,406
Weighted average common shares outstanding used in basic EPS	44,450	44,275
Effect of dilutive SOSARs, PSAs and RSUs	419	255
Weighted average common shares outstanding and common share equivalents used in diluted EPS	44,869	44,530
Earnings per share from continuing operations
Basic	$ 0.19	$ 0.17
Diluted	$ 0.19	$ 0.17

Earnings Per Share - Number of

Earnings Per Share - Number of Potential Common Shares that have been Excluded from Computation of Diluted Earnings Per Share for Indicated Period Due to Their Anti-Dilutive Nature (Detail) - shares shares in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Earnings Per Share [Abstract]
Potential common shares	1,082	1,231

Accumulated Other Comprehensi_3

Accumulated Other Comprehensive Income - Schedule of Changes in Accumulated Other Comprehensive Income (Losses) (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	$ (58,653)	$ (77,896)
Other comprehensive income (loss) before reclassifications (net of tax)	(9,919)	(13,620)
Amounts reclassified from accumulated other comprehensive income (net of tax)	79	(1,701)
Net current period other comprehensive income (loss)	(9,840)	(15,321)
Ending Balance	(68,493)	(93,217)
Currency Translation Adjustments [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	(42,525)	(76,346)
Other comprehensive income (loss) before reclassifications (net of tax)	(13,193)	(13,903)
Net current period other comprehensive income (loss)	(13,193)	(13,903)
Ending Balance	(55,718)	(90,249)
Unrealized Gain (Loss) on Cash Flow Hedges [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	(2,496)	4,316
Other comprehensive income (loss) before reclassifications (net of tax)	3,274	283
Amounts reclassified from accumulated other comprehensive income (net of tax)	(13)	(1,600)
Net current period other comprehensive income (loss)	3,261	(1,317)
Ending Balance	765	2,999
Change in Pensions [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	(12,844)	(7,253)
Amounts reclassified from accumulated other comprehensive income (net of tax)	138	148
Net current period other comprehensive income (loss)	138	148
Ending Balance	(12,706)	(7,105)
Change in Other Postretirement Defined Benefit Plans [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	(788)	1,387
Amounts reclassified from accumulated other comprehensive income (net of tax)	(46)	(249)
Net current period other comprehensive income (loss)	(46)	(249)
Ending Balance	$ (834)	$ 1,138

Accumulated Other Comprehensi_4

Accumulated Other Comprehensive Income - Schedule of Amounts Reclassified from Accumulated Other Comprehensive Income and Into the Condensed Consolidated Statements of Income (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Defined Benefit Plan Disclosure [Line Items]
Costs of products sold	$ 186,378	$ 194,685
Other, net	224	753
Income tax provision (benefit)	7,190	2,608
Net income	8,394	7,406
Interest expense	1,531	1,778
Reclassifications Out of Accumulated Other Comprehensive Income [Member]
Defined Benefit Plan Disclosure [Line Items]
Net income	79	(1,701)
Reclassifications Out of Accumulated Other Comprehensive Income [Member] | Accumulated Net (Gain) Loss from Cash Flow Hedges Attributable to Parent [Member]
Defined Benefit Plan Disclosure [Line Items]
Net income	(13)	(1,600)
Reclassifications Out of Accumulated Other Comprehensive Income [Member] | Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Other, net	211	172
Income tax provision (benefit)	(73)	(24)
Net income	138	148
Reclassifications Out of Accumulated Other Comprehensive Income [Member] | Pension Benefits [Member] | Prior Service Costs [Member]
Defined Benefit Plan Disclosure [Line Items]
Other, net	12	12
Reclassifications Out of Accumulated Other Comprehensive Income [Member] | Pension Benefits [Member] | Actuarial Losses [Member]
Defined Benefit Plan Disclosure [Line Items]
Other, net	199	160
Reclassifications Out of Accumulated Other Comprehensive Income [Member] | Other Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Other, net	(46)	(325)
Income tax provision (benefit)		76
Net income	(46)	(249)
Reclassifications Out of Accumulated Other Comprehensive Income [Member] | Other Pension Plan [Member] | Prior Service Costs [Member]
Defined Benefit Plan Disclosure [Line Items]
Other, net	(58)	(116)
Reclassifications Out of Accumulated Other Comprehensive Income [Member] | Other Pension Plan [Member] | Actuarial Gains [Member]
Defined Benefit Plan Disclosure [Line Items]
Other, net	12	(209)
Reclassifications Out of Accumulated Other Comprehensive Income [Member] | Interest Rate Swap [Member]
Defined Benefit Plan Disclosure [Line Items]
Income tax provision (benefit)	(7)
Reclassifications Out of Accumulated Other Comprehensive Income [Member] | Interest Rate Swap [Member] | Accumulated Net (Gain) Loss from Cash Flow Hedges Attributable to Parent [Member]
Defined Benefit Plan Disclosure [Line Items]
Net income	14
Interest expense	(21)
Reclassifications Out of Accumulated Other Comprehensive Income [Member] | Cash Flow Hedges [Member] | Accumulated Net (Gain) Loss from Cash Flow Hedges Attributable to Parent [Member]
Defined Benefit Plan Disclosure [Line Items]
Costs of products sold	(24)	2,182
Income tax provision (benefit)	51	(582)
Net income	$ (27)	$ (1,600)

Stock-Based Compensation - Addi

Stock-Based Compensation - Additional Information (Detail) - shares	3 Months Ended		63 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Mar. 31, 2021
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Retirement eligibility target period	1 year
Restricted Stock Units (RSU) [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
The vesting graded scale	Approximately 40% of fair value of the awards granted in 2021 were RSUs, which vest based on the passage of time, generally over a three-year period or in certain instances the RSUs were issued with five-year cliff vesting.
Percentage of awards granted	40.00%
Cumulative performance targets	3 years
Additional service period	5 years
Performance Share Awards (PSAs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percentage of awards granted	60.00%
Cumulative performance targets	2 years
Additional service period	1 year
Market index period	3 years
Grants under performance share awards	161,453	168,663
Stock Only Stock Appreciation Rights (SOSARs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period of stock	3 years
Vesting term	10 years
Share-based payment award, shares issued in period			0

Stock-Based Compensation - Summ

Stock-Based Compensation - Summary of RSU and PSA Activity (Detail) - Restricted Stock Units (RSU) and Performance Share Awards (PSAs) [Member] - shares	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Beginning Balance	1,071,652	896,463
Granted	287,805	294,315
Forfeited	(90,355)	(17,455)
Shares delivered	(123,038)	(78,509)
Ending Balance	1,146,064	1,094,814

Stock-Based Compensation - Comp

Stock-Based Compensation - Compensation Expense for Periods Included in Continuing Operations (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Restricted Stock Units (RSU) and Performance Share Awards (PSAs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation expense	$ 1,208	$ 1,085

Stock-Based Compensation - Sche

Stock-Based Compensation - Schedule of Information Related to Outstanding SOSARS (Detail) - Stock Only Stock Appreciation Rights (SOSARs) [Member] - $ / shares	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Beginning Balance, Outstanding	1,082,413	1,291,947
Granted
Exercised		(44,710)
Canceled / forfeited		(2,841)
Ending Balance, Outstanding	1,082,413	1,244,396
Beginning Balance, Weighted Average Exercise Price, Outstanding	$ 20.40	$ 20.05
Weighted Average Exercise Price, Granted
Weighted Average Exercise Price, Exercised		12.94
Weighted Average Exercise Price, Canceled / forfeited		17.27
Ending Balance, Weighted Average Exercise Price, Outstanding	$ 20.40	$ 20.31

Retirement Plans and Other Po_3

Retirement Plans and Other Post-Retirement Benefits - Schedule of Net Periodic Costs of Pension and Post Retirement Medical Benefit Plans Included in Continuing Operations (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost		$ 44
Interest cost	$ 250	301
Amortization of prior service cost/(credit)	12	12
Amortization of actuarial loss (gain)	199	160
Total net periodic benefit expense/(income)	461	517
Other Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	7	7
Interest cost	32	46
Amortization of prior service cost/(credit)	(58)	(116)
Amortization of actuarial loss (gain)	12	(209)
Total net periodic benefit expense/(income)	$ (7)	$ (272)

Income Taxes - Additional Infor

Income Taxes - Additional Information (Detail) - USD ($)	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2020
Income Tax Contingency [Line Items]
Pretax income	$ 15,584,000	$ 10,014,000
Income tax expense (benefit)	7,190,000	$ 2,608,000
Decrease in valuation allowance	(1,000,000)
Gross unrecognized tax benefits	47,200,000		$ 46,300,000
Unrecognized tax benefits that would impact effective tax rate	36,700,000
Minimum [Member]
Income Tax Contingency [Line Items]
Gross unrecognized tax benefits balance may decrease within the next twelve months	0
Maximum [Member]
Income Tax Contingency [Line Items]
Gross unrecognized tax benefits balance may decrease within the next twelve months	6,300,000
United States - Federal [Member]
Income Tax Contingency [Line Items]
Income tax expense (benefit)	0
Net operating loss carryforwards	4,500,000
Foreign Tax Authority [Member] | Germany [Member]
Income Tax Contingency [Line Items]
Income tax expense (benefit)	$ 500,000

Income Taxes - Summary of Tax Y

Income Taxes - Summary of Tax Years that Remain Subject to Examination by Major Jurisdiction (Detail)	3 Months Ended
	Mar. 31, 2021
United States [Member] | United States - Federal [Member]
Income Tax Examination [Line Items]
Examinations not yet initiated	2014 - 2015; 2017 - 2020
United States [Member] | United States - State [Member]
Income Tax Examination [Line Items]
Examinations not yet initiated	2016 - 2020
Examinations in progress	2015 - 2018
Canada [Member] | Foreign Tax Authority [Member]
Income Tax Examination [Line Items]
Examinations not yet initiated	2013 - 2018; 2020
Examinations in progress	2019
Germany [Member] | Foreign Tax Authority [Member]
Income Tax Examination [Line Items]
Examinations not yet initiated	2016 - 2020
France [Member] | Foreign Tax Authority [Member]
Income Tax Examination [Line Items]
Examinations not yet initiated	2018 - 2020
United Kingdom [Member] | Foreign Tax Authority [Member]
Income Tax Examination [Line Items]
Examinations not yet initiated	2019 - 2020
Philippines [Member] | Foreign Tax Authority [Member]
Income Tax Examination [Line Items]
Examinations not yet initiated	2019 - 2020
Examinations in progress	2018

Income Taxes - Summary of Infor

Income Taxes - Summary of Information Included in Continuing Operations Related to Interest on Uncertain Tax Positions (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2020
Income Tax Disclosure [Abstract]
Interest expense (income)	$ 0.2	$ 0.1
Accrued interest payable	$ 2		$ 1.8

Inventories - Inventories, Net

Inventories - Inventories, Net of Reserves (Detail) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Inventory Disclosure [Abstract]
Raw materials	$ 57,700	$ 55,466
In-process and finished	101,830	97,109
Supplies	43,803	43,655
Total	$ 203,333	$ 196,230

Leases - Summary of Information

Leases - Summary of Information Related to Leases (Detail) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Leases [Abstract]
Right of use asset	$ 15,605	$ 11,789
Weighted average discount rate	2.95%	2.94%
Weighted average remaining maturity (months)	89 months	66 months

Leases - Summary of Operating L

Leases - Summary of Operating Lease Expense (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Leases [Abstract]
Operating lease expense	$ 1,347	$ 1,442

Leases - Summary of Future Mini

Leases - Summary of Future Minimum Lease Payments (Detail) $ in Thousands	Mar. 31, 2021USD ($)
Leases [Abstract]
2021	$ 3,518
2022	3,475
2023	2,039
2024	1,537
2025	1,278
Thereafter	$ 7,440

Short-Term Debt - Additional In

Short-Term Debt - Additional Information (Details) - USD ($) $ in Thousands	Mar. 30, 2021	Mar. 31, 2021
Short Term Debt [Line Items]
Short-term debt		$ 11,725
Glatfelter Gernsbach GmbH [Member]
Short Term Debt [Line Items]
Short-term debt	$ 11,700
Short-term debt, Lender	Commerzbank AG
Fixed interest rate of borrowings	0.75%
Maturity date of loan	Mar. 29, 2022

Long-Term Debt - Summary of Lon

Long-Term Debt - Summary of Long-Term Debt (Detail) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Debt Instrument [Line Items]
Total long-term debt	$ 296,755	$ 315,419
Less current portion	(23,942)	(25,057)
Unamortized deferred issuance costs	(1,734)	(1,898)
Long-term debt, net of current portion	271,079	288,464
Revolving Credit Facility, Due Feb. 2024 [Member]
Debt Instrument [Line Items]
Total long-term debt	36,531	36,813
2.40% Term Loan, Due Jun. 2022 [Member]
Debt Instrument [Line Items]
Total long-term debt	2,094	2,629
Term Loan, Due Feb. 2024 [Member]
Debt Instrument [Line Items]
Total long-term debt	235,379	249,715
2.05% Term Loan, Due Mar. 2023 [Member]
Debt Instrument [Line Items]
Total long-term debt	12,516	14,737
1.30% Term Loan, Due Jun. 2023 [Member]
Debt Instrument [Line Items]
Total long-term debt	3,769	4,382
1.55% Term Loan, Due Sep. 2025 [Member]
Debt Instrument [Line Items]
Total long-term debt	$ 6,466	$ 7,143

Long-Term Debt - Summary of L_2

Long-Term Debt - Summary of Long-Term Debt (Parenthetical) (Detail)	3 Months Ended
	Mar. 31, 2021	Dec. 31, 2020	Jul. 01, 2019
Debt Instrument [Line Items]
Long-term debt, maturity date	Feb. 8, 2024
Interest rate on debt			1.25%
2.40% Term Loan, Due Jun. 2022 [Member]
Debt Instrument [Line Items]
Long-term debt, maturity date	Jun. 30, 2022
Interest rate on debt	2.40%	2.40%
Term Loan, Due Feb. 2024 [Member]
Debt Instrument [Line Items]
Long-term debt, maturity date	Feb. 29, 2024
2.05% Term Loan, Due Mar. 2023 [Member]
Debt Instrument [Line Items]
Long-term debt, maturity date	Mar. 31, 2023
Interest rate on debt	2.05%	2.05%
1.30% Term Loan, Due Jun. 2023 [Member]
Debt Instrument [Line Items]
Long-term debt, maturity date	Jun. 30, 2023
Interest rate on debt	1.30%	1.30%
1.55% Term Loan, Due Sep. 2025 [Member]
Debt Instrument [Line Items]
Long-term debt, maturity date	Sep. 30, 2025
Interest rate on debt	1.55%	1.55%
Revolving Credit Facility, Due Feb. 2024 [Member]
Debt Instrument [Line Items]
Long-term debt, maturity date	Feb. 29, 2024

Long-Term Debt - Additional Inf

Long-Term Debt - Additional Information (Detail)	3 Months Ended
	Mar. 31, 2021USD ($)	Dec. 31, 2020USD ($)	Mar. 31, 2021EUR (€)	Jul. 01, 2019	Feb. 08, 2019USD ($)	Feb. 08, 2019EUR (€)
Debt Instrument [Line Items]
Interest rate on debt				1.25%
Debt instrument covenant compliance leverage ratio, threshold	4	4.5
Debt instrument covenant compliance leverage ratio, actual	1.8
Long-term debt, maturity date	Feb. 8, 2024
Term Loans [Member]
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity | €			€ 220,000,000			€ 220,000,000
5.375% Notes [Member]
Debt Instrument [Line Items]
Interest rate on debt	5.375%		5.375%
Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity					$ 400,000,000
Federal fund rate spread	1.00%
Revolving Credit Facility [Member] | Minimum [Member]
Debt Instrument [Line Items]
Federal fund rate spread	0.125%
Revolving Credit Facility [Member] | Maximum [Member]
Debt Instrument [Line Items]
Federal fund rate spread	1.00%
Revolving Credit Facility [Member] | Federal Funds Rate [Member]
Debt Instrument [Line Items]
Federal fund rate spread	0.50%
Revolving Credit Facility [Member] | Euro Rate [Member] | Minimum [Member]
Debt Instrument [Line Items]
Federal fund rate spread	1.125%
Revolving Credit Facility [Member] | Euro Rate [Member] | Maximum [Member]
Debt Instrument [Line Items]
Federal fund rate spread	2.00%
Revolving Credit Facility [Member] | EURIBOR [Member] | Minimum [Member]
Debt Instrument [Line Items]
Federal fund rate spread	1.125%
Revolving Credit Facility [Member] | EURIBOR [Member] | Maximum [Member]
Debt Instrument [Line Items]
Federal fund rate spread	2.00%
Letters of Credit [Member]
Debt Instrument [Line Items]
Letters of credit issued	$ 7,300,000	$ 7,300,000
Letters of credit outstanding	$ 0

Long-Term Debt - Summary of Deb

Long-Term Debt - Summary of Debts Borrowed by Subsidiary (Detail) - EUR (€) € in Thousands	May 04, 2016	Apr. 26, 2016	Oct. 10, 2015	Sep. 04, 2014	Apr. 11, 2013	Mar. 31, 2021	Jul. 01, 2019
Debt Instrument [Line Items]
Interest Rate							1.25%
Maturity						Feb. 8, 2024
IKB Deutsche Industriebank AG Borrowing Agreements [Member] | Glatfelter Gernsbach GmbH [Member] | IKB Deutsche Industriebank AG Member
Debt Instrument [Line Items]
Original Principal	€ 7,195	€ 10,000	€ 2,608	€ 10,000	€ 42,700
Interest Rate	1.55%	1.30%	1.55%	2.40%	2.05%
Maturity	Sep. 30, 2025	Jun. 30, 2023	Sep. 30, 2025	Jun. 30, 2022	Mar. 31, 2023

Fair Value of Financial Instr_3

Fair Value of Financial Instruments - Carrying Value and Fair Value of Long-Term Debt (Detail) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Carrying Value	$ 296,755	$ 315,419
Fair Value	297,023	315,646
Revolving Credit Facility Due Mar. 2020 And Nov. 2016 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Carrying Value	36,531	36,813
Fair Value	36,531	36,813
Term Loan, Due Feb. 2024 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Carrying Value	235,379	249,715
Fair Value	235,379	249,715
2.40% Term Loan, Due Jun. 2022 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Carrying Value	2,094	2,629
Fair Value	2,116	2,651
2.05% Term Loan, Due Mar. 2023 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Carrying Value	12,516	14,737
Fair Value	12,669	14,873
1.30% Term Loan, Due Jun. 2023 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Carrying Value	3,769	4,382
Fair Value	3,784	4,384
1.55% Term Loan, Due Sep. 2025 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Carrying Value	6,466	7,143
Fair Value	$ 6,544	$ 7,210

Fair Value of Financial Instr_4

Fair Value of Financial Instruments - Carrying Value and Fair Value of Long-Term Debt (Parenthetical) (Detail)	Mar. 31, 2021	Dec. 31, 2020	Jul. 01, 2019
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Percent on aggregate principal amount of outstanding			1.25%
2.40% Term Loan, Due Jun. 2022 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Percent on aggregate principal amount of outstanding	2.40%	2.40%
2.05% Term Loan, Due Mar. 2023 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Percent on aggregate principal amount of outstanding	2.05%	2.05%
1.30% Term Loan, Due Jun. 2023 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Percent on aggregate principal amount of outstanding	1.30%	1.30%
1.55% Term Loan, Due Sep. 2025 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Percent on aggregate principal amount of outstanding	1.55%	1.55%

Financial Derivatives and Hed_3

Financial Derivatives and Hedging Activities - Additional Information (Detail) $ in Millions	3 Months Ended
	Mar. 31, 2021USD ($)	Mar. 31, 2020USD ($)	Mar. 31, 2021EUR (€)	Oct. 31, 2019EUR (€)	Feb. 08, 2019EUR (€)
Derivative [Line Items]
Pre-tax gain from changes in currency exchange rates | $	$ 11	$ 5.9
Term Loans [Member]
Derivative [Line Items]
Line of credit facility, maximum borrowing capacity			€ 220,000,000		€ 220,000,000
Floating-to-fixed Interest Rate Swap Agreement [Member]
Derivative [Line Items]
Derivative notional amount				€ 180,000,000
Derivative fixed interest rate				0.0395%
Loans variable rate of interest				€ 180,000,000
Maximum [Member] | Fair Value, Measurements [Member]
Derivative [Line Items]
Accumulated other comprehensive income realization period	18 months
Minimum [Member]
Derivative [Line Items]
Long-term debt percentage bearing fixed Interest rate				0.00%
Minimum [Member] | Fair Value, Measurements [Member]
Derivative [Line Items]
Accumulated other comprehensive income realization period	12 months
Designated as Hedging [Member] | Cash Flow Hedges [Member] | Maximum [Member]
Derivative [Line Items]
Maturities of foreign currency derivative contracts	18 months
Designated as Hedging [Member] | Cash Flow Hedges [Member] | Minimum [Member]
Derivative [Line Items]
Maturities of foreign currency derivative contracts	1 month
Not Designated as Hedging [Member]
Derivative [Line Items]
Maturities of foreign currency derivative contracts	1 month

Financial Derivatives and Hed_4

Financial Derivatives and Hedging Activities - Outstanding Derivatives Used to Hedge Foreign Exchange Risks (Detail)	Mar. 31, 2021USD ($)	Mar. 31, 2021EUR (€)	Mar. 31, 2021PHP (₱)	Mar. 31, 2021CAD ($)	Mar. 31, 2021GBP (£)	Dec. 31, 2020USD ($)	Dec. 31, 2020EUR (€)	Dec. 31, 2020PHP (₱)	Dec. 31, 2020CAD ($)	Dec. 31, 2020GBP (£)
Cash Flow Hedges [Member] | Philippine Peso / Euro [Member] | Designated as Hedging [Member] | Sell Notional [Member]
Derivative Instruments And Hedging Activities Disclosures [Line Items]
Derivative notional amount | €							€ 18,522,000
Cash Flow Hedges [Member] | Euro / British Pound [Member] | Designated as Hedging [Member] | Sell Notional [Member]
Derivative Instruments And Hedging Activities Disclosures [Line Items]
Derivative notional amount | €		€ 17,219,000					€ 18,638,000
Cash Flow Hedges [Member] | U.S Dollar / Euro [Member] | Designated as Hedging [Member] | Sell Notional [Member]
Derivative Instruments And Hedging Activities Disclosures [Line Items]
Derivative notional amount						$ 1,041,000
Cash Flow Hedges [Member] | Canadian Dollar / U.S. Dollar [Member] | Designated as Hedging [Member] | Sell Notional [Member]
Derivative Instruments And Hedging Activities Disclosures [Line Items]
Derivative notional amount						70,000
Cash Flow Hedges [Member] | Euro / Philippine Peso [Member] | Designated as Hedging [Member] | Buy Notional [Member]
Derivative Instruments And Hedging Activities Disclosures [Line Items]
Derivative notional amount | ₱			₱ 1,003,403,000					₱ 853,686,000
Cash Flow Hedges [Member] | British Pound / Philippine Peso [Member] | Designated as Hedging [Member] | Buy Notional [Member]
Derivative Instruments And Hedging Activities Disclosures [Line Items]
Derivative notional amount | ₱			₱ 1,006,093,000					₱ 1,081,791,000
Cash Flow Hedges [Member] | Euro / U.S. Dollar [Member] | Designated as Hedging [Member] | Buy Notional [Member]
Derivative Instruments And Hedging Activities Disclosures [Line Items]
Derivative notional amount	$ 72,770,000					69,324,000
Cash Flow Hedges [Member] | U.S. Dollar / Canadian Dollar [Member] | Designated as Hedging [Member] | Buy Notional [Member]
Derivative Instruments And Hedging Activities Disclosures [Line Items]
Derivative notional amount				$ 34,707,000					$ 34,847,000
Foreign Currency Hedges [Member] | Euro / British Pound [Member] | Not Designated as Hedging [Member] | Sell Notional [Member]
Derivative Instruments And Hedging Activities Disclosures [Line Items]
Derivative notional amount	500,000					600,000
Foreign Currency Hedges [Member] | U.S Dollar / Euro [Member] | Not Designated as Hedging [Member] | Sell Notional [Member]
Derivative Instruments And Hedging Activities Disclosures [Line Items]
Derivative notional amount	250,000
Foreign Currency Hedges [Member] | Euro / U.S. Dollar [Member] | Not Designated as Hedging [Member] | Buy Notional [Member]
Derivative Instruments And Hedging Activities Disclosures [Line Items]
Derivative notional amount						7,500,000
Foreign Currency Hedges [Member] | U.S. Dollar / British Pound [Member] | Not Designated as Hedging [Member] | Sell Notional [Member]
Derivative Instruments And Hedging Activities Disclosures [Line Items]
Derivative notional amount	$ 25,850,000					$ 25,250,000
Foreign Currency Hedges [Member] | British Pound / Euro [Member] | Not Designated as Hedging [Member] | Sell Notional [Member]
Derivative Instruments And Hedging Activities Disclosures [Line Items]
Derivative notional amount | £					£ 2,200,000					£ 1,900,000

Financial Derivatives and Hed_5

Financial Derivatives and Hedging Activities - Fair Values of Derivative Instruments (Detail) - Forward Foreign Currency Exchange Contracts [Member] - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Designated as Hedging [Member] | Prepaid Expenses and Other Current Assets [Member]
Derivatives Fair Value [Line Items]
Derivative asset, fair value	$ 1,876	$ 577
Designated as Hedging [Member] | Other Current Liabilities [Member]
Derivatives Fair Value [Line Items]
Derivative liability, fair value	406	4,342
Designated as Hedging [Member] | Interest Rate Swap [Member] | Other Current Liabilities [Member]
Derivatives Fair Value [Line Items]
Derivative liability, fair value	108	136
Not Designated as Hedging [Member] | Prepaid Expenses and Other Current Assets [Member]
Derivatives Fair Value [Line Items]
Derivative asset, fair value	66	456
Not Designated as Hedging [Member] | Other Current Liabilities [Member]
Derivatives Fair Value [Line Items]
Derivative liability, fair value	$ 349	$ 118

Financial Derivatives and Hed_6

Financial Derivatives and Hedging Activities - Income or (Loss) from Derivative Instruments Recognized in Results of Operations (Detail) - Forward Foreign Currency Exchange Contracts [Member] - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Costs of Products Sold [Member] | Designated as Hedging [Member]
Derivative Instruments Gain Loss [Line Items]
Effective portion of derivative instruments, gain (loss)	$ (24)	$ 2,182
Interest Expense [Member] | Designated as Hedging [Member]
Derivative Instruments Gain Loss [Line Items]
Derivative instruments, gain (loss)	21
Other - Net [Member] | Not Designated as Hedging [Member]
Derivative Instruments Gain Loss [Line Items]
Derivative instruments, gain (loss)	$ 270	$ (619)

Financial Derivatives and Hed_7

Financial Derivatives and Hedging Activities - Fair Value Amounts Recorded as Component of Accumulated Other Comprehensive Income (Loss) Before Taxes (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Derivative Instruments And Hedging Activities Disclosure [Abstract]
Balance at January 1,	$ (3,460)	$ 5,859
Deferred gains (losses) on cash flow hedges	4,558	463
Reclassified to earnings	3	(2,182)
Balance at March 31,	$ 1,101	$ 4,140

Commitments, Contingencies an_3

Commitments, Contingencies and Legal Proceedings - Additional Information (Detail) $ in Thousands	3 Months Ended
	Mar. 31, 2021USD ($)Operable_Unit	Dec. 31, 2020USD ($)
Commitments Contingencies And Litigation [Line Items]
Number of operable units | Operable_Unit	5
Term of agreement with third party for monitoring and maintenance in OU1-OU4a	30 years
Difference recorded in escrow account	$ 1,600
Total amount available in escrow account	8,900
Reserve for Environmental liabilities, current portion	3,600	$ 3,700
Other Long-Term Liabilities [Member]
Commitments Contingencies And Litigation [Line Items]
Reserve for Environmental liabilities, remaining portion	$ 14,500
Minimum [Member]
Commitments Contingencies And Litigation [Line Items]
Period over which cash expenditure to be incurred for monitoring activities	30 years

Commitments, Contingencies an_4

Commitments, Contingencies and Legal Proceedings - Schedule of Reserves (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Environmental Remediation Obligations [Abstract]
Beginning balance	$ 18,455	$ 21,870
Payments	(420)	(131)
Accretion	51	52
Ending balance	$ 18,086	$ 21,791

Segment Information - Schedule

Segment Information - Schedule of Financial and Other Information by Segment (Detail) T in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2021USD ($)T	Mar. 31, 2020USD ($)T
Segment Reporting Information [Line Items]
Net sales	$ 225,674	$ 231,560
Type of Revenue [Extensible List]	Product [Member]	Product [Member]
Cost of products sold	$ 186,378	$ 194,685
Type of Cost, Good or Service [Extensible List]	Product [Member]	Product [Member]
Gross profit	$ 39,296	$ 36,875
SG&A	22,827	24,594
Gains on dispositions of plant, equipment and timberlands, net	(850)
Operating income	17,319	12,281
Non-operating expense	(1,735)	(2,267)
Income from continuing operations before income taxes	$ 15,584	$ 10,014
Supplementary Data
Net tons sold | T	63,004	71,022
Depreciation, depletion and amortization	$ 13,733	$ 15,402
Capital expenditures	5,379	7,014
Composite Fibers [Member]
Segment Reporting Information [Line Items]
Net sales	141,249	$ 132,711
Type of Revenue [Extensible List]		Product [Member]
Cost of products sold	114,267	$ 106,985
Type of Cost, Good or Service [Extensible List]		Product [Member]
Gross profit	26,982	$ 25,726
SG&A	10,917	10,624
Operating income	16,065	15,102
Income from continuing operations before income taxes	$ 16,065	$ 15,102
Supplementary Data
Net tons sold | T	34,140	35,983
Depreciation, depletion and amortization	$ 6,981	$ 6,466
Capital expenditures	2,773	3,956
Airlaid Materials [Member]
Segment Reporting Information [Line Items]
Net sales	$ 84,425	$ 98,849
Type of Revenue [Extensible List]	Product [Member]	Product [Member]
Cost of products sold	$ 72,585	$ 82,246
Type of Cost, Good or Service [Extensible List]	Product [Member]	Product [Member]
Gross profit	$ 11,840	$ 16,603
SG&A	4,643	4,581
Operating income	7,197	12,022
Income from continuing operations before income taxes	$ 7,197	$ 12,022
Supplementary Data
Net tons sold | T	28,864	35,039
Depreciation, depletion and amortization	$ 5,848	$ 5,451
Capital expenditures	$ 1,739	$ 2,103
Other and Unallocated [Member]
Segment Reporting Information [Line Items]
Type of Revenue [Extensible List]	Product [Member]	Product [Member]
Cost of products sold	$ (474)	$ 5,454
Type of Cost, Good or Service [Extensible List]	Product [Member]	Product [Member]
Gross profit	$ 474	$ (5,454)
SG&A	7,267	9,389
Gains on dispositions of plant, equipment and timberlands, net	(850)
Operating income	(5,943)	(14,843)
Non-operating expense	(1,735)	(2,267)
Income from continuing operations before income taxes	(7,678)	(17,110)
Supplementary Data
Depreciation, depletion and amortization	904	3,485
Capital expenditures	$ 867	$ 955