Ecovyst (ECVT) 10-K 17 Mar 21 2020 FY Annual report Financial data

Cover

Cover - USD ($)	12 Months Ended
	Dec. 31, 2020	Mar. 12, 2021	Jun. 30, 2020
Cover [Abstract]
Document Type	10-K
Document Annual Report	true
Document Period End Date	Dec. 31, 2020
Document Transition Report	false
Entity File Number	001-38221
Entity Registrant Name	PQ Group Holdings Inc.
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	81-3406833
Entity Address, Address Line One	300 Lindenwood Drive
Entity Address, City or Town	Malvern
Entity Address, State or Province	PA
Entity Address, Postal Zip Code	19355
City Area Code	(610)
Local Phone Number	651-4400
Title of 12(b) Security	Common stock, par value $0.01 per share
Trading Symbol	PQG
Security Exchange Name	NYSE
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
ICFR Auditor Attestation Flag	true
Entity Shell Company	false
Entity Public Float			$ 537,729,982
Entity Common Stock, Shares Outstanding		136,937,196
Entity Central Index Key	0001708035
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	FY
Amendment Flag	false

CONSOLIDATED STATEMENTS OF INCO

CONSOLIDATED STATEMENTS OF INCOME - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Income Statement [Abstract]
Sales	$ 1,107,363	$ 1,199,914	$ 1,228,926
Cost of goods sold	834,007	901,512	925,534
Gross profit	273,356	298,402	303,392
Selling, general and administrative expenses	125,294	129,516	131,402
Goodwill impairment charge	260,000	0	0
Other operating expense, net	50,986	21,378	16,427
Operating (loss) income	(162,924)	147,508	155,563
Equity in net income from affiliated companies	(21,237)	(46,022)	(37,569)
Interest expense, net	66,979	87,072	90,758
Debt extinguishment costs	25,028	3,400	7,751
Other (income) expense, net	(6,109)	(2,372)	10,603
(Loss) income from continuing operations before income taxes and noncontrolling interest	(227,585)	105,430	84,020
(Benefit) provision for income taxes	(48,122)	39,677	33,641
Net (loss) income from continuing operations	(179,463)	65,753	50,379
Net (loss) income from discontinued operations, net of tax	(102,241)	14,557	9,242
Net (loss) income	(281,704)	80,310	59,621
Less: Net (loss) income attributable to the noncontrolling interest - continuing operations	(3,198)	617	1,108
Less: Net income (loss) attributable to the noncontrolling interest - discontinued operations	265	154	213
Net (loss) income attributable to PQ Group Holdings Inc.	(278,771)	79,539	58,300
(Loss) income from continuing operations	(176,265)	65,136	49,271
(Loss) income from discontinued operations	$ (102,506)	$ 14,403	$ 9,029
Net (loss) income per share:
Basic (loss) income per share - continuing operations	$ (1.30)	$ 0.48	$ 0.37
Diluted (loss) income per share - continuing operations	(1.30)	0.48	0.37
Basic (loss) income per share - discontinued operations	(0.76)	0.11	0.07
Diluted (loss) income per share - discontinued operations	(0.76)	0.11	0.07
Basic (loss) income per share	(2.06)	0.59	0.44
Diluted (loss) income per share	$ (2.06)	$ 0.59	$ 0.43
Weighted average shares outstanding:
Basic (shares)	135,528,977	134,389,667	133,380,567
Diluted (shares)	135,528,977	135,548,694	134,684,931

CONSOLIDATED STATEMENTS OF COMP

CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (LOSS) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Other comprehensive income (loss), net of tax:
Net income	$ (281,704)	$ 80,310	$ 59,621
Pension and postretirement benefits	1,938	2,430	(7,958)
Net (loss) gain from hedging activities	166	(2,665)	(330)
Foreign currency translation	(17,519)	22,889	(35,056)
Total other comprehensive income (loss)	(15,415)	22,654	(43,344)
Comprehensive (loss) income	(297,119)	102,964	16,277
Less: Comprehensive (loss) income attributable to noncontrolling interests	(3,856)	1,543	1,392
Comprehensive (loss) income attributable to PQ Group Holdings Inc.	$ (293,263)	$ 101,421	$ 14,885

CONSOLIDATED BALANCE SHEETS

CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
ASSETS
Cash and cash equivalents	$ 135,531	$ 53,861
Accounts receivable, net	132,619	140,044
Inventories, net	127,436	137,622
Prepaid and other current assets	32,554	31,591
Disposal Group, Including Discontinued Operation, Assets, Current	0	206,369
Total current assets	428,140	569,487
Investments in affiliated companies	458,452	472,814
Property, plant and equipment, net	983,235	1,011,156
Goodwill	717,738	973,578
Other intangible assets, net	526,303	555,272
Right-of-use lease assets	48,239	48,417
Other long-term assets	35,714	27,373
Long-term assets held for sale	0	663,644
Total assets	3,197,821	4,321,741
LIABILITIES
Notes payable and current maturities of long-term debt	0	0
Accounts payable	112,333	114,994
Operating lease liabilities—current	15,194	11,857
Accrued liabilities	73,811	85,410
Disposal Group, Including Discontinued Operation, Liabilities, Current	0	58,103
Total current liabilities	201,338	270,364
Long-term debt, excluding current portion	1,400,369	1,843,224
Deferred tax liabilities	175,901	209,425
Operating lease liabilities—noncurrent	32,019	34,908
Other long-term liabilities	111,015	91,304
Disposal Group, Including Discontinued Operation, Liabilities, Noncurrent	0	87,198
Total liabilities	1,920,642	2,536,423
Commitments and contingencies (Note 24)
EQUITY
Common stock, par value (usd per share)	$ 0.01	$ 0.01
Common stock, shares authorized (shares)	450,000,000	450,000,000
Common stock, shares issued (shares)	137,102,143	136,861,382
Common stock, shares outstanding (shares)	136,318,557	136,464,961
Common Stock, Value, Issued	$ 1,371	$ 1,369
Preferred stock, par value (usd per share)	$ 0.01	$ 0.01
Preferred stock, shares authorized (shares)	50,000,000	50,000,000
Preferred stock, shares issued (shares)	0	0
Preferred stock, shares outstanding (shares)	0	0
Preferred Stock, Value, Issued	$ 0	$ 0
Additional paid-in capital	1,477,859	1,696,899
(Accumulated deficit) retained earnings	$ (175,758)	$ 103,013
Treasury stock (shares)	783,586	396,421
Treasury Stock, Value	$ (11,081)	$ (6,483)
Accumulated other comprehensive loss	(15,265)	(15,348)
Total PQ Group Holdings Inc. equity	1,277,126	1,779,450
Noncontrolling interest	53	5,868
Total equity	1,277,179	1,785,318
Total liabilities and equity	$ 3,197,821	$ 4,321,741

CONSOLIDATED STATEMENTS OF STOC

CONSOLIDATED STATEMENTS OF STOCKHOLDERS’ EQUITY - USD ($) $ in Thousands	Total	Cumulative effect adjustment from adoption of new accounting standards	Adjusted balance	Common stock	Common stockAdjusted balance	Additional paid-in capital	Additional paid-in capitalAdjusted balance	Retained earnings (accumulated deficit)	Retained earnings (accumulated deficit)Cumulative effect adjustment from adoption of new accounting standards	Retained earnings (accumulated deficit)Adjusted balance	Treasury stock, at cost	Treasury stock, at cost Adjusted balance	Accumulated other comprehensive income (loss)	Accumulated other comprehensive income (loss)Cumulative effect adjustment from adoption of new accounting standards	Accumulated other comprehensive income (loss)Adjusted balance	Non-controlling interest	Non-controlling interestAdjusted balance
Beginning balance, shares at Dec. 31, 2017				135,244,379							0
Beginning balance, value at Dec. 31, 2017	$ 1,631,919			$ 1,352		$ 1,655,114		$ (32,777)			$ 0		$ 4,311			$ 3,919
Increase (Decrease) in Stockholders' Equity
Net (loss) income	59,621							58,300								1,321
Other comprehensive income (loss)	(43,344)												(43,415)			71
Stock repurchases, shares											(166,224)
Stock repurchases, value	(2,920)										$ (2,920)
Distributions to noncontrolling interests	(726)															(726)
Stock compensation expense	19,464					19,464
Shares issued under equity incentive plan, net of forfeitures, shares				513,890							0
Shares issued under equity incentive plan, net of forfeitures, value	131			$ 6		125					$ 0
Ending balance, shares at Dec. 31, 2018				135,758,269							(166,224)
Ending balance, value at Dec. 31, 2018	1,664,145	$ (175)	$ 1,663,970	$ 1,358	$ 1,358	1,674,703	$ 1,674,703	25,523	$ (2,049)	$ 23,474	$ (2,920)	$ (2,920)	(39,104)	$ 1,874	$ (37,230)	4,585	$ 4,585
Increase (Decrease) in Stockholders' Equity
Net (loss) income	80,310							79,539								771
Other comprehensive income (loss)	22,654												21,882			772
Stock repurchases, shares											(230,197)
Stock repurchases, value	(3,563)										$ (3,563)
Distributions to noncontrolling interests	(260)															(260)
Stock compensation expense	18,225					18,225
Shares issued under equity incentive plan, net of forfeitures, shares				1,103,113							0
Shares issued under equity incentive plan, net of forfeitures, value	3,982			$ 11		3,971					$ 0
Ending balance, shares at Dec. 31, 2019				136,861,382							(396,421)
Ending balance, value at Dec. 31, 2019	1,785,318			$ 1,369		1,696,899		103,013			$ (6,483)		(15,348)			5,868
Increase (Decrease) in Stockholders' Equity
Net (loss) income	(281,704)							(278,771)								(2,933)
Other comprehensive income (loss)	$ (15,415)												(14,492)			(923)
Stock repurchases, shares	(211,700)										(387,165)
Stock repurchases, value	$ (4,598)										$ (4,598)
Distributions to noncontrolling interests	(1,219)															(1,219)
Dividends paid on common stock ($1.80 per share)	(243,749)					(243,749)
Disposal of business	(13,835)												14,575			740
Stock compensation expense	24,366					24,366
Shares issued under equity incentive plan, net of forfeitures, shares				240,761							0
Shares issued under equity incentive plan, net of forfeitures, value	345			$ 2		343					$ 0
Ending balance, shares at Dec. 31, 2020				137,102,143							(783,586)
Ending balance, value at Dec. 31, 2020	$ 1,277,179			$ 1,371		$ 1,477,859		$ (175,758)			$ (11,081)		$ (15,265)			$ 53

CONSOLIDATED STATEMENTS OF CASH

CONSOLIDATED STATEMENTS OF CASH FLOWS $ in Thousands	12 Months Ended
	Dec. 31, 2020USD ($)	Dec. 31, 2019USD ($)	Dec. 31, 2018USD ($)
Cash flows from operating activities:
Net (loss) income	$ (281,704)	$ 80,310	$ 59,621
Net (loss) income from discontinued operations, net of tax	102,241	(14,557)	(9,242)
Adjustments to reconcile net (loss) income to net cash provided by operating activities:
Depreciation	114,641	111,032	111,491
Amortization	37,199	40,765	42,440
Goodwill impairment charge	260,000	0	0
Amortization of deferred financing costs and original issue discount	3,750	3,786	4,230
Debt extinguishment costs	22,658	3,400	5,627
Foreign currency exchange (gain) loss	(4,172)	2,410	12,543
Pension and postretirement healthcare benefit expense	879	3,536	2,280
Pension and postretirement healthcare benefit funding	(9,138)	(8,825)	(6,805)
Deferred income tax provision (benefit)	(64,693)	15,489	4,072
Net (gain) loss on asset disposals	(11,392)	(13,207)	4,190
Stock compensation	21,527	16,212	18,419
Equity in net income from affiliated companies	(21,237)	(46,022)	(37,569)
Dividends received from affiliated companies	40,098	40,073	40,195
Net interest income on swaps designated as net investment hedges	(4,963)	(8,480)	(4,859)
Gain on contract termination	0	0	(20,612)
Other, net	(9,479)	(5,292)	(907)
Working capital changes that provided (used) cash, excluding the effect of acquisitions and dispositions:
Receivables	7,031	11,407	(4,191)
Inventories	9,392	(9,981)	(7,165)
Prepaids and other current assets	2,016	2,294	(6,996)
Accounts payable	4,163	(576)	(3,491)
Accrued liabilities	(13,435)	3,886	9,855
Net cash provided by operating activities, continuing operations	205,382	227,660	213,126
Net cash provided by operating activities, discontinued operations	18,216	40,103	35,518
Net cash provided by operating activities	223,598	267,763	248,644
Cash flows from investing activities:
Purchases of property, plant and equipment	(97,135)	(111,102)	(111,795)
Investment in affiliated companies	0	0	(5,000)
Net proceeds received from the sale of Performance Materials	624,256	0	0
Proceeds from sale of assets	9,375	17,600	12,380
Proceeds from sale of product line	18,000	27,658	0
Proceeds from sale of investment	1,761	0	0
Proceeds from settlement of swaps designated as net investment hedges	0	38,070	0
Net interest proceeds on swaps designated as net investment hedges	4,963	8,480	4,859
Other, net	1,015	475	829
Net cash provided by (used in) investing activities, continuing operations	562,235	(18,819)	(98,727)
Net cash (used in) provided by investing activities, discontinued operations	(10,763)	(16,540)	(20,563)
Net cash (used in) provided by investing activities	551,472	(35,359)	(119,290)
Cash flows from financing activities:
Draw down of revolving credit facilities	140,626	177,874	119,134
Repayments of revolving credit facilities	(140,626)	(177,874)	(144,134)
Issuance of long-term debt, net of original issue discount and financing fees	640,340	0	1,267,000
Debt issuance costs	(8,987)	0	(6,395)
Repayments of long-term debt	(1,091,134)	(215,000)	(1,367,959)
Debt prepayment fees	(10,550)	0	0
Dividends paid to stockholders	243,749	0	0
Repurchases of common shares	(4,598)	(3,563)	(2,920)
Proceeds from stock options exercised	373	3,975	131
Other, net	(2,868)	(317)	(134)
Net cash used in financing activities, continuing operations	(721,173)	(214,905)	(135,277)
Net cash used in financing activities, discontinued operations	(1,647)	(1,188)	(1,948)
Net cash used in financing activities	(722,820)	(216,093)	(137,225)
Effect of exchange rate changes on cash, cash equivalents and restricted cash	11,052	(2,120)	354
Net change in cash, cash equivalents and restricted cash	63,302	14,191	(7,517)
Cash, cash equivalents and restricted cash at beginning of period	73,917	59,726	67,243
Cash, cash equivalents and restricted cash at end of period	137,219	73,917	59,726
Less cash, cash equivalents and restricted cash of discontinued operations	0	(18,725)	(21,127)
Cash, cash equivalents and restricted cash at end of period of continuing operations	$ 137,219	$ 55,192	$ 38,599

CONSOLIDATED STATEMENTS OF ST_2

CONSOLIDATED STATEMENTS OF STOCKHOLDERS’ EQUITY (Parenthetical) - $ / shares	Dec. 14, 2020	Dec. 31, 2020
Statement of Stockholders' Equity [Abstract]
Dividends paid on common stock (in dollars per share)	$ 1.80	$ 1.80

Background and Basis of Present

Background and Basis of Presentation	12 Months Ended
	Dec. 31, 2020
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Background and Basis of Presentation	1. Background and Basis of Presentation: Description of Business PQ Group Holdings Inc. and subsidiaries (the “Company” or “PQ Group Holdings”) is a leading integrated and innovative global provider of specialty catalysts, chemicals and services. The Company supports customers globally through its strategically located network of manufacturing facilities. The Company believes that its products, which are predominantly inorganic, and services contribute to improving the sustainability of the environment. Basis of Presentation The Company has three uniquely positioned specialty businesses: Refining Services provides sulfuric acid recycling to the North American refining industry; Catalysts serves the packaging and engineered plastics industry and the global refining, petrochemical and emissions control industries through its Zeolyst joint venture; and Performance Chemicals supplies diverse product end uses, including personal and industrial cleaning products, fuel-efficient tires, surface coatings, and food and beverage products. Effective December 14, 2020, the Company completed the sale of its Performance Materials business and the results of operations of this business have been presented as discontinued operations in the consolidated statements of income for all periods presented. See Note 4 for more information on the assets and liabilities classified as held for sale. The notes to the consolidated financial statements, unless otherwise indicated, are on a continuing operations basis. The Company’s Refining Services segment typically experiences seasonal fluctuations as a result of higher demand for gasoline products in the summer months and lower demand in the winter months. These demand fluctuations result in higher sales and working capital requirements in the second and third quarter. COVID-19 In March 2020, the outbreak of a novel coronavirus (“COVID-19”) was declared a national emergency in the United States. COVID-19 continues to spread in the United States and other parts of the world and has adversely impacted economic activity and contributed to volatility in financial markets. In response to the COVID-19 pandemic, the federal government and various state, local and foreign governments have issued decrees and orders that have disrupted many businesses and implemented social distancing, travel and other restrictions. In response to these restrictions, the Company has taken a variety of actions, including an international travel ban, distribution of personal protective equipment to employees and work-at-home requirements for many of the Company’s employees who are not an integral part of its manufacturing operations. The Company has also implemented and refined its existing business continuity plans in an effort to minimize operational disruptions. The Company’s manufacturing operations, as well as the operations of its key vendors and the majority of its key customers, have continued to operate with limited interruptions. The extent and timing of the impact of the COVID-19 pandemic on the Company’s business led to lower sales volume demand beginning in the second quarter of 2020. The Company is not aware of any specific event or circumstance that would require an update to our estimates or judgments or a revision of the carrying value of its assets or liabilities as of the date of the issuance of the consolidated financial statements. These estimates may change, as the pandemic continues to evolve and the duration remains uncertain, and may adversely impact the Company’s results of operations, financial condition or cash flow.

Summary of Significant Accounti

Summary of Significant Accounting Policies	12 Months Ended
	Dec. 31, 2020
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	2. Summary of Significant Accounting Policies: Principles of Consolidation. The consolidated financial statements include the accounts of the Company and its controlled subsidiaries. Investments in affiliated companies are recorded at cost plus the Company’s equity in their undistributed earnings. All intercompany transactions have been eliminated. Noncontrolling interests represent third-party equity ownership in certain of the Company’s consolidated subsidiaries and are presented as a component of equity separate from the equity attributable to the Company’s shareholders. The noncontrolling interests’ share in the Company’s net earnings are included in net income attributable to the noncontrolling interest in the Company’s consolidated statements of income, and their portion of the Company’s comprehensive income is included in comprehensive income (loss) attributable to noncontrolling interests in the Company’s consolidated statements of comprehensive income (loss). The Company’s noncontrolling interests relate to third-party minority ownership interests held in certain of the Company’s foreign subsidiaries acquired as part of a former business combination. Foreign Currency Translation. All assets and liabilities of foreign subsidiaries and affiliated companies are translated to U.S. dollars using exchange rates in effect at the balance sheet date. Adjustments resulting from translation of the balance sheets and intercompany loans, which are considered permanent, are included in stockholders’ equity as part of accumulated other comprehensive income (loss). Adjustments resulting from translation of certain intercompany loans, which are not considered permanent and are denominated in foreign currencies, are included in other (income) expense, net in the consolidated statements of income. The Company considers intercompany loans to be of a permanent or long-term nature if management expects and intends that the loans will not be repaid. For the years ended December 31, 2020, 2019 and 2018, all intercompany loan arrangements were determined to be non-permanent based on management’s intention as well as actual lending and repayment activity. Therefore, the foreign currency transaction gains or losses associated with the intercompany loans were recorded in the consolidated statements of income for the years ended December 31, 2020, 2019 and 2018. Income and expense items are translated at average exchange rates during the year. Net foreign currency exchange (gains) and losses included in other (income) expense, net were $(4,172), $2,410 and $12,543 for the years ended December 31, 2020, December 31, 2019 and December 31, 2018, respectively. The net foreign currency losses realized in 2020 were driven by the non-permanent intercompany debt denominated in local currency and translated to U.S. dollars. The net foreign currency losses realized in 2019 and in 2018 were primarily driven by the Euro-denominated term loan (which was settled as part of the February 2018 term loan refinancing, see Note 17 to these consolidated financial statements for further information) and the non-permanent intercompany debt denominated in local currency and translated to U.S. dollars. Cash and Cash Equivalents. Cash and cash equivalents include highly liquid investments with original terms to maturity of 90 days or less from the time of purchase. Restricted Cash. Restricted cash, which is restricted as to withdrawal or usage, is classified separately from cash and cash equivalents on the Company’s consolidated balance sheets. The Company’s total restricted cash balances were $1,688 and $1,331 as of December 31, 2020 and 2019, respectively, and are included on the Company’s consolidated balance sheets as other current assets. Accounts Receivable and Allowance for Credit Losses. Trade accounts receivable are recorded at the invoiced amount and do not bear interest. The allowance for credit losses is the Company’s best estimate of the amount of probable credit losses in its existing accounts receivable and is reviewed during each reporting period over their contractual life. The Company recognizes an allowance for credit losses based on historical collection experience, current regional economic and market conditions, the aging of accounts receivable and assessments of current creditworthiness of customers. Account balances are charged against the allowance when the Company believes it is probable that the associated receivables will not be recovered. If the financial condition of the Company’s customers were to deteriorate resulting in an impairment of their ability to make payments, additional allowances may be required. The Company does not have any off-balance sheet credit exposure related to its customers. As of December 31, 2020 and 2019, the Company’s allowance for credit losses was $1,521 and $2,068, respectively. Inventories. Certain domestic inventories are stated at the lower of cost or market and valued using the last-in, first-out (“LIFO”) method. All other inventories are stated at the lower of cost and net realizable value and valued using the weighted average cost or first-in, first-out (“FIFO”) methods. Property, Plant and Equipment. Property, plant and equipment are carried at cost and include expenditures for new facilities, major renewals and betterments. The Company capitalizes the cost of furnace rebuilds as part of property, plant and equipment. Maintenance, repairs and minor renewals are charged to expense as incurred. The Company capitalizes certain internal costs associated with the implementation of purchased software. When property, plant and equipment is retired or otherwise disposed of, the net carrying amount is eliminated with any gain or loss on disposition recognized in earnings at that time. Depreciation is provided on the straight-line method based on the estimated useful lives of the assets, which generally range from 15 to 33 years for buildings and improvements and 3 to 10 years for machinery and equipment. Leasehold improvements are depreciated using the straight-line method based on the shorter of the useful life of the improvement or remaining lease term. The Company capitalizes the interest cost associated with the development and construction of significant new plant and equipment and depreciates that amount over the lives of the related assets. Capitalized interest recorded during the years ended December 31, 2020, 2019 and 2018 was $1,780, $1,981 and $3,576, respectively. Leases . The Company has operating and finance lease agreements with remaining lease terms as of December 31, 2020 of up to 30 years, including leases of land, buildings, railcars, vehicles, manufacturing equipment and general office equipment. Some leases include options to terminate or extend for one or more years. These options are incorporated in the Company’s lease term when it is reasonably certain that the option will be exercised. Some leases include options to purchase, which the Company assesses under the guidance to determine if these leases should be classified as finance lease agreements. When the Company enters into an arrangement, at inception, the Company determines if the arrangement contains a lease and whether that lease meets the classification criteria of a finance or operating lease. Some of the Company’s lease arrangements contain lease components (e.g. minimum rent payments) and non-lease components (e.g. maintenance). The Company accounts for the lease and non-lease components separately based on the estimated standalone price of each component. Certain of the Company’s lease agreements include rental payments that are adjusted periodically for an index or rate and these are initially measured using the index or rate in effect at the commencement date. Variable lease expense is recognized in the period in which the obligation for those payments is incurred. The Company’s lease agreements do not contain any material residual value guarantees or material restrictive covenants. The Company recognizes a right-of-use lease asset and lease liability at the lease commencement date based on the present value of the remaining lease payments over the lease term. The Company assesses its leasing arrangements to determine the rate implicit in the lease arrangement. Historically, the Company’s leasing arrangements do not contain the information necessary to determine the rate implicit in the lease. As such, the Company utilizes its incremental borrowing rate over the relevant lease term, which is the rate of interest that it would have to pay to borrow on a collateralized basis over a similar term an amount equal to the lease payments in a similar economic environment. The incremental borrowing rate is determined at the lease commencement date and is developed utilizing a readily available market interest rate curve adjusted for the Company’s credit quality. The Company has elected to use a portfolio approach to apply its incremental borrowing rate to individual leases based on lease term and geographic jurisdiction. Short-term leases, which have an initial term of twelve months or less, are not recorded on the Company’s balance sheet. Lease expense for operating leases is recognized on a straight-line basis over the lease term. Lease expense for financing leases is bifurcated into two components, with the amortization expense component of the right-of-use asset recognized on a straight-line basis and the interest expense component recognized using the effective interest method over the lease term. The amortization expense component of the right-of-use lease asset is included in cost of goods sold and in selling, general and administrative expenses and the interest expense component is included in interest expense, net on the consolidated statements of income. Spare Parts. Spare parts are maintained by the Company’s facilities to keep machinery and equipment in working order. Spare parts are capitalized and included in other long-term assets. Spare parts are measured at cost and are not depreciated or expensed until utilized; however, reserves may be provided on aged spare parts. When a spare part is utilized as part of an improvement to property, plant and equipment, the carrying value is depreciated over the applicable life once placed in service. Otherwise, the spare part is expensed and charged as a cost of production when utilized. Investments in Affiliated Companies. Investments in affiliated companies are accounted for using the equity method of accounting if the investment provides the Company with the ability to exercise significant influence, but not control, over the investee. Significant influence is generally deemed to exist if the Company’s ownership interest in the voting stock of the investee ranges between 20% and 50%, although other factors, such as representation on the investee’s board of directors and the impact of commercial arrangements, are considered in determining whether the equity method of accounting is appropriate. Under the equity method of accounting, the investments in equity-method investees are recorded in the consolidated balance sheets as investments in affiliated companies, and the Company’s share of the investees’ earnings or losses, together with other than temporary impairments in value, is recorded as equity in net income from affiliated companies in the consolidated statements of income. Any differences between the Company’s cost of an equity method investment and the underlying equity in the net assets of the investment, such as fair value step-ups resulting from acquisitions, are accounted for according to their nature and impact the amounts recognized as equity in net income from affiliated companies in the consolidated statements of income. The Company evaluates all distributions received from its equity method investments using the nature of distribution approach. Under this approach, the Company evaluates the nature of activities of the investee that generated the distribution. The distributions received are either classified as a return on investment, which is presented as a component of operating activities on the Company’s consolidated statements of cash flows, or as a return of investment, which is presented as a component of investing activities on the Company’s consolidated statements of cash flows. The Company evaluates its equity method investments for impairment whenever events or changes in circumstances indicate that the carrying amounts of such investments may be impaired. If a decline in the value of an equity method investment is determined to be other than temporary, a loss is recorded in earnings in the current period. Goodwill and Intangible Assets. Goodwill is an asset representing the future economic benefits arising from other assets acquired in a former business combination that are not individually identified and separately recognized. The Company is required to test goodwill associated with each of its reporting units for impairment at least annually and whenever events or circumstances indicate that it is more likely than not that goodwill may be impaired. The Company performs its annual goodwill impairment test as of October 1. Goodwill is tested for impairment at the reporting unit level. In performing tests for goodwill impairment, the Company is able to use its discretion to first perform an optional qualitative assessment about the likelihood of the carrying value of a reporting unit exceeding its fair value. The qualitative assessment need not be applied to all reporting units. If the Company determines that it is more likely than not that the fair value of a reporting unit is less than its carrying amount based on the qualitative assessment, the Company will perform a quantitative goodwill impairment test to identify the potential goodwill impairment and measure the amount of the goodwill impairment loss, if any, to be recognized for that reporting unit. For the annual assessments in 2020 and 2019, the Company bypassed the option to perform the qualitative assessment and proceeded directly to performing the quantitative goodwill impairment test for each of our reporting units. The quantitative test identifies both the potential existence of impairment and the amount of impairment loss. In applying the quantitative test, the Company calculates and compares the reporting unit’s estimated fair value to its carrying value, including goodwill. If the fair value of a reporting unit exceeds its carrying value, goodwill is not impaired. If the carrying value of a reporting unit exceeds its implied fair value, an impairment charge is recognized, requiring recognition of a goodwill impairment charge for the differential up to the carrying value of goodwill. An impairment loss cannot exceed the carrying value of goodwill assigned to a reporting unit and the loss establishes a new basis in the goodwill. Subsequent reversal of an impairment loss is not permitted. For intangible assets other than goodwill, definite-lived intangible assets are amortized over their respective estimated useful lives. Intangible assets with indefinite lives are not amortized, but rather are tested for impairment at least annually or more frequently if events occur or circumstances change that would more likely than not reduce the fair value of the intangible asset below its carrying amount. The Company tests its indefinite-lived intangible assets as of October 1 of each year in conjunction with its annual goodwill impairment test. Impairment Assessment of Long-Lived Assets. The Company performs an impairment review of property, plant and equipment and definite-lived intangible assets when facts and circumstances indicate that the carrying value of an asset or asset group may not be recoverable from its undiscounted future cash flows. When evaluating long-lived assets for impairment, if the carrying amount of an asset or asset group is found not to be recoverable, a potential impairment loss may be recognized. An impairment loss is measured by comparing the carrying amount of the asset or asset group to its fair value. Fair value is determined using quoted market prices when available, or other techniques including discounted cash flows. The Company’s estimates of future cash flows involve assumptions concerning future operating performance, economic conditions and technological changes that may affect the future useful lives of the assets. Derivative Financial Instruments. The Company utilizes certain derivative financial instruments to enhance its ability to manage risk, including exposure to interest rate, commodity price and foreign currency fluctuations that exist as part of ongoing business operations. Derivative instruments are entered into for periods consistent with the related underlying exposures and do not constitute positions independent of those exposures. All derivatives designated as hedges are recognized on the consolidated balance sheets at fair value. The Company may designate a derivative as a hedge of the fair value of a recognized asset or liability or of an unrecognized firm commitment (fair value hedge), a hedge of a forecasted transaction or the variability of cash flows to be received or paid related to a recognized asset or liability (cash flow hedge), a foreign currency fair-value or cash-flow hedge (foreign currency hedge), or a hedge of a net investment in a foreign operation (net investment hedge). The Company’s hedging strategies include derivatives designated as cash flow hedges and net investment hedges. Changes in the fair value of a derivative that is highly effective and that is designated and qualifies as a cash flow hedge are recorded in other comprehensive income and subsequently reclassified into earnings in the same period(s) in which the hedged transaction affects earnings. Changes in the fair value of a derivative that is highly effective and that is designated and qualifies as a hedge of a net investment in a foreign operation are recorded in the foreign currency translation adjustment account within accumulated other comprehensive income, where the associated gains and losses will remain until such time that the hedged net investment (foreign subsidiary) is sold or liquidated. Changes in the fair value of a derivative that is not designated or does not qualify as a hedge are recorded in the consolidated statements of income. Cash flows from derivative instruments are reported in the same cash flow category as the cash flows from the items being hedged. The Company formally documents all relationships between hedging instruments and hedged items, as well as its risk-management objective and strategy for undertaking various hedge transactions. The Company also formally assesses whether each hedging relationship is highly effective in achieving offsetting changes in fair values or cash flows of the hedged item during the period, both at the inception of the hedge and on an ongoing basis. If it is determined that a derivative is not highly effective as a hedge, or if a derivative ceases to be a highly-effective hedge, hedge accounting is discontinued with respect to that derivative prospectively. Fair Value Measurements. The Company measures fair value using the guidelines under U.S. generally accepted accounting principles (“GAAP”). An asset’s fair value is defined as the price at which the asset could be exchanged in a current transaction between market participants. A liability’s fair value is defined as the amount that would be paid to transfer the liability to a market participant, not the amount that would be paid to settle the liability with the creditor. See Note 6 to these consolidated financial statements regarding the application of fair value measurements. The carrying values of cash, accounts receivable, accounts payable and accrued liabilities approximate fair value due to the short-term nature of these items. See Note 17 to these consolidated financial statements regarding the fair value of debt. Revenue Recognition. In determining the appropriate amount of revenue to be recognized as the Company fulfills its obligations under its agreements, the Company performs the following steps: (i) identification of the contract with the customer; (ii) determination of whether the promised goods or services are performance obligations, including whether they are distinct in the context of the contract; (iii) measurement of the transaction price; (iv) allocation of the transaction price to the performance obligations based on estimated selling prices; and (v) recognition of revenue when (or as) the Company satisfies each performance obligation. The Company identifies a contract when an agreement with a customer creates legally enforceable rights and obligations, which occurs when a contract has been approved by both parties, the parties are committed to perform their respective obligations, each party’s rights and payment terms are clearly identified, commercial substance exists and it is probable that the Company will collect the consideration to which it is entitled. The Company may offer rebates to customers who have reached a specified volume of optional purchases. The Company recognizes rebates given to customers as a reduction of revenue based on an allocation of the cost of honoring rebates earned and claimed to each of the underlying revenue transactions that result in progress by the customer toward earning the rebate. Rebates are recognized at the time revenue is recorded. The Company measures the rebate obligation based on the estimated amount of sales that will result in a rebate at the adjusted sales price per the respective sales agreement. Shipping and Handling Costs. Amounts billed to a customer in a sale transaction related to shipping and handling, if any, represent revenues earned for the goods provided and are classified as revenue. Costs related to shipping and handling of products shipped to customers are classified as cost of goods sold. Refer to Note 5 for disclosures regarding the recognition of revenue for shipping and handling costs that are billed to customers. Research and Development. Research and development costs of $11,597, $12,514 and $13,719 for the years ended December 31, 2020, 2019 and 2018, respectively, were expensed as incurred and reported in selling, general and administrative expenses in the consolidated statements of income. Income Taxes. The Company operates within multiple taxing jurisdictions and is subject to tax filing requirements and potential audits within these jurisdictions. The Company uses the asset and liability method in accounting for income taxes. Deferred tax assets and liabilities are recorded for temporary differences between the tax basis of assets and liabilities and their reported amounts in the financial statements, using statutory tax rates in effect for the year in which the differences are expected to reverse. The effect on deferred tax assets and liabilities of a change in tax rates is recognized in the results of operations in the period that includes the enactment date. The Company evaluates its deferred tax assets each period to ensure that estimated future taxable income will be sufficient in character (e.g., capital gain versus ordinary income treatment), amount and timing, to result in their realizability. A valuation allowance is recorded to reduce the carrying amounts of deferred tax assets, unless it is more likely than not that those assets will be realized. Generally, APB 23 of ASC Topic 740, Income Taxes (“ASC 740”), provides guidance with respect to establishing deferred income taxes on earnings from foreign subsidiaries, to the extent that these earnings are considered to be available for repatriation. Further, ASC 740-30 requires that deferred taxes be established with respect to the earnings of a foreign subsidiary, unless existing tax law provides a means by which the investment in a subsidiary can be recovered tax-free. The Company has determined that it is able to repatriate the non-permanently reinvested earnings of its foreign subsidiaries in a tax-free manner. As such, the Company is able to asset, for purposes of ASC 740-30, that no deferred income taxes are needed with respect to earnings from foreign subsidiaries. The Company recognizes a financial statement benefit for positions taken for tax return purposes when it will be more likely than not (i.e. greater than 50%) that the positions will be sustained upon tax examination, based solely on the technical merits of the tax positions. Otherwise, no tax benefit is recognized. The tax benefits recognized are measured based on the largest benefit that has a greater than 50% likelihood of being realized upon ultimate settlement. The Company recognizes potential accrued interest and penalties related to unrecognized tax benefits as a component of income tax expense. Tax examinations are often complex as tax authorities may disagree with the treatment of items reported by the Company and may require several years to resolve. These accrued liabilities represent a provision for taxes that are reasonably expected to be incurred on the basis of available information but which are not certain. Pursuant to the Securities and Exchange Commission (“SEC”) Staff Accounting Bulletin No.118 (“SAB 118”), the Company was allowed a measurement period of up to one year after the enactment date of the Tax Cuts and Jobs Act (“TCJA”) to finalize the recording of any related tax impacts with respect to its transition tax liability. In accordance with SAB 118, the Company finalized the impacts of the transition tax as of December 31, 2018 and recorded a measurement period adjustment of $2,102 as a benefit to tax expense. There was no cash tax outlay associated with the final transition tax amount, as the Company elected to utilize net operating loss (“NOL”) carryforwards to offset the associated taxable income. Based on FASB guidance, the Company is permitted to make an accounting policy election to either (1) treat the taxes incurred as a result of the Global Intangible Low Taxed Income (“GILTI”) provision as a current-period expense when incurred or (2) factor such amounts into its measurement of deferred taxes. The Company has elected to treat any expense incurred as a current-period expense. Asset Retirement Obligations. The Company records a liability when the fair value of any future obligation to retire a long-lived asset as a result of an existing or enacted law, statute, ordinance or contract is reasonably estimable. The Company also records a liability for the fair value of a conditional asset retirement obligation if the fair value can be reasonably estimated. When the liability is initially recorded, the Company capitalizes the cost by increasing the amount of the related long-lived asset. Over time, the Company adjusts the liability to its present value by recognizing accretion expense as an operating expense in the consolidated statements of income each period, and the capitalized cost is depreciated over the useful life of the related asset. Upon settlement of the liability, the Company records a gain or loss if the actual costs differ from the accrued amount. The Company has recorded asset retirement obligations (“AROs”) in other long-term liabilities in order to recognize legal obligations associated with the retirement of tangible long-lived assets. The Company has assessed whether an ARO is required at each manufacturing facility and has recorded an obligation for those locations for which an obligation exists. The most significant of these are primarily attributable to environmental remediation liabilities associated with current operations that were incurred during the course of normal operations. The Company has AROs that are conditional in nature. The Company identified certain conditional AROs upon which it was able to reasonably estimate their fair value and recorded a liability. These AROs were triggered upon commitments by the Company to comply with local, state and national laws to remove environmentally hazardous materials. The AROs have been recognized on a discounted basis using a credit adjusted risk free rate. Accretion of the AROs is recorded in other operating expense, net in the Company’s consolidated statements of income. The following table includes the changes in the Company’s ARO liability during the years ended December 31, 2020 and 2019: Years ended 2020 2019 Beginning balance $ 4,555 $ 4,224 Accretion expense 342 311 Foreign exchange impact 46 20 Ending balance $ 4,943 $ 4,555 Environmental Expenditures. Environmental expenditures that pertain to current operations or to future revenues are expensed or capitalized consistent with the Company’s capitalization policy for property, plant and equipment. Expenditures that result from the remediation of an existing condition caused by past operations and that do not contribute to current or future revenues are expensed. Liabilities are recognized for remedial activities when the remediation is probable and the cost can be reasonably estimated. Recoveries of expenditures for environmental remediation are recognized as assets only when recovery is deemed probable. See Note 24 to these consolidated financial statements regarding commitments and contingencies and Note 16 regarding the accrued environmental reserve. Deferred Financing Costs. Financing costs incurred in connection with the issuance of long-term debt are deferred and presented as a direct reduction from the related debt instruments on the Company’s consolidated balance sheets. Deferred financing costs are amortized as interest expense using the effective interest method over the respective terms of the associated debt instruments. Stock-Based Compensation. The Company applies the fair value based method to account for stock options, restricted stock awards, restricted stock units and performance stock units issued in connection with its equity incentive plans. Stock-based compensation expense is recognized on a straight-line basis over the vesting periods of the respective awards, and the Company accounts for forfeitures of equity incentive awards as they occur. In connection with the vesting of restricted stock awards, restricted stock units and performance stock units, shares of common stock may be delivered to the Company by employees to satisfy withholding tax obligations at the instruction of the employee award holders. These transactions when they occur are accounted for as stock repurchases by the Company, with the shares returned to treasury stock at a cost representing the payment by the Company of the tax obligations on behalf of the employees in lieu of shares for the vesting event. See Note 22 to these consolidated financial statements regarding compensation expense associated with the Company’s equity incentive awards. Pensions and Postretirement Benefits. The Company maintains qualified and non-qualified defined benefit pension plans that cover employees in the United States and Canada, as well as certain employees in other international locations. Benefits for a majority of the plans are based on average final pay and years of service. Our funding policy, consistent with statutory requirements, is based on actuarial computations utilizing the projected unit credit method of calculation. Not all defined benefit pension plans are funded. In the United States and Canada, the pension plans’ assets include equity and fixed income securities. In our other international locations, the pension plans’ assets include equity and fixed income securities, as well as insurance contracts. Certain assumptions are made regarding the occurrence of future events affecting pension costs, such as mortality, withdrawal, disablement and retirement, changes in compensation and benefits, and discount rates to reflect the time value of money. The major elements in determining pension income and expense are pension liability discount rates and the expected return on plan assets. The Company references rates of return on high-quality, fixed income investments when estimating the discount rate, and the expected period over which payments will be made based upon historical experience. The long-term rate of return used to calculate the expected return on plan assets is the average rate of return estimated to be earned on invested funds for providing pension benefits. In addition to pension benefits, the Company provides certain health care benefits for employees who meet age, participation and length of service requirements at retirement. The Company uses explicit assumptions using the best estimat

New Accounting Standards

New Accounting Standards	12 Months Ended
	Dec. 31, 2020
Accounting Standards Update and Change in Accounting Principle [Abstract]
Recently adopted accounting standards	3. New Accounting Standards: Recently Adopted Accounting Standards In June 2016, the Financial Accounting Standards Board (“FASB”) issued guidance that affects loans, trade receivables and any other financial assets that have the contractual right to receive cash. Under the new guidance, an entity is required to recognize expected credit losses rather than incurred losses for financial assets. The new guidance is effective for fiscal years beginning after December 15, 2019 and interim periods within those fiscal years. The Company adopted the new guidance effective January 1, 2020, with no material impact to the Company’s consolidated financial position, results of operations or cash flows. In August 2018, the FASB issued guidance which modifies certain disclosure requirements over fair value measurements. The guidance is effective for fiscal years beginning after December 15, 2019, including all interim periods within that fiscal year. The Company adopted the new guidance effective January 1, 2020. The Company does not currently classify any of its derivative contracts or restoration plan assets as Level 3 assets or liabilities, nor did the Company have any transfers amongst fair value levels during the year ended December 31, 2020. As a result, the guidance did not have an impact on Company’s the fair value measurement disclosures upon adoption. In January 2017, the FASB issued guidance which eliminates the second step from the traditional two-step goodwill impairment test. Under current guidance, an entity performed the first step of the goodwill impairment test by comparing the fair value of a reporting unit with its carrying amount; if an impairment loss was indicated, the entity computed the implied fair value of goodwill to determine whether an impairment loss existed, and if so, the amount to recognize. Under the new guidance, an impairment loss is recognized for the amount by which the carrying amount exceeds the reporting unit’s fair value (the Step 1 test), with no further testing required. Any impairment loss recognized is limited to the amount of goodwill allocated to the reporting unit. The new guidance is effective for public companies that are Securities and Exchange Commission (“SEC”) registrants for fiscal years beginning after December 15, 2019. The Company adopted the new guidance on January 1, 2020, and applied the guidance prospectively to its goodwill impairment tests. Accounting Standards Not Yet Adopted as of December 31, 2020 In December 2019, the FASB issued new guidance to simplify the accounting for income taxes by removing certain exceptions to the general principles and also simplification of areas such as franchise taxes, step-up in tax basis goodwill, separate entity financial statements and interim recognition of enactment of tax laws or rate changes. The new guidance is effective for fiscal years beginning after December 15, 2020 and interim periods within those fiscal years, with early adoption permitted. The Company is currently evaluating the impact of this new guidance on its consolidated financial statements. In March 2020, the FASB issued guidance to address certain accounting consequences from the anticipated transition from the use of the London Interbank Offered Rate (“LIBOR”) and other interbank offered rates to alternative reference rates. The new guidance contains practical expedients for reference rate reform related activities that impact debt, leases, derivatives and other contracts. The guidance is optional and may be elected over time as reference rate reform activities occur. During the year ended December 31, 2020, the Company elected to apply the hedge accounting expedients related to probability and the assessments of effectiveness for future LIBOR-indexed cash flows to assume that the index upon which future hedged transactions will be based on matches the index of the corresponding derivatives. Application of these expedients preserves the presentation of derivatives consistent with past presentation. The Company continues to evaluate the impact of the guidance and may apply other elections as applicable as additional changes in the market occur.
Accounting standards not yet adopted	Accounting Standards Not Yet Adopted as of December 31, 2020 In December 2019, the FASB issued new guidance to simplify the accounting for income taxes by removing certain exceptions to the general principles and also simplification of areas such as franchise taxes, step-up in tax basis goodwill, separate entity financial statements and interim recognition of enactment of tax laws or rate changes. The new guidance is effective for fiscal years beginning after December 15, 2020 and interim periods within those fiscal years, with early adoption permitted. The Company is currently evaluating the impact of this new guidance on its consolidated financial statements. In March 2020, the FASB issued guidance to address certain accounting consequences from the anticipated transition from the use of the London Interbank Offered Rate (“LIBOR”) and other interbank offered rates to alternative reference rates. The new guidance contains practical expedients for reference rate reform related activities that impact debt, leases, derivatives and other contracts. The guidance is optional and may be elected over time as reference rate reform activities occur. During the year ended December 31, 2020, the Company elected to apply the hedge accounting expedients related to probability and the assessments of effectiveness for future LIBOR-indexed cash flows to assume that the index upon which future hedged transactions will be based on matches the index of the corresponding derivatives. Application of these expedients preserves the presentation of derivatives consistent with past presentation. The Company continues to evaluate the impact of the guidance and may apply other elections as applicable as additional changes in the market occur.

Performance Materials Divestitu

Performance Materials Divestiture	12 Months Ended
	Dec. 31, 2020
Discontinued Operations and Disposal Groups [Abstract]
Performance Materials Divestiture	4. Performance Materials Divestiture: On December 14, 2020, the Company completed the sale of its Performance Materials business to Potters Buyer, LLC (the “Purchaser”), an affiliate of The Jordan Company, L.P., for a purchase price of $650,000. The net cash proceeds to the Company from the sale were $624,256 after certain customary adjustments for indebtedness, working capital and cash at the closing of the transaction. The Company classified the proceeds within net cash provided by (used in) investing activities – continuing operations in the consolidated statements of cash flows and used the net proceeds from the sale as well as cash on hand to pay down debt and issue a special cash dividend of $1.80/share to stockholders. In the fourth quarter of 2020, the Performance Materials business met the criteria set forth in Accounting Standards Codification 205-20, Presentation of Financial Statements – Discontinued Operations (“ASC 205-20”), as the sale represents a strategic shift that will have a major effect on the Company’s operations and financial results. As a result, the Company’s consolidated financial statements for all periods presented reflect the Performance Materials business as a discontinued operation. The divested business was historically reported in the Performance Materials reportable segment, with the exception of certain Australian operations that were historically reported in the Performance Chemicals reportable segment. The total transaction costs incurred in connection with the sale were approximately $13,161 for the year ended December 31, 2020. The Company recorded a pre-tax loss on sale of $70,878, which is included in (loss) income from discontinued operations, net of tax in the Company’s consolidated statements of income for the year ended December 31, 2020. The following is a reconciliation of the loss recorded on the sale: Net proceeds received from the sale of Performance Materials $ 624,256 Transaction costs (13,161) Net assets derecognized (681,973) Loss on sale of Performance Materials $ (70,878) In c onnection with the sale of Performance Materials and the related loss, as noted above, the Company has recognized a tax expense of $58,008 within d iscontinued operations. The following table summarizes the results of discontinued operations for the periods presented: Years ended 2020 2019 2018 Sales $ 342,738 $ 373,686 $ 386,921 Cost of goods sold 251,917 281,566 308,679 Selling, general and administrative expenses 33,195 37,364 37,226 Other operating expense, net 18,289 14,462 13,023 Operating income 39,337 40,294 27,993 Equity in net income from affiliated companies (37) (12) (42) Interest expense, net (1) 16,210 24,453 22,965 Other (income) expense, net (3,481) 274 474 Loss on sale of Performance Materials 70,878 — — (Loss) Income from discontinued operations before income tax (44,233) 15,579 4,596 Provision (benefit) for income taxes 58,008 1,022 (4,646) (Loss) income from discontinued operations, net of tax $ (102,241) $ 14,557 $ 9,242 (1) The closing of the transaction triggered the Company’s obligation to provide partial repayment under both its Amended and Restated Term Loan Credit Agreement, dated May 4, 2016, and its New Term Loan Credit Agreement, dated as of July 22, 2020. As such, interest expense has been allocated to discontinued operations on the basis of the Company’s mandatory repayment of $275,787 of the Senior Secured Term Loan Facility due February 2027 and its mandatory payment of $188,722 of the New Senior Secured Term Loan Facility due February 2027. Net income attributable to the noncontrolling interest related to the Performance Materials business, net of tax was $265, $154, and $213 for the years ended December 31, 2020, 2019, and 2018, respectively. The following table summarizes the assets and liabilities of discontinued operations at December 31, 2019: December 31, ASSETS Cash and cash equivalents $ 18,423 Accounts receivables, net 40,484 Inventories, net 143,323 Prepaid and other current assets 4,139 Investments in affiliated companies 115 Property, plant and equipment, net 175,614 Goodwill 286,227 Other intangible assets, net 121,113 Right-of-use lease assets 8,878 Other long-term assets 71,697 Total assets held for sale $ 870,013 LIABILITIES Notes payable and current maturities of long-term debt $ 7,766 Accounts payable 30,267 Operating lease liabilities—current 3,326 Accrued liabilities 16,744 Long-term debt, excluding current portion 55,972 Deferred income taxes 8,612 Operating lease liabilities—noncurrent 5,248 Other long-term liabilities 17,366 Total liabilities held for sale $ 145,301 In connection with the transaction, the Company entered into a Transition Services Agreement with the Purchaser pursuant to which the Purchaser is receiving certain services to provide for the orderly transition of various functions and processes after the closing of the transaction. The services under the Transition Services Agreement include information technology, accounting, tax, financial services, human resources, facilities, and other administrative support services. These services are being provided at cost for a period of 9 months, with three 30-day extensions available. Additionally, in connection with the transaction, the Company entered into various supply agreements with the Purchaser. Cash flows associated with these transition services and supply agreements are not expected to be material to the Company’s results of operations. 8. Dispositions: Magnesium Silicate Product Line Sale On July 1, 2020, the Company completed the sale of its magnesium silicate product line within its Performance Chemicals segment for $18,000 and recorded a pre-tax gain on sale of $4,958. The transaction was recorded as an asset sale, with the gain on disposition included in the other operating expense, net line item in the Company’s condensed consolidated statement of income for the year ended December 31, 2020 (see Note 9 to these condensed consolidated financial statements for additional details). At the time of disposition, the carrying value of the Company’s inventory related to this non-core product line was $1,556. The Company allocated $11,486 of the consideration received to a contract liability for deferred revenue. Concurrent with the product line sale, the Company entered into a tolling arrangement with the buyer in which the Company agreed to manufacture the product for the buyer through June 2025. The Company deferred $11,486 of the $18,000 consideration received as a liability, to be recognized as the Company executes its performance obligations over the term of the contractual agreement with the buyer. Sulfate Salts Product Line Sale On June 28, 2019, the Company completed the sale of a portion of its sulfate salts product line within its Performance Chemicals segment for $28,000, with net cash consideration of $27,658 and a pre-tax gain on sale of $11,518. The transaction was recorded as an asset sale, with the gain on disposition included in the other operating expense, net line item in the Company’s consolidated statement of income for the year ended December 31, 2019 (see Note 9 to these consolidated financial statements for additional details). At the time of disposition, the carrying value of the Company’s net working capital related to this non-core product line was $4,215. In addition to the net working capital sold as part of the transaction, the Company also derecognized $3,276 of property, plant and equipment related to the product line and allocated $9,000 of the consideration received to a liability for deferred revenue. Concurrent with the product line sale, the Company entered into a tolling arrangement with the buyer in which the Company will use its existing manufacturing facilities for the product line to manufacture the product for the buyer, the majority of which runs until June 2021. The Company deferred $9,000 of the consideration received as a liability, to be recognized as the Company executes its performance obligations over the term of the contractual agreement with the buyer. Additionally, the Company concluded that an embedded lease arrangement exists as a result of the combination of the sale and tolling agreements. Given the ability of the buyer to control substantially all of the output of the facilities and the existence of bargain purchase options on the manufacturing assets, the Company determined that the buyer is effectively leasing the assets from the Company and derecognized the associated property, plant and equipment under a sales-type leasing arrangement. The gain on the sale of fixed assets is included as part of the Company’s overall gain on sale related to the transaction, with the Company’s net investment in the leased assets having been settled as part of the consideration received in the transaction with no additional future cash flows to be recognized on the lease. Sale of Assets On December 19, 2019, the Company completed the sale of real property for $19,100, with net cash consideration of $17,100 and a holdback receivable to be settled by December 2021 of $1,000, and recorded a pre-tax gain on sale of $7,150. On December 30, 2019, the Company entered into a leaseback arrangement with the buyer-lessor which expires in December 2021. The Company recorded the asset sale separately from the leaseback, with the gain on disposition included in the other operating expense, net line item in the Company’s consolidated statement of income for the year ended December 31, 2019 (see Note 9 to these consolidated financial statements for additional details).

Revenue from Contracts with Cus

Revenue from Contracts with Customers	12 Months Ended
	Dec. 31, 2020
Revenue from Contract with Customer [Abstract]
Revenue from Contracts with Customers	5. Revenue from Contracts with Customers: Revenue Recognition Model As described in Note 2, the Company applies the five-step revenue recognition model to each contract with its customers. Evidence of a contract between the Company and its customers may take the form of a master service agreement (“MSA”), a MSA in combination with an underlying purchase order, a combination of a pricing quote with an underlying purchase order or an individual purchase order received from a customer. The Company and certain of its customers enter into MSAs that establish the terms, including prices, under which orders to purchase goods may be placed. In cases where the MSA contains a distinct order for goods or contains an enforceable minimum quantity to be purchased by the customer, the Company considers the MSA to be evidence of a contract between the Company and its customer as the MSA creates enforceable rights and obligations. In cases where the MSA does not contain a distinct order for goods, the Company’s contract with a customer is the purchase order issued under the MSA. Customers of the Company may also negotiate orders via pricing quotes, which typically detail product pricing, delivery terms and payment information. When a customer procures goods under this method, the Company considers the combination of the pricing quote and the purchase order to create enforceable rights and obligations. Absent either a MSA or pricing quote, the Company considers an individual purchase order remitted by a customer to create enforceable rights and obligations. The Company identifies a performance obligation in a contract for each promised good that is separately identifiable from other promises in the contract and for which the customer can benefit from the good. The majority of the Company’s contracts have a single performance obligation, which is the promise to transfer individual goods to the customer. Single performance obligations are satisfied according to the shipping terms noted within the MSA or purchase order. The Company has certain contracts that include multiple performance obligations under which the purchase price for each distinct performance obligation is defined in the contract. These distinct performance obligations may include stand-ready provisions, which are arrangements to provide a customer assurance that they will have access to output from the Company’s manufacturing facilities, or monthly reservations of capacity fees. The Company considers stand-ready provisions and reservation of capacity fees to be performance obligations satisfied over time. Revenues related to stand-ready provisions and reservation of capacity fees are recognized on a ratable basis throughout the contract term and billed to the customer on a monthly basis. As described above, the Company’s MSAs with its customers may outline prices for individual products or contract provisions. MSAs in the Company’s Performance Chemicals and Refining Services segments may contain provisions whereby raw material costs are passed-through to the customer per the terms of their contract. The Company’s exposure to fluctuations in raw material prices is limited, as the majority of pass-through contract provisions reset based on fluctuations in the underlying raw material price. MSAs in the Company’s Refining Services segment also contain take-or-pay arrangements, whereby the customer would incur a penalty in the form of a volume shortfall fee. During the year ended December 31, 2020, some customers fell short of monthly orders due to the pandemic and take-or-pay were acted upon. In 2019, there have been no issues in which Refining Services customers failed to meet their contractual obligations. Revenue from product sales are recorded at the sales price, which includes estimates of variable consideration for which reserves are established and which result from discounts, returns or other allowances that are offered within contracts between the Company and its customers. The Company recognizes revenues when performance obligations under the terms of a contract with its customer are satisfied, which generally occurs at a point in time by transferring control of a product to the customer. The Company determines the point in time when a customer obtains control of a product and the Company satisfies the performance obligation by considering factors including when the Company has a right to payment for the product, the customer has legal title to the product, the Company has transferred possession of the product, the customer has assumed the risks and rewards of ownership of the product and the customer has accepted the product. Revenue is measured as the amount of consideration the Company expects to receive in exchange for transferring goods. The Company does not have any significant payment terms as payment is received at, or shortly after, the point of sale. Refining Services Contracts between the Company’s Refining Services segment and its customers are typically evidenced by entering into a MSA which generally has a term in excess of one year. Though each MSA is unique, the terms may include performance obligations such as stand-ready provisions and minimum purchase requirements. Stand-ready provisions within these contracts are billed on a monthly basis, as the performance obligation resets on a monthly basis and does not carry-over to the following month. Certain of the Company’s Refining Services MSAs contain minimum purchase requirements that expire within the calendar year. The Company reviews each contract with minimum purchase requirements to determine if the customer will meet the provisions within the current calendar year. During the years ended December 31, 2020 and 2019, there have been no issues in which Refining Services customers failed to meet their contractual obligations. Contracts within Refining Services may also contain raw material pricing adjustments which are typically based on a commodity index or Refining Services’ cost to acquire the commodity. These raw material pass-through provisions reset on a periodic basis and prospectively adjust the raw material cost component of the goods sold to the customer. The Company accounts for the raw material costs on a prospective basis, as the price changes affect the future consideration of the sale of goods. Catalysts The Company’s Catalysts segment sells customized products to its customers. These customized products are reformulations of existing Catalysts products, tailored to meet individual customer specifications. Prior to entering into an arrangement, the Company will allow a customer to obtain a sample of goods to ensure that it meets their needs. The customer will enter into a long-term supply arrangement that outlines the specification of the products to be sold and contains terms and conditions under which purchase orders are issued. These supply arrangements typically have a duration from one to ten years. Although the duration of these supply arrangements are in excess of one year, a contract is formed between the Company and its customer upon receipt of a purchase order. Performance Chemicals Contracts between the Company’s Performance Chemicals segment and its customers are typically evidenced by entering into a supply arrangement that outlines the specification of the products to be sold and contains terms and conditions under which purchase orders are issued. Certain Performance Chemicals supply arrangements may contain raw material pricing adjustments which are typically based on a commodity index. These raw material pass-through provisions reset on a periodic basis and prospectively adjust the raw material cost component of the goods sold to the customer. The Company accounts for the raw material pass-through costs on a prospective basis, as the price changes affect the future consideration of the sale of goods. Contract Assets and Liabilities A contract asset is a right to consideration in exchange for goods that the Company has transferred to a customer when that right is conditional on something other than the passage of time. A contract liability exists when the Company receives consideration in advance of the fulfillment of its performance obligations. The Company has no contract assets recorded on its consolidated balance sheets as of December 31, 2020 and 2019, respectively. The Company recognized a €10,216 ($11,486) contract liability associated with the sale of its magnesium silicate product line in July 2020, of which €9,202 ($11,318) of deferred revenue remained as of December 31, 2020. The Company recognized revenue o f €1,014 ($1,197) relat ed to this contract liability during the year ended December 31, 2020. Refer to Note 8 of these condensed consolidated financial statements for additional information related to the sale of the product line. The Company recognized a $9,000 contract liability associated with the sale of a portion of its sulfate salts product line in June 2019, of which $2,070 and $6,450 of deferred revenue remained as of December 31, 2020 and 2019, respectively. The Company recognized revenue of $4,374 and $2,550 related to this contract liability during the year ended December 31, 2020 and 2019, respectively. Refer to Note 8 of these consolidated financial statements for additional information related to the sale of the product line. Practical Expedients and Accounting Policy Elections The Company has elected to use certain practical expedients and has made certain accounting policy elections as permitted under the new revenue recognition guidance. The majority of the Company’s contracts with customers are based on an individual purchase order; thus, the duration of these contracts are for one year or less. As described above, the Company’s performance obligations reset either monthly or at the end of the calendar year. The Company has made an accounting policy election to omit certain disclosures related to these performance obligations, as the initial term of the Company’s performance obligations are for a term of one year or less. The Company uses an output method to recognize revenues related to performance obligations satisfied over time. These performance obligations, as described above, are satisfied within a calendar year. As such, the Company has elected to utilize the “as-invoiced” practical expedient, which permits the Company to recognize revenue in the amount to which it has a right to invoice the customer, provided that the amount corresponds directly with the value provided by the performance obligation as completed to date. When the Company performs shipping and handling activities after the transfer of control to the customer (e.g. when control transfers prior to delivery), they are considered fulfillment activities as opposed to separate performance obligations, and the Company recognizes revenue upon the transfer of control to the customer. Accordingly, the costs associated with these shipping and handling activities are accrued when the related revenue is recognized under the Company’s policy election. The Company does not utilize sales-based commissions plans, and as a result, the Company does not capitalize any costs which could be considered incremental costs of obtaining a contract. Sales, value added and other taxes the Company collects concurrent with revenue producing activities are excluded from revenues. Disaggregated Revenue The Company’s primary means of disaggregating revenues is by reportable segment, which can be found in Note 14 to these consolidated financial statements. The Company’s portfolio of products are integrated into a variety of end uses, which are described in the table below: Key End Uses Key Products Industrial & process chemicals • Silicate precursors for the tire industry • Silica gels for surface coatings Fuels & emission control • Refinery catalysts • Emission control catalysts • Catalyst recycling services Packaging & engineered plastics • Catalysts for high-density polyethlene and chemicals syntheses • Antiblocks for film packaging • Sulfur derivatives for nylon production • Silicate precursors for catalysts used in plastics manufacturing • Silicate for catalyst manufacturing Consumer products • Silica gels for edible oil and beer clarification • Precipitated silicas, silicates and zeolites for the dentifrice and dishwasher and Natural resources • Silicates for drilling muds • Silicates and alum for water treatment mining • Bleaching aids for paper The following table disaggregates the Company’s sales, by segment and end use, for the years ended December 31, 2020, 2019 and 2018: Year ended December 31, 2020 Refining Services Catalysts Performance Chemicals Total Industrial & process chemicals $ 70,648 $ 125 $ 279,296 $ 350,069 Fuels & emission control (1) 225,042 — — 225,042 Packaging & engineered plastics 38,772 93,882 47,451 180,105 Consumer products — — 235,792 235,792 Natural resources 67,451 — 52,165 119,616 Total segment sales 401,913 94,007 614,704 1,110,624 Inter-segment sales eliminations (3,256) (5) — (3,261) Total $ 398,657 $ 94,002 $ 614,704 $ 1,107,363 Year ended December 31, 2019 Refining Services Catalysts Performance Chemicals Total Industrial & process chemicals $ 80,661 $ 96 $ 299,651 $ 380,408 Fuels & emission control (1) 252,294 — — 252,294 Packaging & engineered plastics 48,056 85,571 51,725 185,352 Consumer products — — 260,495 260,495 Natural resources 66,070 — 58,692 124,762 Total segment sales 447,081 85,667 670,563 1,203,311 Inter-segment sales eliminations (3,397) — — (3,397) Total $ 443,684 $ 85,667 $ 670,563 $ 1,199,914 Year ended December 31, 2018 Refining Services Catalysts Performance Chemicals Total Industrial & process chemicals $ 77,866 $ 86 $ 315,827 $ 393,779 Fuels & emission control (1) 246,452 — — 246,452 Packaging & engineered plastics 59,168 72,013 53,623 184,804 Consumer products — — 272,187 272,187 Natural resources 72,076 — 62,865 134,941 Total segment sales 455,562 72,099 704,502 1,232,163 Inter-segment sales eliminations (3,237) — — (3,237) Total $ 452,325 $ 72,099 $ 704,502 $ 1,228,926 (1) As described in Note 1, the Company experiences seasonal sales fluctuations to customers in the fuels & emission control end use.

Fair Value Measurements

Fair Value Measurements	12 Months Ended
	Dec. 31, 2020
Fair Value Disclosures [Abstract]
Fair Value Measurements	6. Fair Value Measurements: Fair values are based on quoted market prices when available. When market prices are not available, fair values are generally estimated using discounted cash flow analyses, incorporating current market inputs for similar financial instruments with comparable terms and credit quality. In instances where there is little or no market activity for the same or similar instruments, the Company estimates fair values using methods, models and assumptions that management believes a hypothetical market participant would use to determine a current transaction price. These valuation techniques involve some level of management estimation and judgment that becomes significant with increasingly complex instruments or pricing models. Where appropriate, adjustments are included to reflect the risk inherent in a particular methodology, model or input used. The Company’s financial assets and liabilities carried at fair value have been classified based upon a fair value hierarchy. The hierarchy gives the highest ranking to fair values determined using unadjusted quoted prices in active markets for identical assets and liabilities (Level 1) and the lowest ranking to fair values determined using methodologies and models with unobservable inputs (Level 3). The classification of an asset or a liability is based on the lowest level input that is significant to its measurement. For example, a Level 3 fair value measurement may include inputs that are both observable (Levels 1 and 2) and unobservable (Level 3). The levels of the fair value hierarchy are as follows: • Level 1—Values are unadjusted quoted prices for identical assets and liabilities in active markets accessible at the measurement date. Active markets provide pricing data for trades occurring at least weekly and include exchanges and dealer markets. • Level 2—Inputs include quoted prices for similar assets or liabilities in active markets, quoted prices from those willing to trade in markets that are not active, or other inputs that are observable or can be corroborated by market data for the term of the instrument. Such inputs include market interest rates and volatilities, spreads and yield curves. • Level 3—Certain inputs are unobservable (supported by little or no market activity) and significant to the fair value measurement. Unobservable inputs reflect the Company’s best estimate of what hypothetical market participants would use to determine a transaction price for the asset or liability at the reporting date. The following table presents information about the Company’s assets and liabilities that were measured at fair value on a recurring basis as of December 31, 2020 and 2019, and indicates the fair value hierarchy of the valuation techniques the Company utilized to determine such fair value. December 31, Quoted Prices in Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Assets: Derivative contracts (Note 19) $ 3,249 $ — $ 3,249 $ — Restoration plan assets 3,724 3,724 — — Total $ 6,973 $ 3,724 $ 3,249 $ — Liabilities: Derivative contracts (Note 19) $ 34,466 $ — $ 34,466 $ — December 31, Quoted Prices in Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Assets: Derivative contracts (Note 19) $ 3,928 $ — $ 3,928 $ — Restoration plan assets 4,199 4,199 — — Total $ 8,127 $ 4,199 $ 3,928 $ — Liabilities: Derivative contracts (Note 19) $ 11,376 $ — $ 11,376 $ — The following table presents information about the Company’s assets and liabilities that were measured at fair value on a non-recurring basis as of December 31, 2020 (there were no such assets or liabilities measured during the year ended December 31, 2019). The Company performed its annual impairment test on its goodwill on October 1, 2020, and determined that an impairment existed with respect to the Performance Chemicals segment. As a result, the Company recorded a non cash goodwill impairment charge of $260,000. Refer to Note 15 to these consolidated financial statements for a description of the valuation techniques the Company utilized to determine such fair value and for the results of the impairment testing procedures performed. As of Quoted Prices in Significant Other Significant Total Assets: Goodwill (1) $ 717,738 $ — $ 717,738 $ — $ (260,000) (1) Goodwill with a carrying amount of $973,578 was written down to $717,738 as part of the Company’s annual impairment assessment on October 1, 2020. This resulted in an impairment charge of $260,000 on the consolidated statements of income. Restoration plan assets The fair values of the Company’s restoration plan assets are determined through quoted prices in active markets. Restoration plan assets are assets held in a Rabbi trust to fund the obligations of the Company’s defined benefit supplementary retirement plans and include various stock and fixed income mutual funds. See Note 21 to these consolidated financial statements regarding defined benefit supplementary retirement plans. The Company’s restoration plan assets are included in other long-term assets on its consolidated balance sheets. Gains and losses related to these investments are included in other expense, net in the Company’s consolidated statements of income. Unrealized gains associated with the underlying stock and fixed income mutual funds were $545 and $944 as of December 31, 2020 and 2019, respectively and an unrealized loss of $346 as of December 31, 2018. Derivative contracts Derivative assets and liabilities can be exchange-traded or traded over-the-counter (“OTC”). The Company generally values exchange-traded derivatives using models that calibrate to market transactions and eliminate timing differences between the closing price of the exchange-traded derivatives and their underlying instruments. OTC derivatives are valued using market transactions and other market evidence whenever possible, including market-based inputs to models, model calibration to market transactions, broker or dealer quotations or alternative pricing sources with reasonable levels of price transparency. When models are used, the selection of a particular model to value an OTC derivative depends on the contractual terms of, and specific risks inherent in, the instrument as well as the availability of pricing information in the market. The Company generally uses similar models to value similar instruments. Valuation models require a variety of inputs, including contractual terms, market prices and rates, forward curves, measures of volatility, and correlations of such inputs. For OTC derivatives that trade in liquid markets, such as forward contracts, swaps and options, model inputs can generally be corroborated by observable market data by correlation or other means, and model selection does not involve significant management judgment. The Company has interest rate caps and cross currency swaps that are fair valued using Level 2 inputs. In addition, the Company applies a credit valuation adjustment to reflect credit risk which is calculated based on credit default swaps. To the extent that the Company’s net exposure under a specific master agreement is an asset, the Company utilizes the counterparty’s default swap rate. If the net exposure under a specific master agreement is a liability, the Company utilizes a default swap rate comparable to PQ Group Holdings. The credit valuation adjustment is added to the discounted fair value to reflect the exit price that a market participant would be willing to receive to assume the Company’s liabilities or that a market participant would be willing to pay for the Company’s assets.

Stockholders' Equity

Stockholders' Equity	12 Months Ended
	Dec. 31, 2020
Equity [Abstract]
Stockholders' Equity	7. Stockholders' Equity: Accumulated Other Comprehensive Income (Loss) The following table presents the components of accumulated other comprehensive income (loss), net of tax, as of December 31, 2020 and 2019: December 31, 2020 2019 Amortization and unrealized gains (losses) on pension and postretirement plans, net of tax of $(1,649) and $(994) $ 5,278 $ 3,568 Net changes in fair values of derivatives, net of tax of $549 and $604 (660) (1,838) Foreign currency translation adjustments, net of tax of $1,223 and $7,474 (19,883) (17,078) Accumulated other comprehensive loss $ (15,265) $ (15,348) The following table presents the tax effects of each component of other comprehensive income (loss) for the years ended December 31, 2020, 2019 and 2018: Years ended 2020 2019 2018 Pre-tax amount Tax benefit/ After-tax amount Pre-tax amount Tax benefit/ After-tax amount Pre-tax amount Tax benefit/ After-tax amount Defined benefit and other postretirement plans: Amortization of net gains and (losses) $ 2,824 $ (712) $ 2,112 $ 2,970 $ (423) $ 2,547 $ (10,279) $ 2,380 $ (7,899) Amortization of prior service cost (232) 58 (174) (156) 39 (117) (78) 19 (59) Benefit plans, net 2,592 (654) 1,938 2,814 (384) 2,430 (10,357) 2,399 (7,958) Net (loss) gain from hedging activities 221 (55) 166 (3,553) 888 (2,665) (441) 110 (331) Foreign currency translation (1) (11,268) (6,251) (17,519) 20,539 2,350 22,889 (39,419) 4,364 (35,055) Other comprehensive income (loss) $ (8,455) $ (6,960) $ (15,415) $ 19,800 $ 2,854 $ 22,654 $ (50,217) $ 6,873 $ (43,344) (1) The income tax benefit or expense included in other comprehensive income is attributed to the portion of foreign currency translation associated with the Company’s cross-currency interest rate swaps, for which the tax effect is based on the applicable U.S. deferred income tax rate. See Note 19 to these consolidated financial statements for information regarding the Company’s cross currency interest rate swaps. The following table presents the change in accumulated other comprehensive income (loss), net of tax, by component for the years ended December 31, 2020 and 2019: Defined benefit Net gain (loss) from hedging activities Foreign Total December 31, 2018 $ (546) $ 637 $ (39,195) $ (39,104) Other comprehensive income (loss) before reclassifications 2,497 (3,388) 22,117 21,226 Amounts reclassified from accumulated other comprehensive income (1) (67) 723 — 656 Net current period other comprehensive loss 2,430 (2,665) 22,117 21,882 Tax Cuts and Jobs Act, reclassification from AOCI to retained earnings 1,684 190 — 1,874 December 31, 2019 3,568 (1,838) (17,078) (15,348) Other comprehensive income (loss) before reclassifications 1,850 125 (16,596) (14,621) Amounts reclassified from accumulated other comprehensive income (1) 88 41 — 129 Disposal of business (228) 1,012 13,791 14,575 Net current period other comprehensive income (loss) 1,710 1,178 (2,805) 83 December 31, 2020 $ 5,278 $ (660) $ (19,883) $ (15,265) (1) See the following table for details about these reclassifications. Amounts in parentheses indicate debits. The following table presents the reclassifications out of accumulated other comprehensive income for the years ended December 31, 2020 and 2019. Details about Accumulated Other Amount Reclassified from Accumulated Other Comprehensive Income (1) Affected Line Item in the Years ended 2020 2019 Amortization of defined benefit and other postretirement plans: Prior service credit (cost) $ 119 $ 133 Other income (expense) (2) Actuarial gains (losses) (232) (21) Other income (expense) (2) (113) 112 Total before tax 25 (45) Tax benefit (expense) $ (88) $ 67 Net of tax Gains and losses on cash flow hedges: Interest rate caps $ (54) $ (625) Interest expense Natural gas swaps — (335) Cost of goods sold (54) (960) Total before tax 13 237 Tax benefit $ (41) $ (723) Net of tax Total reclassifications for the period $ (129) $ (656) Net of tax (1) Amounts in parentheses indicate debits to profit/loss. (2) These accumulated other comprehensive income (loss) components are components of net periodic pension and other postretirement cost (see Note 21 to these consolidated financial statements for additional details).

Dispositions Dispositions

Dispositions Dispositions	12 Months Ended
	Dec. 31, 2020
Discontinued Operations and Disposal Groups [Abstract]
Disposal Groups, Including Discontinued Operations, Disclosure [Text Block]	4. Performance Materials Divestiture: On December 14, 2020, the Company completed the sale of its Performance Materials business to Potters Buyer, LLC (the “Purchaser”), an affiliate of The Jordan Company, L.P., for a purchase price of $650,000. The net cash proceeds to the Company from the sale were $624,256 after certain customary adjustments for indebtedness, working capital and cash at the closing of the transaction. The Company classified the proceeds within net cash provided by (used in) investing activities – continuing operations in the consolidated statements of cash flows and used the net proceeds from the sale as well as cash on hand to pay down debt and issue a special cash dividend of $1.80/share to stockholders. In the fourth quarter of 2020, the Performance Materials business met the criteria set forth in Accounting Standards Codification 205-20, Presentation of Financial Statements – Discontinued Operations (“ASC 205-20”), as the sale represents a strategic shift that will have a major effect on the Company’s operations and financial results. As a result, the Company’s consolidated financial statements for all periods presented reflect the Performance Materials business as a discontinued operation. The divested business was historically reported in the Performance Materials reportable segment, with the exception of certain Australian operations that were historically reported in the Performance Chemicals reportable segment. The total transaction costs incurred in connection with the sale were approximately $13,161 for the year ended December 31, 2020. The Company recorded a pre-tax loss on sale of $70,878, which is included in (loss) income from discontinued operations, net of tax in the Company’s consolidated statements of income for the year ended December 31, 2020. The following is a reconciliation of the loss recorded on the sale: Net proceeds received from the sale of Performance Materials $ 624,256 Transaction costs (13,161) Net assets derecognized (681,973) Loss on sale of Performance Materials $ (70,878) In c onnection with the sale of Performance Materials and the related loss, as noted above, the Company has recognized a tax expense of $58,008 within d iscontinued operations. The following table summarizes the results of discontinued operations for the periods presented: Years ended 2020 2019 2018 Sales $ 342,738 $ 373,686 $ 386,921 Cost of goods sold 251,917 281,566 308,679 Selling, general and administrative expenses 33,195 37,364 37,226 Other operating expense, net 18,289 14,462 13,023 Operating income 39,337 40,294 27,993 Equity in net income from affiliated companies (37) (12) (42) Interest expense, net (1) 16,210 24,453 22,965 Other (income) expense, net (3,481) 274 474 Loss on sale of Performance Materials 70,878 — — (Loss) Income from discontinued operations before income tax (44,233) 15,579 4,596 Provision (benefit) for income taxes 58,008 1,022 (4,646) (Loss) income from discontinued operations, net of tax $ (102,241) $ 14,557 $ 9,242 (1) The closing of the transaction triggered the Company’s obligation to provide partial repayment under both its Amended and Restated Term Loan Credit Agreement, dated May 4, 2016, and its New Term Loan Credit Agreement, dated as of July 22, 2020. As such, interest expense has been allocated to discontinued operations on the basis of the Company’s mandatory repayment of $275,787 of the Senior Secured Term Loan Facility due February 2027 and its mandatory payment of $188,722 of the New Senior Secured Term Loan Facility due February 2027. Net income attributable to the noncontrolling interest related to the Performance Materials business, net of tax was $265, $154, and $213 for the years ended December 31, 2020, 2019, and 2018, respectively. The following table summarizes the assets and liabilities of discontinued operations at December 31, 2019: December 31, ASSETS Cash and cash equivalents $ 18,423 Accounts receivables, net 40,484 Inventories, net 143,323 Prepaid and other current assets 4,139 Investments in affiliated companies 115 Property, plant and equipment, net 175,614 Goodwill 286,227 Other intangible assets, net 121,113 Right-of-use lease assets 8,878 Other long-term assets 71,697 Total assets held for sale $ 870,013 LIABILITIES Notes payable and current maturities of long-term debt $ 7,766 Accounts payable 30,267 Operating lease liabilities—current 3,326 Accrued liabilities 16,744 Long-term debt, excluding current portion 55,972 Deferred income taxes 8,612 Operating lease liabilities—noncurrent 5,248 Other long-term liabilities 17,366 Total liabilities held for sale $ 145,301 In connection with the transaction, the Company entered into a Transition Services Agreement with the Purchaser pursuant to which the Purchaser is receiving certain services to provide for the orderly transition of various functions and processes after the closing of the transaction. The services under the Transition Services Agreement include information technology, accounting, tax, financial services, human resources, facilities, and other administrative support services. These services are being provided at cost for a period of 9 months, with three 30-day extensions available. Additionally, in connection with the transaction, the Company entered into various supply agreements with the Purchaser. Cash flows associated with these transition services and supply agreements are not expected to be material to the Company’s results of operations. 8. Dispositions: Magnesium Silicate Product Line Sale On July 1, 2020, the Company completed the sale of its magnesium silicate product line within its Performance Chemicals segment for $18,000 and recorded a pre-tax gain on sale of $4,958. The transaction was recorded as an asset sale, with the gain on disposition included in the other operating expense, net line item in the Company’s condensed consolidated statement of income for the year ended December 31, 2020 (see Note 9 to these condensed consolidated financial statements for additional details). At the time of disposition, the carrying value of the Company’s inventory related to this non-core product line was $1,556. The Company allocated $11,486 of the consideration received to a contract liability for deferred revenue. Concurrent with the product line sale, the Company entered into a tolling arrangement with the buyer in which the Company agreed to manufacture the product for the buyer through June 2025. The Company deferred $11,486 of the $18,000 consideration received as a liability, to be recognized as the Company executes its performance obligations over the term of the contractual agreement with the buyer. Sulfate Salts Product Line Sale On June 28, 2019, the Company completed the sale of a portion of its sulfate salts product line within its Performance Chemicals segment for $28,000, with net cash consideration of $27,658 and a pre-tax gain on sale of $11,518. The transaction was recorded as an asset sale, with the gain on disposition included in the other operating expense, net line item in the Company’s consolidated statement of income for the year ended December 31, 2019 (see Note 9 to these consolidated financial statements for additional details). At the time of disposition, the carrying value of the Company’s net working capital related to this non-core product line was $4,215. In addition to the net working capital sold as part of the transaction, the Company also derecognized $3,276 of property, plant and equipment related to the product line and allocated $9,000 of the consideration received to a liability for deferred revenue. Concurrent with the product line sale, the Company entered into a tolling arrangement with the buyer in which the Company will use its existing manufacturing facilities for the product line to manufacture the product for the buyer, the majority of which runs until June 2021. The Company deferred $9,000 of the consideration received as a liability, to be recognized as the Company executes its performance obligations over the term of the contractual agreement with the buyer. Additionally, the Company concluded that an embedded lease arrangement exists as a result of the combination of the sale and tolling agreements. Given the ability of the buyer to control substantially all of the output of the facilities and the existence of bargain purchase options on the manufacturing assets, the Company determined that the buyer is effectively leasing the assets from the Company and derecognized the associated property, plant and equipment under a sales-type leasing arrangement. The gain on the sale of fixed assets is included as part of the Company’s overall gain on sale related to the transaction, with the Company’s net investment in the leased assets having been settled as part of the consideration received in the transaction with no additional future cash flows to be recognized on the lease. Sale of Assets On December 19, 2019, the Company completed the sale of real property for $19,100, with net cash consideration of $17,100 and a holdback receivable to be settled by December 2021 of $1,000, and recorded a pre-tax gain on sale of $7,150. On December 30, 2019, the Company entered into a leaseback arrangement with the buyer-lessor which expires in December 2021. The Company recorded the asset sale separately from the leaseback, with the gain on disposition included in the other operating expense, net line item in the Company’s consolidated statement of income for the year ended December 31, 2019 (see Note 9 to these consolidated financial statements for additional details).

Other Operating Expense, Net

Other Operating Expense, Net	12 Months Ended
	Dec. 31, 2020
Other Income and Expenses [Abstract]
Other Operating Expense, Net	9. Other Operating Expense, Net: A summary of other operating expense, net is as follows: Years ended 2020 2019 2018 Amortization expense $ 26,923 $ 26,888 $ 27,258 Transaction and other related costs (1) 8,274 407 491 Restructuring, integration and business optimization costs (2) 13,028 2,692 5,819 Net (gain) loss on asset disposals (3) (134) (13,207) 4,190 Insurance recoveries (4) — — (5,480) Write-off of long-term supply contract obligation (Note 25) — — (20,612) Environmental related costs 1,092 2,522 638 Other, net 1,803 2,076 4,123 $ 50,986 $ 21,378 $ 16,427 (1) Transaction and other related costs during the year ended December 31, 2020 primarily related to costs incurred from the strategic review of the Company’s Performance Chemicals business. Refer to Note 29 of these consolidated financial statements for additional details. (2) During the year ended December 31, 2020 , the Company’s results were impacted by costs associated with the execution of the Company’s strategic initiatives. The costs incurred during the year ended December 31, 2020 primarily relate to demolition and decommissioning costs related to various asset sales. The costs incurred during the years ended December 31, 2019 and 2018 relate to severance charges for certain executives and employees, transition/duplicate staffing, professional fees and other expenses related to the Company’s organization changes. (3) During the year ended December 31, 2020, the Company recognized a gain of $4,958 related to the sale of a product line and a gain of $672 related to the sale of its interest in the Quaker Holdings joint venture, which were offset by fixed asset write-offs. During the year ended December 31, 2019, the Company recognized a gain of $11,518 related to the sale of a product line and a gain of $7,150 related to a property sale, which were partially offset by fixed asset write-offs. Refer to Note 8 of these consolidated financial statements for additional details. (4) During the year ended December 31, 2018, the Company recognized $6,450 of insurance recoveries in its consolidated statement of income related to the Company’s claim for losses sustained during Hurricane Harvey in August 2017. For the year ended December 31, 2018, $5,480 was recorded as a gain in other operating expense, net, as reimbursement of expenses, $207 was recorded as a gain in net loss on asset disposals within other operating expense, net, for the Company’s previously recognized property losses, and $763 represented recoveries in excess of the Company’s property losses which was recorded as a non-operating gain in other expense, net, in the Company’s consolidated statement of income.

Inventories, Net

Inventories, Net	12 Months Ended
	Dec. 31, 2020
Inventory Disclosure [Abstract]
Inventories	10. Inventories, Net: Inventories, net are classified and valued as follows: December 31, 2020 2019 Finished products and work in process $ 102,388 $ 106,980 Raw materials 25,048 30,642 $ 127,436 $ 137,622 Valued at lower of cost or market: LIFO basis $ 55,283 $ 60,190 Valued at lower of cost and net realizable value: FIFO or average cost basis 72,153 77,432 $ 127,436 $ 137,622 The domestic inventory acquired as part of a previous business combination is valued based on the LIFO method. Therefore, the fair value allocated to the acquired LIFO inventory was treated as the new base inventory value. If inventories valued under the LIFO basis had been valued using the FIFO method, inventories would have been $4,255 lower and $974 higher than reported as of December 31, 2020 and 2019, respectively, driven primarily by the purchase accounting fair value step-up of the LIFO inventory base value associated with the business combination.

Investments in Affiliated Compa

Investments in Affiliated Companies	12 Months Ended
	Dec. 31, 2020
Equity Method Investments and Joint Ventures [Abstract]
Investments in Affiliated Companies	11. Investments in Affiliated Companies: The Company accounts for investments in affiliated companies under the equity method. Affiliated companies accounted for on the equity method as of December 31, 2020 are as follows: Company Country Percent PQ Silicates Ltd. Taiwan 50% Zeolyst International USA 50% Zeolyst C.V. Netherlands 50% Following is summarized information of the combined investments (1) : December 31, 2020 2019 Current assets $ 219,002 $ 248,685 Noncurrent assets 254,416 256,104 Current liabilities 66,423 52,638 Noncurrent liabilities 36,788 5,950 Years ended 2020 2019 2018 Sales $ 278,414 $ 380,381 $ 351,839 Gross profit 89,471 144,828 126,505 Operating income 54,010 106,195 88,294 Net income 55,722 107,112 88,411 (1) Summarized information of the combined investments is presented at 100%; the Company’s share of the net assets and net income of affiliates is calculated based on the percent ownership specified in the table above. In March 2020, the Company sold its 49% interest in the Quaker Holdings joint venture to a third party. Prior to the Company’s disposition of its shares in the joint venture, the Company received a liquidating dividend of $729 as well as $1,032 for the sale of the joint venture shares, which was included in the proceeds from sale of investment within the investing activities section of the Company’s consolidated statement of cash flows. The Company’s investments in affiliated companies balance as of December 31, 2020 and 2019 includes net purchase accounting fair value adjustments of $243,899 and $250,532, respectively, related a prior business combination, consisting primarily of goodwill and intangible assets such as customer relationships, technical know-how and trade names. Consolidated equity in net income from affiliates is net of $6,634, $7,534 and $6,634 of amortization expense related to purchase accounting fair value adjustments for the years ended December 31, 2020, 2019 and 2018, respectively. The following table summarizes the activity related to the Company’s investments in affiliated companies balance on the consolidated balance sheets: Years ended 2020 2019 Balance at beginning of period $ 472,814 $ 468,055 Equity in net income of affiliated companies 27,871 53,556 Charges related to purchase accounting fair value adjustments (6,634) (7,534) Dividends received (40,989) (40,073) Foreign currency translation adjustments 5,390 (1,190) Balance at end of period $ 458,452 $ 472,814 The Company had net receivables due from affiliates of $3,814 and $3,586 as of December 31, 2020 and 2019, respectively, which are included in prepaid and other current assets. Net receivables due from affiliates are generally non-trade receivables. Sales to affiliates were $9,144, $4,181 and $2,823 for the years ended December 31, 2020, 2019 and 2018, respectively. The Company did not purchase goods from affiliates during the years ended December 31, 2020, 2019 and 2018. On December 18, 2013, PQ Holdings and its joint venture, Zeolyst International, entered into a ten year real estate tax abatement agreement with the Unified Government of Wyandotte County, Kansas. The agreement utilizes an Industrial Revenue Bond (“IRB”) financing structure to achieve a 75% real estate tax abatement on the value of the improvements that were constructed during the expansion of PQ Holdings and Zeolyst International’s facilities at the jointly-operated Kansas City, Kansas plant. A similar tax abatement agreement has been executed on an annual basis since December 18, 2013 with respect to additional plant expansions during those years. During the year ended December 31, 2019, the original IRB financing structure from December 2013 was exhausted. In order to fund future plant expansions, the Company entered into an additional IRB financing structure on December 19, 2019 with similar terms and conditions, which also provides for 75% real estate tax abatement on the value of future improvements. The financing obligations and the industrial bonds receivable have been presented net, as the financing obligations and the industrial bonds meet the criteria for right of set off conditions under GAAP.

Property, Plant and Equipment

Property, Plant and Equipment	12 Months Ended
	Dec. 31, 2020
Property, Plant and Equipment [Abstract]
Property, Plant and Equipment	12. Property, Plant and Equipment: A summary of property, plant and equipment, at cost, and related accumulated depreciation is as follows: December 31, 2020 2019 Land $ 158,517 $ 160,321 Buildings 168,204 160,653 Machinery and equipment 1,097,949 1,027,775 Construction in progress 78,641 76,242 1,503,311 1,424,991 Less: accumulated depreciation (520,076) (413,835) $ 983,235 $ 1,011,156 Depreciation expense was $114,641, $111,032 and $111,491 for the years ended December 31, 2020, 2019 and 2018, respectively.

Leases

Leases	12 Months Ended
	Dec. 31, 2020
Leases [Abstract]
Lessee, Finance Leases	13. Leases: Operating lease costs of $16,817 and $15,125 are included in cost of goods sold and in selling, general and administrative expenses on the consolidated statement of income for the year ended December 31, 2020 and 2019, respectively. Finance lease, short-term lease and variable lease costs for the years ended December 31, 2020 and 2019 were not material. Lease income is not material to the results of operations for the years ended December 31, 2020 and 2019. The Company entered into a sale-leaseback transaction during the year ended December 31, 2019. Disclosures related to this transaction can be found within Note 8 to these consolidated financial statements. The table below presents the operating and finance right-of-use lease assets and lease liabilities recognized on the consolidated balance sheet as of December 31, 2020 and 2019: Classification December 31, December 31, Assets Operating lease assets Right-of-use lease assets $ 48,239 $ 48,417 Finance lease assets Property, plant and equipment, net 1,752 1,556 Total leased assets $ 49,991 $ 49,973 Liabilities Current: Operating lease liabilities Operating lease liabilities—current $ 15,194 $ 11,857 Finance lease liabilities Accrued liabilities 262 185 Noncurrent: Operating lease liabilities Operating lease liabilities—noncurrent 32,019 34,908 Finance lease liabilities Other long-term liabilities 366 315 Total lease liabilities $ 47,841 $ 47,265 The Company’s weighted average remaining lease term and weighted average discount rate for operating and financing leases as of December 31, 2020 are as follows: December 31, December 31, Weighted average remaining lease term (in years): Operating leases 5.18 5.51 Finance leases 2.45 2.65 Weighted average discount rate: Operating leases 5.55 % 5.66 % Finance leases 4.67 % 4.67 % Maturities of lease liabilities as of December 31, 2020 are as follows: Year Operating Finance 2021 $ 17,363 $ 406 2022 10,707 161 2023 8,655 40 2024 6,404 35 2025 3,917 8 Thereafter 7,785 — Total lease payments 54,831 650 Less: Interest (7,618) (22) Total lease liabilities $ 47,213 $ 628 (1) Refer to the above table regarding the Company’s right-of-use lease assets and lease liabilities for the presentation of the lease liabilities in the Company’s consolidated balance sheet at December 31, 2020. The following table presents other information related to the Company’s operating and finance leases and the impact on the Company’s consolidated statement of cash flows: Years ended 2020 2019 Cash paid for amounts included in the measurement of lease liabilities: Payments on operating leases included in operating cash flows $ 16,135 $ 14,814 Interest payments under finance lease obligations included in operating cash flows 21 26 Principal payments under finance lease obligations included in financing cash flows 209 177 Right-of-use assets obtained in exchange for new lease liabilities (non-cash): Operating leases 14,439 8,798 Finance leases 353 —
Lessee, Operating Leases	13. Leases: Operating lease costs of $16,817 and $15,125 are included in cost of goods sold and in selling, general and administrative expenses on the consolidated statement of income for the year ended December 31, 2020 and 2019, respectively. Finance lease, short-term lease and variable lease costs for the years ended December 31, 2020 and 2019 were not material. Lease income is not material to the results of operations for the years ended December 31, 2020 and 2019. The Company entered into a sale-leaseback transaction during the year ended December 31, 2019. Disclosures related to this transaction can be found within Note 8 to these consolidated financial statements. The table below presents the operating and finance right-of-use lease assets and lease liabilities recognized on the consolidated balance sheet as of December 31, 2020 and 2019: Classification December 31, December 31, Assets Operating lease assets Right-of-use lease assets $ 48,239 $ 48,417 Finance lease assets Property, plant and equipment, net 1,752 1,556 Total leased assets $ 49,991 $ 49,973 Liabilities Current: Operating lease liabilities Operating lease liabilities—current $ 15,194 $ 11,857 Finance lease liabilities Accrued liabilities 262 185 Noncurrent: Operating lease liabilities Operating lease liabilities—noncurrent 32,019 34,908 Finance lease liabilities Other long-term liabilities 366 315 Total lease liabilities $ 47,841 $ 47,265 The Company’s weighted average remaining lease term and weighted average discount rate for operating and financing leases as of December 31, 2020 are as follows: December 31, December 31, Weighted average remaining lease term (in years): Operating leases 5.18 5.51 Finance leases 2.45 2.65 Weighted average discount rate: Operating leases 5.55 % 5.66 % Finance leases 4.67 % 4.67 % Maturities of lease liabilities as of December 31, 2020 are as follows: Year Operating Finance 2021 $ 17,363 $ 406 2022 10,707 161 2023 8,655 40 2024 6,404 35 2025 3,917 8 Thereafter 7,785 — Total lease payments 54,831 650 Less: Interest (7,618) (22) Total lease liabilities $ 47,213 $ 628 (1) Refer to the above table regarding the Company’s right-of-use lease assets and lease liabilities for the presentation of the lease liabilities in the Company’s consolidated balance sheet at December 31, 2020. The following table presents other information related to the Company’s operating and finance leases and the impact on the Company’s consolidated statement of cash flows: Years ended 2020 2019 Cash paid for amounts included in the measurement of lease liabilities: Payments on operating leases included in operating cash flows $ 16,135 $ 14,814 Interest payments under finance lease obligations included in operating cash flows 21 26 Principal payments under finance lease obligations included in financing cash flows 209 177 Right-of-use assets obtained in exchange for new lease liabilities (non-cash): Operating leases 14,439 8,798 Finance leases 353 —

Reportable Segments

Reportable Segments	12 Months Ended
	Dec. 31, 2020
Segment Reporting [Abstract]
Reportable Segments	14. Reportable Segments: The Company has organized its business around three operating segments based on the review of discrete financial results for each of the operating segments by the Company’s chief operating decision maker (the Company’s Chairman of the Board, President and Chief Executive Officer), or CODM, for performance assessment and resource allocation purposes. Each of the Company’s operating segments represents a reportable segment under GAAP. The Company’s reportable segments are organized based on the nature and economic characteristics of the Company’s products. The Company’s three reportable segments are as follows: (1) Refining Services provides sulfuric acid recycling to the North American refining industry; (2) Catalysts serves the packaging and engineered plastics and the global refining, petrochemical and emissions control industries; and (3) Performance Chemicals supplies diverse product end uses, including personal and industrial cleaning products, fuel-efficient tires, surface coatings, and food and beverage products. The Catalysts segment includes equity in net income from Zeolyst International and Zeolyst C.V. (collectively, the “Zeolyst Joint Venture”), each of which are 50/50 joint ventures with CRI Zeolites Inc. (a wholly-owned subsidiary of Royal Dutch Shell). The Zeolyst Joint Venture is accounted for using the equity method in the Company’s consolidated financial statements (see Note 11 to these consolidated financial statements for further information). Company management evaluates the Catalysts segment’s performance, including the Zeolyst Joint Venture, on a proportionate consolidation basis. Accordingly, the revenues and expenses used to compute the Catalysts segment’s adjusted earnings before interest, income taxes, depreciation and amortization (“Adjusted EBITDA”) include the Zeolyst Joint Venture’s results of operations on a proportionate basis based on the Company’s 50% ownership level. Since the Company uses the equity method of accounting for the Zeolyst Joint Venture, these items are eliminated when reconciling to the Company’s consolidated results of operations. The Company’s management evaluates the operating results of each reportable segment based upon Adjusted EBITDA. Adjusted EBITDA consists of EBITDA, which is a measure defined as net income before interest, income taxes, depreciation and amortization (each of which is included in the Company’s consolidated statements of income), and adjusted for certain items as discussed below. Summarized financial information for the Company’s reportable segments is shown in the following table: Years ended 2020 2019 2018 Sales: Refining Services $ 401,913 $ 447,081 $ 455,562 Catalysts (1) 94,007 85,667 72,099 Performance Chemicals 614,704 670,563 704,502 Eliminations (2) (3,261) (3,397) (3,237) Total $ 1,107,363 $ 1,199,914 $ 1,228,926 Segment Adjusted EBITDA: (3) Refining Services $ 157,198 $ 175,640 $ 176,499 Catalysts (4) 74,504 107,808 81,067 Performance Chemicals 142,372 151,547 168,196 Total Segment Adjusted EBITDA (5) $ 374,074 $ 434,995 $ 425,762 (1) Excludes the Company’s proportionate share of sales from the Zeolyst Joint Venture accounted for using the equity method. The proportionate share of sales is $128,623, $170,338 and $156,687 for the years ended December 31, 2020, 2019 and 2018, respectively. (2) The Company eliminates intersegment sales when reconciling to the Company’s consolidated statements of income. (3) The Company defines Adjusted EBITDA as EBITDA adjusted for certain items as noted in the reconciliation below. Management evaluates the performance of its segments and allocates resources based on several factors, of which the primary measure is Adjusted EBITDA. Adjusted EBITDA should not be considered as an alternative to net income as an indicator of the Company’s operating performance. Adjusted EBITDA as defined by the Company may not be comparable with EBITDA or Adjusted EBITDA as defined by other companies. (4) The Adjusted EBITDA from the Zeolyst Joint Venture included in the Catalysts segment is $42,515 for the year ended December 31, 2020, which includes $21,157 of equity in net income plus $6,634 of amortization of investment in affiliate step-up plus $14,724 of joint venture depreciation, amortization and interest. The Adjusted EBITDA from the Zeolyst Joint Venture included in the Catalysts segment is $68,138 for the year ended December 31, 2019, which includes $45,899 of equity in net income plus $7,534 of amortization of investment in affiliate step-up plus $14,705 of joint venture depreciation, amortization and interest. The Adjusted EBITDA from the Zeolyst Joint Venture included in the Catalysts segment is $56,663 for the year ended December 31, 2018, which includes $37,437 of equity in net income plus $6,634 of amortization of investment in affiliate step-up plus $12,592 of joint venture depreciation, amortization and interest. (5) Total Segment Adjusted EBITDA differs from the Company’s consolidated Adjusted EBITDA due to unallocated corporate expenses. A reconciliation of net income attributable to PQ Group Holdings to Segment Adjusted EBITDA is as follows: Years ended 2020 2019 2018 Reconciliation of net (loss) income attributable to PQ Group Holdings Inc. to Segment Adjusted EBITDA Net (loss) income from continuing operations $ (176,265) $ 65,136 $ 49,271 (Benefit) provision for income taxes (48,122) 39,677 33,641 Interest expense, net 66,979 87,072 90,758 Depreciation and amortization 151,840 151,797 153,931 Segment EBITDA (5,568) 343,682 327,601 Joint venture depreciation, amortization and interest 14,724 14,705 12,592 Amortization of investment in affiliate step-up 6,634 7,534 6,634 Goodwill impairment charge 260,000 — — Debt extinguishment costs 25,028 3,400 7,751 Net (gain) loss on asset disposals (134) (13,207) 4,190 Foreign currency exchange (gain) loss (4,172) 2,410 12,543 LIFO (benefit) expense (5,229) 9,700 3,039 Transaction and other related costs 8,618 415 490 Equity-based compensation 21,527 16,212 18,419 Restructuring, integration and business optimization expenses 15,596 3,554 8,707 Defined benefit pension plan cost 12 2,960 411 Gain on contract termination (1) — — (20,612) Other 959 2,597 6,155 Adjusted EBITDA 337,995 393,962 387,920 Unallocated corporate expenses 36,079 41,033 37,842 Segment Adjusted EBITDA $ 374,074 $ 434,995 $ 425,762 (1) Includes the non-cash write-off of a long-term supply contract obligation (see Note 25), which was recorded as a reduction in other operating expense, net in the consolidated statement of income for the year ended December 31, 2018. The Company’s consolidated results include equity in net income from affiliated companies of $21,237, $46,022 and $37,569 for the years ended December 31, 2020, 2019, and 2018, respectively. This is primarily comprised of equity in net income of $21,157, $45,899 and $37,437 in the Catalysts segment from the Zeolyst Joint Venture for the years ended December 31, 2020, 2019 and 2018, respectively. The remaining equity in net income for the Company is included in the Performance Chemicals segment, which was attributed to smaller investments and was not material. The Company’s equity in net income from affiliated companies in the consolidated results includes amortization expense related to purchase accounting fair value adjustments associated with the Zeolyst Joint Venture as a result of a prior business combination. Capital expenditures for the Company’s reportable segments are shown in the following table: Years ended 2020 2019 2018 Capital expenditures: Refining Services $ 31,799 $ 42,310 $ 46,617 Catalysts (1) 11,177 8,984 8,390 Performance Chemicals 40,864 53,910 56,759 Corporate (2) 13,295 5,898 29 Capital expenditures per the consolidated statements of cash flows $ 97,135 $ 111,102 $ 111,795 (1) Excludes the Company’s proportionate share of capital expenditures from the Zeolyst Joint Venture. (2) Includes corporate capital expenditures, the cash impact from changes in capital expenditures in accounts payable and capitalized interest. Total assets by segment are not disclosed by the Company because the information is not prepared or used by the CODM to assess performance and to allocate resources. Sales and long-lived assets by geographic area are presented in the following tables. Sales are attributed to countries based upon location of products shipped. Years ended 2020 2019 2018 Sales (1) : United States $ 655,015 $ 735,752 $ 740,190 Netherlands 108,338 117,211 127,803 United Kingdom 107,539 99,048 101,277 Other foreign countries 236,471 247,903 259,656 Total $ 1,107,363 $ 1,199,914 $ 1,228,926 (1) Except for the United States, no sales in an individual country exceeded 10% of the Company’s total sales. December 31, 2020 2019 Long-lived assets (1) : United States $ 749,635 $ 784,699 Netherlands 53,006 49,559 United Kingdom 100,392 92,229 Other foreign countries 128,441 133,086 Total $ 1,031,474 $ 1,059,573 (1) Long-lived assets includes property, plant and equipment, net and right-of-use lease assets.

Goodwill and Other Intangible A

Goodwill and Other Intangible Assets	12 Months Ended
	Dec. 31, 2020
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill and Other Intangible Assets	15. Goodwill and Other Intangible Assets: The changes in the carrying amount of goodwill for the years ended December 31, 2020 and 2019 is summarized as follows: Refining Services Catalysts Performance Total Balance as of December 31, 2018 $ 311,892 $ 77,759 $ 580,023 $ 969,674 Foreign exchange impact — 852 3,052 3,904 Balance as of December 31, 2019 311,892 78,611 583,075 973,578 Goodwill impairment — — (260,000) (260,000) Foreign exchange impact — 1,062 3,098 4,160 Balance as of December 31, 2020 $ 311,892 $ 79,673 $ 326,173 $ 717,738 The carrying amounts of goodwill at December 31, 2020, 2019 and 2018 are net of the following accumulated impairment losses: Refining Services Catalysts Performance Total Accumulated impairment losses as of December 31, 2018 — — — — Accumulated impairment losses as of December 31, 2019 — — — — Accumulated impairment losses as of December 31, 2020 — — (260,000) (260,000) The Company completed its annual goodwill impairment assessments as of October 1, 2020 and 2019. For the annual assessments, the Company bypassed the option to perform the qualitative assessment and proceeded directly to performing the quantitative goodwill impairment test for each of its reporting units. The quantitative test identifies both the potential existence of impairment and the amount of impairment loss. For each of the October 1, 2020 and 2019 assessments, the Company identified three reporting units, which align with the Company’s operating segments. The Company determined the fair value of its reporting units using a split between a market approach and an income, or discounted cash flow, approach. Fair value is defined as the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date. The Company estimates reporting unit market approach fair value using publicly traded comparable company values and applies the selected market multiples to each reporting unit’s trailing twelve months adjusted EBITDA. The Company estimates reporting unit income-based fair value using the discounted cash flow approach. This approach requires use of significant assumptions about future cash flows and based on management’s assessment of a number of factors. Such factors include reporting unit revenue growth rates from implementation of strategic plans, operating margin growth rates, the perpetual growth rate, and the weighted average cost of capital, as well as the reporting unit’s recent performance and management’s ability to execute on planned future strategic initiatives. Discount rate assumptions are based on an assessment of the risk inherent in those future cash flows. Based on the Company’s announced strategic review of the Performance Chemicals reporting unit in the fourth quarter, the Company concluded the market approach was more appropriate to estimate the fair value of the reporting unit for the annual impairment test. The Company reviewed the recent reporting unit performance and peer company performance under current market conditions. As a result, the Company recorded a goodwill impairment charge of $260,000 in the fourth quarter of 2020, included in goodwill impairment charge in the consolidated statements of income related to the Performance Chemicals reporting unit. The carrying value of the Performance Chemicals reporting unit's goodwill was $326,173 at December 31, 2020. No other goodwill impairments were identified as a result of the 2020 testing. As of October 1, 2019, the fair values of each of the Company’s reporting units exceeded their respective carrying values and therefore, no goodwill impairment exists for the year ended December 31, 2019. In addition to the annual goodwill impairment assessment, the Company also performed the annual impairment test over its other indefinite-lived intangible assets as of October 1, 2020 and 2019. The fair values of the Company’s indefinite-lived trade names and trademarks were in excess of their carrying amounts as of the respective testing dates, and as such, there was no further impairment of the Company’s indefinite-lived intangible assets for the years ended December 31, 2020 and 2019. Gross carrying amounts and accumulated amortization for intangible assets other than goodwill are as follows: December 31, 2020 December 31, 2019 Gross Accumulated Net Gross Accumulated Net Technical know-how $ 180,768 $ (47,207) $ 133,561 $ 177,873 $ (37,102) $ 140,771 Customer relationships 325,773 (134,842) 190,931 321,434 (106,627) 214,807 Contracts — — — 16,200 (15,258) 942 Trademarks 7,709 (2,399) 5,310 7,600 (1,858) 5,742 Permits 9,100 (9,100) — 9,100 (9,100) — In-process research and development 500 (25) 475 — — — Total definite-lived intangible assets 523,850 (193,573) 330,277 532,207 (169,945) 362,262 Indefinite-lived trade names 108,713 — 108,713 106,811 — 106,811 Indefinite-lived trademarks 82,613 — 82,613 80,999 — 80,999 In-process research and development 4,700 — 4,700 5,200 — 5,200 Total intangible assets $ 719,876 $ (193,573) $ 526,303 $ 725,217 $ (169,945) $ 555,272 The Company amortizes technical know-how over periods that range from eleven years to twenty years, customer relationships over periods that range from seven years to fifteen years, trademarks over periods that range from eleven years to fifteen years, contracts over periods that range from two years to sixteen years, and permits over five years. In-process research and development intangible assets are considered indefinite-lived until such time as the associated projects are completed, at which time amortization commences on the assets, or abandoned, which results in the impairment of the assets. Amortization expense related to technical know-how, contracts and permits is included in cost of goods sold in the consolidated statements of income and was $9,369, $13,877 and $13,579 for the years ended December 31, 2020, 2019 and 2018, respectively. Amortization expense related to customer relationships and trademarks is included in other operating expense, net in the consolidated statements of income and was $26,923, $26,888 and $27,258 for the years ended December 31, 2020, 2019 and 2018, respectively. Estimated future aggregate amortization expense of intangible assets is as follows: Year Amount 2021 $ 36,292 2022 36,292 2023 36,292 2024 36,292 2025 36,292 Thereafter 148,817 Total estimated future aggregate amortization expense $ 330,277

Accrued Liabilities

Accrued Liabilities	12 Months Ended
	Dec. 31, 2020
Payables and Accruals [Abstract]
Accrued Liabilities	16. Accrued Liabilities: The following table summarizes the components of accrued liabilities as follows: December 31, 2020 2019 Compensation and bonus $ 35,251 $ 40,374 Interest 11,573 19,110 Property tax 2,656 2,250 Environmental reserves (Note 24) 4,309 4,548 Income taxes 869 4,900 Commissions and rebates 854 1,459 Pension, postretirement and supplemental retirement plans (Note 21) 1,852 1,825 Derivative liabilities 1,954 420 Other 14,493 10,524 $ 73,811 $ 85,410

Long-term Debt

Long-term Debt	12 Months Ended
	Dec. 31, 2020
Debt Disclosure [Abstract]
Long-term Debt	17. Long-term Debt: The summary of long-term debt is as follows: December 31, 2020 2019 Senior Secured Term Loan Facility due February 2027 $ 671,710 $ 947,497 New Senior Secured Term Loan Facility due February 2027 459,653 — 6.75% Senior Secured Notes due 2022 — 625,000 5.75% Senior Unsecured Notes due 2025 295,000 295,000 ABL Facility — — Total debt 1,426,363 1,867,497 Original issue discount (15,641) (13,434) Deferred financing costs (10,353) (10,839) Total debt, net of original issue discount and deferred financing costs 1,400,369 1,843,224 Less: current portion — — Total long-term debt, excluding current portion $ 1,400,369 $ 1,843,224 Senior Secured Credit Facilities On May 4, 2016, the Company entered into senior secured credit facilities (collectively, the “2016 Senior Secured Credit Facilities”) comprised of a $1,200,000 term loan facility, which consisted of a $900,000 U.S. dollar-denominated tranche and a $300,000 Euro-denominated (or €265,000) tranche (the “2016 Term Loan Facility”), and a $200,000 asset-based revolving credit facility (the “ABL Facility”). On February 8, 2018 (the “Third Amendment Closing Date”), PQ Corporation (the “Borrower”), an indirect, wholly owned subsidiary of the Company, refinanced its existing U.S. Dollar and Euro denominated senior secured term loan facilities with a new $1,267,000 senior secured term loan facility (the “ Senior Secured Term Loan Facility”) by entering into the Third Amendment Agreement to the 2016 Term Loan Facility (the “Third Amendment”), which amended and restated the Term Loan Credit Agreement dated as of May 4, 2016, among the Borrower, CPQ Midco I Corporation, Credit Suisse AG, Cayman Island Branch, as administrative agent and collateral agent, and the lenders and the other parties party thereto from time to time (as amended prior to the Third Amendment, the “Existing Credit Agreement” and as amended and restated by the Amendment, the “New Credit Agreement”). On February 7, 2020, the Company amended its Senior Secured Term Loan Facility to, among other things, (a) reduce the interest rate applicable to all LIBOR rate tranche B-1 term loans to LIBOR plus 2.25% per annum, (b) reduce the interest rate applicable to all base rate tranche B-1 term loans to the alternate base rate plus 1.25% per annum and (c) extend the maturity date of all tranche B-1 term loans to February 7, 2027. On July 22, 2020, the Company entered into an agreement for a new senior secured term loan facility (the “New Senior Secured Term Loan Facility”, collectively with the Senior Secured Term Loan Facility, the “Term Loan Facilities”) in an aggregate principal amount of $650,000 with an original issue discount of 1.5% and interest at a floating rate of LIBOR (with a 1.0% minimum LIBOR floor) plus 3.0% per annum. The proceeds were used to redeem its existing $625,000 of 6.75% Senior Secured Notes due 2022 and pay the associated early redemption premiums. The New Senior Secured Term Loan Facility requires scheduled quarterly amortization payments, each equal to 0.25% of the original principal amount of the loans under the New Senior Secured Term Loan Facility. As of December 31, 2020, the Senior Secured Term Loan Facility accrued interest at a floating rate of LIBOR plus 2.50% per annum and is scheduled to mature in February 2027. The Term Loan Facility requires scheduled quarterly amortization payments, each equal to 0.25% of the original principal amount of the loans under the Term Loan Facility. On the Third Amendment Closing Date, the Company also entered into multiple cross currency swap arrangements to hedge foreign currency risk. The swaps were designed to enable the Company to effectively convert a portion of its fixed-rate U.S. dollar denominated debt obligations into approximately €280,000. The swaps were to mature in February 2023. In October 2019, the Company settled all of its cross-currency interest rate swap arrangements (the “February 2018 swaps”) and concurrently entered into new cross-currency interest rate swap arrangements (the “October 2019 swaps”) with the same notional amount of €280,000 equivalent ($344,403 as of December 31, 2020) and same maturity of February 2023. Consistent with the February 2018 swaps, the October 2019 swaps are designed to enable the Company to effectively convert a portion of its fixed-rate U.S. dollar-denominated debt obligations under the Term Loan Facility into a Euro-denominated equivalent. The October 2019 swaps have been designated and qualify as net investment hedges of the Company’s foreign currency exchange rate exposure on the net investments of certain of its Euro-denominated subsidiaries. The settlement of the February 2018 swaps resulted in cash proceeds to the Company of $38,070, which the Company used for additional debt repayment on the Company’s Senior Secured Term Loan Facility. The Company may at any time or from time to time voluntarily prepay loans under the Term Loan Facilities in whole or in part without premium or penalty. The Term Loan Facilities requires mandatory prepayments from (i) 50% of “Excess Cash Flow” (as defined in the New Credit Agreement) on an annual basis with step downs to lower percentages based on the Borrower’s leverage ratio, if applicable, (ii) net cash proceeds from the issuance or incurrence of certain indebtedness and (iii) net cash proceeds received from certain non-ordinary course disposition of assets and casualty events to the extent such net cash proceeds were not reinvested in the Company’s business within a certain specified time period. Prepayments are applied to remaining amortization installments in direct order of maturity. The remaining principal balance of the term loans are due upon maturity. In addition, the New Credit Agreement contains customary affirmative and negative covenants and events of default, all of which are substantially the same as under the Existing Credit Agreement. The Borrower and certain Canadian and European subsidiaries of the Borrower also have a $200,000 asset-based revolving credit facility (the “ABL Facility”) which provides for $150,000 in U.S. available borrowings, up to $10,000 in Canadian available borrowings and up to $40,000 of European available borrowings. Borrowings under the ABL Facility bear interest at a rate equal to the LIBOR rate or the base rate elected by the Company at the time of the borrowing plus a margin of between 1.50%-2.00% or 0.50%-1.00%, respectively, depending on availability under the ABL Facility. In addition, there is an annual commitment fee equal to 0.375%, with a step-down to 0.25% based on the average usage of the revolving credit borrowings available. As of December 31, 2020, there were no revolving credit borrowings under the ABL Facility. Revolving credit borrowings are payable at the option of the Company throughout the term of the ABL Facility with the balance due May 4, 2021. On March 20, 2020, the Company amended its existing ABL Facility to increase the aggregate amount of the revolving loan commitments available by $50,000 to $250,000, consisting of up to $195,000 in U.S. commitments, up to $15,000 in Canadian commitments and up to $40,000 in European commitments. The maturity of the facility has been extended to March 20, 2025. Following the amendment, the borrowings under the amended ABL Facility bear interest at a rate equal to the LIBOR rate or the base rate plus a margin of between 1.25% to 1.75% or 0.25% to 0.75% respectively. The Company has the ability to request letters of credit under the ABL Facility. The Company had $18,190 of letters of credit outstanding as of December 31, 2020, which reduce available borrowings under the ABL Facility by such amounts. The Term Loan Facilities are guaranteed by CPQ Midco I Corporation, a subsidiary of the Company and the direct parent of the Borrower (“Holdings”) and substantially all of the Borrower’s wholly owned U.S. subsidiaries. The obligations under the Term Facility are secured (i) by a first-priority security interest in, among other things, a pledge of substantially all of the Borrower’s and the guarantors’ assets (other than collateral securing the ABL Facility on a first-priority basis) and (ii) by a second-priority security interest in receivables, inventory, deposit accounts and other collateral of the Borrower and the U.S. subsidiary guarantors securing the ABL Facility. The liens securing the Term Loan Facilities and the guarantees are pari passu with the liens securing the Senior Secured Notes subject to the pari passu intercreditor agreement. The obligations of the Borrower under the ABL Facility are guaranteed by Holdings and the same U.S. subsidiary guarantors that guarantee the Term Loan Facilities, the obligations of the Canadian Borrowers under the ABL Facility are guaranteed by a Canadian subsidiary of the Borrower and the obligations of the European Borrowers under the ABL Facility are guaranteed by certain other European subsidiaries of the Borrower. The obligations of the borrowers and guarantors under the ABL Facility are secured (i) by a first-priority security interest in, among other things, substantially all of their receivables, inventory, deposit accounts and other collateral securing the ABL Facility on a first-priority basis and (ii) by a second-priority security interest in the property and assets of Holdings, the Borrower and the U.S. subsidiary guarantors that secure the Term Loan Facilities. In addition, the ABL Facility is secured by the equity interests in, and substantially all of the assets of, certain foreign guarantors in connection with the Canadian dollar-denominated and Euro-denominated availability. The Term Loan Facilities and the ABL Facility contain various non-financial restrictive covenants. Each limits the ability of PQ Corporation and its restricted subsidiaries to incur certain indebtedness or liens, merge, consolidate or liquidate, dispose of certain property, make investments or declare or pay dividends, make optional payments, modify certain debt instruments, enter into certain transactions with affiliates, enter into certain sales and leasebacks, and certain other non-financial restrictive covenants. The ABL Facility also contains one financial covenant which applies when minimum availability under the ABL Facility exceeds a certain threshold. During such time, the Company is required to maintain a fixed-charge coverage ratio of at least 1.0 to 1.0. The Company is in compliance with all debt covenants as of December 31, 2020 and 2019, respectively. During the year ended December 31, 2020, the Company prepaid $466,134 of outstanding principal balance on its Term Loan Facilities. The Company wrote off $162 of previously unamortized deferred financing costs and original issue discount of $12,781 as debt extinguishment costs. The prepayments were applied against the remaining scheduled installments of principal due in respect of the loans under the Term Loan Facilities in direct order of maturity. During the year ended December 31, 2019, the Company prepaid $210,000 of outstanding principal balance on the Senior Secured Term Loan Facility. The Company wrote off $1,027 of previously unamortized deferred financing costs and original issue discount of $2,414 as debt extinguishment costs. The prepayments were applied against the remaining scheduled installments of principal due in respect of the loans under the Senior Secured Term Loan Facility in direct order of maturity. Debt extinguishment costs resulting from Term Loan amendments As a result of amending the Term Loan Facilities during the year ended December 31, 2020, the Company recorded $2,188 of new creditor and third-party financing costs as debt extinguishment costs. In addition, previous unamortized deferred financing costs of $97 and original issue discount of $228 associated with the previously outstanding debt were written off as debt extinguishment costs. As a result of amending the Term Loan Facilities during the year ended December 31, 2018, the Company recorded $2,124 of new creditor and third-party financing costs as debt extinguishment costs. In addition, previous unamortized deferred financing costs of $1,403 and original issue discount of $2,352 associated with the previously outstanding debt were written off as debt extinguishment costs. 6.75% Senior Secured Notes - Redeemed in 2020 On May 4, 2016, the Borrower issued $625,000 of 6.750% Senior Secured Notes due November 2022 (the “6.75% Senior Secured Notes”) in transactions exempt from or not subject to registration under the Securities Act pursuant to Rule 144A and Regulation S under the Securities Act of 1933. The 6.75% Senior Secured Notes were guaranteed by guaranteed by PQ Holdings Inc. and by the U.S. subsidiary guarantors that guarantee the Term Loan Facility and were secured by liens on the assets of the Borrower and the U.S. subsidiary guarantors on a pari passu with the liens securing the Term Loan Facility subject to the pari passu intercreditor agreement. The guarantee by PQ Holdings Inc. was unsecured. The indenture relating to the 6.75% Senior Secured Notes contains various limitations on the Company’s and its restricted subsidiaries’ ability to incur additional indebtedness, pay dividends or repay certain debt, make loans and investments, sell assets, create liens, enter into transactions with affiliates, enter into agreements restricting the Borrower’s subsidiaries ability to pay dividends, and merge and consolidate with other companies, among other things. Interest on the 6.75% Senior Secured Notes was payable on May 15 and November 15 of each year, commencing November 15, 2016. No principal payments were required with respect to the 6.75% Senior Secured Notes prior to their final maturity. Prior to redeeming the notes, the 6.75% Senior Secured Notes had mature on date of November 15, 2022. The 6.75% Senior Secured Notes were redeemable, in whole or in part, at the redemption prices (expressed as percentages of principal amount of the 6.75% Senior Secured Notes to be redeemed) set forth below, plus accrued and unpaid interest, if any, to, but not including, the redemption date, if redeemed on or after any of the dates below until the subsequent date below: Year Percentage May 15, 2020 101.688% May 15, 2021 and thereafter 100.000% As a result of redeeming the 6.75% Senior Secured Notes due 2022, the Company paid a redemption premium of $10,550 which was recorded as debt extinguishment costs during the year ended December 31, 2020. In addition, previous unamortized deferred financing costs of $2,085 and original issue discount of $1,186 associated with the previously outstanding debt were written off as debt extinguishment costs for the year ended December 31, 2020. New Senior Secured Term Loan Facility due February 2027 In July 2020, the Company entered into an agreement for a new senior secured term loan facility in an aggregate principal amount of $650,000 with an original issue discount of 1.5% and interest at a floating rate of LIBOR (with a 1.0% minimum LIBOR floor) plus 3.0% per annum. The proceeds were used to redeem its existing $625,000 of 6.75% Senior Secured Notes due 2022 and pay the associated early redemption premiums. The new senior secured term loan facility requires scheduled quarterly amortization payments, each equal to 0.25% of the original principal amount of the loans under the new senior secured term loan facility. 5.75% Senior Unsecured Notes due 2025 On December 11, 2017, the Borrower issued $300,000 aggregate principal amount of 5.75% Senior Unsecured Notes due 2025 (the “5.75% Senior Unsecured Notes”) in a private placement exempt from the registration requirements of the Securities Act. The 5.75% Senior Unsecured Notes mature on December 15, 2025. Interest on the 5.75% Senior Unsecured Notes is to be paid semi-annually on February 15 and August 15, commencing August 15, 2018, at an annual rate of 5.75%. The indenture relating to the 5.75% Senior Unsecured Notes contained various limitations on the Borrower’s and its restricted subsidiaries’ ability to incur additional indebtedness, pay dividends or repay certain debt, make loans and investments, sell assets, create liens, enter into transactions with affiliates, enter into agreements restricting the Borrower’s subsidiaries ability to pay dividends, and merge and consolidate with other companies, among other things. No principal payments are required with respect to the Senior Secured Notes prior to their final maturity. The obligations of the Borrower under the 5.75% Senior Unsecured Notes and the related indenture are guaranteed by its U.S. subsidiary guarantors that guarantee the Term Loan Facility. The obligations of the Company under the 5.75% Senior Unsecured Notes and the indenture are unsecured. If any Event of Default (other than a default relating to certain events of bankruptcy or insolvency of PQ Corporation or certain of its subsidiaries) occurs and is continuing under the Indenture, the Trustee or the Holders of at least 30% in principal amount of the then total outstanding notes by notice to the Company may declare the principal, premium, if any, interest and any other monetary obligations on all the then outstanding notes to be due and payable immediately. If an event of default arising from certain events of bankruptcy or insolvency of the Company occurs, the principal of, premium, if any, and interest on all the Senior Secured Notes shall become immediately due and payable without any declaration or other act on the part of the trustee or any holders. At any time prior to December 15, 2020, the Borrower may, at its option and on one more occasions, redeem (a) up to 40% of the aggregate principal amount of the 5.75% Senior Unsecured Notes with the cash proceeds from certain equity offerings at a redemption price equal to the sum of 105.75% of the aggregate principal amount thereof plus accrued and unpaid interest thereon, and (b) all or part of the 5.75% Senior Unsecured Notes at 100.00% of the aggregate principal amount redeemed plus accrued and unpaid interest thereon and a make-whole premium (the “Applicable Premium”). The Applicable Premium is equal to the greater of: (a) 1% of the principal amount of notes redeemed, or (b) the excess, if any, of: (1) the present value at the redemption date of (i) the redemption price of such notes at December 15, 2020 (as set forth in the table below), plus (ii) all required remaining scheduled interest payments due on such notes through December 15, 2020 (excluding accrued but unpaid interest to, but excluding, the redemption date), computed using a discount rate equal to the applicable United States Treasury rate as of such redemption date plus 50 basis points; over (2) the outstanding principal amount of such notes on the redemption date. On or after December 15, 2020, the 5.75% Senior Unsecured Notes are redeemable, in whole or in part, at the redemption prices (expressed as percentages of principal amount of the 5.75% Senior Unsecured Notes to be redeemed) set forth below, plus accrued and unpaid interest, if any, to, but not including, the redemption date, if redeemed on or after any of the dates below until the subsequent date below: Year Percentage December 15, 2020 102.875% December 15, 2021 101.438% December 15, 2022 and thereafter 100.000% Upon the occurrence of a change of control, as defined, each holder will have the right to require the Company to purchase all or any part of such holder’s Senior Secured Notes at a purchase price in cash equal to 101% of the principal amount, plus accrued and unpaid interest. Fair Value of Debt The fair value of a financial instrument is defined as the exchange price that would be received for an asset or paid to transfer a liability (an exit price) in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants. As of December 31, 2020 and 2019, the fair value of the senior secured term loans and senior secured and unsecured notes was $1,427,123 and $1,905,822, respectively. The fair value is classified as Level 2 based upon the fair value hierarchy (see Note 6 to these consolidated financial statements for further information on fair value measurements). Aggregate Long-term Debt Maturities The aggregate long-term debt maturities are: Year Amount 2021 $ — 2022 — 2023 — 2024 — 2025 295,000 Thereafter 1,131,363 $ 1,426,363

Other Long-term Liabilities

Other Long-term Liabilities	12 Months Ended
	Dec. 31, 2020
Other Liabilities Disclosure [Abstract]
Other Long-term Liabilities	18. Other Long-term Liabilities: The following table summarizes the components of other long-term liabilities as follows: December 31, 2020 2019 Pension benefits $ 40,812 $ 52,060 Other postretirement benefits 3,644 1,668 Supplemental retirement plans 11,376 10,632 Derivative liabilities 32,512 10,956 Deferred revenue 13,388 6,450 Reserve for uncertain tax positions 345 873 Asset retirement obligation 4,943 4,555 Other 3,995 4,110 $ 111,015 $ 91,304

Financial Instruments

Financial Instruments	12 Months Ended
	Dec. 31, 2020
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Financial Instruments	19. Financial Instruments: The Company uses (1) interest rate related derivative instruments to manage its exposure related to changes in interest rates on its variable-rate debt instruments and (2) foreign currency related derivative instruments to manage its foreign currency exposure to its net investments in certain foreign operations. The Company does not speculate using derivative instruments. By using derivative financial instruments to hedge exposures to changes in interest rates and foreign currency, the Company exposes itself to credit risk and market risk. Credit risk is the failure of the counterparty to perform under the terms of the derivative contract. When the fair value of a derivative contract is an asset, the counterparty owes the Company, which creates credit risk for the Company. When the fair value of a derivative contract is a liability, the Company owes the counterparty and, therefore, the Company is not exposed to the counterparty’s credit risk in those circumstances. The Company minimizes counterparty credit risk in derivative instruments by entering into transactions with high quality counterparties. The derivative instruments entered into by the Company do not contain credit-risk-related contingent features. Market risk is the adverse effect on the value of a derivative instrument that results from a change in interest rates or currency exchange rates. The market risk associated with interest rate contracts is managed by establishing and monitoring parameters that limit the types and degree of market risk that may be undertaken. Use of Derivative Financial Instruments to Manage Interest Rate Risk. The Company is exposed to fluctuations in interest rates on its senior secured credit facilities. Changes in interest rates will not affect the market value of such debt but will affect the amount of the Company’s interest payments over the term of the loans. Likewise, an increase in interest rates could have a material impact on the Company’s cash flow. The Company hedges the interest rate fluctuations on debt obligations through interest rate cap agreements. The Company records these agreements at fair value as assets or liabilities in its consolidated balance sheet. As the derivatives are designated and qualify as cash flow hedges, the gains or losses on the interest rate cap agreements are recorded in stockholders’ equity as a component of OCI, net of tax. Reclassifications of the gains and losses on the interest rate cap agreements into earnings are recorded as part of interest expense in the consolidated statements of income as the Company makes its interest payments on the hedged portion of its senior secured credit facilities. Fair value is determined based on estimated amounts that would be received or paid to terminate the contracts at the reporting date based on quoted market prices. In July 2016, the Company entered into interest rate cap agreements, paying a premium of $1,551 to mitigate interest rate volatility from July 2016 through July 2020 by employing varying cap rates, ranging from 1.50% to 3.00% on $1,000,000 of notional variable-rate debt. In November 2018, the Company entered into additional interest rate cap agreements to mitigate interest rate volatility from July 2020 through July 2022, with a cap rate of 3.50% on $500,000 of notional variable-rate debt and a $3,380 premium annuitized during the effective period. During the year ended December 31, 2020, the Company restructured its $500,000 of notional variable-rate debt interest rate cap agreements from July 2020 through July 2022, to lower the interest cap rate to 2.50% with an incremental $130 premium annuitized during the effective period. In March 2020, the Company again amended such interest rate cap agreements to lower the cap rate to 0.84% from 2.50% on $500,000 of notional variable-rate debt and paid an additional incremental $900 premium annuitized during the effective period. The term remains unchanged from July 2020 through July 2022. The total cumulative annuitized premium on the $500,000 of notional variable-rate debt is $4,410. The cap rate in effect at December 31, 2020 was 0.84% associated with the $500,000 of notional variable-rate debt. In July 2020, the Company entered into additional interest rate cap agreements to mitigate interest rate volatility from August 2020 to August 2023, with a cap rate of 1.00% on $400,000 of notional variable-rate debt. With the Company’s prepayments on its Term Loan Facility during 2019 (see Note 17 to these consolidated financial statements for additional information), the original forecasted interest rate payments associated with the dedesginated portion of the interest rate cap agreement are no longer probable of occurring. As a result of the discontinuance of cash flow hedge accounting on this portion of the interest rate cap agreement, the Company immediately reclassified into earnings the loss deferred in AOCI related to the dedesignated portion of the hedge, which was not material. Any future gains and losses associated with the dedesignated portion of the interest rate cap agreement through its maturity in July 2020 was recognized in earnings. Use of Derivative Financial Instruments to Manage Foreign Currency Risk. The Company is exposed to risks related to its net investments in foreign operations due to fluctuations in foreign currency exchange rates, particularly between the United States dollar and the Euro. In connection with the February 2018 term loan refinancing (see Note 17 to these consolidated financial statements), the Company entered into multiple cross currency interest rate swap arrangements with an aggregate notional amount of €280,000 to hedge this exposure on the net investments of certain of its Euro-denominated subsidiaries. The Company records these swap agreements at fair value as assets or liabilities in its consolidated balance sheet. In October 2019, the Company settled all of its February 2018 swaps and concurrently entered into the October 2019 swaps with the same notional amount of €280,000 ($344,403 as of December 31, 2020) and same maturity date of February 2023, which resulted in cash proceeds to the Company of $38,070. Consistent with the February 2018 swaps, the October 2019 swaps are designed to enable the Company to effectively convert a portion of its fixed-rate U.S. dollar-denominated debt obligations under the Term Loan Facility into a Euro-denominated equivalent. The October 2019 swaps have been designated and qualify as net investment hedges of the Company’s foreign currency exchange rate exposure on the net investments of certain of its Euro-denominated subsidiaries. As the derivatives are designated and qualify as net investment hedges, changes in the fair value of the swaps attributable to changes in the spot exchange rates are recognized in cumulative translation adjustment (“CTA”) within OCI and are held there until the hedged net investments are sold or substantially liquidated. Changes in the fair value of the swaps attributable to the cross currency basis spread are excluded from the assessment of hedge effectiveness and are recorded in current period earnings. Upon such sale or liquidation, the amount recognized in CTA is reclassified to earnings and reported in the same line item as the gain or loss on the liquidation of the net investments. The fair values of derivative instruments held as of December 31, 2020 and 2019 are shown below: December 31, Balance sheet location 2020 2019 Derivative assets: Derivatives designed as net investment hedges: Cross currency swaps Prepaid and other current assets 3,249 3,928 Total derivative assets $ 3,249 $ 3,928 Derivative liabilities: Derivatives designated as cash flow hedges: Interest rate caps Accrued liabilities 1,954 420 Interest rate caps Other long-term liabilities 1,750 2,822 3,704 3,242 Derivatives designated as net investment hedges: Cross currency swaps Other long-term liabilities 30,762 8,134 Total derivative liabilities $ 34,466 $ 11,376 The following table shows the effect of the Company’s derivative instruments designated as hedges on accumulated other comprehensive income (loss) (“AOCI”) and the statements of income for the years ended December 31, 2020, 2019 and 2018: Years ended December 31, 2020 2019 2018 Location of gain (loss) reclassified from AOCI into income Amount of gain (loss) recognized in OCI on derivatives Amount of gain (loss) reclassified from AOCI into income Amount of gain (loss) recognized in OCI on derivatives Amount of gain (loss) reclassified from AOCI into income Amount of gain (loss) recognized in OCI on derivatives Amount of gain (loss) reclassified from AOCI into income Interest rate caps Interest (expense) income $ (167) $ (54) $ (3,304) $ (625) $ (981) $ (256) The following table shows the effect of the Company’s cash flow hedge accounting on the consolidated statements of income for the years ended December 31, 2020, 2019 and 2018: Location and amount of gain (loss) recognized in income on cash flow hedging relationships Years ended December 31, 2020 2019 2018 Cost of goods sold Interest (expense) income Cost of goods sold Interest (expense) income Cost of goods sold Interest (expense) income Total amounts of income and expense line items presented in the statement of income in which the effects of cash flow hedges are recorded $ (834,007) $ (66,979) $ (901,512) $ (87,072) $ (925,534) $ (90,758) The effects of cash flow hedging: Gain (loss) on cash flow hedging relationships: Interest contracts: Amount of gain (loss) reclassified from AOCI into income — (54) — (625) — (256) The following table shows the effect of the Company’s net investment hedges on AOCI and the consolidated statements of income for the years ended December 31, 2020, 2019 and 2018: Amount of gain (loss) recognized in OCI on derivative Location of gain (loss) reclassified from AOCI into income Amount of gain (loss) reclassified from AOCI into income Location of gain (loss) recognized in income on derivative (amount excluded from effectiveness testing) Amount of gain (loss) recognized in income on derivative (amount excluded from effectiveness testing) Years ended Years ended Years ended 2020 2019 2018 2020 2019 2018 2020 2019 2018 Cross currency swaps $ (23,622) $ 17,077 $ 18,843 Net (loss) income from discontinued operations, net of tax $ 1,967 $ — $ — Interest (expense) income $ 5,090 $ 7,320 $ 6,752 There are $281 amounts of unrealized losses in AOCI that are expected to be reclassified to the consolidated statement of income over the next twelve months as of December 31, 2020.

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2020
Income Tax Disclosure [Abstract]
Income Taxes	20. Income Taxes: Income (loss) before income taxes and noncontrolling interest within or outside the United States are shown below: Years ended 2020 2019 2018 Domestic $ (175,143) $ 41,019 $ (1,559) Foreign (52,442) 64,411 85,579 Total $ (227,585) $ 105,430 $ 84,020 The provision (benefit) for income taxes as shown in the accompanying consolidated statements of income consists of the following: Years ended 2020 2019 2018 Current: Federal $ — $ (3) $ — State 1,087 1,381 2,507 Foreign 15,484 22,810 27,062 16,571 24,188 29,569 Deferred: Federal (58,744) 11,824 10,875 State (2,910) 3,175 67 Foreign (3,039) 490 (6,870) (64,693) 15,489 4,072 Provision (benefit) for income taxes $ (48,122) $ 39,677 $ 33,641 A reconciliation of income tax expense (benefit) at the U.S. federal statutory income tax rate to actual income tax expense is as follows: Years ended 2020 2019 2018 Tax at statutory rate $ (47,793) $ 22,140 $ 17,644 State income taxes, net of federal income tax benefit (2,324) 6,802 2,541 Tax on global intangible low-taxed income 7,820 8,741 14,465 Change in valuation allowances 135 1,415 5,070 Rate changes 4,274 1,054 (4,016) Foreign withholding taxes 258 (6,116) 142 Foreign tax rate differential 1,240 3,278 6,439 Non-taxable interest (5,353) — — Non-deductible goodwill 53,342 — — Foreign tax credits (56,359) — — Permanent difference created by foreign exchange gain or loss (1,324) 1,852 (4,839) Other, net (2,038) 511 (3,805) Provision (benefit) for income taxes $ (48,122) $ 39,677 $ 33,641 Deferred tax assets (liabilities) are comprised of the following: December 31, 2020 2019 Deferred tax assets: Net operating loss carryforwards $ 28,145 $ 77,062 Section 163(j) interest disallowance carryforward 266 16,535 Pension 12,701 14,359 Operating lease liability 11,803 14,455 Other 36,545 29,298 State credits 12,733 12,280 Foreign tax credit 62,752 — Valuation allowance (37,880) (39,379) $ 127,065 $ 124,610 Deferred tax liabilities: Depreciation $ (107,805) $ (103,796) Inventory (4,946) (11,481) Intangible assets (162,301) (184,764) Operating lease right-of-use assets (12,060) (14,278) Other (15,348) (22,619) $ (302,460) $ (336,938) Net deferred tax liabilities $ (175,395) $ (212,328) The change in net deferred tax liabilities for the years ended December 31, 2020 and 2019 was primarily related to the usage of U.S. federal and state net operating losses reducing those deferred tax assets, activity related to book amortization of intangible assets with no corresponding tax basis reducing those deferred tax liabilities, activity with respect to tax deductible goodwill, as well as the election for full expensing on certain assets creating additional deferred tax liabilities for depreciable property. Further, the increase of the foreign tax credits on the deferred tax assets and the decrease of the Section 163(j) interest disallowance carryforward accounted for the change in net deferred tax liabilities for year ended December 31, 2020. The net change in the total valuation allowance was a decrease of $1,499 in 2020. The valuation allowance at December 31, 2020 was primarily related to foreign and state net operating loss carryforwards and tax credits that, in the judgment of management, are not more likely than not to be realized. In assessing the ability to realize deferred tax assets, management considered whether it is more likely than not that some portion or all of the deferred tax assets will not be realized. The ultimate realization of deferred tax assets is dependent upon the generation of future taxable income during the periods in which those temporary differences become deductible. Management considered the scheduled reversal of deferred tax liabilities (including the impact of available carryback and carryforward periods), projected future taxable income, and tax-planning strategies that are prudent in making this assessment. In order to fully realize deferred tax assets, the Company will need to generate future taxable income prior to the expiration of the net operating loss and credit carryforwards. The amount of the deferred tax assets considered realizable, however, could be reduced in the near term if estimates of future taxable income during the carryforward period are reduced. The cumulative unremitted earnings of foreign subsidiaries outside the United States are considered permanently reinvested, for which no withholding taxes have been provided. Such earnings are expected to be reinvested indefinitely and, as a result, no deferred tax liability has been recognized with regard to such earnings. Determination of the deferred withholding tax liability on these unremitted earnings is not practicable. The following table summarizes the activity related to the Company’s gross unrecognized tax benefits: Years ended 2020 2019 Balance at beginning of period $ 8,310 $ 9,434 Increases related to prior year tax positions — 22 Decreases related to prior year tax positions (14) (1,046) Increases related to current year tax positions 164 — Decreases related to settlements with taxing authorities (626) (100) Balance at end of period $ 7,834 $ 8,310 The total unrecognized tax benefits of $7,834 and $8,310 as of December 31, 2020 and 2019, respectively. If these amounts are recognized in future periods, it would affect the effective tax rate on income from continuing operations for the years in which they are recognized. Interest and penalties released related to uncertain tax positions amounted to $35 and $701 for the years ended December 31, 2020 and 2019, respectively. To the extent interest and penalties are not assessed with respect to uncertain tax positions, amounts accrued will be reduced and reflected as a reduction of the overall income tax provision in the period for which the event occurs requiring the adjustment. The $112 and $181 in accrued interest and penalties as of December 31, 2020 and 2019, respectively, is recorded in other long-term liabilities on the consolidated balance sheets. The Company files numerous consolidated and separate income tax returns in the U.S. federal jurisdiction and in many state and foreign jurisdictions. The following describes the open tax years, by significant tax jurisdiction, as of December 31, 2020: Jurisdiction Period United States-Federal 2007-Present United States-State 2007-Present Canada (1) 2012-Present Netherlands 2014-Present Mexico 2016-Present United Kingdom 2014-Present Brazil 2016-Present (1) Includes federal as well as local jurisdictions Given that the Company has utilized U.S. and state net operating loss in the current and prior years, the statute for examination by the U.S. and state taxing authorities will typically remain open for a period following the use of such net operating loss carryforwards, extending the period for examination beyond the years indicated above. The Company has subsidiaries in various states, provinces and countries that are currently under audit for years ranging from 2014 through 2018. To date, no material adjustments have been proposed as a result of these audits. As of December 31, 2020, the Company does not believe that there are any positions for which it is reasonably possible that the total amount of unrecognized tax benefits will significantly increase or decrease within the next 12 months. As of December 31, 2020, the Company no longer has a federal NOL carryforward. As of December 31, 2020, the Company has foreign tax credit carryforwards of $62,752, which are net of $7,658 of uncertain tax position balances, which is permissible per ASU 2013-11. These carryforwards have a ten year carryforward, of which $13,241 are set to expire in 2021. Cumulative state net operating losses carrying forward into December 31, 2020 are $24,467. A valuation allowance of $14,344 has been applied against the total state net operating loss deferred tax assets, leaving losses of $10,123 that have been recognized for financial accounting purposes for the portion of those losses that the Company believes, on a more likely than not basis, will be realized. Foreign net operating losses of $3,678, of which $68 will begin to expire in 2028, $160 will begin to expire in 2036, with the remaining $3,450 carrying forward indefinitely, are available to reduce future foreign income taxes payable. A valuation allowance of $3,531 has been applied to deferred tax assets related to foreign net operating loss carry-forwards, leaving a net deferred tax asset relating to foreign net operating losses of $147 that has been recognized for financial accounting purposes. Cash payments for income taxes, net of refunds, are as follows: Years ended 2020 2019 2018 Domestic $ 2,198 $ 1,879 $ 2,154 Foreign 20,810 12,354 17,654 $ 23,008 $ 14,233 $ 19,808

Benefit Plans

Benefit Plans	12 Months Ended
	Dec. 31, 2020
Retirement Benefits [Abstract]
Benefit Plans	21. Benefit Plans: The Company sponsors defined benefit pension plans covering employees in the United States and certain employees at its foreign subsidiaries. Benefits for a majority of the plans are based on average final pay and years of service. The Company’s funding policy is to fund the minimum required contribution under local statutory requirements. The Company sponsors unfunded plans to provide certain health care benefits to retired employees in the United States and Canada. The plans pay a stated percentage of medical expenses reduced by deductibles and other coverage. The plans are unfunded and obligations are paid out of the Company’s operations. The Company also has defined benefit supplementary retirement plans which provide benefits for certain U.S. employees in excess of qualified plan limitations. The obligations are paid out of the Company’s general assets, including assets held in a Rabbi trust, or restoration plan assets. The Company uses a December 31 measurement date for all of its defined benefit pension, postretirement medical and supplementary retirement plans. The following discussion includes information for the Eco Services benefit plans for all periods presented, and the acquired PQ Holdings benefit plans beginning on the date of a former business combination. The Eco Services benefit plans include two defined benefit pension plans and one retiree health plan, all based in the U.S. The PQ Holdings benefit plans include a U.S. defined benefit pension plan as well as the defined benefit pension plans for all of the Company’s foreign subsidiaries, two retiree health plans (one each in the U.S and Canada), and the Company’s defined benefit supplementary retirement plans. Of the Company’s three defined benefit pension plans covering employees in the U.S., only the Eco Services Hourly Pension Plan continues to accrue benefits for certain participants; however, this plan will be frozen to future accruals as of December 31, 2020. All future accruals were frozen for the PQ Corporation Retirement Plan as of December 31, 2006 and for the Eco Services Pension Equity Plan as of December 31, 2016. With respect to the Company’s three retiree health plans, the PQ Holdings plans in the U.S. and Canada were closed to new retirees as of December 31, 2006. The Eco Services Postretirement Life and Dental Plan was closed to new retirees effective July 1, 2017. The Company’s defined benefit supplementary retirement plans were frozen to future accruals as of December 31, 2006. Defined Benefit Pension Plans The following tables summarize changes in the benefit obligation, plan assets and funded status of the Company’s significant defined benefit pension plans as well as the components of net periodic benefit cost, including key assumptions: U.S. Foreign December 31, December 31, 2020 2019 2020 2019 Change in benefit obligation: Benefit obligation at beginning of period $ 267,392 $ 246,311 $ 101,192 $ 84,435 Service cost 769 978 3,895 3,210 Interest cost 8,595 10,281 2,193 2,627 Participant contributions — — 574 550 Plan curtailments — (2,795) (1,603) — Plan settlements (1,455) (1,669) (105) (102) Benefits paid (12,713) (10,862) (1,759) (1,833) Expenses paid — — (353) (328) Actuarial (gains) losses 25,894 25,148 4,664 13,459 Translation adjustment — — 6,191 (826) Benefit obligation at end of the period $ 288,482 $ 267,392 $ 114,889 $ 101,192 Change in plan assets: Fair value of plan assets at beginning of period $ 231,413 $ 195,755 $ 85,308 $ 74,050 Actual return on plan assets 41,405 43,116 6,646 10,564 Employer contributions 5,187 5,073 3,348 3,084 Employee contributions — — 574 550 Plan settlements (1,455) (1,669) (105) (102) Benefits paid (12,713) (10,862) (1,759) (1,833) Expenses paid — — (353) (328) Translation adjustment — — 5,209 (677) Fair value of plan assets at end of the period $ 263,837 $ 231,413 $ 98,868 $ 85,308 Funded status of the plans (underfunded) $ (24,645) $ (35,979) $ (16,021) $ (15,884) The total actuarial losses for the year ended December 31, 2020 across the Company’s U.S. plans was $25,894, which was driven by declines in the discount rates of $26,642 and declines in general demographic experience of $1,261, which was offset by favorable changes in mortality assumptions of $2,009. The total actuarial losses for the year ended December 31, 2020 across the Company’s foreign plans was $4,664, which was driven by declines in the discount rates of $5,981 and declines in general demographic experience of $56 and favorable changes in mortality assumptions of $1,372. The total actuarial losses for the year ended December 31, 2019 across the Company’s U.S. was $25,148, which was driven by declines in the discount rates of $26,604 and declines in general demographic experience of $2,953, which was offset by favorable changes in mortality assumptions of $4,409. The total actuarial losses for the year ended December 31, 2019 across the Company’s foreign plans was $13,459, which was driven by declines in the discount rates of $13,837, which was offset by favorable changes in general demographic experience of $312 and favorable changes in mortality assumptions of $66. Amounts recognized in the consolidated balance sheets consist of: U.S. Foreign December 31, December 31, 2020 2019 2020 2019 Current liability — — (46) (6) Noncurrent liability (24,645) (35,979) (15,975) (15,878) Accumulated other comprehensive income (loss) (4,463) 8,687 1,075 (4,988) Net amount recognized $ (29,108) $ (27,292) $ (14,946) $ (20,872) Amounts recognized in accumulated other comprehensive income (loss) consist of: U.S. Foreign December 31, December 31, 2020 2019 2020 2019 Net gain (loss) 13,964 10,922 (6,550) (7,634) Gross amount recognized 13,964 10,922 (6,550) (7,634) Deferred income taxes (18,427) (2,235) 7,625 2,646 Net amount recognized $ (4,463) $ 8,687 $ 1,075 $ (4,988) Components of net periodic benefit cost consist of: U.S. Foreign Years ended Years ended 2020 2019 2018 2020 2019 2018 Service cost $ 769 $ 978 $ 1,019 $ 3,895 $ 3,210 $ 3,104 Interest cost 8,595 10,281 9,599 2,193 2,627 2,637 Expected return on plan assets (12,547) (11,508) (12,851) (2,270) (2,427) (2,490) Amortization of prior service cost — — — — 24 — Amortization of net (gain) loss — — — 148 (29) 49 Curtailment gain recognized — — (576) — — — Settlement (gain) loss recognized 78 49 — (14) (1) — Net periodic expense (benefit) $ (3,105) $ (200) $ (2,809) $ 3,952 $ 3,404 $ 3,300 All components of net periodic benefit cost other than service cost are presented within other expense (income), net in the Company’s consolidated statements of income. The net amount of projected benefit obligation and plan assets for all underfunded and unfunded plans was $53,081 and $63,514 as of December 31, 2020 and 2019, respectively, and was classified as noncurrent liabilities. The total accumulated benefit obligation as of December 31, 2020 and 2019 for the Company’s U.S. pension plans was $288,482 and $266,992, respectively. The total accumulated benefit obligation as of December 31, 2020 and 2019 for the Company’s foreign pension plans was $110,605 and $96,891, respectively. The following table presents selected information about the Company’s pension plans with accumulated benefit obligations in excess of plan assets: U.S. Foreign December 31, December 31, 2020 2019 2020 2019 Projected benefit obligation $ 288,482 $ 267,392 $ 92,679 82,662 Accumulated benefit obligation 288,482 266,992 88,394 80,021 Fair value of plan assets 263,837 231,413 76,658 68,104 The following table presents selected information about the Company’s pension plans with projected benefit obligations in excess of plan assets: U.S. Foreign December 31, December 31, 2020 2019 2020 2019 Projected benefit obligation $ 288,482 $ 267,392 $ 92,679 101,192 Fair value of plan assets 263,837 231,413 76,658 85,308 Significant weighted average assumptions used in determining the pension obligations include the following: U.S. Foreign December 31, December 31, 2020 2019 2020 2019 Discount rate 2.42 % 3.32 % 1.78 % 2.34 % Rate of compensation increase (1) N/A 3.00 % 2.05 % 2.07 % Significant weighted average assumptions used in determining net periodic benefit cost include the following: U.S. Foreign Years ended Years ended 2020 2019 2018 2020 2019 2018 Discount rate 3.32 % 4.32 % 3.74 % 2.34 % 3.19 % 3.11 % Rate of compensation increase (1) 3.00 % 3.00 % 3.00 % 2.07 % 2.08 % 2.22 % Expected return on assets 5.55 % 6.00 % 6.00 % 2.82 % 3.30 % 3.37 % (1) Includes only plans not frozen to benefit accruals for the respective periods. The discount rate for each of the U.S. plans was determined by utilizing a yield curve model. The model develops a spot rate curve based on the yields available from a broad-based universe of high quality corporate bonds. The discount rate is then set as the weighted average spot rate, using the respective plan’s expected benefit cash flows as the weights. The investment objective for the U.S. plans is to generate returns sufficient to meet future obligations. The strategy to meet the objective includes generating attractive returns using higher returning assets such as equity securities and balancing risk using less volatile assets such as fixed income securities. The U.S. plans invest in an allocation of assets across the two broadly-defined financial asset categories of equity and fixed income securities. The target allocations for the plan assets across the three U.S. plans are as follows: 45% equity securities and 55% fixed income investments for the PQ Corporation Retirement Plan; 40% equity securities and 60% fixed income investments for the Eco Services Pension Equity Plan; and 60% equity securities and 40% fixed income investments for the Eco Services Hourly Pension Plan. Similar considerations are applied to the investment objectives of the non-U.S. plans as well as the asset classes available in each location and any legal restrictions on plan investments. The Company classifies plan assets based upon a fair value hierarchy (see Note 6 to these consolidated financial statements for further information). The classification of each asset within the hierarchy is based on the lowest level input that is significant to its measurement. The fair value hierarchy consists of three levels as follows: • Level 1—Values are unadjusted quoted prices for identical assets and liabilities in active markets accessible at the measurement date. Active markets provide pricing data for trades occurring at least weekly and include exchanges and dealer markets. Level 1 assets primarily include investments in publicly traded equity securities and mutual funds. These securities (or the underlying investments of the funds) are actively traded and valued using quoted prices for identical securities from the market exchanges. • Level 2—Inputs include quoted prices for similar assets or liabilities in active markets, quoted prices from those willing to trade in markets that are not active, or other inputs that are observable or can be corroborated by market data for the term of the instrument. Such inputs include market interest rates and volatilities, spreads and yield curves. Level 2 assets primarily consist of fixed-income securities and commingled funds that are not actively traded or whose underlying investments are valued using observable marketplace inputs. The fair value of plan assets invested in fixed-income securities is generally determined using valuation models that use observable inputs such as interest rates, bond yields, low-volume market quotes and quoted prices for similar assets. Plan assets that are invested in commingled funds are valued using a unit price or net asset value (“NAV”) that is based on the underlying investments of the fund. • Level 3—Certain inputs are unobservable (supported by little or no market activity) and significant to the fair value measurement. Unobservable inputs reflect the Company’s best estimate of what hypothetical market participants would use to determine a transaction price for the asset or liability at the reporting date. Level 3 assets include investments covered by insurance contracts and real estate funds valued using significant unobservable inputs. The following tables set forth by level, within the fair value hierarchy, plan assets at fair value: December 31, 2020 Total Level 1 Level 2 Level 3 Cash and cash equivalents $ 787 $ 787 $ — $ — Equity securities: U.S. investment funds 79,777 79,777 — — International investment funds 64,986 53,792 11,194 — Fixed income securities: Government securities 39,541 33,505 6,036 — Corporate bonds 16,771 16,668 103 — Investment fund bonds 112,024 — 112,024 — Other: Insurance contracts 48,819 — 42,983 5,836 Total $ 362,705 $ 184,529 $ 172,340 $ 5,836 December 31, 2019 Total Level 1 Level 2 Level 3 Cash and cash equivalents $ 950 $ 950 $ — $ — Equity securities: U.S. investment funds 67,374 67,374 — — International investment funds 54,908 44,905 10,003 — Fixed income securities: Government securities 31,040 23,500 7,540 — Corporate bonds 14,900 14,782 118 — Investment fund bonds 106,198 1,170 105,028 — Other: Insurance contracts 41,351 — 36,637 4,714 Total $ 316,721 $ 152,681 $ 159,326 $ 4,714 The changes in the Level 3 pension plan assets are as follows for the years ended December 31: Insurance Contracts 2020 2019 Beginning balance $ 4,714 $ 4,322 Actual return on plan assets 113 111 Benefits paid (78) (69) Contributions 577 441 Exchange rate changes and other 510 (91) Ending balance $ 5,836 $ 4,714 The Company expects to contribute $446 to the U.S. pension plans and $3,559 to the foreign pension plans in 2021. The following benefit payments, which reflect expected future service, as appropriate, are expected to be paid: Year U.S. Foreign 2021 $ 17,138 $ 2,204 2022 16,200 2,384 2023 16,278 2,610 2024 16,254 2,898 2025 15,968 3,144 Years 2026-2030 78,910 19,027 Certain of the Company’s foreign subsidiaries maintain other defined benefit plans that are consistent with statutory practices. These plans are not included in the disclosures above as they are not significant to the Company’s consolidated financial statements. Supplemental Retirement Plans The following tables summarize changes in the benefit obligation, plan assets and funded status of the Company’s defined benefit supplementary retirement plans, as well as the components of net periodic benefit cost, including key assumptions: December 31, 2020 2019 Change in benefit obligation: Benefit obligation at beginning of period $ 11,652 $ 11,868 Interest cost 352 465 Benefits paid (1,001) (1,045) Actuarial (gains) losses 1,412 364 Benefit obligation at end of period $ 12,415 $ 11,652 Change in plan assets: Fair value of plan assets at beginning of period $ — $ — Employer contributions 1,001 1,045 Benefits paid (1,001) (1,045) Fair value of plan assets at end of period $ — $ — Funded status of the plans (underfunded) $ (12,415) $ (11,652) The total actuarial losses for the year ended December 31, 2020 across the Company’s supplemental retirement plans was $1,412, which was driven by declines in the discount rates of $871, declines in general demographic experience of $234 and declines in mortality assumptions of $307. The total actuarial losses for the year ended December 31, 2019 across the Company’s supplemental retirement plans was $364, which was driven by declines in the discount rates of $971, which was offset by favorable changes in general demographic experience of $281 and favorable changes in mortality assumptions of $326. Amounts recognized in the consolidated balance sheets consist of: December 31, 2020 2019 Current liability $ (1,039) $ (1,019) Noncurrent liability (11,376) (10,633) Accumulated other comprehensive income 633 253 Net amount recognized $ (11,782) $ (11,399) Amounts recognized in accumulated other comprehensive income consist of: December 31, 2020 2019 Net gain $ (731) $ 681 Gross amount recognized (731) 681 Deferred income taxes 1,364 (428) Net amount recognized $ 633 $ 253 Components of net periodic benefit cost consist of: Years ended 2020 2019 2018 Interest cost $ 352 $ 465 $ 450 Amortization of net (gain) loss — (10) — Net periodic expense $ 352 $ 455 $ 450 Interest cost is presented within other expense (income), net in the Company’s consolidated statements of income. The accumulated benefit obligation of the Company’s defined benefit supplemental retirement plans as of December 31, 2020 and 2019 was $12,415 and $11,652, respectively. The discount rate used in determining the defined benefit supplemental retirement plan obligation was 2.20% and 3.10% as of December 31, 2020 and 2019, respectively. The discount rate used in determining net periodic benefit cost was 3.10%, 4.20% and 3.60% for the years ended December 31, 2020, 2019 and 2018, respectively. There was no rate of compensation increase for any of the periods presented, as all future accruals were frozen for the defined benefit supplementary retirement plans as of December 31, 2006. There was no rate of interest crediting rate, as there are no cash balance accounts associated with these plans. The Company expects to contribute $1,039 to the defined benefit supplementary retirement plans in 2021. The following benefit payments, which reflect expected future service, as appropriate, are expected to be paid: Year Amount 2021 $ 1,039 2022 1,010 2023 977 2024 944 2025 908 Years 2025-2029 3,944 Other Postretirement Benefit Plans The following tables summarize changes in the benefit obligation, plan assets and funded status of the Company’s other postretirement benefit plans as well as the components of net periodic benefit cost, including key assumptions: December 31, 2020 2019 Change in benefit obligation: Benefit obligation at beginning of period $ 3,452 $ 3,814 Service cost — 10 Interest cost 99 152 Employee contributions 241 253 Plan amendments — (460) Benefits paid (658) (751) Premiums paid (7) (7) Actuarial (gains) losses 225 412 Translation adjustment 15 29 Benefit obligation at end of period $ 3,367 $ 3,452 Change in plan assets: Fair value of plan assets at beginning of period — — Employer contributions 424 505 Employee contributions 241 253 Benefits paid (658) (751) Premiums paid (7) (7) Fair value of plan assets at end of period $ — $ — Funded status of the plans (underfunded) $ (3,367) $ (3,452) The total actuarial losses for the year ended December 31, 2020 across the Company’s U.S. plans was $225, which was driven by declines in the discount rates of $235, and offset by favorable declines in general demographic experience of $1, which was offset by favorable changes in mortality assumptions of $8. The total actuarial losses for the year ended December 31, 2019 across the Company’s U.S. plans was $412, which was driven by declines in the discount rates of $334 and declines in general demographic experience of $172, which was offset by favorable changes in mortality assumptions of $94. Amounts recognized in the consolidated balance sheets consist of: December 31, 2020 2019 Current liability $ (443) $ (537) Noncurrent liability (2,924) (2,915) Accumulated other comprehensive income 680 524 Net amount recognized $ (2,687) $ (2,928) Amounts recognized in accumulated other comprehensive income consist of: December 31, 2020 2019 Prior service credit $ 596 $ 828 Net gain (182) 67 Gross amount recognized 414 895 Deferred income taxes 266 (371) Net amount recognized $ 680 $ 524 Components of net periodic benefit cost consist of: Years ended 2020 2019 2018 Service cost $ — $ 10 $ 16 Interest cost 99 152 150 Amortization of prior service credit (232) (157) (112) Amortization of net gain (29) (33) (26) Net periodic expense (benefit) $ (162) $ (28) $ 28 All components of net periodic benefit cost other than service cost are presented within other expense (income), net in the Company’s consolidated statements of income. The discount rate used in determining the other postretirement benefit plan obligation was 2.18% and 3.06% as of December 31, 2020 and 2019, respectively. The discount rate used in determining net periodic benefit cost was 3.06%, 4.09% and 3.53% for the years ended December 31, 2020, 2019 and 2018, respectively. There was no rate of interest crediting rate, as there are no cash balance accounts associated with these plans. Assumed health care cost trend rates were as follows: December 31, 2020 2019 Immediate trend rate 5.67% 5.91% Ultimate trend rate 4.38% 4.39% Year that the rate reaches ultimate trend rate 2038 2038 The Company expects to contribute $443 to the retiree health plans in 2021. The following benefit payments, which reflect expected future service, as appropriate, are expected to be paid: Year Amount 2021 $ 443 2022 372 2023 297 2024 281 2025 163 Years 2025-2029 816 There are no expected Medicare subsidy receipts expected in future periods. Certain of the Company’s foreign subsidiaries maintain other postretirement benefit plans that are consistent with statutory practices. These plans are not included in the disclosures above as they are not significant to the Company’s consolidated financial statements. Defined Contribution Plans The Company also has defined contribution plans covering domestic employees of the Company and certain subsidiaries. The Company recorded expenses of $11,490, $11,366 and $11,253 related to these plans for the years ended December 31, 2020, 2019 and 2018, respectively.

Stock-Based Compensation

Stock-Based Compensation	12 Months Ended
	Dec. 31, 2020
Stock-Based Compensation [Abstract]
Stock-Based Compensation	22. Stock-Based Compensation: In May 2016, the Company adopted an equity incentive plan, namely the PQ Group Holdings Inc. Stock Incentive Plan (“2016 Plan”). Under the terms of the 2016 Plan, the Company was authorized to issue a total of 8,017,038 shares for common stock awards to employees, directors and affiliates of the Company. Immediately preceding the Company’s initial public offering (“IPO”) as of September 30, 2017, awards with respect to 7,644,518 shares of common stock had been issued under the 2016 Plan. In connection with the IPO, the Company’s board of directors adopted the PQ Group Holdings Inc. 2017 Omnibus Incentive Plan (the “2017 Plan”). Subsequent to the IPO, all equity incentive awards have been granted under the 2017 Plan. The number of shares of common stock reserved for issuance under the 2017 Plan is 7,344,000 shares, which amount was increased by the 372,520 shares remaining available for grant under the 2016 Plan as of the 2017 Plan adoption. Shares that become available for issuance pursuant to the 2016 Plan as a result of forfeiture, cancellation or termination for no consideration will be available for future awards under the 2017 Plan. Shares underlying awards granted under the 2017 Plan that are forfeited, canceled, terminated for no consideration, settled in cash or are withheld for exercise, taxes, etc. will not be deemed as delivered and will also be available for future issuance under the 2017 Plan. On April 30, 2020, the Company’s stockholders approved an amendment and restatement of the 2017 Plan to increase the number of shares available under it by an additional 9,000,000 shares and include more limited share recycling provisions, resulting in fewer shares recycled subsequent to the change. At December 31, 2020, 12,405,315 shares of common stock were available for issuance under the 2017 Plan, after giving effect to the new grants, forfeitures and other activity during the year ended December 31, 2020. 2020 Modifications As more fully described in Note 7 to these consolidated financial statements, the Company’s Board of Directors declared a special cash dividend of $1.80 per share to stockholders of record as of the close of business on December 21, 2020. The dividend declaration also included a dividend equivalent for all unvested restricted stock units, performance stock units and restricted stock awards (collectively, the “awards”) as of December 21, 2020 equal to $1.80 per award. Additionally, the Company’s Board of Directors approved a reduction in the strike price on all outstanding vested and unvested stock options by the amount of the dividend payment. Further, with respect to stock options and awards held by employees of Performance Materials at the time of the sale (see Note 4 to these consolidated financial statements), the Company’s Board of Directors approved modifications to the post-termination stock option exercise, and stock option and award vesting periods. The modifications provide that all stock options held by Performance Materials employees that were vested as of the date of the sale are eligible to be exercised for a period of one year from the date of the sale, through December 14, 2021. Additionally, modifications to unvested stock options and awards allow holders to continue to vest in those instruments under the original terms of the instruments for a period of one year from the date of sale, through December 14 ,2021. The terms of the modifications to the Performance Materials awards are contingent upon the employee providing continued service to the Purchaser. The modifications impacted all holders of the Company’s stock option and awards and resulted in additional stock-based compensation expense of $2,144 for the year ended December 31, 2020. Of this amount, $654 was included in loss from discontinued operations, net of tax on the Company’s consolidated statements of income. Stock Options Under both the 2016 and 2017 Plans, the Company has issued stock options to purchase PQ Group Holdings Inc. common stock as part of its equity incentive compensation program. There are various vesting conditions associated with the stock options issued under the 2016 Plan, including satisfaction of certain service and/or performance based conditions. Under the 2017 Plan, the Company’s stock option grants have been subject to graded vesting conditions based on service. The maximum contractual term of the Company’s stock options is ten years. The following table summarizes the activity of common stock options for the period from December 31, 2017 through the year ended December 31, 2020: Number of Options Weighted Average Exercise Price Weighted Average Remaining Contractual Term (in years) Aggregate Intrinsic Value Outstanding at December 31, 2017 2,715,170 $ 10.18 Granted 241,316 $ 17.50 Exercised (15,332) $ 8.51 Outstanding at December 31, 2018 2,941,154 $ 10.79 Exercised (492,498) $ 8.07 Forfeited (74,299) $ 8.16 Outstanding at December 31, 2019 2,374,357 $ 11.44 Exercised (43,250) $ 8.64 Forfeited (157,776) $ 9.23 Outstanding at December 31, 2020 2,173,331 $ 9.84 (1) 5.94 $ 10,452 Exercisable at December 31, 2020 1,796,519 $ 10.50 (1) 6.00 $ 7,611 (1) Reflects the impact of the reduction in the strike price on all outstanding vested and unvested stock options by $1.80 per share as described above. The aggregate intrinsic value per the above table represents the difference between the fair value the Company’s common stock on the last trading day of the reporting period (determined in accordance with the plan terms) and the exercise price of in-the-money stock options multiplied by the respective number of stock options as of that date. The total intrinsic value of stock options exercised during the year ended December 31, 2019 and the resulting tax benefits recognized by the Company were $3,615; the total intrinsic value of stock options exercised during the years ended December 31, 2020 and 2018 was not material for either year. Additionally, cash proceeds received by the Company from the exercise of stock options were $3,975 during the year ended December 31, 2019 and were not material for the years ended December 31, 2020 and 2018. There were no stock option awards granted during the years ended December 31, 2020 and 2019. The fair values of PQ Group Holdings common stock options granted during the year ended December 31, 2018 were determined on the respective grant dates using a Black-Scholes option pricing model with the following weighted-average assumptions: 2018 Expected term (in years) 5.75 Expected volatility 26.38 % Risk-free interest rate 2.86 % Expected dividend yield 0.00 % Weighted average grant date fair value of options granted $ 5.47 With respect to the stock option awards granted during the year ended December 31, 2018, the Company used the simplified method for plain vanilla stock options to estimate the expected term assumption, since the Company lacked sufficient historical exercise data to provide a reasonable basis upon which to estimate the expected term due to the limited period of time its common stock has been publicly traded. The application of the simplified method involves calculating the average of the time-to-vesting period and the total contractual life of the options. The expected volatility assumption was compared to a range of the actual stock price volatility of a peer group of companies. The risk-free interest rate was based on U.S. Treasury rates in effect at the time of the grant commensurate with the expected term. Restricted Stock Awards, Restricted Stock Units and Performance Stock Units The Company has granted restricted stock awards subject to vesting conditions based on (1) service only, (2) performance only, or (3) a combination of service and performance conditions, dependent on which event occurs first. The vesting requirements for the majority of these awards were based upon the achievement of a performance condition. As defined in the award agreements, each award subject to the performance condition fully vests upon the occurrence of a defined liquidity event upon which certain investment funds affiliated with CCMP receive proceeds exceeding certain thresholds. Although achievement of the performance condition is subject to continued service with the Company, the terms of awards issued with performance conditions stipulate that the performance vesting condition can be attained for a period of six months following separation from service under certain circumstances, depending on the means of separation from the Company and subject to other factors such as individual separation agreements. The same performance vesting condition for the Company’s restricted stock awards also governs the achievement of the performance vesting condition for the Company’s stock options. As of December 31, 2020, all of the Company’s outstanding unvested restricted stock awards were subject to the performance vesting condition. In addition to restricted stock awards, the Company has granted restricted stock units and performance stock units as part of its equity incentive compensation program. Each restricted stock unit provides the recipient with the right to receive a share of common stock subject to graded vesting terms based on service, which generally requires one year of service for members of the Company’s board of directors and three years of service for employees. The value of the restricted stock units granted by the Company is based on the average of the high and low trading prices of the Company’s common stock on the NYSE on the preceding trading day, in accordance with the Company’s policy for valuing such awards. Compensation expense related to the restricted stock units is recognized on a straight-line basis over the respective vesting period. The Company granted performance stock units during the year ended December 31, 2019, which provide the recipients with the right to receive shares of common stock dependent on the achievement of two Company-specific financial performance targets and the provision of service through the vesting date. Attainment of the metrics is measured based on the average levels of achievement across the three The Company also granted performance stock units during the year ended December 31, 2020. The performance stock units granted in 2020 provide the recipients with the right to receive shares of common stock dependent 50% on the achievement of a Company-specific financial performance target and 50% on a total shareholder return (“TSR”) goal, and are generally subject to the provision of service through the vesting date of the award. The Company-specific financial performance target and the TSR goal are measured independently of each other, but achievement of both of the metrics is measured based on the same three-year performance period from January 1, 2020 through December 31, 2022. The TSR goal is based on the Company’s relative TSR performance against the companies included in the Russell 2000 Index over the performance period. Achievement of the Company-specific financial performance target is measured based on the average levels of achievement across the performance period. Depending on the Company’s performance against the predetermined thresholds for achievement, each performance stock unit award recipient is eligible to earn a percentage of the target number of shares granted to the recipient, ranging from zero to 200%. The performance stock units, to the extent earned, will vest on the date the Company’s compensation and governance committee certifies the achievement of the performance metrics for the three-year period ending December 31, 2022, which will occur subsequent to the end of the performance period but before the Company files its annual consolidated financial statements for the year then ended. The value of the portions of the performance stock units granted during the years ended December 31, 2020 and 2019 eligible to be earned based on the achievement of the Company-specific financial performance targets was measured on the same basis as that of the restricted stock units, and based on the target number of shares granted; because the performance vesting conditions affect the ability of the recipients to vest in the awards, they are not factored into the fair value measure of the award. Compensation expense related to such performance stock units is recognized ratably over the requisite service period, and the Company must assess the probability that the performance conditions will be met each reporting period and the level at which they are estimated to be attained. Should the probability assessment change during a given reporting period, the total compensation cost (both recognized and unrecognized) will be adjusted to reflect the revised assessment. The TSR goal, which determines how much of the 50% of the performance stock units granted during 2020 may be earned, is considered a market condition as opposed to a vesting condition. Because a market condition is not considered a vesting condition, it is reflected in the grant date fair value of an award and the associated compensation cost based on the fair value of the award is recognized over the performance period, regardless of whether the Company actually achieves the market condition or the level of achievement, as long as service is provided by the recipient. The Company used a Monte Carlo simulation to estimate the fair value of the portion of the awards subject to the TSR goal. The following table provides the assumptions used to determine the grant date fair value of the market condition-dependent / TSR goal-based portion of the Company’s performance stock units granted during 2020 using a Monte Carlo simulation: Expected dividend yield — % Risk-free interest rate 1.56 % Expected volatility 28.57 % Expected term (in years) 2.95 Grant date fair value $ 24.11 The following table summarizes the activity of restricted stock awards, restricted stock units and performance stock units for the period from December 31, 2017 through the year ended December 31, 2020: Restricted Stock Awards Restricted Stock Units Performance Stock Units Number of Weighted Average Grant Date Fair Value (per share) Number of Weighted Average Grant Date Fair Value (per share) Number of Weighted Average Grant Date Fair Value (per share) Nonvested as of December 31, 2017 2,096,637 $ 8.87 1,654,690 $ 16.97 — $ — Granted 14,498 $ 13.80 161,598 $ 16.12 — $ — Vested (223,298) $ 12.18 (797,859) $ 16.97 — $ — Forfeited (117,177) $ 8.04 (19,643) $ 16.97 — $ — Nonvested as of December 31, 2018 1,770,660 $ 8.39 998,786 $ 16.83 — $ — Granted — $ — 1,245,628 $ 15.42 550,676 $ 15.41 Vested (97,140) $ 12.32 (541,383) $ 16.68 — $ — Forfeited (127,390) $ 8.04 (74,595) $ 16.09 — $ — Nonvested as of December 31, 2019 1,546,130 $ 8.17 1,628,436 $ 15.83 550,676 $ 15.41 Granted — $ — 1,158,605 $ 16.60 456,311 $ 20.29 Vested (29,760) $ 12.32 (816,866) $ 16.17 — $ — Forfeited (619,355) $ 8.04 (129,036) $ 16.28 (41,251) $ 15.95 Nonvested as of December 31, 2020 897,015 $ 13.80 (1) 1,841,139 $ 16.14 965,736 $ 17.69 (1) Reflects the impact of the modification on all unvested restricted stock awards as described above. The total fair value of restricted stock awards that vested during the years ended December 31, 2020, 2019 and 2018 was $510, $1,543 and $3,493, respectively. The total fair value of restricted stock units that vested during the years ended December 31, 2020, 2019 and 2018 was $11,269, $8,493 and $13,628, respectively. None of the Company’s performance stock units vested during the years ended December 31, 2020, 2019 and 2018. Total Stock-Based Compensation Expense For the years ended December 31, 2020, 2019 and 2018, total stock-based compensation expense for the Company was $21,527, $16,212 and $18,419, respectively. The income tax benefit recognized in the statements of income for the years ended December 31, 2020, 2019 and 2018 was $5,664, $3,543 and $4,671. As of December 31, 2020, there was no unrecognized compensation cost related to nonvested stock options or nonvested restricted stock awards subject to service vesting conditions. As of December 31, 2020, there was $20,511 of total unrecognized compensation cost related to nonvested restricted stock units and $10,982 of total unrecognized compensation cost related to nonvested performance stock units considered probable of vesting. The weighted-average period over which these costs are expected to be recognized at December 31, 2020 is 1.59 years for the restricted stock units and 1.63 years for the performance stock units. No expense has been recognized for any restricted stock awards or stock options subject to the performance condition for the years ended December 31, 2020, 2019 and 2018, as the performance-based criteria was not achieved nor considered probable of achievement.

Earnings per Share

Earnings per Share	12 Months Ended
	Dec. 31, 2020
Earnings Per Share [Abstract]
Earnings per Share	23. Earnings per Share: Basic earnings per share is calculated as income (loss) available to common stockholders, divided by the weighted average number of common shares outstanding during the period. The weighted average number of common shares outstanding during the period for the computation of basic earnings per share excludes restricted stock awards that have legally been issued but are nonvested during the period, as the sale of these shares is prohibited pending satisfaction of certain vesting conditions by the award recipients in order to earn the rights to the shares (see Note 22 to these consolidated financial statements for further information regarding outstanding nonvested restricted stock awards). Diluted earnings per share is calculated as income (loss) available to common stockholders, divided by the weighted average number of common and potential common shares outstanding during the period, if dilutive. Potential common shares reflect (1) unvested restricted stock awards and restricted stock units with service vesting conditions, (2) performance stock units with vesting conditions considered probable of achievement and (3) options to purchase common stock, all of which have been included in the diluted earnings per share calculation using the treasury stock method. The reconciliation from basic to diluted weighted average shares outstanding is as follows: Years ended 2020 2019 2018 Weighted average shares outstanding – Basic 135,528,977 134,389,667 133,380,567 Dilutive effect of unvested common shares and restricted stock units with service conditions, performance stock units considered probable of vesting and assumed stock option exercises and conversions — 1,159,027 1,304,364 Weighted average shares outstanding – Diluted 135,528,977 135,548,694 134,684,931 Basic and diluted earnings per share are calculated as follows: Years ended 2020 2019 2018 Numerator: Net (loss) income attributable to PQ Group Holdings Inc. $ (278,771) $ 79,539 $ 58,300 Denominator: Weighted average shares outstanding – Basic 135,528,977 134,389,667 133,380,567 Weighted average shares outstanding – Diluted 135,528,977 135,548,694 134,684,931 Net (loss) income per share: Basic (loss) income per share $ (2.06) $ 0.59 $ 0.44 Diluted (loss) income per share $ (2.06) $ 0.59 $ 0.43 The table below presents the details of the Company’s weighted average equity-based awards outstanding during each respective year that were excluded from the calculation of diluted earnings per share: Years ended 2020 2019 2018 Restricted stock awards with performance only targets not yet achieved 1,225,855 1,584,980 1,643,760 Stock options with performance only targets not yet achieved 507,461 558,283 586,253 Anti-dilutive restricted stock awards, restricted stock units and performance stock units 1,453,120 — 5,162 Anti-dilutive stock options 846,049 863,063 717,612 Restricted stock awards and stock options with performance only vesting conditions are not included in the dilution calculation, as the performance targets have not been achieved nor were probable of achievement as of the end of the respective periods. Certain stock options to purchase shares of common stock were excluded from the computation of diluted earnings per share for the respective periods, because the combination of the options’ exercise price and remaining unamortized stock-based compensation expense was greater than the average market price of the common shares. Anti-dilutive awards are not included in the dilution calculation, as their inclusion would have the effect of increasing diluted income per share.

Commitments and Contingent Liab

Commitments and Contingent Liabilities	12 Months Ended
	Dec. 31, 2020
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingent Liabilities	24. Commitments and Contingent Liabilities: Environmental Contingencies There is a risk of environmental impact in chemical manufacturing operations. The Company’s environmental policies and practices are designed to comply with existing laws and regulations and to minimize the possibility of significant environmental impact. The Company is also subject to various other lawsuits and claims with respect to matters such as governmental regulations, labor and other actions arising out of the normal course of business. While management believes that the liabilities resulting from such lawsuits and claims are not probable or reasonably estimable, certain accruals have been reflected in the Company’s consolidated financial statements, some of which are described in detail within this note. In 2008, the Company sold property located in Tacoma, Washington to the local port authority. In 2009, the port authority commissioned an environmental investigation of portions of the property. In 2010, the port authority advised the Company of alleged soil and groundwater contamination on the property and alleged the Company liable for certain conditions. The Company received and reviewed the environmental investigation documentation and determined it may have liability with respect to some, but not all, of the alleged contamination. At this time, remedial plans are in the feasibility study stage and have not been agreed upon or presented to Washington State for consideration. As of December 31, 2020 and 2019, the Company has recorded reserves of $1,278 and $1,045, respectively, for costs related to this potential liability. The Company has recorded a reserve of $510 and $770 as of December 31, 2020 and 2019, respectively, to address remaining subsurface remedial and wetlands/marsh management activities at the Company’s Martinez, CA site. Although currently a sulfuric acid regeneration plant, the site originally was operated by Mountain Copper Company (“Mococo”) as a copper smelter. Also, the site sold iron pyrite to various customers and allowed their customers to deposit waste iron pyrite cinder and slag on the site. The property is adjacent to Peyton Slough, where Mococo had a permitted discharge point from its process. In 1997, the San Francisco Bay Regional Water Quality Control Board (“RWQCB”) required characterization and remediation of Peyton Slough for Copper, Zinc and Acidic Soils. Various remediation activities were undertaken and completed, and the site has received final concurrence from the Army Corps with respect to the completed work. The RWQCB has agreed that Eco Services has achieved the goals for vegetative cover. The current marsh condition is being sustained by the opening and subsequent closing of the tide gates on a once per year basis. The Company is continuing to indicate to the RWQCB a plan to involve Contra Costa County and work towards development of an alliance for operating, maintaining and funding the tide gates is appropriate. The Company is currently in the process of obtaining permits for the long-term maintenance of Peyton Slough. As of December 31, 2020 and 2019, the Company has recorded a reserve of $427 and $709, respectively, for subsurface remediation and the Soil Vapor Extraction Project at the Company’s Dominguez, CA site. In the 1980s and 1990s, the EPA and the Los Angeles Regional Water Quality Control Board conducted investigations of the site due to historic chlorinated pesticide and chlorinated solvent use. Soil and groundwater beneath the site were impacted by chlorinated solvents and associated breakdown products, petroleum hydrocarbons, chlorinated pesticides and metals. A Corrective Measures Plan approved in October 2011 requires (1) soil vapor extraction (“SVE”) in affected areas, (2) covering of unpaved areas containing pesticide impacted soil, and (3) annual groundwater monitoring of the perched water-bearing zone. Annual groundwater sampling and soil vapor monitoring indicates that the SVE system has been effective in reducing subsurface contaminant levels. The Company is moving in the direction of rendering the SVE system dormant and potentially closing this matter within the next few years following rebound testing, including the preparation of an updated long-term Operations and Maintenance Plan as requested by the California Department of Toxic Substances Control. Purchase Commitments The Company has entered into short and long-term purchase commitments for various key raw materials and energy requirements. The purchase obligations include agreements with various suppliers to purchase goods that are enforceable and legally binding, and that specify all significant terms. Purchases under these agreements are expected to be as follows: Year Amount 2021 $ 13,695 2022 3,263 2023 1,654 2024 1,186 2025 1,183 Thereafter 995 $ 21,976 Letters of Credit At December 31, 2020, the Company had outstanding letters of credit of $18,190. Letters of credit are guarantees of payment to third parties. The Company’s letters of credit are used primarily as collateral for various items, including environmental, energy and insurance payments. The letters of credit are supported by the Company’s ABL facility.

Long-term Supply Contract

Long-term Supply Contract	12 Months Ended
	Dec. 31, 2020
Commitments and Contingencies Disclosure [Abstract]
Long-term Supply Contract	25. Long-term Supply Contract: As part of Solvay’s 2004 sale of its Specialty Phosphates business, Solvay agreed to continue to supply sulfuric acid to a customer in support of the phosphoric acid production for its specialty phosphates business under a preexisting supply agreement. This non-cancelable agreement extends to 2031, and was assumed by the Company in connection with the 2014 Acquisition.

Related Party Transactions

Related Party Transactions	12 Months Ended
	Dec. 31, 2020
Related Party Transactions [Abstract]
Related Party Transactions	26. Related Party Transactions: The Company maintains certain policies and procedures for the review, approval and ratification of related party transactions to ensure that all transactions with selected parties are fair, reasonable and in the Company’s best interests. All significant relationships and transactions are separately identified by management if they meet the definition of a related party or a related party transaction. Related party transactions include transactions that occurred during the year, or are currently proposed, in which the Company was or will be a participant, and for which any related person had or will have a direct or indirect material interest. All related party transactions are reviewed, approved and documented by the appropriate level of the Company’s management in accordance with these policies and procedures. Joint Venture Agreement The Company entered into a joint venture agreement (the “ZI Partnership Agreement”) in 1988 with Shell Catalysts & Technologies, an affiliate of Royal Dutch Shell plc, to form Zeolyst International, a 50/50 joint venture partnership (the “Partnership”). Under the terms of the ZI Partnership Agreement, the Partnership leases certain land used in its Kansas City production facilities from PQ Corporation. This lease, which has been recorded as an operating lease, provided for rental payments to the Company of $310, $305 and $295 during the years ended December 31, 2020, 2019 and 2018, respectively. The terms of this lease are evergreen as long as the ZI Partnership Agreement is in place. The Partnership recognized sales to the Company’s former Performance Materials business of $861, $803 and $645 during the years ended December 31, 2020, 2019 and 2018, respectively. The Partnership purchases certain of its raw materials from the Company and is charged for various manufacturing costs incurred at the Company’s Kansas City production facility. The amount of these costs charged to the Partnership were $16,065, $19,976 and $16,869 for the years ended December 31, 2020, 2019 and 2018, respectively. Certain administrative, marketing, engineering, management-related, and research and development services are provided to the Partnership by the Company. During the years ended December 31, 2020, 2019 and 2018, the Partnership was charged $12,229, $12,871 and $12,727, respectively, for these services. In addition, the Partnership was charged certain product demonstration costs of $1,853, $2,204 and $1,768 during the years ended December 31, 2020, 2019 and 2018, respectively. These charges to the Partnership are recorded as reductions in either cost of goods sold or selling, general and administrative expenses in the consolidated statements of income, depending on the nature of the expenditures. Other From time to time, the Company makes sales to and purchases raw materials from portfolio companies of funds that are affiliated with CCMP and companies that are affiliated with INEOS Capital Partners. The Company had sales of $12,672, $4,841 and $5,587 to companies affiliated with INEOS Capital Partners during the years ended December 31, 2020, 2019, and December 31, 2018 respectively. The Company purchased raw materials of $1,222, $1,203 and $1,495 to companies affiliated with INEOS Capital Partners during the years ended December 31, 2020, 2019, and December 31, 2018 respectively.

Quarterly Financial Summary (Un

Quarterly Financial Summary (Unaudited)	12 Months Ended
	Dec. 31, 2020
Quarterly Financial Information Disclosure [Abstract]
Quarterly Financial Summary (Unaudited)	27. Quarterly Financial Summary (Unaudited): The following tables summarize the Company’s quarterly financial results during the years ended December 31, 2020 and 2019: 2020 First Second Third Fourth Sales $ 295,813 $ 254,896 $ 275,149 $ 281,505 Gross profit 72,295 63,662 70,172 67,227 Operating income 29,214 20,175 33,310 (245,623) Net income (loss) from continuing operations 6,299 7,896 (6,956) (186,702) Net income (loss) from discontinued operations, net of tax (5,790) 8,351 11,392 (116,194) Net (loss) income 509 16,247 4,436 (302,896) Less: Net (loss) income attributable to the noncontrolling interest - continuing operations 234 250 201 (3,883) Less: Net income (loss) attributable to the noncontrolling interest - discontinued operations 51 71 97 46 Net income (loss) attributable to PQ Group Holdings Inc. 224 15,926 4,138 (299,059) Earnings (loss) per common share - basic Continuing operations $ 0.04 $ 0.06 $ (0.05) $ (1.35) Discontinued operations $ (0.04) $ 0.06 $ 0.08 $ (0.86) Net earnings (loss) per share - basic $ — $ 0.12 $ 0.03 $ (2.21) Earnings (loss) per common share - diluted: Continuing operations $ 0.04 $ 0.06 $ (0.05) $ (1.35) Discontinued operations $ (0.04) $ 0.06 $ 0.08 $ (0.86) Net earnings (loss) per share - diluted $ — $ 0.12 $ 0.03 $ (2.21) Weighted average shares outstanding: Basic 135,240,897 135,083,126 135,106,969 135,406,081 Diluted 136,086,082 135,671,830 135,979,118 135,406,081 2019 First Second Third Fourth Sales $ 297,468 $ 311,641 $ 307,271 $ 283,535 Gross profit 67,728 81,863 82,913 65,898 Operating income 28,995 48,840 41,191 28,482 Net income from continuing operations 6,055 19,404 11,888 28,406 Net income (loss) from discontinued operations, net of tax (2,614) 11,315 6,863 (1,007) Net income 3,441 30,719 18,751 27,399 Less: Net income attributable to the noncontrolling interest - continuing operations 231 101 82 203 Less: Net income attributable to the noncontrolling interest - discontinued operations 59 44 24 27 Net income attributable to PQ Group Holdings Inc. 3,151 30,574 18,645 27,169 Earnings (loss) per common share - basic: Continuing operations $ 0.04 $ 0.14 $ 0.09 $ 0.21 Discontinued operations $ (0.02) $ 0.08 $ 0.05 $ (0.01) Net earnings per share - basic $ 0.02 $ 0.23 $ 0.14 $ 0.20 Earnings (loss) per common share - diluted: Continuing operations $ 0.04 $ 0.14 $ 0.09 $ 0.21 Discontinued operations $ (0.02) $ 0.08 $ 0.05 $ (0.01) Net earnings per share - diluted $ 0.02 $ 0.23 $ 0.14 $ 0.20 Weighted average shares outstanding: Basic 133,946,308 134,142,552 134,511,819 134,912,212 Diluted 134,894,354 135,323,024 135,649,710 136,151,739

Supplemental Cash Flow Informat

Supplemental Cash Flow Information	12 Months Ended
	Dec. 31, 2020
Supplemental Cash Flow Elements [Abstract]
Supplemental Cash Flow Information	28. Supplemental Cash Flow Information: The following table presents supplemental cash flow information for the Company: Years ended 2020 2019 2018 Cash paid during the year for: Income taxes, net of refunds $ 35,013 $ 17,406 $ 23,842 Interest (1) 90,291 117,775 110,834 Non-cash investing activity (2) : Capital expenditures acquired on account but unpaid as of the year end 11,630 22,562 23,498 (1) Cash paid for interest is shown net of capitalized interest for the periods presented and excludes $4,963 and $8,480 of net interest proceeds on swaps designated as net investment hedges for the years ended December 31, 2020 and 2019, respectively, which are included within cash flows from investing activities in the Company’s consolidated statements of cash flows. (2) For the supplemental non-cash information on lease liabilities arising from obtaining right-of-use lease assets, see Note 13 to these consolidated financial statements for additional details. The following table provides a reconciliation of cash, cash equivalents and restricted cash reported within the consolidated balance sheets as of December 31, 2020, 2019 and 2018 to the total of the same amounts shown in the consolidated statements of cash flows for the years then ended: December 31, 2020 2019 2018 Cash and cash equivalents $ 135,531 $ 53,861 $ 37,164 Restricted cash included in prepaid and other current assets 1,688 1,331 1,435 Total cash, cash equivalents and restricted cash shown in the consolidated statements of cash flows $ 137,219 $ 55,192 $ 38,599

Subsequent Events

Subsequent Events	12 Months Ended
	Dec. 31, 2020
Subsequent Events [Abstract]
Subsequent Events	29. Subsequent Events: Definitive Agreement to Sell the Company’s Performance Chemicals Business On Marc h 1, 2021, th e Company announced that it entered into a definitive agreement to sell its Performance Chemicals business for a purchase price of $1,100,000, subject to customary purchase price adjustments as set forth in the agreement. The planned sale of the Performance Chemicals business reflects continued advancement by the Company on its ‘Simpler + Stronger’ strategic path. The Company expects to use the after-tax cash proceeds from the sale to reduce debt and return capital to its shareholders, subject to board approval and declarat ion. The transaction is expected to close by the end of 2021, sub ject to regulatory approvals and customary closing conditions. The Company is currently evaluating the impact of this transaction. This transaction met the held for sale criteria in March 2021, an d consequently the financial results of the Performance Chemicals business will be reported in discontinued operations beginning in the first quarter of 2021. Chem32 Acquisition On Februar y 24, 202 1, the Company completed the acquisition of Chem32, a leading supplier of catalyst pre-activation services, for a purchase price of $44,000, subject to customary purchase price adjustments as set forth in the agreement. Other than these items, the Company has evaluated subsequent events since the balance sheet date and determined that there are no additional matters to disclose.

Schedule I - Condensed Financia

Schedule I - Condensed Financial Information of Parent	12 Months Ended
	Dec. 31, 2020
Condensed Financial Information Disclosure [Abstract]
Condensed Financial Information	SCHEDULE I PQ GROUP HOLDINGS INC. AND SUBSIDIARIES (PARENT) CONDENSED FINANCIAL INFORMATION CONDENSED STATEMENTS OF INCOME (in thousands) Years ended 2020 2019 2018 Stock compensation expense $ 25,200 $ 16,212 $ 18,419 Equity in net loss (income) from subsidiaries 253,571 (95,751) (76,719) Net (loss) income (278,771) 79,539 58,300 Other comprehensive income (loss), net of tax: Pension and postretirement benefits 1,938 2,430 (7,958) Net (loss) gain from hedging activities 166 (2,665) (330) Foreign currency translation (16,596) 22,117 (35,127) Total other comprehensive income (loss) (14,492) 21,882 (43,415) Comprehensive (loss) income $ (293,263) $ 101,421 $ 14,885 SCHEDULE I PQ GROUP HOLDINGS INC. AND SUBSIDIARIES (PARENT) CONDENSED FINANCIAL INFORMATION CONDENSED BALANCE SHEETS (in thousands, except share and per share amounts) December 31, December 31, ASSETS Investment in subsidiaries $ 1,277,126 $ 1,779,450 Total assets $ 1,277,126 $ 1,779,450 LIABILITIES Total liabilities $ — $ — STOCKHOLDERS' EQUITY Common stock (0.01 par); authorized shares 450,000,000; issued shares 137,102,143 and 136,861,382 on December 31, 2020 and 2019, respectively; outstanding shares 136,318,557 and 136,464,961 on December 31, 2020 and 2019, respectively 1,371 1,369 Preferred stock (0.01 par); authorized shares 50,000,000; no shares issued or outstanding on December 31, 2020 and 2019, respectively — — Additional paid-in capital 1,477,859 1,696,899 (Accumulated deficit) retained earnings (175,758) 103,013 Treasury stock, at cost; shares 783,586 and 396,421 on December 31, 2020 and 2019, respectively (11,081) (6,483) Accumulated other comprehensive loss (15,265) (15,348) Total PQ Group Holdings Inc. equity 1,277,126 1,779,450 Total liabilities and equity $ 1,277,126 $ 1,779,450 SCHEDULE I PQ GROUP HOLDINGS INC. AND SUBSIDIARIES (PARENT) CONDENSED FINANCIAL INFORMATION CONDENSED STATEMENTS OF CASH FLOWS (in thousands) Years ended 2020 2019 2018 Cash flows from operating activities: Net (loss) income $ (278,771) $ 79,539 $ 58,300 Adjustments to reconcile net (loss) income to net cash provided by operating activities: Equity in net income from subsidiaries 253,571 (95,751) (76,719) Stock compensation expense 25,200 16,212 18,419 Net cash provided by operating activities — — — Cash flows from investing activities: Distribution from subsidiaries 243,779 — — Net cash provided by investing activities 243,779 — — Cash flows from financing activities: Dividends paid to stockholders (243,779) — — Net cash used in financing activities (243,779) — — Effect of exchange rate changes on cash, cash equivalents and restricted cash — — — Net change in cash, cash equivalents and restricted cash — — — Cash, cash equivalents and restricted cash at beginning of period — — — Cash, cash equivalents and restricted cash at end of period of continuing operations $ — $ — $ — SCHEDULE I PQ GROUP HOLDINGS INC. AND SUBSIDIARIES (PARENT) CONDENSED FINANCIAL INFORMATION NOTES TO CONDENSED SCHEDULE I 1. Description of PQ Group Holdings Inc. and Subsidiaries PQ Group Holdings Inc. (“PQ Group Holdings” or the “Parent Company”) is a holding company that conducts substantially all of its business operations through its wholly owned subsidiary, PQ Corporation. As specified in certain of PQ Corporation’s debt agreements entered into concurrently with a series of transactions to reorganize and combine the businesses of PQ Holdings Inc. and Eco Services Operations LLC in May 2016 (the “Business Combination”), as subsequently amended and restated, there are restrictions on the ability of PQ Corporation to make payments to its stockholder, PQ Group Holdings, on behalf of its equity interests (refer to Note 17 to the PQ Group Holdings consolidated financial statements for further information regarding PQ Corporation debt). 2. Basis of Presentation The accompanying condensed Parent Company financial statements are required in accordance with Rule 4-08(e)(3) of Regulation S-X. These condensed financial statements have been presented on a “parent-only” basis. Under a parent-only presentation, the Parent Company’s investment in its consolidated subsidiary is presented under the equity method of accounting. Under the equity method, the investment in subsidiary is stated at cost plus contributions and equity in undistributed income (loss) of the subsidiary, less distributions received since the date of acquisition. For purposes of presenting net income, this presentation assumes that the Parent Company was in existence for the full year ended December 31, 2016, the year of the Business Combination. These parent-only financial statements should be read in conjunction with PQ Group Holdings’ audited consolidated financial statements. 3. Stock-Based Compensation Refer to Note 22 of the notes to the PQ Group Holdings consolidated financial statements for a description of stock-based compensation. 4. Common Stock Refer to Note 23 of the notes to the PQ Group Holdings consolidated financial statements for a description of common stock. 5. Dividends Paid On December 14, 2020, the Company’s Board of Directors declared a special cash dividend of $1.80 per share, using after tax cash proceeds and cash on hand from the sale of the Performance Materials business. The dividend was paid to the Company’s stockholders of record at the close of business on December 21, 2020.

Summary of Significant Accoun_2

Summary of Significant Accounting Policies Summary of Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2020
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation The Company has three uniquely positioned specialty businesses: Refining Services provides sulfuric acid recycling to the North American refining industry; Catalysts serves the packaging and engineered plastics industry and the global refining, petrochemical and emissions control industries through its Zeolyst joint venture; and Performance Chemicals supplies diverse product end uses, including personal and industrial cleaning products, fuel-efficient tires, surface coatings, and food and beverage products. Effective December 14, 2020, the Company completed the sale of its Performance Materials business and the results of operations of this business have been presented as discontinued operations in the consolidated statements of income for all periods presented. See Note 4 for more information on the assets and liabilities classified as held for sale. The notes to the consolidated financial statements, unless otherwise indicated, are on a continuing operations basis. The Company’s Refining Services segment typically experiences seasonal fluctuations as a result of higher demand for gasoline products in the summer months and lower demand in the winter months. These demand fluctuations result in higher sales and working capital requirements in the second and third quarter.
Principles of Consolidation	Principles of Consolidation. The consolidated financial statements include the accounts of the Company and its controlled subsidiaries. Investments in affiliated companies are recorded at cost plus the Company’s equity in their undistributed earnings. All intercompany transactions have been eliminated. Noncontrolling interests represent third-party equity ownership in certain of the Company’s consolidated subsidiaries and are presented as a component of equity separate from the equity attributable to the Company’s shareholders. The noncontrolling interests’ share in the Company’s net earnings are included in net income attributable to the noncontrolling interest in the Company’s consolidated statements of income, and their portion of the Company’s comprehensive income is included in comprehensive income (loss) attributable to noncontrolling interests in the Company’s consolidated statements of comprehensive income (loss). The Company’s noncontrolling interests relate to third-party minority ownership interests held in certain of the Company’s foreign subsidiaries acquired as part of a former business combination.
Foreign Currency Transactions and Translations Policy	Foreign Currency Translation. All assets and liabilities of foreign subsidiaries and affiliated companies are translated to U.S. dollars using exchange rates in effect at the balance sheet date. Adjustments resulting from translation of the balance sheets and intercompany loans, which are considered permanent, are included in stockholders’ equity as part of accumulated other comprehensive income (loss). Adjustments resulting from translation of certain intercompany loans, which are not considered permanent and are denominated in foreign currencies, are included in other (income) expense, net in the consolidated statements of income. The Company considers intercompany loans to be of a permanent or long-term nature if management expects and intends that the loans will not be repaid. For the years ended December 31, 2020, 2019 and 2018, all intercompany loan arrangements were determined to be non-permanent based on management’s intention as well as actual lending and repayment activity. Therefore, the foreign currency transaction gains or losses associated with the intercompany loans were recorded in the consolidated statements of income for the years ended December 31, 2020, 2019 and 2018. Income and expense items are translated at average exchange rates during the year. Net foreign currency exchange (gains) and losses included in other (income) expense, net were $(4,172), $2,410 and $12,543 for the years ended December 31, 2020, December 31, 2019 and December 31, 2018, respectively. The net foreign currency losses realized in 2020 were driven by the non-permanent intercompany debt denominated in local currency and translated to U.S. dollars. The net foreign currency losses realized in 2019 and in 2018 were primarily driven by the Euro-denominated term loan (which was settled as part of the February 2018 term loan refinancing, see Note 17 to these consolidated financial statements for further information) and the non-permanent intercompany debt denominated in local currency and translated to U.S. dollars.
Cash and Cash Equivalents	Cash and Cash Equivalents. Cash and cash equivalents include highly liquid investments with original terms to maturity of 90 days or less from the time of purchase.
Restricted Cash	Restricted Cash. Restricted cash, which is restricted as to withdrawal or usage, is classified separately from cash and cash equivalents on the Company’s consolidated balance sheets. The Company’s total restricted cash balances were $1,688 and $1,331 as of December 31, 2020 and 2019, respectively, and are included on the Company’s consolidated balance sheets as other current assets.
Accounts Receivable and Allowance for Doubtful Accounts	Accounts Receivable and Allowance for Credit Losses. Trade accounts receivable are recorded at the invoiced amount and do not bear interest. The allowance for credit losses is the Company’s best estimate of the amount of probable credit losses in its existing accounts receivable and is reviewed during each reporting period over their contractual life. The Company recognizes an allowance for credit losses based on historical collection experience, current regional economic and market conditions, the aging of accounts receivable and assessments of current creditworthiness of customers. Account balances are charged against the allowance when the Company believes it is probable that the associated receivables will not be recovered. If the financial condition of the Company’s customers were to deteriorate resulting in an impairment of their ability to make payments, additional allowances may be required. The Company does not have any off-balance sheet credit exposure related to its customers. As of December 31, 2020 and 2019, the Company’s allowance for credit losses was $1,521 and $2,068, respectively.
Inventories	Inventories. Certain domestic inventories are stated at the lower of cost or market and valued using the last-in, first-out (“LIFO”) method. All other inventories are stated at the lower of cost and net realizable value and valued using the weighted average cost or first-in, first-out (“FIFO”) methods.
Property, Plant and Equipment	Property, Plant and Equipment. Property, plant and equipment are carried at cost and include expenditures for new facilities, major renewals and betterments. The Company capitalizes the cost of furnace rebuilds as part of property, plant and equipment. Maintenance, repairs and minor renewals are charged to expense as incurred. The Company capitalizes certain internal costs associated with the implementation of purchased software. When property, plant and equipment is retired or otherwise disposed of, the net carrying amount is eliminated with any gain or loss on disposition recognized in earnings at that time. Depreciation is provided on the straight-line method based on the estimated useful lives of the assets, which generally range from 15 to 33 years for buildings and improvements and 3 to 10 years for machinery and equipment. Leasehold improvements are depreciated using the straight-line method based on the shorter of the useful life of the improvement or remaining lease term. The Company capitalizes the interest cost associated with the development and construction of significant new plant and equipment and depreciates that amount over the lives of the related assets. Capitalized interest recorded during the years ended December 31, 2020, 2019 and 2018 was $1,780, $1,981 and $3,576, respectively.
Leases	Leases . The Company has operating and finance lease agreements with remaining lease terms as of December 31, 2020 of up to 30 years, including leases of land, buildings, railcars, vehicles, manufacturing equipment and general office equipment. Some leases include options to terminate or extend for one or more years. These options are incorporated in the Company’s lease term when it is reasonably certain that the option will be exercised. Some leases include options to purchase, which the Company assesses under the guidance to determine if these leases should be classified as finance lease agreements. When the Company enters into an arrangement, at inception, the Company determines if the arrangement contains a lease and whether that lease meets the classification criteria of a finance or operating lease. Some of the Company’s lease arrangements contain lease components (e.g. minimum rent payments) and non-lease components (e.g. maintenance). The Company accounts for the lease and non-lease components separately based on the estimated standalone price of each component. Certain of the Company’s lease agreements include rental payments that are adjusted periodically for an index or rate and these are initially measured using the index or rate in effect at the commencement date. Variable lease expense is recognized in the period in which the obligation for those payments is incurred. The Company’s lease agreements do not contain any material residual value guarantees or material restrictive covenants. The Company recognizes a right-of-use lease asset and lease liability at the lease commencement date based on the present value of the remaining lease payments over the lease term. The Company assesses its leasing arrangements to determine the rate implicit in the lease arrangement. Historically, the Company’s leasing arrangements do not contain the information necessary to determine the rate implicit in the lease. As such, the Company utilizes its incremental borrowing rate over the relevant lease term, which is the rate of interest that it would have to pay to borrow on a collateralized basis over a similar term an amount equal to the lease payments in a similar economic environment. The incremental borrowing rate is determined at the lease commencement date and is developed utilizing a readily available market interest rate curve adjusted for the Company’s credit quality. The Company has elected to use a portfolio approach to apply its incremental borrowing rate to individual leases based on lease term and geographic jurisdiction. Short-term leases, which have an initial term of twelve months or less, are not recorded on the Company’s balance sheet. Lease expense for operating leases is recognized on a straight-line basis over the lease term. Lease expense for financing leases is bifurcated into two components, with the amortization expense component of the right-of-use asset recognized on a straight-line basis and the interest expense component recognized using the effective interest method over the lease term. The amortization expense component of the right-of-use lease asset is included in cost of goods sold and in selling, general and administrative expenses and the interest expense component is included in interest expense, net on the consolidated statements of income.
Spare Parts	Spare Parts. Spare parts are maintained by the Company’s facilities to keep machinery and equipment in working order. Spare parts are capitalized and included in other long-term assets. Spare parts are measured at cost and are not depreciated or expensed until utilized; however, reserves may be provided on aged spare parts. When a spare part is utilized as part of an improvement to property, plant and equipment, the carrying value is depreciated over the applicable life once placed in service. Otherwise, the spare part is expensed and charged as a cost of production when utilized.
Investments in Affiliated Companies	Investments in Affiliated Companies. Investments in affiliated companies are accounted for using the equity method of accounting if the investment provides the Company with the ability to exercise significant influence, but not control, over the investee. Significant influence is generally deemed to exist if the Company’s ownership interest in the voting stock of the investee ranges between 20% and 50%, although other factors, such as representation on the investee’s board of directors and the impact of commercial arrangements, are considered in determining whether the equity method of accounting is appropriate. Under the equity method of accounting, the investments in equity-method investees are recorded in the consolidated balance sheets as investments in affiliated companies, and the Company’s share of the investees’ earnings or losses, together with other than temporary impairments in value, is recorded as equity in net income from affiliated companies in the consolidated statements of income. Any differences between the Company’s cost of an equity method investment and the underlying equity in the net assets of the investment, such as fair value step-ups resulting from acquisitions, are accounted for according to their nature and impact the amounts recognized as equity in net income from affiliated companies in the consolidated statements of income. The Company evaluates all distributions received from its equity method investments using the nature of distribution approach. Under this approach, the Company evaluates the nature of activities of the investee that generated the distribution. The distributions received are either classified as a return on investment, which is presented as a component of operating activities on the Company’s consolidated statements of cash flows, or as a return of investment, which is presented as a component of investing activities on the Company’s consolidated statements of cash flows. The Company evaluates its equity method investments for impairment whenever events or changes in circumstances indicate that the carrying amounts of such investments may be impaired. If a decline in the value of an equity method investment is determined to be other than temporary, a loss is recorded in earnings in the current period.
Goodwill and Intangible Assets	Goodwill and Intangible Assets. Goodwill is an asset representing the future economic benefits arising from other assets acquired in a former business combination that are not individually identified and separately recognized. The Company is required to test goodwill associated with each of its reporting units for impairment at least annually and whenever events or circumstances indicate that it is more likely than not that goodwill may be impaired. The Company performs its annual goodwill impairment test as of October 1. Goodwill is tested for impairment at the reporting unit level. In performing tests for goodwill impairment, the Company is able to use its discretion to first perform an optional qualitative assessment about the likelihood of the carrying value of a reporting unit exceeding its fair value. The qualitative assessment need not be applied to all reporting units. If the Company determines that it is more likely than not that the fair value of a reporting unit is less than its carrying amount based on the qualitative assessment, the Company will perform a quantitative goodwill impairment test to identify the potential goodwill impairment and measure the amount of the goodwill impairment loss, if any, to be recognized for that reporting unit. For the annual assessments in 2020 and 2019, the Company bypassed the option to perform the qualitative assessment and proceeded directly to performing the quantitative goodwill impairment test for each of our reporting units. The quantitative test identifies both the potential existence of impairment and the amount of impairment loss. In applying the quantitative test, the Company calculates and compares the reporting unit’s estimated fair value to its carrying value, including goodwill. If the fair value of a reporting unit exceeds its carrying value, goodwill is not impaired. If the carrying value of a reporting unit exceeds its implied fair value, an impairment charge is recognized, requiring recognition of a goodwill impairment charge for the differential up to the carrying value of goodwill. An impairment loss cannot exceed the carrying value of goodwill assigned to a reporting unit and the loss establishes a new basis in the goodwill. Subsequent reversal of an impairment loss is not permitted. For intangible assets other than goodwill, definite-lived intangible assets are amortized over their respective estimated useful lives. Intangible assets with indefinite lives are not amortized, but rather are tested for impairment at least annually or more frequently if events occur or circumstances change that would more likely than not reduce the fair value of the intangible asset below its carrying amount. The Company tests its indefinite-lived intangible assets as of October 1 of each year in conjunction with its annual goodwill impairment test.
Impairment Assessment of Long-Lived Assets	Impairment Assessment of Long-Lived Assets. The Company performs an impairment review of property, plant and equipment and definite-lived intangible assets when facts and circumstances indicate that the carrying value of an asset or asset group may not be recoverable from its undiscounted future cash flows. When evaluating long-lived assets for
Derivative Financial Instruments	Derivative Financial Instruments. The Company utilizes certain derivative financial instruments to enhance its ability to manage risk, including exposure to interest rate, commodity price and foreign currency fluctuations that exist as part of ongoing business operations. Derivative instruments are entered into for periods consistent with the related underlying exposures and do not constitute positions independent of those exposures. All derivatives designated as hedges are recognized on the consolidated balance sheets at fair value. The Company may designate a derivative as a hedge of the fair value of a recognized asset or liability or of an unrecognized firm commitment (fair value hedge), a hedge of a forecasted transaction or the variability of cash flows to be received or paid related to a recognized asset or liability (cash flow hedge), a foreign currency fair-value or cash-flow hedge (foreign currency hedge), or a hedge of a net investment in a foreign operation (net investment hedge). The Company’s hedging strategies include derivatives designated as cash flow hedges and net investment hedges. Changes in the fair value of a derivative that is highly effective and that is designated and qualifies as a cash flow hedge are recorded in other comprehensive income and subsequently reclassified into earnings in the same period(s) in which the hedged transaction affects earnings. Changes in the fair value of a derivative that is highly effective and that is designated and qualifies as a hedge of a net investment in a foreign operation are recorded in the foreign currency translation adjustment account within accumulated other comprehensive income, where the associated gains and losses will remain until such time that the hedged net investment (foreign subsidiary) is sold or liquidated. Changes in the fair value of a derivative that is not designated or does not qualify as a hedge are recorded in the consolidated statements of income. Cash flows from derivative instruments are reported in the same cash flow category as the cash flows from the items being hedged. The Company formally documents all relationships between hedging instruments and hedged items, as well as its risk-management objective and strategy for undertaking various hedge transactions. The Company also formally assesses whether each hedging relationship is highly effective in achieving offsetting changes in fair values or cash flows of the hedged item during the period, both at the inception of the hedge and on an ongoing basis. If it is determined that a derivative is not highly effective as a hedge, or if a derivative ceases to be a highly-effective hedge, hedge accounting is discontinued with respect to that derivative prospectively.
Fair Value Measurement	Fair Value Measurements. The Company measures fair value using the guidelines under U.S. generally accepted accounting principles (“GAAP”). An asset’s fair value is defined as the price at which the asset could be exchanged in a current transaction between market participants. A liability’s fair value is defined as the amount that would be paid to transfer the liability to a market participant, not the amount that would be paid to settle the liability with the creditor. See Note 6 to these consolidated financial statements regarding the application of fair value measurements. Restoration plan assets The fair values of the Company’s restoration plan assets are determined through quoted prices in active markets. Restoration plan assets are assets held in a Rabbi trust to fund the obligations of the Company’s defined benefit supplementary retirement plans and include various stock and fixed income mutual funds. See Note 21 to these consolidated financial statements regarding defined benefit supplementary retirement plans. The Company’s restoration plan assets are included in other long-term assets on its consolidated balance sheets. Gains and losses related to these investments are included in other expense, net in the Company’s consolidated statements of income. Unrealized gains associated with the underlying stock and fixed income mutual funds were $545 and $944 as of December 31, 2020 and 2019, respectively and an unrealized loss of $346 as of December 31, 2018. Derivative contracts Derivative assets and liabilities can be exchange-traded or traded over-the-counter (“OTC”). The Company generally values exchange-traded derivatives using models that calibrate to market transactions and eliminate timing differences between the closing price of the exchange-traded derivatives and their underlying instruments. OTC derivatives are valued using market transactions and other market evidence whenever possible, including market-based inputs to models, model calibration to market transactions, broker or dealer quotations or alternative pricing sources with reasonable levels of price transparency. When models are used, the selection of a particular model to value an OTC derivative depends on the contractual terms of, and specific risks inherent in, the instrument as well as the availability of pricing information in the market. The Company generally uses similar models to value similar instruments. Valuation models require a variety of inputs, including contractual terms, market prices and rates, forward curves, measures of volatility, and correlations of such inputs. For OTC derivatives that trade in liquid markets, such as forward contracts, swaps and options, model inputs can generally be corroborated by observable market data by correlation or other means, and model selection does not involve significant management judgment. The Company has interest rate caps and cross currency swaps that are fair valued using Level 2 inputs. In addition, the Company applies a credit valuation adjustment to reflect credit risk which is calculated based on credit default swaps. To the extent that the Company’s net exposure under a specific master agreement is an asset, the Company utilizes the counterparty’s default swap rate. If the net exposure under a specific master agreement is a liability, the Company utilizes a default swap rate comparable to PQ Group Holdings. The credit valuation adjustment is added to the discounted fair value to reflect the exit price that a market participant would be willing to receive to assume the Company’s liabilities or that a market participant would be willing to pay for the Company’s assets.
Revenue Recognition	Revenue Recognition. In determining the appropriate amount of revenue to be recognized as the Company fulfills its obligations under its agreements, the Company performs the following steps: (i) identification of the contract with the customer; (ii) determination of whether the promised goods or services are performance obligations, including whether they are distinct in the context of the contract; (iii) measurement of the transaction price; (iv) allocation of the transaction price to the performance obligations based on estimated selling prices; and (v) recognition of revenue when (or as) the Company satisfies each performance obligation. The Company identifies a contract when an agreement with a customer creates legally enforceable rights and obligations, which occurs when a contract has been approved by both parties, the parties are committed to perform their respective obligations, each party’s rights and payment terms are clearly identified, commercial substance exists and it is probable that the Company will collect the consideration to which it is entitled.
Shipping and Handling Costs	Shipping and Handling Costs. Amounts billed to a customer in a sale transaction related to shipping and handling, if any, represent revenues earned for the goods provided and are classified as revenue. Costs related to shipping and handling of products shipped to customers are classified as cost of goods sold. Refer to Note 5 for disclosures regarding the recognition of revenue for shipping and handling costs that are billed to customers.
Research and Development	Research and Development. Research and development costs of $11,597, $12,514 and $13,719 for the years ended December 31, 2020, 2019 and 2018, respectively, were expensed as incurred and reported in selling, general and administrative expenses in the consolidated statements of income.
Income Taxes	Income Taxes. The Company operates within multiple taxing jurisdictions and is subject to tax filing requirements and potential audits within these jurisdictions. The Company uses the asset and liability method in accounting for income taxes. Deferred tax assets and liabilities are recorded for temporary differences between the tax basis of assets and liabilities and their reported amounts in the financial statements, using statutory tax rates in effect for the year in which the differences are expected to reverse. The effect on deferred tax assets and liabilities of a change in tax rates is recognized in the results of operations in the period that includes the enactment date. The Company evaluates its deferred tax assets each period to ensure that estimated future taxable income will be sufficient in character (e.g., capital gain versus ordinary income treatment), amount and timing, to result in their realizability. A valuation allowance is recorded to reduce the carrying amounts of deferred tax assets, unless it is more likely than not that those assets will be realized. Generally, APB 23 of ASC Topic 740, Income Taxes (“ASC 740”), provides guidance with respect to establishing deferred income taxes on earnings from foreign subsidiaries, to the extent that these earnings are considered to be available for repatriation. Further, ASC 740-30 requires that deferred taxes be established with respect to the earnings of a foreign subsidiary, unless existing tax law provides a means by which the investment in a subsidiary can be recovered tax-free. The Company has determined that it is able to repatriate the non-permanently reinvested earnings of its foreign subsidiaries in a tax-free manner. As such, the Company is able to asset, for purposes of ASC 740-30, that no deferred income taxes are needed with respect to earnings from foreign subsidiaries. The Company recognizes a financial statement benefit for positions taken for tax return purposes when it will be more likely than not (i.e. greater than 50%) that the positions will be sustained upon tax examination, based solely on the technical merits of the tax positions. Otherwise, no tax benefit is recognized. The tax benefits recognized are measured based on the largest benefit that has a greater than 50% likelihood of being realized upon ultimate settlement. The Company recognizes potential accrued interest and penalties related to unrecognized tax benefits as a component of income tax expense. Tax examinations are often complex as tax authorities may disagree with the treatment of items reported by the Company and may require several years to resolve. These accrued liabilities represent a provision for taxes that are reasonably expected to be incurred on the basis of available information but which are not certain. Pursuant to the Securities and Exchange Commission (“SEC”) Staff Accounting Bulletin No.118 (“SAB 118”), the Company was allowed a measurement period of up to one year after the enactment date of the Tax Cuts and Jobs Act (“TCJA”) to finalize the recording of any related tax impacts with respect to its transition tax liability. In accordance with SAB 118, the Company finalized the impacts of the transition tax as of December 31, 2018 and recorded a measurement period adjustment of $2,102 as a benefit to tax expense. There was no cash tax outlay associated with the final transition tax amount, as the Company elected to utilize net operating loss (“NOL”) carryforwards to offset the associated taxable income. Based on FASB guidance, the Company is permitted to make an accounting policy election to either (1) treat the taxes incurred as a result of the Global Intangible Low Taxed Income (“GILTI”) provision as a current-period expense when incurred or (2) factor such amounts into its measurement of deferred taxes. The Company has elected to treat any expense incurred as a current-period expense.
Asset Retirement Obligations	Asset Retirement Obligations. The Company records a liability when the fair value of any future obligation to retire a long-lived asset as a result of an existing or enacted law, statute, ordinance or contract is reasonably estimable. The Company also records a liability for the fair value of a conditional asset retirement obligation if the fair value can be reasonably estimated. When the liability is initially recorded, the Company capitalizes the cost by increasing the amount of the related long-lived asset. Over time, the Company adjusts the liability to its present value by recognizing accretion expense as an operating expense in the consolidated statements of income each period, and the capitalized cost is depreciated over the useful life of the related asset. Upon settlement of the liability, the Company records a gain or loss if the actual costs differ from the accrued amount.
Environmental Expenditures	Environmental Expenditures. Environmental expenditures that pertain to current operations or to future revenues are expensed or capitalized consistent with the Company’s capitalization policy for property, plant and equipment. Expenditures that result from the remediation of an existing condition caused by past operations and that do not contribute to current or future revenues are expensed. Liabilities are recognized for remedial activities when the remediation is probable and the cost can be reasonably estimated. Recoveries of expenditures for environmental remediation are recognized as assets only when recovery is deemed probable.
Deferred Finance Costs	Deferred Financing Costs. Financing costs incurred in connection with the issuance of long-term debt are deferred and presented as a direct reduction from the related debt instruments on the Company’s consolidated balance sheets. Deferred financing costs are amortized as interest expense using the effective interest method over the respective terms of the associated debt instruments.
Stock-Based Compensation	Stock-Based Compensation. The Company applies the fair value based method to account for stock options, restricted stock awards, restricted stock units and performance stock units issued in connection with its equity incentive plans. Stock-based compensation expense is recognized on a straight-line basis over the vesting periods of the respective awards, and the Company accounts for forfeitures of equity incentive awards as they occur. In connection with the vesting of restricted stock awards, restricted stock units and performance stock units, shares of common stock may be delivered to the Company by employees to satisfy withholding tax obligations at the instruction of the employee award holders. These transactions when they occur are accounted for as stock repurchases by the Company, with the shares returned to treasury stock at a cost representing the payment by the Company of the tax obligations on behalf of the employees in lieu of shares for the vesting event.
Pensions and Postretirement Benefits	Pensions and Postretirement Benefits. The Company maintains qualified and non-qualified defined benefit pension plans that cover employees in the United States and Canada, as well as certain employees in other international locations. Benefits for a majority of the plans are based on average final pay and years of service. Our funding policy, consistent with statutory requirements, is based on actuarial computations utilizing the projected unit credit method of calculation. Not all defined benefit pension plans are funded. In the United States and Canada, the pension plans’ assets include equity and fixed income securities. In our other international locations, the pension plans’ assets include equity and fixed income securities, as well as insurance contracts. Certain assumptions are made regarding the occurrence of future events affecting pension costs, such as mortality, withdrawal, disablement and retirement, changes in compensation and benefits, and discount rates to reflect the time value of money. The major elements in determining pension income and expense are pension liability discount rates and the expected return on plan assets. The Company references rates of return on high-quality, fixed income investments when estimating the discount rate, and the expected period over which payments will be made based upon historical experience. The long-term rate of return used to calculate the expected return on plan assets is the average rate of return estimated to be earned on invested funds for providing pension benefits. In addition to pension benefits, the Company provides certain health care benefits for employees who meet age, participation and length of service requirements at retirement. The Company uses explicit assumptions using the best estimates available of the plan’s future experience. Principal actuarial assumptions include: discount rates, present value factors, retirement age, participation rates, mortality rates, cost trend rates, Medicare reimbursement rates and per capita claims cost by age. Current interest rates as of the measurement date are used for discount rates in present value calculations. The Company also has defined contribution plans covering domestic employees of the Company and certain subsidiaries.
Contingencies	Contingencies. Certain conditions may exist as of the date the financial statements are issued, which may result in a loss to the Company but which will only be resolved when one or more future events occur or fail to occur. The Company’s management and its legal counsel assess such contingent liabilities, and such assessment inherently involves an exercise of judgment. In assessing loss contingencies related to legal proceedings that are pending against the Company or unasserted claims that may result in such proceedings, the Company and legal counsel evaluate the perceived merits of any legal proceedings or unasserted claims as well as the perceived merits of the amount of relief sought or expected to be sought therein. If the assessment of a contingency indicates that it is probable that a loss has been incurred and the amount of the liability can be estimated, then the estimated liability is accrued in the Company’s financial statements. If the assessment indicates that a loss contingency is not probable, but is reasonably possible, or is probable but cannot be estimated, then the nature of the contingent liability, together with an estimate of the range of possible loss if determinable and material, would be disclosed. Loss contingencies considered remote are generally not disclosed unless they involve guarantees, in which case the nature of the guarantee would be disclosed, including the approximate term, how the guarantee arose, and the events or circumstances that would require the guarantor to perform under the guarantee.
Use of Estimates	Use of 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 disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenues and expenses during the reporting period. Actual results could differ from those estimates.
New Accounting Pronouncements Policy	Recently Adopted Accounting Standards In June 2016, the Financial Accounting Standards Board (“FASB”) issued guidance that affects loans, trade receivables and any other financial assets that have the contractual right to receive cash. Under the new guidance, an entity is required to recognize expected credit losses rather than incurred losses for financial assets. The new guidance is effective for fiscal years beginning after December 15, 2019 and interim periods within those fiscal years. The Company adopted the new guidance effective January 1, 2020, with no material impact to the Company’s consolidated financial position, results of operations or cash flows. In August 2018, the FASB issued guidance which modifies certain disclosure requirements over fair value measurements. The guidance is effective for fiscal years beginning after December 15, 2019, including all interim periods within that fiscal year. The Company adopted the new guidance effective January 1, 2020. The Company does not currently classify any of its derivative contracts or restoration plan assets as Level 3 assets or liabilities, nor did the Company have any transfers amongst fair value levels during the year ended December 31, 2020. As a result, the guidance did not have an impact on Company’s the fair value measurement disclosures upon adoption. In January 2017, the FASB issued guidance which eliminates the second step from the traditional two-step goodwill impairment test. Under current guidance, an entity performed the first step of the goodwill impairment test by comparing the fair value of a reporting unit with its carrying amount; if an impairment loss was indicated, the entity computed the implied fair value of goodwill to determine whether an impairment loss existed, and if so, the amount to recognize. Under the new guidance, an impairment loss is recognized for the amount by which the carrying amount exceeds the reporting unit’s fair value (the Step 1 test), with no further testing required. Any impairment loss recognized is limited to the amount of goodwill allocated to the reporting unit. The new guidance is effective for public companies that are Securities and Exchange Commission (“SEC”) registrants for fiscal years beginning after December 15, 2019. The Company adopted the new guidance on January 1, 2020, and applied the guidance prospectively to its goodwill impairment tests. Accounting Standards Not Yet Adopted as of December 31, 2020 In December 2019, the FASB issued new guidance to simplify the accounting for income taxes by removing certain exceptions to the general principles and also simplification of areas such as franchise taxes, step-up in tax basis goodwill, separate entity financial statements and interim recognition of enactment of tax laws or rate changes. The new guidance is effective for fiscal years beginning after December 15, 2020 and interim periods within those fiscal years, with early adoption permitted. The Company is currently evaluating the impact of this new guidance on its consolidated financial statements. In March 2020, the FASB issued guidance to address certain accounting consequences from the anticipated transition from the use of the London Interbank Offered Rate (“LIBOR”) and other interbank offered rates to alternative reference rates. The new guidance contains practical expedients for reference rate reform related activities that impact debt, leases, derivatives and other contracts. The guidance is optional and may be elected over time as reference rate reform activities occur. During the year ended December 31, 2020, the Company elected to apply the hedge accounting expedients related to probability and the assessments of effectiveness for future LIBOR-indexed cash flows to assume that the index upon which future hedged transactions will be based on matches the index of the corresponding derivatives. Application of these expedients preserves the presentation of derivatives consistent with past presentation. The Company continues to evaluate the impact of the guidance and may apply other elections as applicable as additional changes in the market occur.

Summary of Significant Accoun_3

Summary of Significant Accounting Policies Summary of Significant Accounting Policies (Tables)	12 Months Ended
	Dec. 31, 2020
Accounting Policies [Abstract]
Schedule of Change in Asset Retirement Obligation	The following table includes the changes in the Company’s ARO liability during the years ended December 31, 2020 and 2019: Years ended 2020 2019 Beginning balance $ 4,555 $ 4,224 Accretion expense 342 311 Foreign exchange impact 46 20 Ending balance $ 4,943 $ 4,555

Performance Materials Divesti_2

Performance Materials Divestiture (Tables)	12 Months Ended
	Dec. 31, 2020
Discontinued Operations and Disposal Groups [Abstract]
Discontinued operations	The following is a reconciliation of the loss recorded on the sale: Net proceeds received from the sale of Performance Materials $ 624,256 Transaction costs (13,161) Net assets derecognized (681,973) Loss on sale of Performance Materials $ (70,878) The following table summarizes the results of discontinued operations for the periods presented: Years ended 2020 2019 2018 Sales $ 342,738 $ 373,686 $ 386,921 Cost of goods sold 251,917 281,566 308,679 Selling, general and administrative expenses 33,195 37,364 37,226 Other operating expense, net 18,289 14,462 13,023 Operating income 39,337 40,294 27,993 Equity in net income from affiliated companies (37) (12) (42) Interest expense, net (1) 16,210 24,453 22,965 Other (income) expense, net (3,481) 274 474 Loss on sale of Performance Materials 70,878 — — (Loss) Income from discontinued operations before income tax (44,233) 15,579 4,596 Provision (benefit) for income taxes 58,008 1,022 (4,646) (Loss) income from discontinued operations, net of tax $ (102,241) $ 14,557 $ 9,242 The following table summarizes the assets and liabilities of discontinued operations at December 31, 2019: December 31, ASSETS Cash and cash equivalents $ 18,423 Accounts receivables, net 40,484 Inventories, net 143,323 Prepaid and other current assets 4,139 Investments in affiliated companies 115 Property, plant and equipment, net 175,614 Goodwill 286,227 Other intangible assets, net 121,113 Right-of-use lease assets 8,878 Other long-term assets 71,697 Total assets held for sale $ 870,013 LIABILITIES Notes payable and current maturities of long-term debt $ 7,766 Accounts payable 30,267 Operating lease liabilities—current 3,326 Accrued liabilities 16,744 Long-term debt, excluding current portion 55,972 Deferred income taxes 8,612 Operating lease liabilities—noncurrent 5,248 Other long-term liabilities 17,366 Total liabilities held for sale $ 145,301

Revenue from Contracts with C_2

Revenue from Contracts with Customers Revenue from Contracts with Customers (Tables)	12 Months Ended
	Dec. 31, 2020
Revenue from Contract with Customer [Abstract]
Disaggregation of Revenue	The Company’s portfolio of products are integrated into a variety of end uses, which are described in the table below: Key End Uses Key Products Industrial & process chemicals • Silicate precursors for the tire industry • Silica gels for surface coatings Fuels & emission control • Refinery catalysts • Emission control catalysts • Catalyst recycling services Packaging & engineered plastics • Catalysts for high-density polyethlene and chemicals syntheses • Antiblocks for film packaging • Sulfur derivatives for nylon production • Silicate precursors for catalysts used in plastics manufacturing • Silicate for catalyst manufacturing Consumer products • Silica gels for edible oil and beer clarification • Precipitated silicas, silicates and zeolites for the dentifrice and dishwasher and Natural resources • Silicates for drilling muds • Silicates and alum for water treatment mining • Bleaching aids for paper The following table disaggregates the Company’s sales, by segment and end use, for the years ended December 31, 2020, 2019 and 2018: Year ended December 31, 2020 Refining Services Catalysts Performance Chemicals Total Industrial & process chemicals $ 70,648 $ 125 $ 279,296 $ 350,069 Fuels & emission control (1) 225,042 — — 225,042 Packaging & engineered plastics 38,772 93,882 47,451 180,105 Consumer products — — 235,792 235,792 Natural resources 67,451 — 52,165 119,616 Total segment sales 401,913 94,007 614,704 1,110,624 Inter-segment sales eliminations (3,256) (5) — (3,261) Total $ 398,657 $ 94,002 $ 614,704 $ 1,107,363 Year ended December 31, 2019 Refining Services Catalysts Performance Chemicals Total Industrial & process chemicals $ 80,661 $ 96 $ 299,651 $ 380,408 Fuels & emission control (1) 252,294 — — 252,294 Packaging & engineered plastics 48,056 85,571 51,725 185,352 Consumer products — — 260,495 260,495 Natural resources 66,070 — 58,692 124,762 Total segment sales 447,081 85,667 670,563 1,203,311 Inter-segment sales eliminations (3,397) — — (3,397) Total $ 443,684 $ 85,667 $ 670,563 $ 1,199,914 Year ended December 31, 2018 Refining Services Catalysts Performance Chemicals Total Industrial & process chemicals $ 77,866 $ 86 $ 315,827 $ 393,779 Fuels & emission control (1) 246,452 — — 246,452 Packaging & engineered plastics 59,168 72,013 53,623 184,804 Consumer products — — 272,187 272,187 Natural resources 72,076 — 62,865 134,941 Total segment sales 455,562 72,099 704,502 1,232,163 Inter-segment sales eliminations (3,237) — — (3,237) Total $ 452,325 $ 72,099 $ 704,502 $ 1,228,926 (1) As described in Note 1, the Company experiences seasonal sales fluctuations to customers in the fuels & emission control end use.

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	12 Months Ended
	Dec. 31, 2020
Fair Value Disclosures [Abstract]
Fair Value Measurements, Recurring	The following table presents information about the Company’s assets and liabilities that were measured at fair value on a recurring basis as of December 31, 2020 and 2019, and indicates the fair value hierarchy of the valuation techniques the Company utilized to determine such fair value. December 31, Quoted Prices in Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Assets: Derivative contracts (Note 19) $ 3,249 $ — $ 3,249 $ — Restoration plan assets 3,724 3,724 — — Total $ 6,973 $ 3,724 $ 3,249 $ — Liabilities: Derivative contracts (Note 19) $ 34,466 $ — $ 34,466 $ — December 31, Quoted Prices in Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Assets: Derivative contracts (Note 19) $ 3,928 $ — $ 3,928 $ — Restoration plan assets 4,199 4,199 — — Total $ 8,127 $ 4,199 $ 3,928 $ — Liabilities: Derivative contracts (Note 19) $ 11,376 $ — $ 11,376 $ —
Fair Value Measurements, Nonrecurring	The following table presents information about the Company’s assets and liabilities that were measured at fair value on a non-recurring basis as of December 31, 2020 (there were no such assets or liabilities measured during the year ended December 31, 2019). The Company performed its annual impairment test on its goodwill on October 1, 2020, and determined that an impairment existed with respect to the Performance Chemicals segment. As a result, the Company recorded a non cash goodwill impairment charge of $260,000. Refer to Note 15 to these consolidated financial statements for a description of the valuation techniques the Company utilized to determine such fair value and for the results of the impairment testing procedures performed. As of Quoted Prices in Significant Other Significant Total Assets: Goodwill (1) $ 717,738 $ — $ 717,738 $ — $ (260,000) (1) Goodwill with a carrying amount of $973,578 was written down to $717,738 as part of the Company’s annual impairment assessment on October 1, 2020. This resulted in an impairment charge of $260,000 on the consolidated statements of income.

Stockholders' Equity (Tables)

Stockholders' Equity (Tables)	12 Months Ended
	Dec. 31, 2020
Equity [Abstract]
Schedule of Accumulated Other Comprehensive Income (Loss)	The following table presents the components of accumulated other comprehensive income (loss), net of tax, as of December 31, 2020 and 2019: December 31, 2020 2019 Amortization and unrealized gains (losses) on pension and postretirement plans, net of tax of $(1,649) and $(994) $ 5,278 $ 3,568 Net changes in fair values of derivatives, net of tax of $549 and $604 (660) (1,838) Foreign currency translation adjustments, net of tax of $1,223 and $7,474 (19,883) (17,078) Accumulated other comprehensive loss $ (15,265) $ (15,348) The following table presents the tax effects of each component of other comprehensive income (loss) for the years ended December 31, 2020, 2019 and 2018: Years ended 2020 2019 2018 Pre-tax amount Tax benefit/ After-tax amount Pre-tax amount Tax benefit/ After-tax amount Pre-tax amount Tax benefit/ After-tax amount Defined benefit and other postretirement plans: Amortization of net gains and (losses) $ 2,824 $ (712) $ 2,112 $ 2,970 $ (423) $ 2,547 $ (10,279) $ 2,380 $ (7,899) Amortization of prior service cost (232) 58 (174) (156) 39 (117) (78) 19 (59) Benefit plans, net 2,592 (654) 1,938 2,814 (384) 2,430 (10,357) 2,399 (7,958) Net (loss) gain from hedging activities 221 (55) 166 (3,553) 888 (2,665) (441) 110 (331) Foreign currency translation (1) (11,268) (6,251) (17,519) 20,539 2,350 22,889 (39,419) 4,364 (35,055) Other comprehensive income (loss) $ (8,455) $ (6,960) $ (15,415) $ 19,800 $ 2,854 $ 22,654 $ (50,217) $ 6,873 $ (43,344) (1) The income tax benefit or expense included in other comprehensive income is attributed to the portion of foreign currency translation associated with the Company’s cross-currency interest rate swaps, for which the tax effect is based on the applicable U.S. deferred income tax rate. See Note 19 to these consolidated financial statements for information regarding the Company’s cross currency interest rate swaps. The following table presents the change in accumulated other comprehensive income (loss), net of tax, by component for the years ended December 31, 2020 and 2019: Defined benefit Net gain (loss) from hedging activities Foreign Total December 31, 2018 $ (546) $ 637 $ (39,195) $ (39,104) Other comprehensive income (loss) before reclassifications 2,497 (3,388) 22,117 21,226 Amounts reclassified from accumulated other comprehensive income (1) (67) 723 — 656 Net current period other comprehensive loss 2,430 (2,665) 22,117 21,882 Tax Cuts and Jobs Act, reclassification from AOCI to retained earnings 1,684 190 — 1,874 December 31, 2019 3,568 (1,838) (17,078) (15,348) Other comprehensive income (loss) before reclassifications 1,850 125 (16,596) (14,621) Amounts reclassified from accumulated other comprehensive income (1) 88 41 — 129 Disposal of business (228) 1,012 13,791 14,575 Net current period other comprehensive income (loss) 1,710 1,178 (2,805) 83 December 31, 2020 $ 5,278 $ (660) $ (19,883) $ (15,265)
Reclassification out of Accumulated Other Comprehensive Income	The following table presents the reclassifications out of accumulated other comprehensive income for the years ended December 31, 2020 and 2019. Details about Accumulated Other Amount Reclassified from Accumulated Other Comprehensive Income (1) Affected Line Item in the Years ended 2020 2019 Amortization of defined benefit and other postretirement plans: Prior service credit (cost) $ 119 $ 133 Other income (expense) (2) Actuarial gains (losses) (232) (21) Other income (expense) (2) (113) 112 Total before tax 25 (45) Tax benefit (expense) $ (88) $ 67 Net of tax Gains and losses on cash flow hedges: Interest rate caps $ (54) $ (625) Interest expense Natural gas swaps — (335) Cost of goods sold (54) (960) Total before tax 13 237 Tax benefit $ (41) $ (723) Net of tax Total reclassifications for the period $ (129) $ (656) Net of tax (1) Amounts in parentheses indicate debits to profit/loss. (2) These accumulated other comprehensive income (loss) components are components of net periodic pension and other postretirement cost (see Note 21 to these consolidated financial statements for additional details).

Other Operating Expense, Net (T

Other Operating Expense, Net (Tables)	12 Months Ended
	Dec. 31, 2020
Other Income and Expenses [Abstract]
Schedule of Other Operating Expense, net	A summary of other operating expense, net is as follows: Years ended 2020 2019 2018 Amortization expense $ 26,923 $ 26,888 $ 27,258 Transaction and other related costs (1) 8,274 407 491 Restructuring, integration and business optimization costs (2) 13,028 2,692 5,819 Net (gain) loss on asset disposals (3) (134) (13,207) 4,190 Insurance recoveries (4) — — (5,480) Write-off of long-term supply contract obligation (Note 25) — — (20,612) Environmental related costs 1,092 2,522 638 Other, net 1,803 2,076 4,123 $ 50,986 $ 21,378 $ 16,427 (1) Transaction and other related costs during the year ended December 31, 2020 primarily related to costs incurred from the strategic review of the Company’s Performance Chemicals business. Refer to Note 29 of these consolidated financial statements for additional details. (2) During the year ended December 31, 2020 , the Company’s results were impacted by costs associated with the execution of the Company’s strategic initiatives. The costs incurred during the year ended December 31, 2020 primarily relate to demolition and decommissioning costs related to various asset sales. The costs incurred during the years ended December 31, 2019 and 2018 relate to severance charges for certain executives and employees, transition/duplicate staffing, professional fees and other expenses related to the Company’s organization changes. (3) During the year ended December 31, 2020, the Company recognized a gain of $4,958 related to the sale of a product line and a gain of $672 related to the sale of its interest in the Quaker Holdings joint venture, which were offset by fixed asset write-offs. During the year ended December 31, 2019, the Company recognized a gain of $11,518 related to the sale of a product line and a gain of $7,150 related to a property sale, which were partially offset by fixed asset write-offs. Refer to Note 8 of these consolidated financial statements for additional details. (4) During the year ended December 31, 2018, the Company recognized $6,450 of insurance recoveries in its consolidated statement of income related to the Company’s claim for losses sustained during Hurricane Harvey in August 2017. For the year ended December 31, 2018, $5,480 was recorded as a gain in other operating expense, net, as reimbursement of expenses, $207 was recorded as a gain in net loss on asset disposals within other operating expense, net, for the Company’s previously recognized property losses, and $763 represented recoveries in excess of the Company’s property losses which was recorded as a non-operating gain in other expense, net, in the Company’s consolidated statement of income.

Inventories (Tables)

Inventories (Tables)	12 Months Ended
	Dec. 31, 2020
Inventory Disclosure [Abstract]
Schedule of Inventory, Current	Inventories, net are classified and valued as follows: December 31, 2020 2019 Finished products and work in process $ 102,388 $ 106,980 Raw materials 25,048 30,642 $ 127,436 $ 137,622 Valued at lower of cost or market: LIFO basis $ 55,283 $ 60,190 Valued at lower of cost and net realizable value: FIFO or average cost basis 72,153 77,432 $ 127,436 $ 137,622

Investments in Affiliated Com_2

Investments in Affiliated Companies (Tables)	12 Months Ended
	Dec. 31, 2020
Equity Method Investments and Joint Ventures [Abstract]
Equity Method Investments	Affiliated companies accounted for on the equity method as of December 31, 2020 are as follows: Company Country Percent PQ Silicates Ltd. Taiwan 50% Zeolyst International USA 50% Zeolyst C.V. Netherlands 50% Following is summarized information of the combined investments (1) : December 31, 2020 2019 Current assets $ 219,002 $ 248,685 Noncurrent assets 254,416 256,104 Current liabilities 66,423 52,638 Noncurrent liabilities 36,788 5,950 Years ended 2020 2019 2018 Sales $ 278,414 $ 380,381 $ 351,839 Gross profit 89,471 144,828 126,505 Operating income 54,010 106,195 88,294 Net income 55,722 107,112 88,411 (1) Summarized information of the combined investments is presented at 100%; the Company’s share of the net assets and net income of affiliates is calculated based on the percent ownership specified in the table above. The following table summarizes the activity related to the Company’s investments in affiliated companies balance on the consolidated balance sheets: Years ended 2020 2019 Balance at beginning of period $ 472,814 $ 468,055 Equity in net income of affiliated companies 27,871 53,556 Charges related to purchase accounting fair value adjustments (6,634) (7,534) Dividends received (40,989) (40,073) Foreign currency translation adjustments 5,390 (1,190) Balance at end of period $ 458,452 $ 472,814

Property, Plant and Equipment (

Property, Plant and Equipment (Tables)	12 Months Ended
	Dec. 31, 2020
Property, Plant and Equipment [Abstract]
Property, Plant and Equipment	A summary of property, plant and equipment, at cost, and related accumulated depreciation is as follows: December 31, 2020 2019 Land $ 158,517 $ 160,321 Buildings 168,204 160,653 Machinery and equipment 1,097,949 1,027,775 Construction in progress 78,641 76,242 1,503,311 1,424,991 Less: accumulated depreciation (520,076) (413,835) $ 983,235 $ 1,011,156

Leases (Tables)

Leases (Tables)	12 Months Ended
	Dec. 31, 2020
Leases [Abstract]
Schedule of Right-of-Use Lease Assets and Lease Liabilities	The table below presents the operating and finance right-of-use lease assets and lease liabilities recognized on the consolidated balance sheet as of December 31, 2020 and 2019: Classification December 31, December 31, Assets Operating lease assets Right-of-use lease assets $ 48,239 $ 48,417 Finance lease assets Property, plant and equipment, net 1,752 1,556 Total leased assets $ 49,991 $ 49,973 Liabilities Current: Operating lease liabilities Operating lease liabilities—current $ 15,194 $ 11,857 Finance lease liabilities Accrued liabilities 262 185 Noncurrent: Operating lease liabilities Operating lease liabilities—noncurrent 32,019 34,908 Finance lease liabilities Other long-term liabilities 366 315 Total lease liabilities $ 47,841 $ 47,265
Weighted Average Remaining Lease Term and Discount Rate	The Company’s weighted average remaining lease term and weighted average discount rate for operating and financing leases as of December 31, 2020 are as follows: December 31, December 31, Weighted average remaining lease term (in years): Operating leases 5.18 5.51 Finance leases 2.45 2.65 Weighted average discount rate: Operating leases 5.55 % 5.66 % Finance leases 4.67 % 4.67 %
Maturities of Lease Liabilities	Maturities of lease liabilities as of December 31, 2020 are as follows: Year Operating Finance 2021 $ 17,363 $ 406 2022 10,707 161 2023 8,655 40 2024 6,404 35 2025 3,917 8 Thereafter 7,785 — Total lease payments 54,831 650 Less: Interest (7,618) (22) Total lease liabilities $ 47,213 $ 628 (1) Refer to the above table regarding the Company’s right-of-use lease assets and lease liabilities for the presentation of the lease liabilities in the Company’s consolidated balance sheet at December 31, 2020.
Cash Flow Information Related to Leases	The following table presents other information related to the Company’s operating and finance leases and the impact on the Company’s consolidated statement of cash flows: Years ended 2020 2019 Cash paid for amounts included in the measurement of lease liabilities: Payments on operating leases included in operating cash flows $ 16,135 $ 14,814 Interest payments under finance lease obligations included in operating cash flows 21 26 Principal payments under finance lease obligations included in financing cash flows 209 177 Right-of-use assets obtained in exchange for new lease liabilities (non-cash): Operating leases 14,439 8,798 Finance leases 353 —

Reportable Segments (Tables)

Reportable Segments (Tables)	12 Months Ended
	Dec. 31, 2020
Segment Reporting [Abstract]
Reconciliation of Revenue from Reportable Segments to Consolidated	Summarized financial information for the Company’s reportable segments is shown in the following table: Years ended 2020 2019 2018 Sales: Refining Services $ 401,913 $ 447,081 $ 455,562 Catalysts (1) 94,007 85,667 72,099 Performance Chemicals 614,704 670,563 704,502 Eliminations (2) (3,261) (3,397) (3,237) Total $ 1,107,363 $ 1,199,914 $ 1,228,926 Segment Adjusted EBITDA: (3) Refining Services $ 157,198 $ 175,640 $ 176,499 Catalysts (4) 74,504 107,808 81,067 Performance Chemicals 142,372 151,547 168,196 Total Segment Adjusted EBITDA (5) $ 374,074 $ 434,995 $ 425,762 (1) Excludes the Company’s proportionate share of sales from the Zeolyst Joint Venture accounted for using the equity method. The proportionate share of sales is $128,623, $170,338 and $156,687 for the years ended December 31, 2020, 2019 and 2018, respectively. (2) The Company eliminates intersegment sales when reconciling to the Company’s consolidated statements of income. (3) The Company defines Adjusted EBITDA as EBITDA adjusted for certain items as noted in the reconciliation below. Management evaluates the performance of its segments and allocates resources based on several factors, of which the primary measure is Adjusted EBITDA. Adjusted EBITDA should not be considered as an alternative to net income as an indicator of the Company’s operating performance. Adjusted EBITDA as defined by the Company may not be comparable with EBITDA or Adjusted EBITDA as defined by other companies. (4) The Adjusted EBITDA from the Zeolyst Joint Venture included in the Catalysts segment is $42,515 for the year ended December 31, 2020, which includes $21,157 of equity in net income plus $6,634 of amortization of investment in affiliate step-up plus $14,724 of joint venture depreciation, amortization and interest. The Adjusted EBITDA from the Zeolyst Joint Venture included in the Catalysts segment is $68,138 for the year ended December 31, 2019, which includes $45,899 of equity in net income plus $7,534 of amortization of investment in affiliate step-up plus $14,705 of joint venture depreciation, amortization and interest. The Adjusted EBITDA from the Zeolyst Joint Venture included in the Catalysts segment is $56,663 for the year ended December 31, 2018, which includes $37,437 of equity in net income plus $6,634 of amortization of investment in affiliate step-up plus $12,592 of joint venture depreciation, amortization and interest. (5) Total Segment Adjusted EBITDA differs from the Company’s consolidated Adjusted EBITDA due to unallocated corporate expenses.
Reconciliation of Net Income to Segment Adjusted EBITDA	A reconciliation of net income attributable to PQ Group Holdings to Segment Adjusted EBITDA is as follows: Years ended 2020 2019 2018 Reconciliation of net (loss) income attributable to PQ Group Holdings Inc. to Segment Adjusted EBITDA Net (loss) income from continuing operations $ (176,265) $ 65,136 $ 49,271 (Benefit) provision for income taxes (48,122) 39,677 33,641 Interest expense, net 66,979 87,072 90,758 Depreciation and amortization 151,840 151,797 153,931 Segment EBITDA (5,568) 343,682 327,601 Joint venture depreciation, amortization and interest 14,724 14,705 12,592 Amortization of investment in affiliate step-up 6,634 7,534 6,634 Goodwill impairment charge 260,000 — — Debt extinguishment costs 25,028 3,400 7,751 Net (gain) loss on asset disposals (134) (13,207) 4,190 Foreign currency exchange (gain) loss (4,172) 2,410 12,543 LIFO (benefit) expense (5,229) 9,700 3,039 Transaction and other related costs 8,618 415 490 Equity-based compensation 21,527 16,212 18,419 Restructuring, integration and business optimization expenses 15,596 3,554 8,707 Defined benefit pension plan cost 12 2,960 411 Gain on contract termination (1) — — (20,612) Other 959 2,597 6,155 Adjusted EBITDA 337,995 393,962 387,920 Unallocated corporate expenses 36,079 41,033 37,842 Segment Adjusted EBITDA $ 374,074 $ 434,995 $ 425,762 (1) Includes the non-cash write-off of a long-term supply contract obligation (see Note 25), which was recorded as a reduction in other operating expense, net in the consolidated statement of income for the year ended December 31, 2018.
Capital Expenditures from Segment to Consolidated	Capital expenditures for the Company’s reportable segments are shown in the following table: Years ended 2020 2019 2018 Capital expenditures: Refining Services $ 31,799 $ 42,310 $ 46,617 Catalysts (1) 11,177 8,984 8,390 Performance Chemicals 40,864 53,910 56,759 Corporate (2) 13,295 5,898 29 Capital expenditures per the consolidated statements of cash flows $ 97,135 $ 111,102 $ 111,795 (1) Excludes the Company’s proportionate share of capital expenditures from the Zeolyst Joint Venture. (2) Includes corporate capital expenditures, the cash impact from changes in capital expenditures in accounts payable and capitalized interest.
Revenue from External Customers by Geographic Areas	Sales and long-lived assets by geographic area are presented in the following tables. Sales are attributed to countries based upon location of products shipped. Years ended 2020 2019 2018 Sales (1) : United States $ 655,015 $ 735,752 $ 740,190 Netherlands 108,338 117,211 127,803 United Kingdom 107,539 99,048 101,277 Other foreign countries 236,471 247,903 259,656 Total $ 1,107,363 $ 1,199,914 $ 1,228,926 (1) Except for the United States, no sales in an individual country exceeded 10% of the Company’s total sales.
Long-lived Assets by Geographic Areas	December 31, 2020 2019 Long-lived assets (1) : United States $ 749,635 $ 784,699 Netherlands 53,006 49,559 United Kingdom 100,392 92,229 Other foreign countries 128,441 133,086 Total $ 1,031,474 $ 1,059,573 (1) Long-lived assets includes property, plant and equipment, net and right-of-use lease assets.

Goodwill and Other Intangible_2

Goodwill and Other Intangible Assets Goodwill and Other Intangible Assets (Tables)	12 Months Ended
	Dec. 31, 2020
Goodwill and Intangible Assets Disclosure [Abstract]
Schedule of Goodwill	The changes in the carrying amount of goodwill for the years ended December 31, 2020 and 2019 is summarized as follows: Refining Services Catalysts Performance Total Balance as of December 31, 2018 $ 311,892 $ 77,759 $ 580,023 $ 969,674 Foreign exchange impact — 852 3,052 3,904 Balance as of December 31, 2019 311,892 78,611 583,075 973,578 Goodwill impairment — — (260,000) (260,000) Foreign exchange impact — 1,062 3,098 4,160 Balance as of December 31, 2020 $ 311,892 $ 79,673 $ 326,173 $ 717,738 The carrying amounts of goodwill at December 31, 2020, 2019 and 2018 are net of the following accumulated impairment losses: Refining Services Catalysts Performance Total Accumulated impairment losses as of December 31, 2018 — — — — Accumulated impairment losses as of December 31, 2019 — — — — Accumulated impairment losses as of December 31, 2020 — — (260,000) (260,000)
Schedule of Finite-Lived Intangible Assets	Gross carrying amounts and accumulated amortization for intangible assets other than goodwill are as follows: December 31, 2020 December 31, 2019 Gross Accumulated Net Gross Accumulated Net Technical know-how $ 180,768 $ (47,207) $ 133,561 $ 177,873 $ (37,102) $ 140,771 Customer relationships 325,773 (134,842) 190,931 321,434 (106,627) 214,807 Contracts — — — 16,200 (15,258) 942 Trademarks 7,709 (2,399) 5,310 7,600 (1,858) 5,742 Permits 9,100 (9,100) — 9,100 (9,100) — In-process research and development 500 (25) 475 — — — Total definite-lived intangible assets 523,850 (193,573) 330,277 532,207 (169,945) 362,262 Indefinite-lived trade names 108,713 — 108,713 106,811 — 106,811 Indefinite-lived trademarks 82,613 — 82,613 80,999 — 80,999 In-process research and development 4,700 — 4,700 5,200 — 5,200 Total intangible assets $ 719,876 $ (193,573) $ 526,303 $ 725,217 $ (169,945) $ 555,272
Schedule of Indefinite-Lived Intangible Assets	Gross carrying amounts and accumulated amortization for intangible assets other than goodwill are as follows: December 31, 2020 December 31, 2019 Gross Accumulated Net Gross Accumulated Net Technical know-how $ 180,768 $ (47,207) $ 133,561 $ 177,873 $ (37,102) $ 140,771 Customer relationships 325,773 (134,842) 190,931 321,434 (106,627) 214,807 Contracts — — — 16,200 (15,258) 942 Trademarks 7,709 (2,399) 5,310 7,600 (1,858) 5,742 Permits 9,100 (9,100) — 9,100 (9,100) — In-process research and development 500 (25) 475 — — — Total definite-lived intangible assets 523,850 (193,573) 330,277 532,207 (169,945) 362,262 Indefinite-lived trade names 108,713 — 108,713 106,811 — 106,811 Indefinite-lived trademarks 82,613 — 82,613 80,999 — 80,999 In-process research and development 4,700 — 4,700 5,200 — 5,200 Total intangible assets $ 719,876 $ (193,573) $ 526,303 $ 725,217 $ (169,945) $ 555,272
Schedule of Finite-Lived Intangible Assets, Future Amortization Expense	Estimated future aggregate amortization expense of intangible assets is as follows: Year Amount 2021 $ 36,292 2022 36,292 2023 36,292 2024 36,292 2025 36,292 Thereafter 148,817 Total estimated future aggregate amortization expense $ 330,277

Accrued Liabilities Accrued Lia

Accrued Liabilities Accrued Liabilities (Tables)	12 Months Ended
	Dec. 31, 2020
Payables and Accruals [Abstract]
Schedule of Accrued Liabilities	The following table summarizes the components of accrued liabilities as follows: December 31, 2020 2019 Compensation and bonus $ 35,251 $ 40,374 Interest 11,573 19,110 Property tax 2,656 2,250 Environmental reserves (Note 24) 4,309 4,548 Income taxes 869 4,900 Commissions and rebates 854 1,459 Pension, postretirement and supplemental retirement plans (Note 21) 1,852 1,825 Derivative liabilities 1,954 420 Other 14,493 10,524 $ 73,811 $ 85,410

Long-term Debt (Tables)

Long-term Debt (Tables)	12 Months Ended
	Dec. 31, 2020
Debt Disclosure [Abstract]
Schedule of Long-term Debt Instruments	The summary of long-term debt is as follows: December 31, 2020 2019 Senior Secured Term Loan Facility due February 2027 $ 671,710 $ 947,497 New Senior Secured Term Loan Facility due February 2027 459,653 — 6.75% Senior Secured Notes due 2022 — 625,000 5.75% Senior Unsecured Notes due 2025 295,000 295,000 ABL Facility — — Total debt 1,426,363 1,867,497 Original issue discount (15,641) (13,434) Deferred financing costs (10,353) (10,839) Total debt, net of original issue discount and deferred financing costs 1,400,369 1,843,224 Less: current portion — — Total long-term debt, excluding current portion $ 1,400,369 $ 1,843,224
Debt Instrument Redemption	The 6.75% Senior Secured Notes were redeemable, in whole or in part, at the redemption prices (expressed as percentages of principal amount of the 6.75% Senior Secured Notes to be redeemed) set forth below, plus accrued and unpaid interest, if any, to, but not including, the redemption date, if redeemed on or after any of the dates below until the subsequent date below: Year Percentage May 15, 2020 101.688% May 15, 2021 and thereafter 100.000% On or after December 15, 2020, the 5.75% Senior Unsecured Notes are redeemable, in whole or in part, at the redemption prices (expressed as percentages of principal amount of the 5.75% Senior Unsecured Notes to be redeemed) set forth below, plus accrued and unpaid interest, if any, to, but not including, the redemption date, if redeemed on or after any of the dates below until the subsequent date below: Year Percentage December 15, 2020 102.875% December 15, 2021 101.438% December 15, 2022 and thereafter 100.000%
Fiscal Year Maturity Schedule	The aggregate long-term debt maturities are: Year Amount 2021 $ — 2022 — 2023 — 2024 — 2025 295,000 Thereafter 1,131,363 $ 1,426,363

Other Long-term Liabilities Oth

Other Long-term Liabilities Other Long-term Liabilities (Tables)	12 Months Ended
	Dec. 31, 2020
Other Liabilities Disclosure [Abstract]
Schedule of Other Long-term Liabilities	The following table summarizes the components of other long-term liabilities as follows: December 31, 2020 2019 Pension benefits $ 40,812 $ 52,060 Other postretirement benefits 3,644 1,668 Supplemental retirement plans 11,376 10,632 Derivative liabilities 32,512 10,956 Deferred revenue 13,388 6,450 Reserve for uncertain tax positions 345 873 Asset retirement obligation 4,943 4,555 Other 3,995 4,110 $ 111,015 $ 91,304

Financial Instruments (Tables)

Financial Instruments (Tables)	12 Months Ended
	Dec. 31, 2020
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Fair Value of Derivatives Held	The fair values of derivative instruments held as of December 31, 2020 and 2019 are shown below: December 31, Balance sheet location 2020 2019 Derivative assets: Derivatives designed as net investment hedges: Cross currency swaps Prepaid and other current assets 3,249 3,928 Total derivative assets $ 3,249 $ 3,928 Derivative liabilities: Derivatives designated as cash flow hedges: Interest rate caps Accrued liabilities 1,954 420 Interest rate caps Other long-term liabilities 1,750 2,822 3,704 3,242 Derivatives designated as net investment hedges: Cross currency swaps Other long-term liabilities 30,762 8,134 Total derivative liabilities $ 34,466 $ 11,376
Effect of Derivative Instruments Designated as Hedges on Accumulated Other Comprehensive Income	The following table shows the effect of the Company’s derivative instruments designated as hedges on accumulated other comprehensive income (loss) (“AOCI”) and the statements of income for the years ended December 31, 2020, 2019 and 2018: Years ended December 31, 2020 2019 2018 Location of gain (loss) reclassified from AOCI into income Amount of gain (loss) recognized in OCI on derivatives Amount of gain (loss) reclassified from AOCI into income Amount of gain (loss) recognized in OCI on derivatives Amount of gain (loss) reclassified from AOCI into income Amount of gain (loss) recognized in OCI on derivatives Amount of gain (loss) reclassified from AOCI into income Interest rate caps Interest (expense) income $ (167) $ (54) $ (3,304) $ (625) $ (981) $ (256)
Schedule of Effect of Cash Flow Hedging Instruments on the Statements of Income	The following table shows the effect of the Company’s cash flow hedge accounting on the consolidated statements of income for the years ended December 31, 2020, 2019 and 2018: Location and amount of gain (loss) recognized in income on cash flow hedging relationships Years ended December 31, 2020 2019 2018 Cost of goods sold Interest (expense) income Cost of goods sold Interest (expense) income Cost of goods sold Interest (expense) income Total amounts of income and expense line items presented in the statement of income in which the effects of cash flow hedges are recorded $ (834,007) $ (66,979) $ (901,512) $ (87,072) $ (925,534) $ (90,758) The effects of cash flow hedging: Gain (loss) on cash flow hedging relationships: Interest contracts: Amount of gain (loss) reclassified from AOCI into income — (54) — (625) — (256)
Schedule of Net Investment Hedges in Accumulated Other Comprehensive Income	The following table shows the effect of the Company’s net investment hedges on AOCI and the consolidated statements of income for the years ended December 31, 2020, 2019 and 2018: Amount of gain (loss) recognized in OCI on derivative Location of gain (loss) reclassified from AOCI into income Amount of gain (loss) reclassified from AOCI into income Location of gain (loss) recognized in income on derivative (amount excluded from effectiveness testing) Amount of gain (loss) recognized in income on derivative (amount excluded from effectiveness testing) Years ended Years ended Years ended 2020 2019 2018 2020 2019 2018 2020 2019 2018 Cross currency swaps $ (23,622) $ 17,077 $ 18,843 Net (loss) income from discontinued operations, net of tax $ 1,967 $ — $ — Interest (expense) income $ 5,090 $ 7,320 $ 6,752

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2020
Income Tax Disclosure [Abstract]
Schedule of Income (Loss) before Income Tax, Domestic and Foreign	Income (loss) before income taxes and noncontrolling interest within or outside the United States are shown below: Years ended 2020 2019 2018 Domestic $ (175,143) $ 41,019 $ (1,559) Foreign (52,442) 64,411 85,579 Total $ (227,585) $ 105,430 $ 84,020
Schedule of Components of Income Tax Expense (Benefit)	The provision (benefit) for income taxes as shown in the accompanying consolidated statements of income consists of the following: Years ended 2020 2019 2018 Current: Federal $ — $ (3) $ — State 1,087 1,381 2,507 Foreign 15,484 22,810 27,062 16,571 24,188 29,569 Deferred: Federal (58,744) 11,824 10,875 State (2,910) 3,175 67 Foreign (3,039) 490 (6,870) (64,693) 15,489 4,072 Provision (benefit) for income taxes $ (48,122) $ 39,677 $ 33,641
Schedule of Effective Income Tax Rate Reconciliation	A reconciliation of income tax expense (benefit) at the U.S. federal statutory income tax rate to actual income tax expense is as follows: Years ended 2020 2019 2018 Tax at statutory rate $ (47,793) $ 22,140 $ 17,644 State income taxes, net of federal income tax benefit (2,324) 6,802 2,541 Tax on global intangible low-taxed income 7,820 8,741 14,465 Change in valuation allowances 135 1,415 5,070 Rate changes 4,274 1,054 (4,016) Foreign withholding taxes 258 (6,116) 142 Foreign tax rate differential 1,240 3,278 6,439 Non-taxable interest (5,353) — — Non-deductible goodwill 53,342 — — Foreign tax credits (56,359) — — Permanent difference created by foreign exchange gain or loss (1,324) 1,852 (4,839) Other, net (2,038) 511 (3,805) Provision (benefit) for income taxes $ (48,122) $ 39,677 $ 33,641
Schedule of Deferred Tax Assets and Liabilities	Deferred tax assets (liabilities) are comprised of the following: December 31, 2020 2019 Deferred tax assets: Net operating loss carryforwards $ 28,145 $ 77,062 Section 163(j) interest disallowance carryforward 266 16,535 Pension 12,701 14,359 Operating lease liability 11,803 14,455 Other 36,545 29,298 State credits 12,733 12,280 Foreign tax credit 62,752 — Valuation allowance (37,880) (39,379) $ 127,065 $ 124,610 Deferred tax liabilities: Depreciation $ (107,805) $ (103,796) Inventory (4,946) (11,481) Intangible assets (162,301) (184,764) Operating lease right-of-use assets (12,060) (14,278) Other (15,348) (22,619) $ (302,460) $ (336,938) Net deferred tax liabilities $ (175,395) $ (212,328)
Schedule of Unrecognized Tax Benefits Roll Forward	The following table summarizes the activity related to the Company’s gross unrecognized tax benefits: Years ended 2020 2019 Balance at beginning of period $ 8,310 $ 9,434 Increases related to prior year tax positions — 22 Decreases related to prior year tax positions (14) (1,046) Increases related to current year tax positions 164 — Decreases related to settlements with taxing authorities (626) (100) Balance at end of period $ 7,834 $ 8,310
Open Tax Years	The following describes the open tax years, by significant tax jurisdiction, as of December 31, 2020: Jurisdiction Period United States-Federal 2007-Present United States-State 2007-Present Canada (1) 2012-Present Netherlands 2014-Present Mexico 2016-Present United Kingdom 2014-Present Brazil 2016-Present (1) Includes federal as well as local jurisdictions
Schedule of Tax Payments	Cash payments for income taxes, net of refunds, are as follows: Years ended 2020 2019 2018 Domestic $ 2,198 $ 1,879 $ 2,154 Foreign 20,810 12,354 17,654 $ 23,008 $ 14,233 $ 19,808

Benefit Plans (Tables)

Benefit Plans (Tables)	12 Months Ended
	Dec. 31, 2020
Defined Benefit Pension Plans
Defined Benefit Plan Disclosure
Schedule of Benefit Plans Disclosures	The following tables summarize changes in the benefit obligation, plan assets and funded status of the Company’s significant defined benefit pension plans as well as the components of net periodic benefit cost, including key assumptions: U.S. Foreign December 31, December 31, 2020 2019 2020 2019 Change in benefit obligation: Benefit obligation at beginning of period $ 267,392 $ 246,311 $ 101,192 $ 84,435 Service cost 769 978 3,895 3,210 Interest cost 8,595 10,281 2,193 2,627 Participant contributions — — 574 550 Plan curtailments — (2,795) (1,603) — Plan settlements (1,455) (1,669) (105) (102) Benefits paid (12,713) (10,862) (1,759) (1,833) Expenses paid — — (353) (328) Actuarial (gains) losses 25,894 25,148 4,664 13,459 Translation adjustment — — 6,191 (826) Benefit obligation at end of the period $ 288,482 $ 267,392 $ 114,889 $ 101,192 Change in plan assets: Fair value of plan assets at beginning of period $ 231,413 $ 195,755 $ 85,308 $ 74,050 Actual return on plan assets 41,405 43,116 6,646 10,564 Employer contributions 5,187 5,073 3,348 3,084 Employee contributions — — 574 550 Plan settlements (1,455) (1,669) (105) (102) Benefits paid (12,713) (10,862) (1,759) (1,833) Expenses paid — — (353) (328) Translation adjustment — — 5,209 (677) Fair value of plan assets at end of the period $ 263,837 $ 231,413 $ 98,868 $ 85,308 Funded status of the plans (underfunded) $ (24,645) $ (35,979) $ (16,021) $ (15,884)
Schedule of Amounts Recognized in Balance Sheet	Amounts recognized in the consolidated balance sheets consist of: U.S. Foreign December 31, December 31, 2020 2019 2020 2019 Current liability — — (46) (6) Noncurrent liability (24,645) (35,979) (15,975) (15,878) Accumulated other comprehensive income (loss) (4,463) 8,687 1,075 (4,988) Net amount recognized $ (29,108) $ (27,292) $ (14,946) $ (20,872)
Schedule of Amounts Recognized in Other Comprehensive Income (Loss)	Amounts recognized in accumulated other comprehensive income (loss) consist of: U.S. Foreign December 31, December 31, 2020 2019 2020 2019 Net gain (loss) 13,964 10,922 (6,550) (7,634) Gross amount recognized 13,964 10,922 (6,550) (7,634) Deferred income taxes (18,427) (2,235) 7,625 2,646 Net amount recognized $ (4,463) $ 8,687 $ 1,075 $ (4,988)
Components of Net Periodic Expense	Components of net periodic benefit cost consist of: U.S. Foreign Years ended Years ended 2020 2019 2018 2020 2019 2018 Service cost $ 769 $ 978 $ 1,019 $ 3,895 $ 3,210 $ 3,104 Interest cost 8,595 10,281 9,599 2,193 2,627 2,637 Expected return on plan assets (12,547) (11,508) (12,851) (2,270) (2,427) (2,490) Amortization of prior service cost — — — — 24 — Amortization of net (gain) loss — — — 148 (29) 49 Curtailment gain recognized — — (576) — — — Settlement (gain) loss recognized 78 49 — (14) (1) — Net periodic expense (benefit) $ (3,105) $ (200) $ (2,809) $ 3,952 $ 3,404 $ 3,300
Schedule of Accumulated Benefit Obligations in Excess of Fair Value of Plan Assets	The following table presents selected information about the Company’s pension plans with accumulated benefit obligations in excess of plan assets: U.S. Foreign December 31, December 31, 2020 2019 2020 2019 Projected benefit obligation $ 288,482 $ 267,392 $ 92,679 82,662 Accumulated benefit obligation 288,482 266,992 88,394 80,021 Fair value of plan assets 263,837 231,413 76,658 68,104
Schedule of Projected Benefit Obligations in Excess of Fair Value of Plan Assets	The following table presents selected information about the Company’s pension plans with projected benefit obligations in excess of plan assets: U.S. Foreign December 31, December 31, 2020 2019 2020 2019 Projected benefit obligation $ 288,482 $ 267,392 $ 92,679 101,192 Fair value of plan assets 263,837 231,413 76,658 85,308
Schedule of Assumptions Used	Significant weighted average assumptions used in determining the pension obligations include the following: U.S. Foreign December 31, December 31, 2020 2019 2020 2019 Discount rate 2.42 % 3.32 % 1.78 % 2.34 % Rate of compensation increase (1) N/A 3.00 % 2.05 % 2.07 % Significant weighted average assumptions used in determining net periodic benefit cost include the following: U.S. Foreign Years ended Years ended 2020 2019 2018 2020 2019 2018 Discount rate 3.32 % 4.32 % 3.74 % 2.34 % 3.19 % 3.11 % Rate of compensation increase (1) 3.00 % 3.00 % 3.00 % 2.07 % 2.08 % 2.22 % Expected return on assets 5.55 % 6.00 % 6.00 % 2.82 % 3.30 % 3.37 % (1) Includes only plans not frozen to benefit accruals for the respective periods.
Schedule of Allocation of Plan Assets	The following tables set forth by level, within the fair value hierarchy, plan assets at fair value: December 31, 2020 Total Level 1 Level 2 Level 3 Cash and cash equivalents $ 787 $ 787 $ — $ — Equity securities: U.S. investment funds 79,777 79,777 — — International investment funds 64,986 53,792 11,194 — Fixed income securities: Government securities 39,541 33,505 6,036 — Corporate bonds 16,771 16,668 103 — Investment fund bonds 112,024 — 112,024 — Other: Insurance contracts 48,819 — 42,983 5,836 Total $ 362,705 $ 184,529 $ 172,340 $ 5,836 December 31, 2019 Total Level 1 Level 2 Level 3 Cash and cash equivalents $ 950 $ 950 $ — $ — Equity securities: U.S. investment funds 67,374 67,374 — — International investment funds 54,908 44,905 10,003 — Fixed income securities: Government securities 31,040 23,500 7,540 — Corporate bonds 14,900 14,782 118 — Investment fund bonds 106,198 1,170 105,028 — Other: Insurance contracts 41,351 — 36,637 4,714 Total $ 316,721 $ 152,681 $ 159,326 $ 4,714
Defined Benefit Plan Level 3 Assets	The changes in the Level 3 pension plan assets are as follows for the years ended December 31: Insurance Contracts 2020 2019 Beginning balance $ 4,714 $ 4,322 Actual return on plan assets 113 111 Benefits paid (78) (69) Contributions 577 441 Exchange rate changes and other 510 (91) Ending balance $ 5,836 $ 4,714
Schedule of Expected Benefit Payments	The following benefit payments, which reflect expected future service, as appropriate, are expected to be paid: Year U.S. Foreign 2021 $ 17,138 $ 2,204 2022 16,200 2,384 2023 16,278 2,610 2024 16,254 2,898 2025 15,968 3,144 Years 2026-2030 78,910 19,027
Supplemental Retirement Plans
Defined Benefit Plan Disclosure
Schedule of Benefit Plans Disclosures	The following tables summarize changes in the benefit obligation, plan assets and funded status of the Company’s defined benefit supplementary retirement plans, as well as the components of net periodic benefit cost, including key assumptions: December 31, 2020 2019 Change in benefit obligation: Benefit obligation at beginning of period $ 11,652 $ 11,868 Interest cost 352 465 Benefits paid (1,001) (1,045) Actuarial (gains) losses 1,412 364 Benefit obligation at end of period $ 12,415 $ 11,652 Change in plan assets: Fair value of plan assets at beginning of period $ — $ — Employer contributions 1,001 1,045 Benefits paid (1,001) (1,045) Fair value of plan assets at end of period $ — $ — Funded status of the plans (underfunded) $ (12,415) $ (11,652)
Schedule of Amounts Recognized in Balance Sheet	Amounts recognized in the consolidated balance sheets consist of: December 31, 2020 2019 Current liability $ (1,039) $ (1,019) Noncurrent liability (11,376) (10,633) Accumulated other comprehensive income 633 253 Net amount recognized $ (11,782) $ (11,399)
Schedule of Amounts Recognized in Other Comprehensive Income (Loss)	Amounts recognized in accumulated other comprehensive income consist of: December 31, 2020 2019 Net gain $ (731) $ 681 Gross amount recognized (731) 681 Deferred income taxes 1,364 (428) Net amount recognized $ 633 $ 253
Components of Net Periodic Expense	Components of net periodic benefit cost consist of: Years ended 2020 2019 2018 Interest cost $ 352 $ 465 $ 450 Amortization of net (gain) loss — (10) — Net periodic expense $ 352 $ 455 $ 450
Schedule of Expected Benefit Payments	The following benefit payments, which reflect expected future service, as appropriate, are expected to be paid: Year Amount 2021 $ 1,039 2022 1,010 2023 977 2024 944 2025 908 Years 2025-2029 3,944
Other Postretirement Benefits Plans
Defined Benefit Plan Disclosure
Schedule of Benefit Plans Disclosures	The following tables summarize changes in the benefit obligation, plan assets and funded status of the Company’s other postretirement benefit plans as well as the components of net periodic benefit cost, including key assumptions: December 31, 2020 2019 Change in benefit obligation: Benefit obligation at beginning of period $ 3,452 $ 3,814 Service cost — 10 Interest cost 99 152 Employee contributions 241 253 Plan amendments — (460) Benefits paid (658) (751) Premiums paid (7) (7) Actuarial (gains) losses 225 412 Translation adjustment 15 29 Benefit obligation at end of period $ 3,367 $ 3,452 Change in plan assets: Fair value of plan assets at beginning of period — — Employer contributions 424 505 Employee contributions 241 253 Benefits paid (658) (751) Premiums paid (7) (7) Fair value of plan assets at end of period $ — $ — Funded status of the plans (underfunded) $ (3,367) $ (3,452)
Schedule of Amounts Recognized in Balance Sheet	Amounts recognized in the consolidated balance sheets consist of: December 31, 2020 2019 Current liability $ (443) $ (537) Noncurrent liability (2,924) (2,915) Accumulated other comprehensive income 680 524 Net amount recognized $ (2,687) $ (2,928)
Schedule of Amounts Recognized in Other Comprehensive Income (Loss)	Amounts recognized in accumulated other comprehensive income consist of: December 31, 2020 2019 Prior service credit $ 596 $ 828 Net gain (182) 67 Gross amount recognized 414 895 Deferred income taxes 266 (371) Net amount recognized $ 680 $ 524
Components of Net Periodic Expense	Components of net periodic benefit cost consist of: Years ended 2020 2019 2018 Service cost $ — $ 10 $ 16 Interest cost 99 152 150 Amortization of prior service credit (232) (157) (112) Amortization of net gain (29) (33) (26) Net periodic expense (benefit) $ (162) $ (28) $ 28
Schedule of Assumptions Used	: December 31, 2020 2019 Immediate trend rate 5.67% 5.91% Ultimate trend rate 4.38% 4.39% Year that the rate reaches ultimate trend rate 2038 2038
Schedule of Expected Benefit Payments	The following benefit payments, which reflect expected future service, as appropriate, are expected to be paid: Year Amount 2021 $ 443 2022 372 2023 297 2024 281 2025 163 Years 2025-2029 816

Stock-Based Compensation Stock-

Stock-Based Compensation Stock-Based Compensation (Tables)	12 Months Ended
	Dec. 31, 2020
Stock-Based Compensation [Abstract]
Share-based Compensation Options Activity	The following table summarizes the activity of common stock options for the period from December 31, 2017 through the year ended December 31, 2020: Number of Options Weighted Average Exercise Price Weighted Average Remaining Contractual Term (in years) Aggregate Intrinsic Value Outstanding at December 31, 2017 2,715,170 $ 10.18 Granted 241,316 $ 17.50 Exercised (15,332) $ 8.51 Outstanding at December 31, 2018 2,941,154 $ 10.79 Exercised (492,498) $ 8.07 Forfeited (74,299) $ 8.16 Outstanding at December 31, 2019 2,374,357 $ 11.44 Exercised (43,250) $ 8.64 Forfeited (157,776) $ 9.23 Outstanding at December 31, 2020 2,173,331 $ 9.84 (1) 5.94 $ 10,452 Exercisable at December 31, 2020 1,796,519 $ 10.50 (1) 6.00 $ 7,611
Schedule of Share-based Payment Award, Stock Options, Valuation Assumptions	The fair values of PQ Group Holdings common stock options granted during the year ended December 31, 2018 were determined on the respective grant dates using a Black-Scholes option pricing model with the following weighted-average assumptions: 2018 Expected term (in years) 5.75 Expected volatility 26.38 % Risk-free interest rate 2.86 % Expected dividend yield 0.00 % Weighted average grant date fair value of options granted $ 5.47 Expected dividend yield — % Risk-free interest rate 1.56 % Expected volatility 28.57 % Expected term (in years) 2.95 Grant date fair value $ 24.11
Schedule of Nonvested Restricted Stock Awards, Restricted Stock Units and Performance Stock Unit Activity	The following table summarizes the activity of restricted stock awards, restricted stock units and performance stock units for the period from December 31, 2017 through the year ended December 31, 2020: Restricted Stock Awards Restricted Stock Units Performance Stock Units Number of Weighted Average Grant Date Fair Value (per share) Number of Weighted Average Grant Date Fair Value (per share) Number of Weighted Average Grant Date Fair Value (per share) Nonvested as of December 31, 2017 2,096,637 $ 8.87 1,654,690 $ 16.97 — $ — Granted 14,498 $ 13.80 161,598 $ 16.12 — $ — Vested (223,298) $ 12.18 (797,859) $ 16.97 — $ — Forfeited (117,177) $ 8.04 (19,643) $ 16.97 — $ — Nonvested as of December 31, 2018 1,770,660 $ 8.39 998,786 $ 16.83 — $ — Granted — $ — 1,245,628 $ 15.42 550,676 $ 15.41 Vested (97,140) $ 12.32 (541,383) $ 16.68 — $ — Forfeited (127,390) $ 8.04 (74,595) $ 16.09 — $ — Nonvested as of December 31, 2019 1,546,130 $ 8.17 1,628,436 $ 15.83 550,676 $ 15.41 Granted — $ — 1,158,605 $ 16.60 456,311 $ 20.29 Vested (29,760) $ 12.32 (816,866) $ 16.17 — $ — Forfeited (619,355) $ 8.04 (129,036) $ 16.28 (41,251) $ 15.95 Nonvested as of December 31, 2020 897,015 $ 13.80 (1) 1,841,139 $ 16.14 965,736 $ 17.69

Earnings per Share (Tables)

Earnings per Share (Tables)	12 Months Ended
	Dec. 31, 2020
Earnings Per Share [Abstract]
Schedule of from Basic to Diluted Weighted Average Number of Shares Outstanding	The reconciliation from basic to diluted weighted average shares outstanding is as follows: Years ended 2020 2019 2018 Weighted average shares outstanding – Basic 135,528,977 134,389,667 133,380,567 Dilutive effect of unvested common shares and restricted stock units with service conditions, performance stock units considered probable of vesting and assumed stock option exercises and conversions — 1,159,027 1,304,364 Weighted average shares outstanding – Diluted 135,528,977 135,548,694 134,684,931
Schedule of Earnings Per Share, Basic and Diluted	Basic and diluted earnings per share are calculated as follows: Years ended 2020 2019 2018 Numerator: Net (loss) income attributable to PQ Group Holdings Inc. $ (278,771) $ 79,539 $ 58,300 Denominator: Weighted average shares outstanding – Basic 135,528,977 134,389,667 133,380,567 Weighted average shares outstanding – Diluted 135,528,977 135,548,694 134,684,931 Net (loss) income per share: Basic (loss) income per share $ (2.06) $ 0.59 $ 0.44 Diluted (loss) income per share $ (2.06) $ 0.59 $ 0.43
Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share	The table below presents the details of the Company’s weighted average equity-based awards outstanding during each respective year that were excluded from the calculation of diluted earnings per share: Years ended 2020 2019 2018 Restricted stock awards with performance only targets not yet achieved 1,225,855 1,584,980 1,643,760 Stock options with performance only targets not yet achieved 507,461 558,283 586,253 Anti-dilutive restricted stock awards, restricted stock units and performance stock units 1,453,120 — 5,162 Anti-dilutive stock options 846,049 863,063 717,612

Commitments and Contingent Li_2

Commitments and Contingent Liabilities (Tables)	12 Months Ended
	Dec. 31, 2020
Commitments and Contingencies Disclosure [Abstract]
Expected Purchases Under Purchase Agreements	Purchases under these agreements are expected to be as follows: Year Amount 2021 $ 13,695 2022 3,263 2023 1,654 2024 1,186 2025 1,183 Thereafter 995 $ 21,976

Quarterly Financial Summary (_2

Quarterly Financial Summary (Unaudited) (Tables)	12 Months Ended
	Dec. 31, 2020
Quarterly Financial Information Disclosure [Abstract]
Quarterly Financial Information	The following tables summarize the Company’s quarterly financial results during the years ended December 31, 2020 and 2019: 2020 First Second Third Fourth Sales $ 295,813 $ 254,896 $ 275,149 $ 281,505 Gross profit 72,295 63,662 70,172 67,227 Operating income 29,214 20,175 33,310 (245,623) Net income (loss) from continuing operations 6,299 7,896 (6,956) (186,702) Net income (loss) from discontinued operations, net of tax (5,790) 8,351 11,392 (116,194) Net (loss) income 509 16,247 4,436 (302,896) Less: Net (loss) income attributable to the noncontrolling interest - continuing operations 234 250 201 (3,883) Less: Net income (loss) attributable to the noncontrolling interest - discontinued operations 51 71 97 46 Net income (loss) attributable to PQ Group Holdings Inc. 224 15,926 4,138 (299,059) Earnings (loss) per common share - basic Continuing operations $ 0.04 $ 0.06 $ (0.05) $ (1.35) Discontinued operations $ (0.04) $ 0.06 $ 0.08 $ (0.86) Net earnings (loss) per share - basic $ — $ 0.12 $ 0.03 $ (2.21) Earnings (loss) per common share - diluted: Continuing operations $ 0.04 $ 0.06 $ (0.05) $ (1.35) Discontinued operations $ (0.04) $ 0.06 $ 0.08 $ (0.86) Net earnings (loss) per share - diluted $ — $ 0.12 $ 0.03 $ (2.21) Weighted average shares outstanding: Basic 135,240,897 135,083,126 135,106,969 135,406,081 Diluted 136,086,082 135,671,830 135,979,118 135,406,081 2019 First Second Third Fourth Sales $ 297,468 $ 311,641 $ 307,271 $ 283,535 Gross profit 67,728 81,863 82,913 65,898 Operating income 28,995 48,840 41,191 28,482 Net income from continuing operations 6,055 19,404 11,888 28,406 Net income (loss) from discontinued operations, net of tax (2,614) 11,315 6,863 (1,007) Net income 3,441 30,719 18,751 27,399 Less: Net income attributable to the noncontrolling interest - continuing operations 231 101 82 203 Less: Net income attributable to the noncontrolling interest - discontinued operations 59 44 24 27 Net income attributable to PQ Group Holdings Inc. 3,151 30,574 18,645 27,169 Earnings (loss) per common share - basic: Continuing operations $ 0.04 $ 0.14 $ 0.09 $ 0.21 Discontinued operations $ (0.02) $ 0.08 $ 0.05 $ (0.01) Net earnings per share - basic $ 0.02 $ 0.23 $ 0.14 $ 0.20 Earnings (loss) per common share - diluted: Continuing operations $ 0.04 $ 0.14 $ 0.09 $ 0.21 Discontinued operations $ (0.02) $ 0.08 $ 0.05 $ (0.01) Net earnings per share - diluted $ 0.02 $ 0.23 $ 0.14 $ 0.20 Weighted average shares outstanding: Basic 133,946,308 134,142,552 134,511,819 134,912,212 Diluted 134,894,354 135,323,024 135,649,710 136,151,739

Supplemental Cash Flow Inform_2

Supplemental Cash Flow Information (Tables)	12 Months Ended
	Dec. 31, 2020
Supplemental Cash Flow Elements [Abstract]
Schedule of Cash Flow, Supplemental Disclosures	The following table presents supplemental cash flow information for the Company: Years ended 2020 2019 2018 Cash paid during the year for: Income taxes, net of refunds $ 35,013 $ 17,406 $ 23,842 Interest (1) 90,291 117,775 110,834 Non-cash investing activity (2) : Capital expenditures acquired on account but unpaid as of the year end 11,630 22,562 23,498 (1) Cash paid for interest is shown net of capitalized interest for the periods presented and excludes $4,963 and $8,480 of net interest proceeds on swaps designated as net investment hedges for the years ended December 31, 2020 and 2019, respectively, which are included within cash flows from investing activities in the Company’s consolidated statements of cash flows. (2) For the supplemental non-cash information on lease liabilities arising from obtaining right-of-use lease assets, see Note 13 to these consolidated financial statements for additional details.
Schedule of Cash and Cash Equivalents	The following table provides a reconciliation of cash, cash equivalents and restricted cash reported within the consolidated balance sheets as of December 31, 2020, 2019 and 2018 to the total of the same amounts shown in the consolidated statements of cash flows for the years then ended: December 31, 2020 2019 2018 Cash and cash equivalents $ 135,531 $ 53,861 $ 37,164 Restricted cash included in prepaid and other current assets 1,688 1,331 1,435 Total cash, cash equivalents and restricted cash shown in the consolidated statements of cash flows $ 137,219 $ 55,192 $ 38,599
Restrictions on Cash and Cash Equivalents	The following table provides a reconciliation of cash, cash equivalents and restricted cash reported within the consolidated balance sheets as of December 31, 2020, 2019 and 2018 to the total of the same amounts shown in the consolidated statements of cash flows for the years then ended: December 31, 2020 2019 2018 Cash and cash equivalents $ 135,531 $ 53,861 $ 37,164 Restricted cash included in prepaid and other current assets 1,688 1,331 1,435 Total cash, cash equivalents and restricted cash shown in the consolidated statements of cash flows $ 137,219 $ 55,192 $ 38,599

Schedule I - Condensed Financ_2

Schedule I - Condensed Financial Information of Parent (Tables)	12 Months Ended
	Dec. 31, 2020
Condensed Financial Information Disclosure [Abstract]
Schedule of Condensed Statements of Income	Years ended 2020 2019 2018 Stock compensation expense $ 25,200 $ 16,212 $ 18,419 Equity in net loss (income) from subsidiaries 253,571 (95,751) (76,719) Net (loss) income (278,771) 79,539 58,300 Other comprehensive income (loss), net of tax: Pension and postretirement benefits 1,938 2,430 (7,958) Net (loss) gain from hedging activities 166 (2,665) (330) Foreign currency translation (16,596) 22,117 (35,127) Total other comprehensive income (loss) (14,492) 21,882 (43,415) Comprehensive (loss) income $ (293,263) $ 101,421 $ 14,885
Schedule of Condensed Balance Sheets	December 31, December 31, ASSETS Investment in subsidiaries $ 1,277,126 $ 1,779,450 Total assets $ 1,277,126 $ 1,779,450 LIABILITIES Total liabilities $ — $ — STOCKHOLDERS' EQUITY Common stock (0.01 par); authorized shares 450,000,000; issued shares 137,102,143 and 136,861,382 on December 31, 2020 and 2019, respectively; outstanding shares 136,318,557 and 136,464,961 on December 31, 2020 and 2019, respectively 1,371 1,369 Preferred stock (0.01 par); authorized shares 50,000,000; no shares issued or outstanding on December 31, 2020 and 2019, respectively — — Additional paid-in capital 1,477,859 1,696,899 (Accumulated deficit) retained earnings (175,758) 103,013 Treasury stock, at cost; shares 783,586 and 396,421 on December 31, 2020 and 2019, respectively (11,081) (6,483) Accumulated other comprehensive loss (15,265) (15,348) Total PQ Group Holdings Inc. equity 1,277,126 1,779,450 Total liabilities and equity $ 1,277,126 $ 1,779,450
Schedule of Condensed Statements of Cash Flow	Years ended 2020 2019 2018 Cash flows from operating activities: Net (loss) income $ (278,771) $ 79,539 $ 58,300 Adjustments to reconcile net (loss) income to net cash provided by operating activities: Equity in net income from subsidiaries 253,571 (95,751) (76,719) Stock compensation expense 25,200 16,212 18,419 Net cash provided by operating activities — — — Cash flows from investing activities: Distribution from subsidiaries 243,779 — — Net cash provided by investing activities 243,779 — — Cash flows from financing activities: Dividends paid to stockholders (243,779) — — Net cash used in financing activities (243,779) — — Effect of exchange rate changes on cash, cash equivalents and restricted cash — — — Net change in cash, cash equivalents and restricted cash — — — Cash, cash equivalents and restricted cash at beginning of period — — — Cash, cash equivalents and restricted cash at end of period of continuing operations $ — $ — $ —

Background and Basis of Prese_2

Background and Basis of Presentation (Details) - 12 months ended Dec. 31, 2020	segment	Total
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Reportable segments	3	3
Number of operating segments	3	3

Summary of Significant Accoun_4

Summary of Significant Accounting Policies - Narratives (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Summary of Significant Accounting Policies Table
Foreign currency exchange (gain) loss	$ (4,172)	$ 2,410	$ 12,543
Restricted cash included in prepaid and other current assets	1,688	1,331
Allowance for credit loss	1,521	2,068
Interest costs capitalized	1,780	1,981	3,576
Research and development cost	$ 11,597	12,514	$ 13,719
Tax Cuts and Jobs Act, Incomplete Accounting, Change in Tax Rate, Provisional Income Tax Expense (Benefit)		$ 2,102
Maximum
Summary of Significant Accounting Policies Table
Remaining lease term	30 years
Building and building improvements | Minimum
Summary of Significant Accounting Policies Table
Fixed asset useful life	15 years
Building and building improvements | Maximum
Summary of Significant Accounting Policies Table
Fixed asset useful life	33 years
Machinery and equipment | Minimum
Summary of Significant Accounting Policies Table
Fixed asset useful life	3 years
Machinery and equipment | Maximum
Summary of Significant Accounting Policies Table
Fixed asset useful life	10 years

Summary of Significant Accoun_5

Summary of Significant Accounting Policies - Asset Retirement Obligation (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Asset Retirement Obligation
Beginning balance	$ 4,555	$ 4,224
Accretion expense	342	311
Foreign exchange impact	46	20
Ending balance	$ 4,943	$ 4,555

Performance Materials Divesti_3

Performance Materials Divestiture - Reconciliation of Loss (Details) - USD ($) $ / shares in Units, $ in Thousands	Dec. 14, 2020	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Dispositions [Line Items]
Net proceeds received from the sale of Performance Materials		$ 624,256	$ 0	$ 0
Transaction costs		(13,161)
Net assets derecognized		(681,973)
Loss on sale of Performance Materials		$ (70,878)
Dividends paid on common stock (in dollars per share)	$ 1.80	$ 1.80
Discontinued Operations
Dispositions [Line Items]
Purchase price		$ 650,000
Net proceeds received from the sale of Performance Materials		624,256
Loss on sale of Performance Materials		$ 70,878	$ 0	$ 0
Dividends paid on common stock (in dollars per share)		$ 1.80

Performance Materials Divesti_4

Performance Materials Divestiture - Income Information (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Income Statement [Abstract]
Equity in net income from affiliated companies									$ 21,237	$ 46,022	$ 37,569
Loss on sale of Performance Materials									(70,878)
Net (loss) income from discontinued operations, net of tax	$ (116,194)	$ 11,392	$ 8,351	$ (5,790)	$ (1,007)	$ 6,863	$ 11,315	$ (2,614)	(102,241)	14,557	9,242
Mandatory payments									275,787
Less: Net income (loss) attributable to the noncontrolling interest - discontinued operations	$ 46	$ 97	$ 71	$ 51	$ 27	$ 24	$ 44	$ 59	265	154	213
Term Loan Facility
Income Statement [Abstract]
Mandatory payments									188,722
Discontinued Operations
Income Statement [Abstract]
Sales									342,738	373,686	386,921
Cost of goods sold									251,917	281,566	308,679
Selling, general and administrative expenses									33,195	37,364	37,226
Other operating expense, net									18,289	14,462	13,023
Operating income									39,337	40,294	27,993
Equity in net income from affiliated companies									(37)	(12)	(42)
Interest expense, net									16,210	24,453	22,965
Other (income) expense, net									(3,481)
Other (income) expense, net										274	474
Loss on sale of Performance Materials									70,878	0	0
(Loss) Income from discontinued operations before income tax									(44,233)	15,579	4,596
Provision (benefit) for income taxes									58,008	1,022	(4,646)
Net (loss) income from discontinued operations, net of tax									$ (102,241)	$ 14,557	$ 9,242

Performance Materials Divesti_5

Performance Materials Divestiture - Assets and Liabilities (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2020reporting_unit	Dec. 31, 2019USD ($)
LIABILITIES
Transition Services Agreement, Term	9 months
Transition Services Agreement, Number Of Extensions Available | reporting_unit	3
Transition Services Agreement, Extension Term	30 days
Discontinued Operations
ASSETS
Cash and cash equivalents		$ 18,423
Accounts receivables, net		40,484
Inventories, net		143,323
Prepaid and other current assets		4,139
Investments in affiliated companies		115
Property, plant and equipment, net		175,614
Goodwill		286,227
Other intangible assets, net		121,113
Right-of-use lease assets		8,878
Other long-term assets		71,697
Total assets held for sale		870,013
LIABILITIES
Notes payable and current maturities of long-term debt		7,766
Accounts payable		30,267
Operating lease liabilities—current		3,326
Accrued liabilities		16,744
Long-term debt, excluding current portion		55,972
Deferred income taxes		8,612
Operating lease liabilities—noncurrent		5,248
Other long-term liabilities		17,366
Total liabilities held for sale		$ 145,301

Revenue from Contracts with C_3

Revenue from Contracts with Customers Contract Assets and Liabilities (Details) € in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2020USD ($)	Dec. 31, 2020EUR (€)	Dec. 31, 2019USD ($)	Dec. 31, 2020EUR (€)
Disaggregation of Revenue [Line Items]
Contract asset	$ 0		$ 0
Magnesium silicate product line
Disaggregation of Revenue [Line Items]
Contract liabilities	11,486			€ 10,216
Deferred revenue	11,318			€ 9,202
Revenue recognized	1,197	€ 1,014
Sulfate salts product line
Disaggregation of Revenue [Line Items]
Contract liabilities			9,000
Deferred revenue	2,070		6,450
Revenue recognized	$ (4,374)		$ 2,550

Revenue from Contracts with C_4

Revenue from Contracts with Customers Disaggregated Revenue (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Disaggregation of Revenue [Line Items]
Sales	$ 281,505	$ 275,149	$ 254,896	$ 295,813	$ 283,535	$ 307,271	$ 311,641	$ 297,468	$ 1,107,363	$ 1,199,914	$ 1,228,926
Refining Services
Disaggregation of Revenue [Line Items]
Sales									398,657	443,684	452,325
Catalysts
Disaggregation of Revenue [Line Items]
Sales									94,002	85,667	72,099
Performance Chemicals
Disaggregation of Revenue [Line Items]
Sales									614,704	670,563	704,502
Operating segments
Disaggregation of Revenue [Line Items]
Sales									1,110,624	1,203,311	1,232,163
Operating segments | Industrial & chemical process
Disaggregation of Revenue [Line Items]
Sales									350,069	380,408	393,779
Operating segments | Fuels & emission control
Disaggregation of Revenue [Line Items]
Sales									225,042	252,294	246,452
Operating segments | Packaging & engineered plastics
Disaggregation of Revenue [Line Items]
Sales									180,105	185,352	184,804
Operating segments | Consumer products
Disaggregation of Revenue [Line Items]
Sales									235,792	260,495	272,187
Operating segments | Natural resources
Disaggregation of Revenue [Line Items]
Sales									119,616	124,762	134,941
Operating segments | Refining Services
Disaggregation of Revenue [Line Items]
Sales									401,913	447,081	455,562
Operating segments | Refining Services | Industrial & chemical process
Disaggregation of Revenue [Line Items]
Sales									70,648	80,661	77,866
Operating segments | Refining Services | Fuels & emission control
Disaggregation of Revenue [Line Items]
Sales									225,042	252,294	246,452
Operating segments | Refining Services | Packaging & engineered plastics
Disaggregation of Revenue [Line Items]
Sales									38,772	48,056	59,168
Operating segments | Refining Services | Consumer products
Disaggregation of Revenue [Line Items]
Sales									0	0	0
Operating segments | Refining Services | Natural resources
Disaggregation of Revenue [Line Items]
Sales									67,451	66,070	72,076
Operating segments | Catalysts
Disaggregation of Revenue [Line Items]
Sales									94,007	85,667	72,099
Operating segments | Catalysts | Industrial & chemical process
Disaggregation of Revenue [Line Items]
Sales									125	96	86
Operating segments | Catalysts | Fuels & emission control
Disaggregation of Revenue [Line Items]
Sales									0	0	0
Operating segments | Catalysts | Packaging & engineered plastics
Disaggregation of Revenue [Line Items]
Sales									93,882	85,571	72,013
Operating segments | Catalysts | Consumer products
Disaggregation of Revenue [Line Items]
Sales									0	0	0
Operating segments | Catalysts | Natural resources
Disaggregation of Revenue [Line Items]
Sales									0	0	0
Operating segments | Performance Chemicals
Disaggregation of Revenue [Line Items]
Sales									614,704	670,563	704,502
Operating segments | Performance Chemicals | Industrial & chemical process
Disaggregation of Revenue [Line Items]
Sales									279,296	299,651	315,827
Operating segments | Performance Chemicals | Fuels & emission control
Disaggregation of Revenue [Line Items]
Sales									0	0	0
Operating segments | Performance Chemicals | Packaging & engineered plastics
Disaggregation of Revenue [Line Items]
Sales									47,451	51,725	53,623
Operating segments | Performance Chemicals | Consumer products
Disaggregation of Revenue [Line Items]
Sales									235,792	260,495	272,187
Operating segments | Performance Chemicals | Natural resources
Disaggregation of Revenue [Line Items]
Sales									52,165	58,692	62,865
Eliminations
Disaggregation of Revenue [Line Items]
Sales									(3,261)	(3,397)	(3,237)
Eliminations | Refining Services
Disaggregation of Revenue [Line Items]
Sales									(3,256)	(3,397)	(3,237)
Eliminations | Catalysts
Disaggregation of Revenue [Line Items]
Sales									(5)	0	0
Eliminations | Performance Chemicals
Disaggregation of Revenue [Line Items]
Sales									$ 0	$ 0	$ 0

Fair Value Measurements - Asset

Fair Value Measurements - Assets and Liabilities Measured at Fair Value on a Recurring Basis (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Liabilities:
Derivative contracts	$ 32,512	$ 10,956
Goodwill impairment charge	260,000	0	$ 0
Recurring
Assets:
Derivative contracts	3,249	3,928
Restoration plan assets	3,724	4,199
Total	6,973	8,127
Liabilities:
Derivative contracts	34,466	11,376
Recurring | Quoted Prices in Active Markets (Level 1)
Assets:
Derivative contracts	0	0
Restoration plan assets	3,724	4,199
Total	3,724	4,199
Liabilities:
Derivative contracts	0	0
Recurring | Significant Other Observable Inputs (Level 2)
Assets:
Derivative contracts	3,249	3,928
Restoration plan assets	0	0
Total	3,249	3,928
Liabilities:
Derivative contracts	34,466	11,376
Recurring | Significant Unobservable Inputs (Level 3)
Assets:
Derivative contracts	0	0
Restoration plan assets	0	0
Total	0	0
Liabilities:
Derivative contracts	$ 0	$ 0

Fair Value Measurements - Ass_2

Fair Value Measurements - Assets Measured at Fair Value on a Non-recurring Basis (Details) - USD ($) $ in Thousands	Oct. 01, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Oct. 01, 2020
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Goodwill impairment charge		$ 260,000	$ 0	$ 0
Unrealized Gain (Loss) on Securities		545	$ 944	$ 346
Nonrecurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Goodwill, Gross					$ 973,578
Goodwill implied fair value					$ 717,738
Goodwill impairment charge	$ 260,000
Estimate of Fair Value Measurement | Nonrecurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Goodwill implied fair value		717,738
Estimate of Fair Value Measurement | Nonrecurring | Quoted Prices in Active Markets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Goodwill implied fair value		0
Estimate of Fair Value Measurement | Nonrecurring | Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Goodwill implied fair value		717,738
Estimate of Fair Value Measurement | Nonrecurring | Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Goodwill implied fair value		0
Change Measurement During Period | Nonrecurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Goodwill implied fair value		$ (260,000)

Stockholders' Equity - Componen

Stockholders' Equity - Components of AOCI (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Accumulated Other Comprehensive Income (Loss), Net of Tax
Stockholders equity	$ 1,277,179	$ 1,785,318	$ 1,664,145	$ 1,631,919
Accumulated other comprehensive income (loss)
Accumulated Other Comprehensive Income (Loss), Net of Tax
Stockholders equity	(15,265)	(15,348)	$ (39,104)	$ 4,311
Defined benefit and other postretirement plans
Accumulated Other Comprehensive Income (Loss), Net of Tax
Stockholders equity	5,278	3,568
Tax
Tax related to AOCI	(1,649)	(994)
Net gain (loss) from hedging activities
Accumulated Other Comprehensive Income (Loss), Net of Tax
Stockholders equity	(660)	(1,838)
Tax
Tax related to AOCI	549	604
Foreign currency translation
Accumulated Other Comprehensive Income (Loss), Net of Tax
Stockholders equity	(19,883)	(17,078)
Tax
Tax related to AOCI	$ 1,223	$ 7,474

Stockholders' Equity - Pre-tax

Stockholders' Equity - Pre-tax and After-tax Components of Other Comprehensive Income (Loss) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
After-tax amount
Pre-tax amount	$ (8,455)	$ 19,800	$ (50,217)
Tax benefit / (expense)	(6,960)	2,854	6,873
Total other comprehensive income (loss)	(15,415)	22,654	(43,344)
Amortization of net gains and (losses)
After-tax amount
Pre-tax amount	2,824	2,970	(10,279)
Tax benefit / (expense)	(712)	(423)	2,380
Total other comprehensive income (loss)	2,112	2,547	(7,899)
Amortization of prior service cost
After-tax amount
Pre-tax amount	(232)	(156)	(78)
Tax benefit / (expense)	58	39	19
Total other comprehensive income (loss)	(174)	(117)	(59)
Benefit plans, net
After-tax amount
Pre-tax amount	2,592	2,814	(10,357)
Tax benefit / (expense)	(654)	(384)	2,399
Total other comprehensive income (loss)	1,938	2,430	(7,958)
Net loss (gain) from hedging activities
After-tax amount
Pre-tax amount	221	(3,553)	(441)
Tax benefit / (expense)	(55)	888	110
Total other comprehensive income (loss)	166	(2,665)	(331)
Foreign currency translation
After-tax amount
Pre-tax amount	(11,268)	20,539	(39,419)
Tax benefit / (expense)	(6,251)	2,350	4,364
Total other comprehensive income (loss)	$ (17,519)	$ 22,889	$ (35,055)

Stockholders' Equity - Change b

Stockholders' Equity - Change by Component (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax
Beginning balance	$ 1,779,450
Ending balance	1,277,126	$ 1,779,450
Discontinued Operations
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	(14,575)
Total
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax
Beginning balance	(15,348)	(39,104)
Other comprehensive loss before reclassifications	(14,621)	21,226
Amounts reclassified from accumulated other comprehensive income	129	656
Total other comprehensive income (loss)	83	21,882
Tax Cuts and Jobs Act, reclassification from AOCI to retained earnings, tax effect		1,874
Ending balance	(15,265)	(15,348)
Defined benefit and other postretirement plans
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax
Beginning balance	3,568	(546)
Other comprehensive loss before reclassifications	1,850	2,497
Amounts reclassified from accumulated other comprehensive income	88	(67)
Total other comprehensive income (loss)	1,710	2,430
Tax Cuts and Jobs Act, reclassification from AOCI to retained earnings, tax effect		1,684
Ending balance	5,278	3,568
Defined benefit and other postretirement plans, disposal of business | Discontinued Operations
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	228
Net gain (loss) from hedging activities
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax
Beginning balance	(1,838)	637
Other comprehensive loss before reclassifications	125	(3,388)
Amounts reclassified from accumulated other comprehensive income	41	723
Total other comprehensive income (loss)	1,178	(2,665)
Tax Cuts and Jobs Act, reclassification from AOCI to retained earnings, tax effect		190
Ending balance	(660)	(1,838)
Net gain (loss) from hedging activities, disposal of business | Discontinued Operations
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	(1,012)
Foreign currency translation
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax
Beginning balance	(17,078)	(39,195)
Other comprehensive loss before reclassifications	(16,596)	22,117
Amounts reclassified from accumulated other comprehensive income	0	0
Total other comprehensive income (loss)	(2,805)	22,117
Tax Cuts and Jobs Act, reclassification from AOCI to retained earnings, tax effect		0
Ending balance	(19,883)	$ (17,078)
Foreign currency translation, disposal of business | Discontinued Operations
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	$ (13,791)

Stockholders' Equity - Reclassi

Stockholders' Equity - Reclassifications out of AOCI (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Other expense, net									$ 6,109	$ 2,372	$ (10,603)
Interest expense, net									(66,979)	(87,072)	(90,758)
Cost of goods sold									(834,007)	(901,512)	(925,534)
Income before income taxes an noncontrolling interest									(227,585)	105,430	84,020
Tax benefit (expense)									48,122	(39,677)	(33,641)
Net (loss) income	$ (302,896)	$ 4,436	$ 16,247	$ 509	$ 27,399	$ 18,751	$ 30,719	$ 3,441	(281,704)	80,310	$ 59,621
Amount of gain (loss) reclassified from AOCI into income
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Net (loss) income									(129)	(656)
Defined benefit and other postretirement plans | Amount of gain (loss) reclassified from AOCI into income
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Income before income taxes an noncontrolling interest									(113)	112
Tax benefit (expense)									25	(45)
Net (loss) income									(88)	67
Prior service credit (cost) | Amount of gain (loss) reclassified from AOCI into income
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Other expense, net									119	133
Actuarial gains (losses) | Amount of gain (loss) reclassified from AOCI into income
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Other expense, net									(232)	(21)
Net gain (loss) from hedging activities | Amount of gain (loss) reclassified from AOCI into income
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Income before income taxes an noncontrolling interest									(54)	(960)
Tax benefit (expense)									13	237
Net (loss) income									(41)	(723)
Net gain (loss) from hedging activities | Amount of gain (loss) reclassified from AOCI into income | Interest rate caps
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Interest expense, net									(54)	(625)
Net gain (loss) from hedging activities | Amount of gain (loss) reclassified from AOCI into income | Natural gas swaps
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Cost of goods sold									$ 0	$ (335)

Stock Repurchase Program (Detai

Stock Repurchase Program (Details) - USD ($) $ / shares in Units, $ in Thousands	Dec. 14, 2020	Dec. 31, 2020	Mar. 12, 2020
Equity [Abstract]
Stock Repurchase Program, authorized amount			$ 50,000
Shares acquired		211,700
Average cost per share		$ 9.73
Repurchases of common shares value		$ 2,059
Remaining authorized repurchase amount		$ 47,941
Dividends paid on common stock (in dollars per share)	$ 1.80	$ 1.80

Dispositions Dispositions (Deta

Dispositions Dispositions (Details) - USD ($) $ in Thousands	Dec. 19, 2019	Jun. 28, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Jul. 01, 2020	Dec. 30, 2019
Dispositions [Line Items]
Pre-tax gain on sale			$ 4,958
Deferred revenue			13,388	$ 6,450
Net cash proceeds from sale of product line			18,000	27,658	$ 0
Net cash proceeds from sale of property			9,375	17,600	$ 12,380
Property, plant and equipment, net			983,235	1,011,156
Right-of-use lease asset			48,239	$ 48,417
Operating lease liability			$ 47,213
Sulfate salts product line | Disposed of by sale, not discontinued operations
Dispositions [Line Items]
Sale consideration		$ 28,000
Pre-tax gain on sale		11,518
Deferred revenue		9,000
Net cash proceeds from sale of product line		27,658
Net working capital		4,215
Property, plant and equipment, net		$ 3,276
Property sale | Disposed of by sale, not discontinued operations
Dispositions [Line Items]
Sale consideration	$ 19,100
Pre-tax gain on sale	7,150
Net cash proceeds from sale of property	17,100
Property, plant and equipment, net							$ 10,735
Holdback receivable	$ 1,000
Right-of-use lease asset							3,588
Operating lease liability							$ 3,524
Magnesium silicate product line | Disposed of by sale, not discontinued operations
Dispositions [Line Items]
Sale consideration						$ 18,000
Inventory, Gross						1,556
Deferred revenue						$ 11,486

Other Operating Expense, Net (D

Other Operating Expense, Net (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Other Income and Expenses [Abstract]
Amortization	$ 26,923	$ 26,888	$ 27,258
Transaction and other related costs	8,274	407	491
Restructuring, integration and business optimization costs	13,028	2,692	5,819
Net (gain) loss on asset disposals	(134)	(13,207)	4,190
Insurance recoveries	0	0	(5,480)
Gain on contract termination	0	0	(20,612)
Environmental related costs	1,092	2,522	638
Other, net	1,803	2,076	4,123
Other operating expense, net	50,986	21,378	16,427
Pre-tax gain on sale	4,958
Equity Method Investment, Realized Gain (Loss) on Disposal	$ 672
Gain on sale of product line		11,518
Gain on property sale		$ 7,150
Total gain related to insurance recoveries			(6,450)
Insurance recoveries recorded as gain on asset disposals			207
Insurance recoveries recorded as non-operating income			$ 763

Inventories (Details)

Inventories (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Inventory, Net
Finished products and work in process	$ 102,388	$ 106,980
Raw materials	25,048	30,642
Inventory, Net	127,436	137,622
Valued at lower of cost or market:
LIFO basis	55,283	60,190
Valued at Lower of Cost and Net Realizable Value [Abstract]
FIFO or average cost basis	72,153	77,432
Inventory, Net	$ 127,436	$ 137,622

Inventories, Net - Narratives (

Inventories, Net - Narratives (Details) - Business Combinations - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Inventory
Lower inventory valuation if FIFO rather than LIFO	$ 4,255
Higher inventory valuation if FIFO rather than LIFO		$ (974)

Investments in Affiliated Com_3

Investments in Affiliated Companies - Narratives (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Mar. 31, 2020
Business Acquisition
Liquidating dividend	$ 729
Sale of joint venture shares	1,032
Amortization of investment in affiliate step-up	(6,634)	$ (7,534)
Quaker Holdings
Business Acquisition
Ownership percentage				49.00%
Equity Method Investee
Business Acquisition
Due from related parties	3,814	3,586
Related party sales	9,144	4,181	$ 2,823
Purchases from related party	0
Business Combination
Business Acquisition
Net purchase accounting fair value adjustments	243,899	250,532
Amortization of investment in affiliate step-up	$ 6,634	$ 7,534	$ 6,634

Investments in Affiliated Com_4

Investments in Affiliated Companies - Ownership Percentage (Details)	Dec. 31, 2020
PQ Silicates Ltd.
Schedule of Equity Method Investments [Line Items]
Ownership percentage	50.00%
Zeolyst International
Schedule of Equity Method Investments [Line Items]
Ownership percentage	50.00%
Zeolyst C.V.
Schedule of Equity Method Investments [Line Items]
Ownership percentage	50.00%

Investments in Affiliated Com_5

Investments in Affiliated Companies - Summarized Balance Sheet (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Schedule of Equity Method Investments [Line Items]
Current assets	$ 428,140	$ 569,487
Current liabilities	201,338	270,364
Equity method investments
Schedule of Equity Method Investments [Line Items]
Current assets	219,002	248,685
Noncurrent assets	254,416	256,104
Current liabilities	66,423	52,638
Noncurrent liabilities	$ 36,788	$ 5,950

Investments in Affiliated Com_6

Investments in Affiliated Companies - Summarized Income Statement (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Schedule of Equity Method Investments [Line Items]
Gross profit	$ 67,227	$ 70,172	$ 63,662	$ 72,295	$ 65,898	$ 82,913	$ 81,863	$ 67,728	$ 273,356	$ 298,402	$ 303,392
Operating income	(245,623)	33,310	20,175	29,214	28,482	41,191	48,840	28,995	(162,924)	147,508	155,563
Net income	$ (302,896)	$ 4,436	$ 16,247	$ 509	$ 27,399	$ 18,751	$ 30,719	$ 3,441	(281,704)	80,310	59,621
Equity method investments
Schedule of Equity Method Investments [Line Items]
Sales									278,414	380,381	351,839
Gross profit									89,471	144,828	126,505
Operating income									54,010	106,195	88,294
Net income									$ 55,722	$ 107,112	$ 88,411

Investments in Affiliated Com_7

Investments in Affiliated Companies - Rollforward (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Equity Method Investments
Balance at beginning of period	$ 472,814	$ 468,055
Equity in net income of affiliated companies	27,871	53,556
Charges related to purchase accounting fair value adjustments	(6,634)	(7,534)
Dividends received from affiliated companies	(40,989)	(40,073)
Foreign currency translation adjustments	5,390	(1,190)
Balance at end of period	$ 458,452	$ 472,814

Property, Plant and Equipment_2

Property, Plant and Equipment (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$ 1,503,311	$ 1,424,991
Less: accumulated depreciation	(520,076)	(413,835)
Property, plant and equipment, net	983,235	1,011,156
Land
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	158,517	160,321
Buildings
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	168,204	160,653
Machinery and equipment
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	1,097,949	1,027,775
Construction in progress
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$ 78,641	$ 76,242

Property, Plant and Equipment -

Property, Plant and Equipment - Narratives (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Property, Plant and Equipment [Abstract]
Depreciation	$ 114,641	$ 111,032	$ 111,491

Leases - Narratives (Details)

Leases - Narratives (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Lessee, Lease, Description [Line Items]
Operating lease cost	$ 16,817	$ 15,125
Rent expense under prior guidance			$ 20,594

Leases - Right-of-Use Lease Ass

Leases - Right-of-Use Lease Assets and Lease Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Assets
Operating lease assets	$ 48,239	$ 48,417
Finance lease assets	1,752	1,556
Total leased assets	49,991	49,973
Current:
Operating lease liabilities	15,194	11,857
Finance lease liabilities	262	185
Noncurrent:
Operating lease liabilities	32,019	34,908
Finance lease liabilities	366	315
Total lease liabilities	$ 47,841	$ 47,265
Finance lease asset, balance sheet line item	us-gaap:PropertyPlantAndEquipmentNet
Finance lease liabilities, current, balance sheet line item	us-gaap:AccruedLiabilitiesCurrent
Finance lease liabilities, noncurrent, balance sheet line item	us-gaap:OtherLiabilitiesNoncurrent

Leases - Remaining Average Weig

Leases - Remaining Average Weighted Average Lease Term and Discount Rates (Details)	Dec. 31, 2020	Dec. 31, 2019
Weighted average remaining lease term (in years)
Operating leases	5 years 2 months 4 days	5 years 6 months 3 days
Finance leases	2 years 5 months 12 days	2 years 7 months 24 days
Weighted Average discount rate:
Operating leases	5.55%	5.66%
Finance leases	4.67%	4.67%

Leases - Lease Maturity Schedul

Leases - Lease Maturity Schedule - ASC 842 (Details) $ in Thousands	Dec. 31, 2020USD ($)
Operating Leases
2021	$ 17,363
2022	10,707
2023	8,655
2024	6,404
2025	3,917
Thereafter	7,785
Total lease payments	54,831
Less: Interest	(7,618)
Total lease liabilities	47,213
Finance Leases
2021	406
2022	161
2023	40
2024	35
2025	8
Thereafter	0
Total lease payments	650
Less: Interest	(22)
Total lease liabilities	$ 628

Leases - Other Lease Informatio

Leases - Other Lease Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Cash paid for amounts included in the measurement of lease liabilities: [Abstract]
Payments on operating leases included in operating cash flows	$ 16,135	$ 14,814
Interest payments under finance lease obligations included in operating cash flows	21	26
Principal payments under finance lease obligations included in financing cash flows	209	177
Right-of-Use Assets Obtained in Exchange for New Lease Liabilities (Non-Cash): [Abstract]
Operating leases	14,439	8,798
Right-of-Use Asset Obtained in Exchange for Finance Lease Liability	$ 353	$ 0

Reportable Segments - Narrative

Reportable Segments - Narratives (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2020USD ($)	Dec. 31, 2020segment	Dec. 31, 2020	Dec. 31, 2019USD ($)	Dec. 31, 2018USD ($)
Segment Reporting [Abstract]
Number of operating segments		3	3
Reportable segments		3	3
Equity in net income from affiliated companies	$ 21,237			$ 46,022	$ 37,569

Reportable Segments - Summary F

Reportable Segments - Summary Financial Information by Reportable Segment (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Segment Reporting, Revenue Reconciling Item [Line Items]
Sales	$ 281,505	$ 275,149	$ 254,896	$ 295,813	$ 283,535	$ 307,271	$ 311,641	$ 297,468	$ 1,107,363	$ 1,199,914	$ 1,228,926
Equity in net income from affiliated companies									21,237	46,022	37,569
Charges related to purchase accounting fair value adjustments									(6,634)	(7,534)
Refining Services
Segment Reporting, Revenue Reconciling Item [Line Items]
Sales									398,657	443,684	452,325
Catalysts
Segment Reporting, Revenue Reconciling Item [Line Items]
Sales									94,002	85,667	72,099
Performance Chemicals
Segment Reporting, Revenue Reconciling Item [Line Items]
Sales									614,704	670,563	704,502
Operating segments
Segment Reporting, Revenue Reconciling Item [Line Items]
Sales									1,110,624	1,203,311	1,232,163
Segment Adjusted EBITDA									374,074	434,995	425,762
Operating segments | Refining Services
Segment Reporting, Revenue Reconciling Item [Line Items]
Sales									401,913	447,081	455,562
Segment Adjusted EBITDA									157,198	175,640	176,499
Operating segments | Catalysts
Segment Reporting, Revenue Reconciling Item [Line Items]
Sales									94,007	85,667	72,099
Segment Adjusted EBITDA									74,504	107,808	81,067
Operating segments | Performance Chemicals
Segment Reporting, Revenue Reconciling Item [Line Items]
Sales									614,704	670,563	704,502
Segment Adjusted EBITDA									142,372	151,547	168,196
Eliminations
Segment Reporting, Revenue Reconciling Item [Line Items]
Sales									(3,261)	(3,397)	(3,237)
Zeolyst Joint Venture | Catalysts
Segment Reporting, Revenue Reconciling Item [Line Items]
Sales									128,623	170,338	156,687
Segment Adjusted EBITDA									42,515	68,138	56,663
Equity in net income from affiliated companies									21,157	45,899	37,437
Charges related to purchase accounting fair value adjustments									6,634	7,534	6,634
Joint venture depreciation, amortization, and interest									$ 14,724	$ 14,705	$ 12,592

Reportable Segments - Reconcili

Reportable Segments - Reconciliation of Net Income to Adjusted EBITDA (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Segment Reporting Information
Net (loss) income from continuing operations									$ (176,265)	$ 65,136	$ 49,271
(Benefit) provision for income taxes									(48,122)	39,677	33,641
Interest expense, net									66,979	87,072	90,758
Depreciation and amortization									151,840	151,797	153,931
Segment EBITDA									(5,568)	343,682	327,601
Charges related to purchase accounting fair value adjustments									(6,634)	(7,534)
Debt extinguishment costs									25,028	3,400	7,751
Net (gain) loss on asset disposals									(11,392)	(13,207)	4,190
Foreign currency exchange (gain) loss									(4,172)	2,410	12,543
Transaction and other related costs									8,274	407	491
Equity-based compensation									21,527	16,212	18,419
Gain on contract termination									0	0	(20,612)
Net (loss) income from continuing operations	$ (186,702)	$ (6,956)	$ 7,896	$ 6,299	$ 28,406	$ 11,888	$ 19,404	$ 6,055	(179,463)	65,753	50,379
Corporate, non-segment
Segment Reporting Information
Unallocated corporate expenses									36,079	41,033	37,842
Segment reconciling items
Segment Reporting Information
Joint venture depreciation, amortization, and interest									14,724	14,705	12,592
Charges related to purchase accounting fair value adjustments									6,634	7,534	6,634
Goodwill impairment charge									260,000	0	0
Debt extinguishment costs									25,028	3,400	7,751
Net (gain) loss on asset disposals									(134)	(13,207)	4,190
Foreign currency exchange (gain) loss									(4,172)	2,410	12,543
LIFO (benefit) expense									(5,229)	9,700	3,039
Transaction and other related costs									8,618	415	490
Equity-based compensation									21,527	16,212	18,419
Restructuring, integration and business optimization expenses									15,596	3,554	8,707
Defined benefit pension plan cost									12	2,960	411
Gain on contract termination									0	0	(20,612)
Other									959	2,597	6,155
Operating segments
Segment Reporting Information
Adjusted EBITDA									337,995	393,962	387,920
Segment Adjusted EBITDA									$ 374,074	$ 434,995	$ 425,762

Reportable Segments - Capital E

Reportable Segments - Capital Expenditures (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Revenues from External Customers and Long-Lived Assets
Capital expenditure	$ 97,135	$ 111,102	$ 111,795
Operating segments | Refining Services
Revenues from External Customers and Long-Lived Assets
Capital expenditures gross	31,799	42,310	46,617
Operating segments | Catalysts
Revenues from External Customers and Long-Lived Assets
Capital expenditures gross	11,177	8,984	8,390
Operating segments | Performance Chemicals
Revenues from External Customers and Long-Lived Assets
Capital expenditures gross	40,864	53,910	56,759
Operating segments | Corporate
Revenues from External Customers and Long-Lived Assets
Capital expenditures gross	$ 13,295	$ 5,898	$ 29

Reportable Segments - Sales by

Reportable Segments - Sales by Geography (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Revenues from External Customers and Long-Lived Assets
Sales	$ 281,505	$ 275,149	$ 254,896	$ 295,813	$ 283,535	$ 307,271	$ 311,641	$ 297,468	$ 1,107,363	$ 1,199,914	$ 1,228,926
United States
Revenues from External Customers and Long-Lived Assets
Sales									655,015	735,752	740,190
Netherlands
Revenues from External Customers and Long-Lived Assets
Sales									108,338	117,211	127,803
United Kingdom
Revenues from External Customers and Long-Lived Assets
Sales									107,539	99,048	101,277
Other foreign countries
Revenues from External Customers and Long-Lived Assets
Sales									$ 236,471	$ 247,903	$ 259,656

Reportable Segments - Assets by

Reportable Segments - Assets by Geography (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Revenues from External Customers and Long-Lived Assets
Long-lived assets	$ 1,031,474	$ 1,059,573
United States
Revenues from External Customers and Long-Lived Assets
Long-lived assets	749,635	784,699
Netherlands
Revenues from External Customers and Long-Lived Assets
Long-lived assets	53,006	49,559
United Kingdom
Revenues from External Customers and Long-Lived Assets
Long-lived assets	100,392	92,229
Other foreign countries
Revenues from External Customers and Long-Lived Assets
Long-lived assets	$ 128,441	$ 133,086

Goodwill and Other Intangible_3

Goodwill and Other Intangible Assets - Goodwill Rollforward (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Goodwill
Beginning balance	$ 973,578	$ 969,674
Goodwill impairment charge	(260,000)	0	$ 0
Foreign exchange impact	4,160	3,904
Ending balance	717,738	973,578	969,674
Goodwill, Impaired, Accumulated Impairment Loss, beginning	0	0
Goodwill, Impaired, Accumulated Impairment Loss, ending	260,000	0	0
Refining Services
Goodwill
Beginning balance	311,892	311,892
Goodwill impairment charge	0
Foreign exchange impact	0	0
Ending balance	311,892	311,892	311,892
Goodwill, Impaired, Accumulated Impairment Loss, beginning	0
Goodwill, Impaired, Accumulated Impairment Loss, ending	0	0
Catalysts
Goodwill
Beginning balance	78,611	77,759
Goodwill impairment charge	0
Foreign exchange impact	1,062	852
Ending balance	79,673	78,611	77,759
Goodwill, Impaired, Accumulated Impairment Loss, beginning	0	0
Goodwill, Impaired, Accumulated Impairment Loss, ending	0	0	0
Performance Chemicals
Goodwill
Beginning balance	583,075	580,023
Goodwill impairment charge	(260,000)
Foreign exchange impact	3,098	3,052
Ending balance	326,173	583,075	580,023
Goodwill, Impaired, Accumulated Impairment Loss, beginning	0	0
Goodwill, Impaired, Accumulated Impairment Loss, ending	$ 260,000	$ 0	$ 0

Goodwill and Other Intangible_4

Goodwill and Other Intangible Assets - Narratives (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2020USD ($)	Dec. 31, 2019USD ($)	Dec. 31, 2018USD ($)
Goodwill
Number of reporting units	3
Goodwill impairment charge	$ 260,000	$ 0	$ 0
Goodwill	717,738	973,578	969,674
Amortization expense	26,923	26,888	27,258
Performance Chemicals
Goodwill
Goodwill impairment charge	260,000
Goodwill	326,173	583,075	580,023
Cost of goods sold
Goodwill
Amortization expense	9,369	13,877	13,579
Other operating expenses
Goodwill
Amortization expense	$ 26,923	$ 26,888	$ 27,258

Goodwill and Other Intangible_5

Goodwill and Other Intangible Assets - Schedule of Intangible Assets (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Definite-lived Intangible assets, net
Accumulated Amortization	$ (193,573)	$ (169,945)
Net Balance	330,277
Indefinite-lived intangible assets, net
Gross Carrying Amount	719,876	725,217
Net Balance	526,303	555,272
Indefinite-lived trade names
Indefinite-lived intangible assets, net
Gross Carrying Amount	108,713	106,811
Net Balance	108,713	106,811
Trademarks
Indefinite-lived intangible assets, net
Gross Carrying Amount	82,613	80,999
Net Balance	82,613	80,999
In-process research and development
Indefinite-lived intangible assets, net
Gross Carrying Amount	4,700	5,200
Net Balance	4,700	5,200
Finite-Lived Intangible Assets
Definite-lived Intangible assets, net
Gross Carrying Amount	523,850	532,207
Accumulated Amortization	(193,573)	(169,945)
Net Balance	330,277	362,262
Technical know-how
Definite-lived Intangible assets, net
Gross Carrying Amount	180,768	177,873
Accumulated Amortization	(47,207)	(37,102)
Net Balance	$ 133,561	140,771
Technical know-how | Minimum
Indefinite-lived intangible assets, net
Finite lived intangible assets useful life	11 years
Technical know-how | Maximum
Indefinite-lived intangible assets, net
Finite lived intangible assets useful life	20 years
Customer relationships
Definite-lived Intangible assets, net
Gross Carrying Amount	$ 325,773	321,434
Accumulated Amortization	(134,842)	(106,627)
Net Balance	$ 190,931	214,807
Customer relationships | Minimum
Indefinite-lived intangible assets, net
Finite lived intangible assets useful life	7 years
Customer relationships | Maximum
Indefinite-lived intangible assets, net
Finite lived intangible assets useful life	15 years
Contracts
Definite-lived Intangible assets, net
Gross Carrying Amount	$ 0	16,200
Accumulated Amortization	0	(15,258)
Net Balance	$ 0	942
Contracts | Minimum
Indefinite-lived intangible assets, net
Finite lived intangible assets useful life	2 years
Contracts | Maximum
Indefinite-lived intangible assets, net
Finite lived intangible assets useful life	16 years
Trademarks
Definite-lived Intangible assets, net
Gross Carrying Amount	$ 7,709	7,600
Accumulated Amortization	(2,399)	(1,858)
Net Balance	$ 5,310	5,742
Trademarks | Minimum
Indefinite-lived intangible assets, net
Finite lived intangible assets useful life	11 years
Trademarks | Maximum
Indefinite-lived intangible assets, net
Finite lived intangible assets useful life	15 years
Permits
Definite-lived Intangible assets, net
Gross Carrying Amount	$ 9,100	9,100
Accumulated Amortization	(9,100)	(9,100)
Net Balance	$ 0	0
Indefinite-lived intangible assets, net
Finite lived intangible assets useful life	5 years
In-process research and development
Definite-lived Intangible assets, net
Gross Carrying Amount	$ 500	0
Accumulated Amortization	(25)	0
Net Balance	$ 475	$ 0

Goodwill and Other Intangible_6

Goodwill and Other Intangible Assets - Future Amortization (Details) $ in Thousands	Dec. 31, 2020USD ($)
Finite-Lived Intangible Assets, Net, Amortization Expense, Fiscal Year Maturity
2021	$ 36,292
2022	36,292
2023	36,292
2024	36,292
2025	36,292
Thereafter	148,817
Total estimated future aggregate amortization expense	$ 330,277

Accrued Liabilities Accrued L_2

Accrued Liabilities Accrued Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Payables and Accruals [Abstract]
Compensation and bonus	$ 35,251	$ 40,374
Interest	11,573	19,110
Property tax	2,656	2,250
Environmental reserves	4,309	4,548
Income taxes	869	4,900
Commissions and rebates	854	1,459
Pension, postretirement and supplemental retirement plans	1,852	1,825
Derivative liabilities	1,954	420
Other	14,493	10,524
Accrued Liabilities, Current, Total	$ 73,811	$ 85,410

Long-term Debt (Details)

Long-term Debt (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019	May 04, 2016
Debt Instrument [Line Items]
Total debt	$ 1,426,363	$ 1,867,497
Original issue discount	(15,641)	(13,434)
Deferred financing costs	(10,353)	(10,839)
Total debt, net of original issue discount and deferred financing costs	1,400,369	1,843,224
Less: current portion	0	0
Total long-term debt, excluding current portion	1,400,369	1,843,224
Term Loan Facility
Debt Instrument [Line Items]
Total debt	671,710	947,497
Term Loan Facility | Term Loan Facility
Debt Instrument [Line Items]
Total debt	459,653	0
Senior Notes | 6.75% Senior Secured Notes due 2022
Debt Instrument [Line Items]
Total debt	0	625,000
Debt instrument stated interest rate			6.75%
Senior Notes | 5.75% Senior Unsecured Notes due 2025
Debt Instrument [Line Items]
Total debt	295,000	295,000
ABL Facility
Debt Instrument [Line Items]
Total debt	$ 0	$ 0

Long-term Debt - Senior Secured

Long-term Debt - Senior Secured Credit Facilities (Details) € in Thousands

Jul. 22, 2020USD ($)

Jul. 01, 2020USD ($)

Feb. 07, 2020

Oct. 31, 2019USD ($)

Feb. 08, 2018USD ($)

May 04, 2016USD ($)

Dec. 31, 2020USD ($)

Dec. 31, 2019USD ($)

Dec. 31, 2018USD ($)

Oct. 01, 2019EUR (€)

Feb. 28, 2018EUR (€)

May 04, 2016EUR (€)

Debt Instrument [Line Items]

ABL maximum borrowing capacity

$ 250,000,000

Redemption of 6.75% Senior Secured Notes

1,426,363,000

$ 1,867,497,000

Mandatory payments

275,787,000

Debt Instrument, Original Issue Discount

1.50%

Increase amount of ABL commitments

50,000,000

Term Loan Facility

Debt Instrument [Line Items]

New Term Loan Facility

$ 650,000,000

Mandatory payments

188,722,000

ABL Facility

Debt Instrument [Line Items]

Letters of credit outstanding

18,190,000

Debt instrument, covenant, fixed charge coverage ratio

1

1

Cross currency swaps

Debt Instrument [Line Items]

Cash proceeds on cross currency swap

$ 38,070,000

Net investment hedging | Cross currency swaps

Debt Instrument [Line Items]

Derivative, notional amount

344,403,000

€ 280,000

€ 280,000

Term Loan Facility

Debt Instrument [Line Items]

Redemption of 6.75% Senior Secured Notes

671,710,000

947,497,000

Term Loan Facility | Term Loan Facility

Debt Instrument [Line Items]

Debt instrument face amount

$ 1,267,000,000

Redemption of 6.75% Senior Secured Notes

459,653,000

0

Scheduled quarterly principal payments

0.25%

0.25%

Mandatory payments

466,134,000

210,000,000

Write off of deferred financing costs

162,000

1,027,000

Write-off of original issue discount

12,781,000

2,414,000

Term Loan Facility | Term Loan Facility | LIBOR

Debt Instrument [Line Items]

Debt instrument face amount

$ 650,000

Variable rate on spread

3.00%

2.25%

2.50%

Debt Instrument, Variable Rate Floor

1.00%

Term Loan Facility | Term Loan Facility | Base Rate [Member]

Debt Instrument [Line Items]

Variable rate on spread

1.25%

Term Loan Facility | Prior Term Loan Facility

Debt Instrument [Line Items]

Debt instrument face amount

$ 1,200,000,000

Debt extinguishment costs

2,188,000

$ 2,124,000

Write off of deferred financing costs

97,000

1,403,000

Write-off of original issue discount

228,000

$ 2,352,000

ABL Facility

Debt Instrument [Line Items]

ABL maximum borrowing capacity

$ 200,000,000

Redemption of 6.75% Senior Secured Notes

0

0

Commitment fee percentage

0.375%

Potential commitment fee percentage

0.25%

Senior Notes | 6.75% Senior Secured Notes due 2022

Debt Instrument [Line Items]

Debt instrument face amount

$ 625,000,000

Redemption of 6.75% Senior Secured Notes

$ 0

$ 625,000,000

Minimum | ABL Facility | LIBOR

Debt Instrument [Line Items]

Variable rate on spread

1.50%

1.25%

Minimum | ABL Facility | Base Rate [Member]

Debt Instrument [Line Items]

Variable rate on spread

0.50%

0.25%

Maximum | ABL Facility | LIBOR

Debt Instrument [Line Items]

Variable rate on spread

2.00%

1.75%

Maximum | ABL Facility | Base Rate [Member]

Debt Instrument [Line Items]

Variable rate on spread

1.00%

0.75%

USD

Debt Instrument [Line Items]

ABL maximum borrowing capacity

$ 195,000,000

USD | Term Loan Facility | Prior Term Loan Facility

Debt Instrument [Line Items]

Debt instrument face amount

$ 900,000,000

USD | ABL Facility

Debt Instrument [Line Items]

ABL maximum borrowing capacity

150,000,000

Euro

Debt Instrument [Line Items]

ABL maximum borrowing capacity

40,000,000

Euro | Term Loan Facility | Prior Term Loan Facility

Debt Instrument [Line Items]

Debt instrument face amount

300,000,000

€ 265,000

Canada, Dollars

Debt Instrument [Line Items]

ABL maximum borrowing capacity

$ 15,000,000

Canada | ABL Facility

Debt Instrument [Line Items]

ABL maximum borrowing capacity

10,000,000

Europe | ABL Facility

Debt Instrument [Line Items]

ABL maximum borrowing capacity

$ 40,000,000

Long-term Debt - Secured and Un

Long-term Debt - Secured and Unsecured Notes (Details) - USD ($)	Dec. 11, 2017	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	May 04, 2016
Senior Notes | 6.75% Senior Secured Notes due 2022
Debt Instrument [Line Items]
Debt instrument face amount					$ 625,000,000
Debt instrument stated interest rate					6.75%
Senior Notes | 6.75% Senior Secured Notes due 2022 | Debt Instrument, Redemption, Period Two
Debt Instrument [Line Items]
Debt instrument, redemption price percentage			101.688%
Senior Notes | 6.75% Senior Secured Notes due 2022 | Debt Instrument, Redemption, Period Three
Debt Instrument [Line Items]
Debt instrument, redemption price percentage			100.00%
Unsecured Notes | 5.75% Senior Unsecured Notes due 2025
Debt Instrument [Line Items]
Debt instrument face amount	$ 300,000,000
Debt instrument stated interest rate	5.75%
Debt instrument, redemption price percentage	105.75%		100.00%
Repayment of note		$ 10,550,000
Write off of deferred financing costs			$ 2,085,000
Write-off of original issue discount			$ 1,186,000
Debt instrument, call premium	1.00%
Unsecured Notes | 5.75% Senior Unsecured Notes due 2025 | Change of Control
Debt Instrument [Line Items]
Debt instrument, redemption price percentage			101.00%
Unsecured Notes | 5.75% Senior Unsecured Notes due 2025 | Debt Instrument, Redemption, Period One
Debt Instrument [Line Items]
Debt instrument, redemption price percentage			102.875%
Unsecured Notes | 5.75% Senior Unsecured Notes due 2025 | Debt Instrument, Redemption, Period Two
Debt Instrument [Line Items]
Debt instrument, redemption price percentage			101.438%
Unsecured Notes | 5.75% Senior Unsecured Notes due 2025 | Debt Instrument, Redemption, Period Three
Debt Instrument [Line Items]
Debt instrument, redemption price percentage			100.00%
Unsecured Notes | 5.75% Senior Unsecured Notes due 2025 | Minimum | Event of Default
Debt Instrument [Line Items]
Potential percentage of principal redeemed				30.00%
Unsecured Notes | 5.75% Senior Unsecured Notes due 2025 | Maximum | Exercise of Call Option
Debt Instrument [Line Items]
Potential percentage of principal redeemed	40.00%
United States Treasury [Member] | Unsecured Notes | 5.75% Senior Unsecured Notes due 2025
Debt Instrument [Line Items]
Variable rate on spread	0.50%

Long-term Debt - Other Debt (De

Long-term Debt - Other Debt (Details) - USD ($) $ in Thousands	May 04, 2016	Dec. 31, 2020	Dec. 31, 2019
Debt Instrument [Line Items]
Increase amount of ABL commitments		$ 50,000
ABL maximum borrowing capacity		250,000
USD
Debt Instrument [Line Items]
ABL maximum borrowing capacity		195,000
Canada, Dollars
Debt Instrument [Line Items]
ABL maximum borrowing capacity		15,000
Euro
Debt Instrument [Line Items]
ABL maximum borrowing capacity		$ 40,000
Sovitec debt
Debt Instrument [Line Items]
ABL maximum borrowing capacity	$ 200,000
Sovitec debt | USD
Debt Instrument [Line Items]
ABL maximum borrowing capacity	$ 150,000
Sovitec debt | LIBOR | Minimum
Debt Instrument [Line Items]
Variable rate on spread	1.50%	1.25%
Sovitec debt | LIBOR | Maximum
Debt Instrument [Line Items]
Variable rate on spread	2.00%	1.75%
Sovitec debt | Base Rate [Member] | Minimum
Debt Instrument [Line Items]
Variable rate on spread	0.50%	0.25%
Sovitec debt | Base Rate [Member] | Maximum
Debt Instrument [Line Items]
Variable rate on spread	1.00%	0.75%
Term Loan And Senior Notes
Debt Instrument [Line Items]
Fair value of debt		$ 1,427,123	$ 1,905,822

Long-term Debt - Aggregate Long

Long-term Debt - Aggregate Long-term Debt Maturities (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Long-term Debt, Fiscal Year Maturity
2021	$ 0
2022	0
2023	0
2024	0
2025	295,000
Thereafter	1,131,363
Total debt	$ 1,426,363	$ 1,867,497

Other Long-term Liabilities O_2

Other Long-term Liabilities Other Long-term Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Other Liabilities Disclosure [Abstract]
Pension benefits	$ 40,812	$ 52,060
Other postretirement benefits	3,644	1,668
Supplemental retirement plans	11,376	10,632
Derivative liabilities	32,512	10,956
Deferred revenue	13,388	6,450
Reserve for uncertain tax positions	345	873
Asset retirement obligation	4,943	4,555
Other	3,995	4,110
Other Liabilities, Noncurrent, Total	$ 111,015	$ 91,304

Financial Instruments - Narrati

Financial Instruments - Narratives (Details) € in Thousands, $ in Thousands	Oct. 31, 2019USD ($)	Nov. 30, 2018USD ($)	Mar. 31, 2020USD ($)	Jul. 31, 2016USD ($)	Dec. 31, 2020USD ($)	Dec. 31, 2020USD ($)	Jul. 31, 2020USD ($)	Feb. 28, 2020	Oct. 01, 2019EUR (€)	Nov. 13, 2018USD ($)	Feb. 28, 2018EUR (€)
Derivative [Line Items]
Amount of derivative loss expected to be transfered from OCI					$ 281
Cross currency swaps
Derivative [Line Items]
Cash proceeds on cross currency swap	$ 38,070
Cash flow hedging | July 2016 Interest Rate Cap [Member]
Derivative [Line Items]
Premium paid to acquire derivative instrument				$ 1,551
Derivative, cap interest rate					0.84%	0.84%
Derivative, notional amount				$ 1,000,000
Cash flow hedging | July 2016 Interest Rate Cap [Member] | Minimum
Derivative [Line Items]
Derivative, cap interest rate				1.50%
Cash flow hedging | July 2016 Interest Rate Cap [Member] | Maximum
Derivative [Line Items]
Derivative, cap interest rate				3.00%
Cash flow hedging | November 2018 Interest Rate Cap [Member]
Derivative [Line Items]
Premium paid to acquire derivative instrument		$ 3,380	$ 900		$ 130	$ 4,410
Derivative, cap interest rate			0.84%					2.50%		3.50%
Derivative, notional amount		$ 500,000								$ 500,000
Cash flow hedging | July 2020 Interest Rate Cap
Derivative [Line Items]
Derivative, cap interest rate							1.00%
Derivative, notional amount							$ 400,000
Net investment hedging | Cross currency swaps
Derivative [Line Items]
Derivative, notional amount					$ 344,403	$ 344,403			€ 280,000		€ 280,000

Financial Instruments - Fair Va

Financial Instruments - Fair Value (Details) - Derivatives designated as cash flow hedges: - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Derivative assets:
Total derivative assets	$ 3,249	$ 3,928
Derivative liabilities:
Total derivative liabilities	34,466	11,376
Cash flow hedging
Derivative liabilities:
Total derivative liabilities	3,704	3,242
Cash flow hedging | Accrued liabilities | Interest rate caps
Derivative liabilities:
Total derivative liabilities	1,954	420
Cash flow hedging | Other long-term liabilities | Interest rate caps
Derivative liabilities:
Total derivative liabilities	1,750	2,822
Cash flow hedging | Other long-term liabilities | Cross currency swaps
Derivative liabilities:
Total derivative liabilities	30,762	8,134
Net investment hedging | Prepaid expenses and other current assets | Cross currency swaps
Derivative assets:
Total derivative assets	$ 3,249	$ 3,928

Financial Instruments - Effect

Financial Instruments - Effect on Other Comprehensive Income (Details) - Interest rate caps - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Amount of gain (loss) recognized in OCI on derivatives
Amount of gain (loss) recognized in OCI on derivatives	$ (167)	$ (3,304)	$ (981)
Interest expense
Amount of gain (loss) reclassified from AOCI into income
Amount of gain (loss) reclassified from AOCI into income	$ (54)	$ (625)	$ (256)

Financial Instruments - Cash Fl

Financial Instruments - Cash Flow Hedge Impact on Statements of Income (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Derivative [Line Items]
Cost of goods sold	$ (834,007)	$ (901,512)	$ (925,534)
Interest (expense) income	(66,979)	(87,072)	(90,758)
Gain (loss) on cash flow hedging relationships | Amount of gain (loss) reclassified from AOCI into income
Derivative [Line Items]
Interest (expense) income	$ (54)	$ (625)	$ (256)

Financial Instruments - Net Inv

Financial Instruments - Net Investment Hedge Impact on AOCI (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Net (loss) income from discontinued operations, net of tax
Derivative [Line Items]
Amount of gain (loss) reclassified from AOCI into income	$ 1,967	$ 0	$ 0
Interest (expense) income
Derivative [Line Items]
Amount of gain (loss) recognized in income on derivative (amount excluded from effectiveness testing)	5,090	7,320	6,752
Cross currency swaps
Derivative [Line Items]
Amount of gain (loss) recognized in OCI on derivative	$ (23,622)	$ 17,077	$ 18,843

Income Taxes - Narratives (Deta

Income Taxes - Narratives (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Operating Loss Carryforwards
(Benefit) provision for income taxes	$ (48,122)	$ 39,677	$ 33,641
Net deferred tax liability	175,395	212,328
Unrecognized tax benefit that would impact effective tax rate	7,834	8,310
Interest and penalties from unrecognized tax positions	35	701
Accrued penalties and interest	112	181
Operating loss carryforward	3,678
Net operating loss carryforwards	28,145	$ 77,062
Federal
Operating Loss Carryforwards
Operating loss carryforward	62,752
Federal | Tax Years Prior to 2014 Change in Control
Operating Loss Carryforwards
Operating loss carryforward	7,658
Federal | Tax Years After 2014 Change in Control
Operating Loss Carryforwards
Operating loss carryforward	13,241
State and local
Operating Loss Carryforwards
Operating loss carryforward	24,467
Operating loss carryforward, valuation allowance	14,344
Operating loss carryforward, net of valuation allowance	10,123
Foreign
Operating Loss Carryforwards
Operating loss carryforward, valuation allowance	3,531
Operating loss carryforward, net of valuation allowance	147
Foreign | Tax Year 2019
Operating Loss Carryforwards
Operating carryforward subject to expiration	68
Foreign | Tax Year 2026
Operating Loss Carryforwards
Operating carryforward subject to expiration	160
Foreign | Indefinite
Operating Loss Carryforwards
Operating carryforward not subject to expiration	3,450
Valuation Allowance of Deferred Tax Assets
Operating Loss Carryforwards
Net change in period	$ 1,499

Income Taxes - Income (loss) be

Income Taxes - Income (loss) before Income Taxes and Noncontrolling interest (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Income Tax Disclosure [Abstract]
Domestic	$ (175,143)	$ 41,019	$ (1,559)
Foreign	(52,442)	64,411	85,579
(Loss) income from continuing operations before income taxes and noncontrolling interest	$ (227,585)	$ 105,430	$ 84,020

Income Taxes - Provision for In

Income Taxes - Provision for Income Tax (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Current:
Federal	$ 0	$ (3)	$ 0
State	1,087	1,381	2,507
Foreign	15,484	22,810	27,062
Current income tax	16,571	24,188	29,569
Deferred:
Federal	(58,744)	11,824	10,875
State	(2,910)	3,175	67
Foreign	(3,039)	490	(6,870)
Deferred income tax	(64,693)	15,489	4,072
Total	$ (48,122)	$ 39,677	$ 33,641

Income Taxes - Reconciliation o

Income Taxes - Reconciliation of Statutory Tax Rate (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Income Tax Disclosure [Abstract]
Tax at statutory rate	$ (47,793)	$ 22,140	$ 17,644
State income taxes, net of federal income tax benefit	(2,324)	6,802	2,541
Tax on global intangible low-taxed income	7,820	8,741	14,465
Change in valuation allowances	135	1,415	5,070
Rate changes	4,274	1,054	(4,016)
Foreign withholding taxes	258	(6,116)	142
Foreign tax rate differential	1,240	3,278	6,439
Non-taxable interest	(5,353)	0	0
Non-deductible goodwill	53,342	0	0
Foreign tax credits	(56,359)	0	0
Permanent difference created by foreign exchange gain or loss	(1,324)	1,852	(4,839)
Other, net	(2,038)	511	(3,805)
Total	$ (48,122)	$ 39,677	$ 33,641

Income Taxes - Components of De

Income Taxes - Components of Deferred Tax Asset (Liability) (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Deferred tax assets:
Net operating loss carryforwards	$ 28,145	$ 77,062
Section 163(j) interest disallowance carryforward	266	16,535
Pension	12,701	14,359
Operating lease liability	11,803	14,455
Other	36,545	29,298
State credits	12,733	12,280
Foreign tax credit	62,752	0
Valuation allowance	(37,880)	(39,379)
Deferred tax asset net of valuation	127,065	124,610
Deferred tax liabilities:
Depreciation	(107,805)	(103,796)
Inventory	(4,946)	(11,481)
Intangible assets	(162,301)	(184,764)
Operating lease right-of-use assets	(12,060)	(14,278)
Other	(15,348)	(22,619)
Deferred tax liability	(302,460)	(336,938)
Deferred Tax Liabilities, Net	$ (175,395)	$ (212,328)

Income Taxes - Change in Unreco

Income Taxes - Change in Unrecognized Tax Position (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Income Tax Disclosure [Abstract]
Balance at beginning of period	$ 8,310	$ 9,434
Increases related to prior year tax positions	0	22
Decreases related to prior year tax positions	(14)	(1,046)
Increases related to current year tax positions	164	0
Decreases related to settlements with taxing authorities	626	100
Balance at end of period	$ 7,834	$ 8,310

Income Taxes - Payment for Taxe

Income Taxes - Payment for Taxes (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Operating Loss Carryforwards
Cash paid for taxes	$ 23,008	$ 14,233	$ 19,808
Domestic
Operating Loss Carryforwards
Cash paid for taxes	2,198	1,879	2,154
Foreign
Operating Loss Carryforwards
Cash paid for taxes	$ 20,810	$ 12,354	$ 17,654

Benefit Plans - Change in Benef

Benefit Plans - Change in Benefit Obligation and Plan Assets (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2020USD ($)plan	Dec. 31, 2019USD ($)	Dec. 31, 2018USD ($)
Defined Benefit Plan, Change in Fair Value of Plan Assets
Number Of Defined Benefit Pension Plans | plan	3
Eco Services
Defined Benefit Plan, Change in Fair Value of Plan Assets
Number Of Defined Benefit Pension Plans | plan	2
Number Of Retiree Health Plans | plan	1
PQ Holdings Benefit Plan
Defined Benefit Plan, Change in Fair Value of Plan Assets
Number Of Retiree Health Plans | plan	2
United States | PQ Holdings Benefit Plan
Defined Benefit Plan, Change in Fair Value of Plan Assets
Number Of Retiree Health Plans | plan	1
Foreign | PQ Holdings Benefit Plan
Defined Benefit Plan, Change in Fair Value of Plan Assets
Number Of Retiree Health Plans | plan	1
Defined Benefit Pension Plans
Defined Benefit Plan, Change in Fair Value of Plan Assets
Fair value of plan assets at beginning of period	$ 316,721
Fair value of plan assets at end of the period	362,705	$ 316,721
Defined Benefit Pension Plans | United States
Defined Benefit Plan, Change in Benefit Obligation
Benefit obligation at beginning of period	267,392	246,311
Service cost	769	978	$ 1,019
Interest cost	8,595	10,281	9,599
Participant contributions	0	0
Plan curtailments	0	(2,795)
Plan settlements	(1,455)	(1,669)
Benefits paid	(12,713)	(10,862)
Expenses paid	0	0
Actuarial (gains) losses	25,894	25,148
Translation adjustment	0	0
Benefit obligation at end of the period	288,482	267,392	246,311
Changes in actuarial (gains) losses due to discount rates	26,642	26,604
Changes in actuarial (gains) losses due to demographic experience	1,261	2,953
Changes in actuarial (gains) losses due to mortality assumptions	(2,009)	(4,409)
Defined Benefit Plan, Change in Fair Value of Plan Assets
Fair value of plan assets at beginning of period	231,413	195,755
Actual return on plan assets	41,405	43,116
Employer contributions	5,187	5,073
Employee contributions	0	0
Plan settlements	(1,455)	(1,669)
Benefits paid	(12,713)	(10,862)
Expenses paid	0	0
Translation adjustment	0	0
Fair value of plan assets at end of the period	263,837	231,413	195,755
Funded status of the plans (underfunded)	(24,645)	(35,979)
Defined Benefit Plan, Accumulated Benefit Obligation	288,482	266,992
Defined Benefit Pension Plans | Foreign
Defined Benefit Plan, Change in Benefit Obligation
Benefit obligation at beginning of period	101,192	84,435
Service cost	3,895	3,210	3,104
Interest cost	2,193	2,627	2,637
Participant contributions	574	550
Plan curtailments	(1,603)	0
Plan settlements	(105)	(102)
Benefits paid	(1,759)	(1,833)
Expenses paid	(353)	(328)
Actuarial (gains) losses	4,664	13,459
Translation adjustment	6,191	(826)
Benefit obligation at end of the period	114,889	101,192	84,435
Changes in actuarial (gains) losses due to discount rates	5,981	13,837
Changes in actuarial (gains) losses due to demographic experience	56	(312)
Changes in actuarial (gains) losses due to mortality assumptions	(1,372)	(66)
Defined Benefit Plan, Change in Fair Value of Plan Assets
Fair value of plan assets at beginning of period	85,308	74,050
Actual return on plan assets	6,646	10,564
Employer contributions	3,348	3,084
Employee contributions	574	550
Plan settlements	(105)	(102)
Benefits paid	(1,759)	(1,833)
Expenses paid	(353)	(328)
Translation adjustment	5,209	(677)
Fair value of plan assets at end of the period	98,868	85,308	74,050
Funded status of the plans (underfunded)	(16,021)	(15,884)
Defined Benefit Plan, Accumulated Benefit Obligation	110,605	96,891
Underfunded and Unfunded Plans
Defined Benefit Plan, Change in Fair Value of Plan Assets
Funded status of the plans (underfunded)	53,081	63,514
Supplemental Retirement Plans
Defined Benefit Plan, Change in Benefit Obligation
Benefit obligation at beginning of period	11,652	11,868
Interest cost	352	465	450
Benefits paid	(1,001)	(1,045)
Actuarial (gains) losses	1,412	364
Benefit obligation at end of the period	12,415	11,652	11,868
Changes in actuarial (gains) losses due to discount rates	871	971
Changes in actuarial (gains) losses due to demographic experience	234	(281)
Changes in actuarial (gains) losses due to mortality assumptions	307	(326)
Defined Benefit Plan, Change in Fair Value of Plan Assets
Fair value of plan assets at beginning of period	0	0
Employer contributions	1,001	1,045
Benefits paid	(1,001)	(1,045)
Fair value of plan assets at end of the period	0	0	0
Funded status of the plans (underfunded)	(12,415)	(11,652)
Defined Benefit Plan, Accumulated Benefit Obligation	12,415	11,652
Other Postretirement Benefits Plans
Defined Benefit Plan, Change in Benefit Obligation
Benefit obligation at beginning of period	3,452	3,814
Service cost	0	10	16
Interest cost	99	152	150
Participant contributions	241	253
Plan amendments	0	(460)
Benefits paid	(658)	(751)
Premiums paid	7	7
Actuarial (gains) losses	225	412
Translation adjustment	15	29
Benefit obligation at end of the period	3,367	3,452	3,814
Changes in actuarial (gains) losses due to discount rates	235	334
Changes in actuarial (gains) losses due to demographic experience	(1)	172
Changes in actuarial (gains) losses due to mortality assumptions	(8)	(94)
Defined Benefit Plan, Change in Fair Value of Plan Assets
Fair value of plan assets at beginning of period	0	0
Employer contributions	424	505
Employee contributions	241	253
Benefits paid	(658)	(751)
Premiums paid	7	7
Fair value of plan assets at end of the period	0	0	$ 0
Funded status of the plans (underfunded)	$ (3,367)	$ (3,452)

Benefit Plans - Recognized on t

Benefit Plans - Recognized on the Balance Sheet (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Defined Benefit Pension Plans | United States
Defined Benefit Plan, Amounts for Asset (Liability) Recognized in Statement of Financial Position
Current liability	$ 0	$ 0
Noncurrent liability	(24,645)	(35,979)
Accumulated other comprehensive income (loss)	(4,463)	8,687
Net amount recognized	(29,108)	(27,292)
Defined Benefit Pension Plans | Foreign
Defined Benefit Plan, Amounts for Asset (Liability) Recognized in Statement of Financial Position
Current liability	(46)	(6)
Noncurrent liability	(15,975)	(15,878)
Accumulated other comprehensive income (loss)	1,075	(4,988)
Net amount recognized	(14,946)	(20,872)
Supplemental Retirement Plans
Defined Benefit Plan, Amounts for Asset (Liability) Recognized in Statement of Financial Position
Current liability	(1,039)	(1,019)
Noncurrent liability	(11,376)	(10,633)
Accumulated other comprehensive income (loss)	633	253
Net amount recognized	(11,782)	(11,399)
Other Postretirement Benefits Plans
Defined Benefit Plan, Amounts for Asset (Liability) Recognized in Statement of Financial Position
Current liability	(443)	(537)
Noncurrent liability	(2,924)	(2,915)
Accumulated other comprehensive income (loss)	680	524
Net amount recognized	$ (2,687)	$ (2,928)

Benefit Plans - Accumulated Oth

Benefit Plans - Accumulated Other Comprehensive Income (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Defined Benefit Pension Plans | United States
Accumulated Other Comprehensive (Income) Loss, Defined Benefit Plan, after Tax
Net gain (loss)	$ 13,964	$ 10,922
Gross amount recognized	13,964	10,922
Deferred income taxes	(18,427)	(2,235)
Net amount recognized	(4,463)	8,687
Defined Benefit Pension Plans | Foreign
Accumulated Other Comprehensive (Income) Loss, Defined Benefit Plan, after Tax
Net gain (loss)	(6,550)	(7,634)
Gross amount recognized	(6,550)	(7,634)
Deferred income taxes	7,625	2,646
Net amount recognized	1,075	(4,988)
Supplemental Retirement Plans
Accumulated Other Comprehensive (Income) Loss, Defined Benefit Plan, after Tax
Net gain (loss)	(731)	681
Gross amount recognized	(731)	681
Deferred income taxes	1,364	(428)
Net amount recognized	633	253
Other Postretirement Benefits Plans
Accumulated Other Comprehensive (Income) Loss, Defined Benefit Plan, after Tax
Prior service credit	596	828
Net gain (loss)	(182)	67
Gross amount recognized	414	895
Deferred income taxes	266	(371)
Net amount recognized	$ 680	$ 524

Benefit Plans - Net Periodic Be

Benefit Plans - Net Periodic Benefit Cost (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Defined Benefit Pension Plans | United States
Defined Benefit Plan, Net Periodic Benefit Cost (Credit)
Service cost	$ 769	$ 978	$ 1,019
Interest cost	8,595	10,281	9,599
Expected return on plan assets	(12,547)	(11,508)	(12,851)
Amortization of prior service cost	0	0	0
Amortization of net (gain) loss	0	0	0
Curtailment gain recognized	0	0	(576)
Settlement (gain) loss recognized	78	49	0
Net periodic expense (benefit)	(3,105)	(200)	(2,809)
Defined Benefit Pension Plans | Foreign
Defined Benefit Plan, Net Periodic Benefit Cost (Credit)
Service cost	3,895	3,210	3,104
Interest cost	2,193	2,627	2,637
Expected return on plan assets	(2,270)	(2,427)	(2,490)
Amortization of prior service cost	0	24	0
Amortization of net (gain) loss	148	(29)	49
Curtailment gain recognized	0	0	0
Settlement (gain) loss recognized	(14)	(1)	0
Net periodic expense (benefit)	3,952	3,404	3,300
Supplemental Retirement Plans
Defined Benefit Plan, Net Periodic Benefit Cost (Credit)
Interest cost	352	465	450
Amortization of net (gain) loss	0	(10)	0
Net periodic expense (benefit)	352	455	450
Other Postretirement Benefits Plans
Defined Benefit Plan, Net Periodic Benefit Cost (Credit)
Service cost	0	10	16
Interest cost	99	152	150
Amortization of prior service cost	(232)	(157)	(112)
Amortization of net (gain) loss	(29)	(33)	(26)
Net periodic expense (benefit)	$ (162)	$ (28)	$ 28

Benefit Plans - Accumulated Ben

Benefit Plans - Accumulated Benefit Obligation (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Defined Benefit Pension Plans | United States
Defined Benefit Plan Disclosure
Accumulated benefit obligation	$ 288,482	$ 266,992
Defined Benefit Plan, Funded (Unfunded) Status of Plan
Projected benefit obligation	288,482	267,392
Accumulated benefit obligation	288,482	266,992
Fair value of plan assets	263,837	231,413
Defined Benefit Pension Plans | Foreign
Defined Benefit Plan Disclosure
Accumulated benefit obligation	110,605	96,891
Defined Benefit Plan, Funded (Unfunded) Status of Plan
Projected benefit obligation	92,679	82,662
Accumulated benefit obligation	88,394	80,021
Fair value of plan assets	76,658	68,104
Supplemental Retirement Plans
Defined Benefit Plan Disclosure
Accumulated benefit obligation	$ 12,415	$ 11,652

Benefit Plans - Projected Benef

Benefit Plans - Projected Benefit Obligation (Details) - Defined Benefit Pension Plans - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
United States
Defined Benefit Plan Disclosure
Projected benefit obligation	$ 288,482	$ 267,392	$ 246,311
Defined Benefit Plan, Funded (Unfunded) Status of Plan
Projected benefit obligation	288,482	267,392
Plan assets	263,837	231,413
Foreign
Defined Benefit Plan Disclosure
Projected benefit obligation	114,889	101,192	$ 84,435
Defined Benefit Plan, Funded (Unfunded) Status of Plan
Projected benefit obligation	92,679	101,192
Plan assets	$ 76,658	$ 85,308

Benefit Plans - Weighted Averag

Benefit Plans - Weighted Average Assumptions for Pension Obligation (Details)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Defined Benefit Pension Plans | United States
Defined Benefit Plan, Weighted Average Assumptions Used in Calculating Benefit Obligation
Discount rate	2.42%	3.32%
Rate of compensation increase		3.00%
Defined Benefit Pension Plans | Foreign
Defined Benefit Plan, Weighted Average Assumptions Used in Calculating Benefit Obligation
Discount rate	1.78%	2.34%
Rate of compensation increase	2.05%	2.07%
Supplemental Retirement Plans
Defined Benefit Plan, Weighted Average Assumptions Used in Calculating Benefit Obligation
Discount rate	2.20%	3.10%
Other Postretirement Benefits Plans
Defined Benefit Plan, Weighted Average Assumptions Used in Calculating Benefit Obligation
Discount rate	2.18%	3.06%
Immediate trend rate	5.67%	5.91%
Ultimate trend rate	4.38%	4.39%
Year that the rate reaches ultimate trend rate	2038	2038

Benefit Plans - Weighted Aver_2

Benefit Plans - Weighted Average Assumptions for Net Periodic Cost (Details)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Defined Benefit Pension Plans | United States
Defined Benefit Plan, Weighted Average Assumptions Used in Calculating Net Periodic Benefit Cost
Discount rate	3.32%	4.32%	3.74%
Rate of compensation increase	3.00%	3.00%	3.00%
Expected return on assets	5.55%	6.00%	6.00%
Defined Benefit Pension Plans | Foreign
Defined Benefit Plan, Weighted Average Assumptions Used in Calculating Net Periodic Benefit Cost
Discount rate	2.34%	3.19%	3.11%
Rate of compensation increase	2.07%	2.08%	2.22%
Expected return on assets	2.82%	3.30%	3.37%
Supplemental Retirement Plans
Defined Benefit Plan, Weighted Average Assumptions Used in Calculating Net Periodic Benefit Cost
Discount rate	3.10%	4.20%	3.60%
Other Postretirement Benefits Plans
Defined Benefit Plan, Weighted Average Assumptions Used in Calculating Net Periodic Benefit Cost
Discount rate	3.06%	4.09%	3.53%

Benefit Plans - Plan Assets (De

Benefit Plans - Plan Assets (Details) - Defined Benefit Pension Plans - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Defined Benefit Plan Disclosure
Fair value of plan assets	$ 362,705	$ 316,721
Level 1
Defined Benefit Plan Disclosure
Fair value of plan assets	184,529	152,681
Level 2
Defined Benefit Plan Disclosure
Fair value of plan assets	172,340	159,326
Level 3
Defined Benefit Plan Disclosure
Fair value of plan assets	5,836	4,714	$ 4,322
Cash and cash equivalents
Defined Benefit Plan Disclosure
Fair value of plan assets	787	950
Cash and cash equivalents | Level 1
Defined Benefit Plan Disclosure
Fair value of plan assets	787	950
Cash and cash equivalents | Level 2
Defined Benefit Plan Disclosure
Fair value of plan assets	0	0
Cash and cash equivalents | Level 3
Defined Benefit Plan Disclosure
Fair value of plan assets	$ 0	0
Equity Securities | PQ Corporation Retirement Plan
Defined Benefit Plan Disclosure
Target asset plan allocation percentage	45.00%
Equity Securities | Eco Services Pension Equity Plan
Defined Benefit Plan Disclosure
Target asset plan allocation percentage	40.00%
Equity Securities | Eco Services Hourly Pension Plan
Defined Benefit Plan Disclosure
Target asset plan allocation percentage	60.00%
U.S. investment funds
Defined Benefit Plan Disclosure
Fair value of plan assets	$ 79,777	67,374
U.S. investment funds | Level 1
Defined Benefit Plan Disclosure
Fair value of plan assets	79,777	67,374
U.S. investment funds | Level 2
Defined Benefit Plan Disclosure
Fair value of plan assets	0	0
U.S. investment funds | Level 3
Defined Benefit Plan Disclosure
Fair value of plan assets	0	0
International investment funds
Defined Benefit Plan Disclosure
Fair value of plan assets	64,986	54,908
International investment funds | Level 1
Defined Benefit Plan Disclosure
Fair value of plan assets	53,792	44,905
International investment funds | Level 2
Defined Benefit Plan Disclosure
Fair value of plan assets	11,194	10,003
International investment funds | Level 3
Defined Benefit Plan Disclosure
Fair value of plan assets	$ 0	0
Fixed income securities | PQ Corporation Retirement Plan
Defined Benefit Plan Disclosure
Target asset plan allocation percentage	55.00%
Fixed income securities | Eco Services Pension Equity Plan
Defined Benefit Plan Disclosure
Target asset plan allocation percentage	60.00%
Fixed income securities | Eco Services Hourly Pension Plan
Defined Benefit Plan Disclosure
Target asset plan allocation percentage	40.00%
Government securities
Defined Benefit Plan Disclosure
Fair value of plan assets	$ 39,541	31,040
Government securities | Level 1
Defined Benefit Plan Disclosure
Fair value of plan assets	33,505	23,500
Government securities | Level 2
Defined Benefit Plan Disclosure
Fair value of plan assets	6,036	7,540
Government securities | Level 3
Defined Benefit Plan Disclosure
Fair value of plan assets	0	0
Corporate bonds
Defined Benefit Plan Disclosure
Fair value of plan assets	16,771	14,900
Corporate bonds | Level 1
Defined Benefit Plan Disclosure
Fair value of plan assets	16,668	14,782
Corporate bonds | Level 2
Defined Benefit Plan Disclosure
Fair value of plan assets	103	118
Corporate bonds | Level 3
Defined Benefit Plan Disclosure
Fair value of plan assets	0	0
Investment fund bonds
Defined Benefit Plan Disclosure
Fair value of plan assets	112,024	106,198
Investment fund bonds | Level 1
Defined Benefit Plan Disclosure
Fair value of plan assets	0	1,170
Investment fund bonds | Level 2
Defined Benefit Plan Disclosure
Fair value of plan assets	112,024	105,028
Investment fund bonds | Level 3
Defined Benefit Plan Disclosure
Fair value of plan assets	0	0
Insurance contracts
Defined Benefit Plan Disclosure
Fair value of plan assets	48,819	41,351
Insurance contracts | Level 1
Defined Benefit Plan Disclosure
Fair value of plan assets	0	0
Insurance contracts | Level 2
Defined Benefit Plan Disclosure
Fair value of plan assets	42,983	36,637
Insurance contracts | Level 3
Defined Benefit Plan Disclosure
Fair value of plan assets	$ 5,836	$ 4,714

Benefit Plans - Level 3 Rollfor

Benefit Plans - Level 3 Rollforward (Details) - Defined Benefit Pension Plans - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Defined Benefit Plan Disclosure
Fair value of plan assets at beginning of period	$ 316,721
Fair value of plan assets at end of the period	362,705	$ 316,721
Level 3
Defined Benefit Plan Disclosure
Fair value of plan assets at beginning of period	4,714	4,322
Actual return on plan assets	113	111
Benefits paid	(78)	(69)
Contributions	577	441
Exchange rate changes and other	510	(91)
Fair value of plan assets at end of the period	$ 5,836	$ 4,714

Benefit Plans - Benefit Plan, F

Benefit Plans - Benefit Plan, Future Payments (Details) $ in Thousands	Dec. 31, 2020USD ($)
Defined Benefit Pension Plans | United States
Defined Benefit Plan, Expected Future Benefit Payment
2021	$ 17,138
2022	16,200
2023	16,278
2024	16,254
2025	15,968
Years 2026-2030	78,910
Expected future payments	446
Defined Benefit Pension Plans | Foreign
Defined Benefit Plan, Expected Future Benefit Payment
2021	2,204
2022	2,384
2023	2,610
2024	2,898
2025	3,144
Years 2026-2030	19,027
Expected future payments	3,559
Supplemental Retirement Plans
Defined Benefit Plan, Expected Future Benefit Payment
2021	1,039
2022	1,010
2023	977
2024	944
2025	908
Years 2026-2030	3,944
Expected future payments	1,039
Other Postretirement Benefits Plans
Defined Benefit Plan, Expected Future Benefit Payment
2021	443
2022	372
2023	297
2024	281
2025	163
Years 2026-2030	816
Expected future payments	$ 443

Benefit Plans - Defined Contrib

Benefit Plans - Defined Contribution Plan (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Retirement Benefits [Abstract]
Defined Contribution expense	$ 11,490	$ 11,366	$ 11,253

Stock-Based Compensation - Narr

Stock-Based Compensation - Narratives (Details) - USD ($)	Dec. 14, 2020	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Sep. 30, 2017	Apr. 30, 2020	Oct. 03, 2017	May 04, 2016
Share-based Compensation Arrangement by Share-based Payment Award
Dividends paid on common stock (in dollars per share)	$ 1.80	$ 1.80
Additional stock compensation expense		$ 2,144,000
Proceeds from stock options exercised		373,000	$ 3,975,000	$ 131,000
Stock compensation expense		21,527,000	16,212,000	18,419,000
Stock compensation expense, tax benefit		$ 5,664,000	3,543,000	4,671,000
Discontinued Operations
Share-based Compensation Arrangement by Share-based Payment Award
Dividends paid on common stock (in dollars per share)		$ 1.80
Additional stock compensation expense		$ 654,000
Stock Option
Share-based Compensation Arrangement by Share-based Payment Award
Expiration period		10 years
Intrinsic value of stock options exercised		$ 3,615,000
Proceeds from stock options exercised		3,975,000
Restricted Stock Units
Share-based Compensation Arrangement by Share-based Payment Award
Unrecognized stock-based compensation expense, other than options		$ 20,511,000
Unrecognized stock-based compensation expense, period for recognition		1 year 7 months 2 days
Fair value of awards vested		$ 11,269,000	8,493,000	13,628,000
Performance Stock Units
Share-based Compensation Arrangement by Share-based Payment Award
Award requisite service period		3 years
Unrecognized stock-based compensation expense, other than options		$ 10,982,000
Unrecognized stock-based compensation expense, period for recognition		1 year 7 months 17 days
Performance Shares
Share-based Compensation Arrangement by Share-based Payment Award
Stock compensation expense		$ 0
Restricted Stock Awards
Share-based Compensation Arrangement by Share-based Payment Award
Fair value of awards vested		$ 510,000	$ 1,543,000	$ 3,493,000
Board of Directors | Restricted Stock Units
Share-based Compensation Arrangement by Share-based Payment Award
Award vesting period		1 year
Employee | Restricted Stock Units
Share-based Compensation Arrangement by Share-based Payment Award
Award vesting period		3 years
Exit event exceeding threshold | Performance Shares
Share-based Compensation Arrangement by Share-based Payment Award
Award vesting percentage		100.00%
2016 Stock Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award
Shares authorized (shares)								8,017,038
Share awards issued (shares)					7,644,518
2017 Omnibus Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award
Shares reserved for issuance (shares)							7,344,000
Number of shares available for grant (shares)		12,405,315				9,000,000	372,520
Minimum | Performance Stock Units
Share-based Compensation Arrangement by Share-based Payment Award
Award vesting percentage		0.00%
Maximum | Performance Stock Units
Share-based Compensation Arrangement by Share-based Payment Award
Award vesting percentage		200.00%

Stock-Based Compensation - Stoc

Stock-Based Compensation - Stock Option Activity (Details) - Stock Option - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding
Beginning balance (shares)	2,374,357	2,941,154	2,715,170
Granted (shares)			241,316
Exercised (shares)	(43,250)	(492,498)	(15,332)
Forfeited (shares)	(157,776)	(74,299)
Ending balance (shares)	2,173,331	2,374,357	2,941,154
Exercisable (shares)	1,796,519
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price
Beginning balance (weighted average exercise price, usd per share)	$ 11.44	$ 10.79	$ 10.18
Granted (weighted average exercise price, usd per share)			17.50
Exercised (weighted average exercise price, usd per share)	8.64	8.07	8.51
Forfeited (weighted average exercise price, usd per share)	9.23	8.16
Ending balance (weighted average exercise price, usd per share)	9.84	$ 11.44	$ 10.79
Exercisable (weighted average exercise price, usd per share)	$ 10.50
Outstanding (weighted average contractual term)	5 years 11 months 8 days
Outstanding (aggregate intrinsic value)	$ 10,452
Exercisable (weighted average contractual term)	6 years
Exercisable (aggregate intrinsic value)	$ 7,611
Expiration period	10 years

Stock-Based Compensation - St_2

Stock-Based Compensation - Stock Option Assumptions and Methodology (Details) - $ / shares	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2018
Monte Carlo simulation
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions and Methodology
Expected dividend yield, Monte Carlo simulation	0.00%
Risk-free interest rate, Monte Carlo simulation	1.56%
Expected volatility rate, Monte Carlo simulation	28.57%
Expected term, Monte Carlo simulation	2 years 11 months 12 days
Grant date fair value, Monte Carlo simulation	24.11
Stock Option | Black-Sholes option pricing model
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions and Methodology
Expected term (in years)		5 years 9 months
Expected volatility		26.38%
Risk-free interest rate		2.86%
Expected dividend yield		0.00%
Weighted average grant date fair value of options granted (usd per share)		$ 5.47

Stock-Based Compensation - Rest

Stock-Based Compensation - Restricted Stock Awards and Units (Details) - $ / shares	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Restricted Stock Awards
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares
Beginning balance nonvested (shares)	1,546,130	1,770,660	2,096,637
Granted (shares)	0	0	14,498
Vested (shares)	(29,760)	(97,140)	(223,298)
Forfeited (shares)	(619,355)	(127,390)	(117,177)
Ending balance nonvested (shares)	897,015	1,546,130	1,770,660
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value
Beginning balance nonvested (weighted average grant date fair value, usd per share)	$ 8.17	$ 8.39	$ 8.87
Granted (weighted average grant date fair value, usd per share)	0	0	13.80
Vested (weighted average grant date fair value, usd per share)	12.32	12.32	12.18
Forfeited (weighted average grant date fair value, usd per share)	8.04	8.04	8.04
Ending balance nonvested (weighted average grant date fair value, usd per share)	$ 13.80	$ 8.17	$ 8.39
Restricted Stock Units
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares
Beginning balance nonvested (shares)	1,628,436	998,786	1,654,690
Granted (shares)	1,158,605	1,245,628	161,598
Vested (shares)	(816,866)	(541,383)	(797,859)
Forfeited (shares)	(129,036)	(74,595)	(19,643)
Ending balance nonvested (shares)	1,841,139	1,628,436	998,786
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value
Beginning balance nonvested (weighted average grant date fair value, usd per share)	$ 15.83	$ 16.83	$ 16.97
Granted (weighted average grant date fair value, usd per share)	16.60	15.42	16.12
Vested (weighted average grant date fair value, usd per share)	16.17	16.68	16.97
Forfeited (weighted average grant date fair value, usd per share)	16.28	16.09	16.97
Ending balance nonvested (weighted average grant date fair value, usd per share)	$ 16.14	$ 15.83	$ 16.83
Performance Stock Units
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares
Beginning balance nonvested (shares)	550,676	0	0
Granted (shares)	456,311	550,676	0
Vested (shares)	0	0	0
Forfeited (shares)	(41,251)	0	0
Ending balance nonvested (shares)	965,736	550,676	0
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value
Beginning balance nonvested (weighted average grant date fair value, usd per share)	$ 15.41	$ 0	$ 0
Granted (weighted average grant date fair value, usd per share)	20.29	15.41	0
Vested (weighted average grant date fair value, usd per share)	0	0	0
Forfeited (weighted average grant date fair value, usd per share)	15.95	0	0
Ending balance nonvested (weighted average grant date fair value, usd per share)	$ 17.69	$ 15.41	$ 0

Earnings per Share - Reconcilia

Earnings per Share - Reconciliation from Basic to Diluted Weighted Average Shares Outstanding (Details) - shares	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Earnings Per Share [Abstract]
Weighted average shares outstanding – Basic (shares)	135,406,081	135,106,969	135,083,126	135,240,897	134,912,212	134,511,819	134,142,552	133,946,308	135,528,977	134,389,667	133,380,567
Dilutive effect of unvested common shares and restricted stock units with service conditions, performance stock units considered probable of vesting and assumed stock option exercises and conversions (shares)									0	1,159,027	1,304,364
Weighted average shares outstanding – Diluted (shares)	135,406,081	135,979,118	135,671,830	136,086,082	136,151,739	135,649,710	135,323,024	134,894,354	135,528,977	135,548,694	134,684,931

Earnings per Share - Reconcil_2

Earnings per Share - Reconciliation of Net Income (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Numerator:
Net income attributable to PQ Group Holdings Inc.	$ (299,059)	$ 4,138	$ 15,926	$ 224	$ 27,169	$ 18,645	$ 30,574	$ 3,151	$ (278,771)	$ 79,539	$ 58,300
Denominator:
Weighted average shares outstanding – Basic (shares)	135,406,081	135,106,969	135,083,126	135,240,897	134,912,212	134,511,819	134,142,552	133,946,308	135,528,977	134,389,667	133,380,567
Weighted average shares outstanding – Diluted (shares)	135,406,081	135,979,118	135,671,830	136,086,082	136,151,739	135,649,710	135,323,024	134,894,354	135,528,977	135,548,694	134,684,931
Net (loss) income per share:
Basic (loss) income per share	$ (2.21)	$ 0.03	$ 0.12	$ 0	$ 0.20	$ 0.14	$ 0.23	$ 0.02	$ (2.06)	$ 0.59	$ 0.44
Diluted (loss) income per share	$ (2.21)	$ 0.03	$ 0.12	$ 0	$ 0.20	$ 0.14	$ 0.23	$ 0.02	$ (2.06)	$ 0.59	$ 0.43

Earnings per Share - Anti-dilut

Earnings per Share - Anti-dilutive Shares (Details) - shares	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Restricted stock awards with performance only targets not yet achieved
Antidilutive Securities Excluded from Computation of Earnings Per Share
Antidilutive shares	1,225,855	1,584,980	1,643,760
Stock options with performance only targets not yet achieved
Antidilutive Securities Excluded from Computation of Earnings Per Share
Antidilutive shares	507,461	558,283	586,253
Anti-dilutive restricted stock awards, restricted stock units and performance stock units
Antidilutive Securities Excluded from Computation of Earnings Per Share
Antidilutive shares	1,453,120	0	5,162
Anti-dilutive stock options
Antidilutive Securities Excluded from Computation of Earnings Per Share
Antidilutive shares	846,049	863,063	717,612

Commitments and Contingent Li_3

Commitments and Contingent Liabilities - Narratives (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Soil And Groundwater Contamination
Loss Contingencies
Accrual for environmental loss contingencies	$ 1,278	$ 1,045
Subsurface Remedial and Wetlands/Marsh Management
Loss Contingencies
Accrual for environmental loss contingencies	510	770
Subsurface Remediation and Soil Vapor Extraction
Loss Contingencies
Accrual for environmental loss contingencies	427	$ 709
ABL Facility
Loss Contingencies
Letters of credit outstanding	$ 18,190

Commitments and Contingent Li_4

Commitments and Contingent Liabilities - Schedule of Purchase Obligations (Details) $ in Thousands	Dec. 31, 2020USD ($)
Purchase Obligation, Fiscal Year Maturity
2021	$ 13,695
2022	3,263
2023	1,654
2024	1,186
2025	1,183
Thereafter	995
Total purchase commitments	$ 21,976

Long-term Supply Contract (Deta

Long-term Supply Contract (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 01, 2014
Commitments and Contingencies Disclosure [Abstract]
Supply agreement liability				$ 27,300
Gain on contract termination	$ 0	$ 0	$ 20,612

Related Party Transactions (Det

Related Party Transactions (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Related Party Transaction
Debt extinguishment costs	$ 10,550	$ 0	$ 0
Corporate Joint Venture | Operating Lease Rental Payments
Related Party Transaction
Related party sales	310	305	295
Corporate Joint Venture | Sales from Partnership to Company
Related Party Transaction
Purchases from related party	861	803	645
Corporate Joint Venture | Manufacturing Costs
Related Party Transaction
Related party sales	16,065	19,976	16,869
Corporate Joint Venture | Services
Related Party Transaction
Related party sales	12,229	12,871	12,727
Corporate Joint Venture | Product Demonstration Costs
Related Party Transaction
Related party sales	1,853	2,204	1,768
INEOS Capital Partners
Related Party Transaction
Related party sales	12,672	4,841	5,587
Purchases from related party	$ 1,222	$ 1,203	$ 1,495

Quarterly Financial Summary (_3

Quarterly Financial Summary (Unaudited) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Quarterly Financial Information Disclosure [Abstract]
Sales	$ 281,505	$ 275,149	$ 254,896	$ 295,813	$ 283,535	$ 307,271	$ 311,641	$ 297,468	$ 1,107,363	$ 1,199,914	$ 1,228,926
Gross profit	67,227	70,172	63,662	72,295	65,898	82,913	81,863	67,728	273,356	298,402	303,392
Operating income	(245,623)	33,310	20,175	29,214	28,482	41,191	48,840	28,995	(162,924)	147,508	155,563
Net (loss) income from continuing operations	(186,702)	(6,956)	7,896	6,299	28,406	11,888	19,404	6,055	(179,463)	65,753	50,379
Net (loss) income from discontinued operations, net of tax	(116,194)	11,392	8,351	(5,790)	(1,007)	6,863	11,315	(2,614)	(102,241)	14,557	9,242
Net income	(302,896)	4,436	16,247	509	27,399	18,751	30,719	3,441	(281,704)	80,310	59,621
Less: Net (loss) income attributable to the noncontrolling interest - continuing operations	(3,883)	201	250	234	203	82	101	231	(3,198)	617	1,108
Net income attributable to PQ Group Holdings Inc.	$ (299,059)	$ 4,138	$ 15,926	$ 224	$ 27,169	$ 18,645	$ 30,574	$ 3,151	$ (278,771)	$ 79,539	$ 58,300
Earnings (loss) per common share - basic
Basic (loss) income per share - continuing operations	$ (1.35)	$ (0.05)	$ 0.06	$ 0.04	$ 0.21	$ 0.09	$ 0.14	$ 0.04	$ (1.30)	$ 0.48	$ 0.37
Basic (loss) income per share - discontinued operations	(0.86)	0.08	0.06	(0.04)	(0.01)	0.05	0.08	(0.02)	(0.76)	0.11	0.07
Basic (loss) income per share	(2.21)	0.03	0.12	0	0.20	0.14	0.23	0.02	(2.06)	0.59	0.44
Earnings (loss) per common share - diluted:
Diluted (loss) income per share - continuing operations	(1.35)	(0.05)	0.06	0.04	0.21	0.09	0.14	0.04	(1.30)	0.48	0.37
Diluted (loss) income per share - discontinued operations	(0.86)	0.08	0.06	(0.04)	(0.01)	0.05	0.08	(0.02)	(0.76)	0.11	0.07
Diluted (loss) income per share	$ (2.21)	$ 0.03	$ 0.12	$ 0	$ 0.20	$ 0.14	$ 0.23	$ 0.02	$ (2.06)	$ 0.59	$ 0.43
Weighted average shares outstanding:
Basic (shares)	135,406,081	135,106,969	135,083,126	135,240,897	134,912,212	134,511,819	134,142,552	133,946,308	135,528,977	134,389,667	133,380,567
Diluted (shares)	135,406,081	135,979,118	135,671,830	136,086,082	136,151,739	135,649,710	135,323,024	134,894,354	135,528,977	135,548,694	134,684,931
Less: Net income (loss) attributable to the noncontrolling interest - discontinued operations	$ 46	$ 97	$ 71	$ 51	$ 27	$ 24	$ 44	$ 59	$ 265	$ 154	$ 213

Supplemental Cash Flow Inform_3

Supplemental Cash Flow Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Cash paid during the year for:
Income taxes, net of refunds	$ 35,013	$ 17,406	$ 23,842
Interest	90,291	117,775	110,834
Non-cash investing activity:
Capital expenditures acquired on account but unpaid as of the year end	$ 11,630	$ 22,562	$ 23,498

Supplemental Cash Flow Inform_4

Supplemental Cash Flow Information - Cash and Restricted Cash Reconciliation (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Cash and Restricted Cash Reconciliation [Abstract]
Cash and cash equivalents	$ 135,531	$ 53,861	$ 37,164
Restricted cash included in prepaid and other current assets	1,688	1,331	1,435
Total cash, cash equivalents and restricted cash shown in the consolidated statements of cash flows	$ 137,219	$ 55,192	$ 38,599
Restricted cash, balance sheet line item	us-gaap:PrepaidExpenseAndOtherAssetsCurrent

Subsequent Events (Details)

Subsequent Events (Details) - Subsequent Event - USD ($) $ in Thousands	Mar. 01, 2021	Feb. 24, 2021
Subsequent Event [Line Items]
Proceeds from Divestiture of Businesses	$ 1,100,000
Total consideration, net of cash acquired		$ 44,000

Schedule I - Condensed Statemen

Schedule I - Condensed Statements of Income (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Condensed Financial Statements, Captions
Stock compensation									$ 21,527	$ 16,212	$ 18,419
Net income attributable to PQ Group Holdings Inc.	$ (299,059)	$ 4,138	$ 15,926	$ 224	$ 27,169	$ 18,645	$ 30,574	$ 3,151	(278,771)	79,539	58,300
Other comprehensive income (loss), net of tax:
Comprehensive income attributable to PQ Group Holdings Inc.									(293,263)	101,421	14,885
Parent Company
Condensed Financial Statements, Captions
Stock compensation									25,200	16,212	18,419
Equity in net loss (income) from subsidiaries									253,571	(95,751)	(76,719)
Net income attributable to PQ Group Holdings Inc.									(278,771)	79,539	58,300
Other comprehensive income (loss), net of tax:
Pension and postretirement benefits									1,938	2,430	(7,958)
Net (loss) gain from hedging activities									166	(2,665)	(330)
Foreign currency translation									(16,596)	22,117	(35,127)
Total other comprehensive income (loss)									(14,492)	21,882	(43,415)
Comprehensive income attributable to PQ Group Holdings Inc.									$ (293,263)	$ 101,421	$ 14,885

Schedule I - Condensed Balance

Schedule I - Condensed Balance Sheet (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
ASSETS
Total assets	$ 3,197,821	$ 4,321,741
LIABILITIES
Total liabilities	1,920,642	2,536,423
STOCKHOLDERS' EQUITY
Common stock	1,371	1,369
Preferred stock	0	0
Additional paid-in capital	1,477,859	1,696,899
(Accumulated deficit) retained earnings	(175,758)	103,013
Treasury Stock, Value	(11,081)	(6,483)
Accumulated other comprehensive loss	(15,265)	(15,348)
Total PQ Group Holdings Inc. equity	1,277,126	1,779,450
Total liabilities and equity	3,197,821	4,321,741
Parent Company
ASSETS
Investment in subsidiaries	1,277,126	1,779,450
Total assets	1,277,126	1,779,450
LIABILITIES
Total liabilities	0	0
STOCKHOLDERS' EQUITY
Common stock	1,371	1,369
Preferred stock	0	0
Additional paid-in capital	1,477,859	1,696,899
(Accumulated deficit) retained earnings	(175,758)	103,013
Treasury Stock, Value	(11,081)	(6,483)
Accumulated other comprehensive loss	(15,265)	(15,348)
Total PQ Group Holdings Inc. equity	1,277,126	1,779,450
Total liabilities and equity	$ 1,277,126	$ 1,779,450

Schedule I - Condensed Balanc_2

Schedule I - Condensed Balance Sheet Shares Data (Details) - $ / shares	Dec. 31, 2020	Dec. 31, 2019
Stockholders' Equity Attributable to Parent
Common stock, par value (usd per share)	$ 0.01	$ 0.01
Common stock, shares authorized (shares)	450,000,000	450,000,000
Common stock, shares issued (shares)	137,102,143	136,861,382
Common stock, shares outstanding (shares)	136,318,557	136,464,961
Preferred stock, par value (usd per share)	$ 0.01	$ 0.01
Preferred stock, shares authorized (shares)	50,000,000	50,000,000
Preferred stock, shares issued (shares)	0	0
Preferred stock, shares outstanding (shares)	0	0
Treasury stock (shares)	783,586	396,421
Parent Company
Stockholders' Equity Attributable to Parent
Common stock, par value (usd per share)	$ 0.01	$ 0.01
Common stock, shares authorized (shares)	450,000,000	450,000,000
Common stock, shares issued (shares)	137,102,143	136,861,382
Common stock, shares outstanding (shares)	136,318,557	136,464,961
Preferred stock, par value (usd per share)	$ 0.01	$ 0.01
Preferred stock, shares authorized (shares)	50,000,000	50,000,000
Preferred stock, shares issued (shares)	0	0
Preferred stock, shares outstanding (shares)	0	0
Treasury stock (shares)	783,586	396,421

Schedule I - Condensed Statem_2

Schedule I - Condensed Statement of Cash Flow (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Cash flows from operating activities:
Net (loss) income	$ (299,059)	$ 4,138	$ 15,926	$ 224	$ 27,169	$ 18,645	$ 30,574	$ 3,151	$ (278,771)	$ 79,539	$ 58,300
Adjustments to reconcile net (loss) income to net cash provided by operating activities:
Stock compensation									21,527	16,212	18,419
Net cash provided by operating activities									223,598	267,763	248,644
Cash flows from investing activities:
Dividends received from affiliated companies									40,989	40,073
Net cash (used in) provided by investing activities									551,472	(35,359)	(119,290)
Cash flows from financing activities:
Net cash (used in) provided by financing activities									(722,820)	(216,093)	(137,225)
Cash, cash equivalents and restricted cash at beginning of period				53,861				37,164	53,861	37,164
Cash, cash equivalents and restricted cash at end of period	135,531				53,861				135,531	53,861	37,164
Parent Company
Cash flows from operating activities:
Net (loss) income									(278,771)	79,539	58,300
Equity in net income from subsidiaries									253,571	(95,751)	(76,719)
Adjustments to reconcile net (loss) income to net cash provided by operating activities:
Stock compensation									25,200	16,212	18,419
Net cash provided by operating activities									0	0	0
Cash flows from investing activities:
Dividends received from affiliated companies									243,779	0	0
Net cash (used in) provided by investing activities									243,779	0	0
Cash flows from financing activities:
Dividends paid to stockholders									(243,779)	0	0
Net cash (used in) provided by financing activities									(243,779)	0	0
Effect of exchange rate changes on cash, cash equivalents and restricted cash									0	0	0
Net change in cash, cash equivalents and restricted cash									0	0	0
Cash, cash equivalents and restricted cash at beginning of period				$ 0				$ 0	0	0
Cash, cash equivalents and restricted cash at end of period	$ 0				$ 0				$ 0	$ 0	$ 0