Enviri (NVRI) 10-Q 2 Nov 21 2021 Q3 Quarterly report Financial data

Cover Page

Cover Page - shares	9 Months Ended
	Sep. 30, 2021	Oct. 29, 2021
Cover [Abstract]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Sep. 30, 2021
Document Transition Report	false
Entity File Number	001-03970
Entity Registrant Name	HARSCO CORP
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	23-1483991
Entity Address, Address Line One	350 Poplar Church Road,
Entity Address, City or Town	Camp Hill,
Entity Address, State or Province	PA
Entity Address, Postal Zip Code	17011
City Area Code	717
Local Phone Number	763-7064
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Shell Company	false
Entity Small Business	false
Entity Emerging Growth Company	false
Title of 12(b) Security	Common stock, par value $1.25 per share
Trading Symbol	HSC
Security Exchange Name	NYSE
Entity Common Stock, Shares Outstanding		79,203,660
Entity Central Index Key	0000045876
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2021
Document Fiscal Period Focus	Q3
Amendment Flag	false

CONDENSED CONSOLIDATED BALANCE

CONDENSED CONSOLIDATED BALANCE SHEETS (Unaudited) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Current assets:
Cash and cash equivalents	$ 75,578	$ 76,454
Restricted cash	4,525	3,215
Trade accounts receivable, net	425,897	407,390
Other receivables	39,454	34,253
Inventories	163,072	173,013
Current portion of contract assets	100,731	54,754
Prepaid Expense, Current	62,022	56,099
Other current assets	16,303	10,645
Total current assets	887,582	815,823
Property, plant and equipment, net	678,325	668,209
Right-of-use assets, net	98,841	96,849
Goodwill	896,728	902,074
Intangible assets, net	413,538	438,565
Deferred income tax assets	10,689	15,274
Other assets	52,470	56,493
Total assets	3,038,173	2,993,287
Current liabilities:
Short-term borrowings	13,892	7,450
Current maturities of long-term debt	9,181	13,576
Accounts payable	229,244	218,039
Accrued compensation	56,364	45,885
Income taxes payable	11,994	3,499
Current portion of advances on contracts	58,034	39,917
Current portion of operating lease liabilities	25,112	24,862
Other current liabilities	174,461	184,727
Total current liabilities	578,282	537,955
Long-term debt	1,333,574	1,271,189
Retirement plan liabilities	175,362	231,335
Advances on contracts	9,732	45,017
Operating lease liabilities	72,090	69,860
Environmental liabilities	28,589	29,424
Deferred tax liabilities	31,669	40,653
Other liabilities	55,648	54,455
Total liabilities	2,284,946	2,279,888
COMMITMENTS AND CONTINGENCIES
HARSCO CORPORATION STOCKHOLDERS' EQUITY
Common stock	144,856	144,288
Additional paid-in capital	213,095	204,078
Accumulated other comprehensive loss	(634,759)	(645,741)
Retained earnings	1,818,846	1,797,759
Treasury stock	(846,502)	(843,230)
Total Harsco Corporation stockholders’ equity	695,536	657,154
Noncontrolling interests	57,691	56,245
Total equity	753,227	713,399
Total liabilities and equity	$ 3,038,173	$ 2,993,287

CONDENSED CONSOLIDATED STATEMEN

CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS (Unaudited) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021		Sep. 30, 2020
Revenues from continuing operations:
Total revenues	$ 544,301	$ 509,398	$ 1,642,976		$ 1,355,520
Costs and expenses from continuing operations:
Selling, general and administrative expenses	82,090	87,954	247,798		241,224
Research and development expenses	764	568	2,210		2,620
Other (income) expenses, net	(2,835)	3,633	(7,810)		9,074
Total costs and expenses	514,381	504,334	1,552,013		1,345,707
Operating income from continuing operations	29,920	5,064	90,963		9,813
Interest income	618	604	1,841		1,613
Interest expense	(16,004)	(15,794)	(48,854)		(43,396)
Unused debt commitment fees, amendment fees and loss on extinguishment of debt	(198)	0	(5,506)		(1,920)
Defined benefit pension income	3,906	1,859	11,833		5,171
Income (loss) from continuing operations before income taxes and equity income	18,242	(8,267)	50,277		(28,719)
Income tax benefit (expense) from continuing operations	(6,989)	1,654	(19,782)		4,640
Equity income (loss) of unconsolidated entities, net	(293)	9	(488)		176
Income (loss) from continuing operations	10,960	(6,604)	30,007		(23,903)
Discontinued operations:
Gain (loss) on sale of discontinued business	0	0	0		18,371
Loss from discontinued businesses	(1,528)	(1,531)	(4,770)		(1,232)
Income tax benefit (expense) from discontinued businesses	396	(204)	1,236		(9,803)
Income (loss) from discontinued operations, net of tax	(1,132)	(1,735)	(3,534)		7,336
Net income (loss)	9,828	(8,339)	26,473		(16,567)
Less: Net income attributable to noncontrolling interests	(2,264)	(1,239)	(5,386)		(3,472)
Net income (loss) attributable to Harsco Corporation	7,564	(9,578)	21,087		(20,039)
Amounts attributable to Harsco Corporation common stockholders:
Income (loss) from continuing operations, net of tax	8,696	(7,843)	24,621		(27,375)
Income (loss) from discontinued operations, net of tax	(1,132)	(1,735)	(3,534)		7,336
Net income (loss) attributable to Harsco Corporation	$ 7,564	$ (9,578)	$ 21,087		$ (20,039)
Weighted-average shares of common stock outstanding	79,287	79,000	79,214		78,916
Basic earnings (loss) per common share attributable to Harsco Corporation common stockholders:
Continuing operations (in dollars per share)	$ 0.11	$ (0.10)	$ 0.31		$ (0.35)
Discontinued operations (in dollars per share)	(0.01)	(0.02)	(0.04)		0.09
Basic earnings (loss) per share attributable to Harsco Corporation common stockholders (in dollars per share)	$ 0.10	$ (0.12)	$ 0.27	[1]	$ (0.25)	[1]
Diluted weighted-average shares of common stock outstanding (in shares)	80,275	79,000	80,356		78,916
Diluted earnings (loss) per common share attributable to Harsco Corporation common stockholders:
Continuing operations (in dollars per share)	$ 0.11	$ (0.10)	$ 0.31		$ (0.35)
Discontinued operations (in dollars per share)	(0.01)	(0.02)	(0.04)		0.09
Diluted earnings (loss) per share attributable to Harsco Corporation common stockholders (in dollars per share)	$ 0.09	$ (0.12)	$ 0.26	[1]	$ (0.25)	[1]
Products And Services, Service Revenue
Revenues from continuing operations:
Total revenues	$ 438,624	$ 384,506	$ 1,299,805		$ 1,021,738
Costs and expenses from continuing operations:
Cost of services sold	348,243	313,330	1,031,258		835,879
Product Revenues
Revenues from continuing operations:
Total revenues	105,677	124,892	343,171		333,782
Costs and expenses from continuing operations:
Cost of services sold	$ 86,119	$ 98,849	$ 278,557		$ 256,910
[1]	Does not total due to rounding.

CONDENSED CONSOLIDATED STATEM_2

CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (Unaudited) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Statement of Comprehensive Income [Abstract]
Net income (loss)	$ 9,828	$ (8,339)	$ 26,473	$ (16,567)
Other comprehensive income (loss):
Foreign currency translation adjustments, net of deferred income taxes	(27,587)	17,527	(15,437)	(35,244)
Net loss on cash flow hedging instruments, net of deferred income taxes	822	(263)	1,745	(1,622)
Pension liability adjustments, net of deferred income taxes	17,768	(9,153)	23,812	28,037
Unrealized gain (loss) on marketable securities, net of deferred income taxes	0	9	25	(22)
Total other comprehensive income (loss)	(8,997)	8,120	10,145	(8,851)
Total comprehensive income (loss)	831	(219)	36,618	(25,418)
Less: Comprehensive (income) loss attributable to noncontrolling interests	(1,820)	(2,795)	(4,549)	(4,053)
Comprehensive loss attributable to Harsco Corporation	$ (989)	$ (3,014)	$ 32,069	$ (29,471)

CONDENSED CONSOLIDATED STATEM_3

CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (Unaudited) (Parenthetical) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Statement of Comprehensive Income [Abstract]
Foreign currency translation adjustments, deferred income taxes	$ (1,850)	$ 2,418	$ (675)	$ (2,323)
Net gain (loss) on cash flow hedging instruments, deferred income taxes	(217)	(125)	(519)	141
Pension liability adjustments, deferred income taxes	(358)	(323)	(1,054)	(2,356)
Unrealized gain (loss) on marketable securities, deferred income taxes	$ 0	$ (4)	$ (9)	$ 8

CONDENSED CONSOLIDATED STATEM_4

CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (Unaudited) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020
Cash flows from operating activities:
Net income (loss)	$ 26,473	$ (16,567)
Adjustments to reconcile net income (loss) to net cash provided by operating activities:
Depreciation	98,383	93,864
Amortization	26,554	24,721
Deferred income tax (benefit) expense	(8,911)	2,346
Equity (income) loss of unconsolidated entities, net	488	(176)
Gain on sale from discontinued business	0	(18,371)
Loss on early extinguishment of debt	2,668	0
Other, net	(1,147)	(336)
Changes in assets and liabilities, net of acquisitions and dispositions of businesses:
Accounts receivable	(32,563)	26,308
Increase (Decrease) in Income Taxes Receivable	735	(11,168)
Inventories	3,557	(11,801)
Contract assets	(52,205)	(26,775)
Right-of-use assets	21,050	18,195
Accounts payable	12,111	(1,488)
Accrued interest payable	(7,840)	(9,984)
Accrued compensation	12,098	1,795
Advances on contracts	(13,997)	19,145
Operating lease liabilities	(20,554)	(17,864)
Retirement plan liabilities, net	(36,700)	(23,902)
Income taxes payable - Gain on sale of discontinued businesses	0	(10,342)
Other assets and liabilities	16,550	4,676
Net cash provided by operating activities	46,750	42,276
Cash flows from investing activities:
Purchases of property, plant and equipment	(109,507)	(79,096)
Purchases of businesses, net of cash acquired	0	(432,855)
Proceeds from Divestiture of Businesses	0	37,219
Proceeds from sales of assets	15,512	4,473
Expenditures for intangible assets	(287)	(169)
Proceeds from notes receivable	6,400	0
Net proceeds (payments) from settlement of foreign currency forward exchange contracts	(1,064)	536
Other investing activities, net	181	(197)
Net cash used by investing activities	(88,765)	(470,089)
Cash flows from financing activities:
Short-term borrowings, net	4,650	1,712
Current maturities and long-term debt:
Additions	507,468	580,903
Reductions	(452,351)	(111,999)
Dividends paid to noncontrolling interests	(3,103)	0
Stock-based compensation - Employee taxes paid	(3,273)	(4,188)
Payment of contingent consideration	(734)	(2,342)
Deferred financing costs	(7,828)	(1,928)
Other financing activities, net	(601)	(1,368)
Net cash provided by financing activities	44,228	460,790
Effect of exchange rate changes on cash and cash equivalents, including restricted cash	(1,779)	(6,567)
Net increase in cash and cash equivalents, including restricted cash	434	26,410
Cash and cash equivalents, including restricted cash, at beginning of period	79,669	59,732
Cash and cash equivalents, including restricted cash, at end of period	80,103	86,142
Supplemental Cash Flow Information [Abstract]
Change in accrual for purchases of property, plant and equipment included in accounts payable	$ 2,357	$ 3,060

CONDENSED CONSOLIDATED STATEM_5

CONDENSED CONSOLIDATED STATEMENTS OF EQUITY (Unaudited) - USD ($) $ in Thousands	Total	Common Stock Issued	Common Stock Treasury	Additional Paid-in Capital	Retained Earnings	Accumulated Other Comprehensive Loss	Noncontrolling Interests
Beginning balance at Dec. 31, 2019	$ 789,659	$ 143,400	$ (838,893)	$ 200,595	$ 1,824,100	$ (587,622)	$ 48,079
Increase (Decrease) in Stockholders' Equity
Net income (loss)	1,227				141		1,086
Total other comprehensive income	(30,002)					(28,854)	(1,148)
Vesting of restricted stock units and other stock grants, net	(889)	230	(889)	(230)
Vesting of performance share units, net	(3,205)	589	(3,205)	(589)
Amortization of unearned portion of stock-based compensation, net of forfeitures	2,080			2,080
Ending balance at Mar. 31, 2020	758,870	144,219	(842,987)	201,856	1,824,241	(616,476)	48,017
Beginning balance at Dec. 31, 2019	789,659	143,400	(838,893)	200,595	1,824,100	(587,622)	48,079
Increase (Decrease) in Stockholders' Equity
Net income (loss)	(16,567)
Total other comprehensive income	(8,851)
Ending balance at Sep. 30, 2020	766,414	144,268	(843,098)	206,113	1,804,061	(597,052)	52,122
Beginning balance at Mar. 31, 2020	758,870	144,219	(842,987)	201,856	1,824,241	(616,476)	48,017
Increase (Decrease) in Stockholders' Equity
Net income (loss)	(9,455)				(10,602)		1,147
Total other comprehensive income	13,031					12,858	173
Stock appreciation rights exercised, net	(16)	8	(16)	(8)
Vesting of performance share units, net	0	18	0	(18)
Amortization of unearned portion of stock-based compensation, net of forfeitures	2,086			2,086
Ending balance at Jun. 30, 2020	764,516	144,245	(843,003)	203,916	1,813,639	(603,618)	49,337
Increase (Decrease) in Stockholders' Equity
Net income (loss)	(8,339)				(9,578)		1,239
Total other comprehensive income	8,120					6,566	1,554
Stock appreciation rights exercised, net	(8)	3	(8)	(3)
Vesting of restricted stock units and other stock grants, net	(87)	20	(87)	(20)
Amortization of unearned portion of stock-based compensation, net of forfeitures	2,220			2,220
Noncontrolling Interest, Decrease from Distributions to Noncontrolling Interest Holders	(8)						(8)
Ending balance at Sep. 30, 2020	766,414	144,268	(843,098)	206,113	1,804,061	(597,052)	52,122
Beginning balance at Dec. 31, 2020	713,399	144,288	(843,230)	204,078	1,797,759	(645,741)	56,245
Increase (Decrease) in Stockholders' Equity
Net income (loss)	1,565				135		1,430
Total other comprehensive income	1,229					2,295	(1,066)
Stock appreciation rights exercised, net	(70)	9	(70)	(9)
Vesting of restricted stock units and other stock grants, net	(1,850)	312	(1,850)	(312)
Vesting of performance share units, net	(1,032)	155	(1,032)	(155)
Amortization of unearned portion of stock-based compensation, net of forfeitures	3,342			3,342
Ending balance at Mar. 31, 2021	716,583	144,764	(846,182)	206,944	1,797,894	(643,446)	56,609
Beginning balance at Dec. 31, 2020	713,399	144,288	(843,230)	204,078	1,797,759	(645,741)	56,245
Increase (Decrease) in Stockholders' Equity
Net income (loss)	26,473
Total other comprehensive income	10,145
Ending balance at Sep. 30, 2021	753,227	144,856	(846,502)	213,095	1,818,846	(634,759)	57,691
Beginning balance at Mar. 31, 2021	716,583	144,764	(846,182)	206,944	1,797,894	(643,446)	56,609
Increase (Decrease) in Stockholders' Equity
Net income (loss)	15,080				13,388		1,692
Total other comprehensive income	17,913					17,240	673
Stock appreciation rights exercised, net	(219)	28	(219)	(28)
Vesting of restricted stock units and other stock grants, net	0	44		(44)
Amortization of unearned portion of stock-based compensation, net of forfeitures	3,120			3,120
Noncontrolling Interest, Decrease from Distributions to Noncontrolling Interest Holders	(3,094)						(3,094)
Ending balance at Jun. 30, 2021	749,383	144,836	(846,401)	209,992	1,811,282	(626,206)	55,880
Increase (Decrease) in Stockholders' Equity
Net income (loss)	9,828				7,564		2,264
Total other comprehensive income	(8,997)					(8,553)	(444)
Vesting of restricted stock units and other stock grants, net	(101)	20	(101)	(20)
Amortization of unearned portion of stock-based compensation, net of forfeitures	3,123			3,123
Noncontrolling Interest, Decrease from Distributions to Noncontrolling Interest Holders	(9)						(9)
Ending balance at Sep. 30, 2021	$ 753,227	$ 144,856	$ (846,502)	$ 213,095	$ 1,818,846	$ (634,759)	$ 57,691

CONDENSED CONSOLIDATED STATEM_6

CONDENSED CONSOLIDATED STATEMENTS OF EQUITY (Unaudited) (Parenthetical) - USD ($) $ in Thousands	3 Months Ended
	Sep. 30, 2021	Jun. 30, 2021	Mar. 31, 2021	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020
Statement of Stockholders' Equity [Abstract]
Total other comprehensive income, deferred income taxes	$ (2,425)	$ 34	$ 134	$ 1,966	$ (1,229)	$ (5,267)
Vesting of restricted stock units and other stock grants (in shares)	10,824	34,986	144,967	10,910	14,211	104,840
Stock appreciation rights exercised (in shares)		13,061	3,842	1,609	6,744
Stock Issued During Period, Shares, Other			69,127			265,151
Noncontrolling Interest, Decrease from Distributions to Noncontrolling Interest Holders	$ (9)	$ (3,094)		$ (8)

Basis of Presentation

Basis of Presentation	9 Months Ended
	Sep. 30, 2021
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of Presentation	Basis of Presentation The Company has prepared these unaudited condensed consolidated financial statements in accordance with U.S. GAAP for interim financial information and with the instructions to Form 10-Q and Rule 10-01 of Regulation S-X of the SEC. Accordingly, the unaudited condensed consolidated financial statements do not include all information and disclosure required by U.S. GAAP for annual financial statements. The December 31, 2020 Condensed Consolidated Balance Sheet information contained in this Quarterly Report on Form 10-Q was derived from the 2020 audited consolidated financial statements. The unaudited condensed consolidated financial statements should be read in conjunction with the audited consolidated financial statements, including the notes thereto, included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2020. In the opinion of management, all adjustments (all of which are of a normal recurring nature) that are necessary for a fair statement are reflected in the unaudited condensed consolidated financial statements. Restricted Cash The Company had restricted cash of $4.5 million and $3.2 million at September 30, 2021 and December 31, 2020, respectively, and the restrictions are primarily related to collateral provided for certain guarantees of the Company's performance. Impact of COVID-19 Beginning in early 2020, overall global economic conditions were significantly impacted by COVID-19. The Company operated, since the onset of the pandemic, as a provider of certain essential services in the U.S. and other countries and overall business conditions have strengthened since the second quarter of 2020. And while COVID-19 continues to impact various lines of business within the Company and certain operations including as a result of subsequent supply-chain challenges and labor-market tightness, the Company expects that business conditions will improve meaningfully in 2021 compared with 2020. The Company did not record any long-lived asset impairments, indefinite-lived asset impairments, goodwill impairments, significant inventory write-downs or incremental accounts receivable reserves for current expected credit losses during the three or nine months ended September 30, 2021. However, should economic conditions deteriorate, including as a result of COVID-19 such charges are possible in future periods, which could have an adverse effect on the Company's future results of operations, cash flows, or financial condition. Reclassifications Certain reclassifications have been made to prior year amounts to conform with current year classifications.

Recently Adopted and Recently I

Recently Adopted and Recently Issued Accounting Standards	9 Months Ended
	Sep. 30, 2021
Accounting Changes and Error Corrections [Abstract]
Recently Adopted and Recently Issued Accounting Standards	Recently Adopted and Recently Issued Accounting Standards The following accounting standards have been adopted in 2021: On January 1, 2021 the Company adopted changes issued by the FASB which are intended to reduce complexity and simplify the accounting for income taxes in accordance with U.S. GAAP by removing certain exceptions related to investments, intraperiod allocations and interim calculations and clarifying existing guidance to improve consistent application. These changes did not have a material impact on the Company's condensed consolidated financial statements. The following accounting standards have been issued and become effective for the Company at a future date: In March 2020 the FASB issued changes that provide companies with optional guidance to ease the potential accounting burden associated with transitioning from reference rates that are expected to be discontinued. In response to the concerns about risks of IBORs and, particularly, the risk of cessation of LIBOR, regulators in several jurisdictions around the world have undertaken reference rate reform initiatives to identify alternative reference rates that are more observable or transaction-based and less susceptible to manipulation. The changes provide optional expedients and exceptions for applying U.S. GAAP to contracts, hedging relationships, and other transactions affected by reference rate reform if certain criteria are met. In January 2021, the FASB issued additional clarification changes. The changes must be adopted no later than December 31, 2022 with early adoption permitted. Management does not believe these changes will have a material impact on its condensed consolidated financial statements. In August 2020, the FASB issued changes which simplified the accounting for certain financial instruments with characteristics of liabilities and equity, including convertible instruments and contracts on an entity’s own equity. The changes must be

Acquisitions and Dispositions

Acquisitions and Dispositions	9 Months Ended
	Sep. 30, 2021
Business Combinations [Abstract]
Acquisitions and Dispositions	Acquisitions and Dispositions ESOL On April 6, 2020 the Company completed the acquisition of 100% of ESOL, an established hazardous waste transportation, processing and services provider with a comprehensive portfolio of disposal solutions for customers primarily across the industrial, retail and healthcare markets from Stericycle, Inc. for $429.0 million of cash consideration, inclusive of post-closing adjustments. In addition, as part of the acquisition, the Company entered into a non-compete agreement with Stericycle, Inc. The fair value recorded for the assets acquired and liabilities assumed for ESOL is as follows: Final (In millions) April 6 Measurement Period Adjustments September 30 Cash and cash equivalents $ 0.4 $ — $ 0.4 Trade accounts receivable 124.1 (1.5) 122.6 Inventory 5.0 — 5.0 Other current assets 0.7 (0.7) — Property, plant and equipment 105.3 (3.9) 101.4 Right-of-use assets 56.0 — 56.0 Goodwill 152.0 1.3 153.3 Intangible assets 161.0 — 161.0 Other assets 0.2 — 0.2 Accounts payable (48.6) (1.5) (50.1) Accrued expenses (17.5) (1.8) (19.3) Current portion of operating lease liabilities (16.6) — (16.6) Other current liabilities (6.4) (0.2) (6.6) Environmental liabilities (24.4) — (24.4) Deferred income taxes (15.5) (1.5) (17.0) Operating lease liabilities (39.4) — (39.4) Total identifiable net assets of ESOL 436.3 (9.8) 426.5 Non-compete agreement 2.5 — 2.5 Total identifiable net assets of ESOL, including non-compete agreement $ 438.8 $ (9.8) $ 429.0 The goodwill is primarily attributed to expected operational efficiencies and synergies from the expanded geographical scale of hazardous waste processing facilities resulting from combining the ESOL business with the existing Clean Earth business of the Company, as well as the value associated with the assembled workforce of ESOL. The Company expects $36.8 million of goodwill to be deductible for income tax purposes through 2030. The following table details the valuation of identifiable intangible assets and amortization periods for ESOL and the non-compete agreement entered into by the Company upon acquisition of ESOL: Final (Dollars in millions) Weighted-Average Amortization Period April 6 Measurement Period Adjustments September 30 Permits and rights 22 years $ 138.0 $ — $ 138.0 Customer relationships 10 years 23.0 — 23.0 Total identifiable intangible assets of ESOL 161.0 — 161.0 Non-compete agreement 4 years 2.5 — 2.5 Total identifiable intangible assets acquired $ 163.5 $ — $ 163.5 The Company valued the identifiable intangible assets using methodologies under the income approach including the multi-period excess earnings method, the distributor method, and the with-and-without method. The three and nine months ended September 30, 2020 include ESOL direct acquisition and integration costs of $10.6 million and $41.0 million, respectively, which are included in the Selling, general and administrative expenses, within the Corporate function, in the Company's Condensed Consolidated Statements of Operations. In addition to the acquisition and integration costs reflected in the Company's Condensed Consolidated Statements of Operations, the debt issuance costs associated with the issuance of debt to fund the acquisition are reflected, net of amortization subsequent to the acquisition date, as Long-term debt on the Company's Condensed Consolidated Balance Sheets. Clean Earth On June 28, 2019, the Company acquired 100% of the outstanding stock of Clean Earth, one of the largest U.S. providers of specialty waste processing and beneficial reuse solutions for hazardous wastes, contaminated materials and dredged volumes, for an enterprise valuation of approximately $625 million on a cash free, debt free basis, subject to normal working capital adjustments. The Company transferred approximately $628 million of cash consideration and agreed to reimburse the sellers for any usage of assumed net operating losses in a post-closing period for up to five years. Pro forma financial information The pro forma information below gives effect to the ESOL acquisition as if it had been completed on January 1, 2019. The pro forma information is not necessarily indicative of the Company’s results of operations had the acquisition been completed on the above date, nor is it necessarily indicative of future results. The pro forma information does not reflect any cost savings from operating efficiencies or synergies that could result from the acquisition and does not reflect the additional revenue opportunities following the acquisition. The pro forma information below includes the adjustments necessary to reflect additional depreciation and amortization expense based on the estimated fair value and useful lives of intangible assets and fixed assets acquired; includes additional interest expense of approximately $4.7 million for the nine months ended September 30, 2020 on the acquisition related borrowings used to finance the acquisition and excludes certain directly attributable acquisition and integration costs. In addition, the historical ESOL results include $8.9 million for the nine months ended September 30, 2020 of corporate expenses charged to ESOL from Stericycle. Nine Months Ended September 30 (In millions) 2020 Pro forma revenues $ 1,486.2 Pro forma net income (loss) attributed to Harsco Corporation (including discontinued operations) (a) 1.0 (a) Pro forma net income includes the after tax gain on the sale of IKG of approximately $9 million for the nine months ended September 30, 2020. Harsco Industrial Segment In January 2020 the Company sold IKG, and together with the 2019 sales of AXC and PK, this completed the divestiture of the former Harsco Industrial Segment originally announced in May 2019. The Harsco Industrial Segment has historically been a separate reportable segment with primary operations in North America and Latin America. In accordance with U.S. GAAP, the results of the former Harsco Industrial Segment are presented as discontinued operations and, as such, have been excluded from both continuing operations and segment results for the three and nine months ended September 30, 2020. Certain key selected financial information included in net income (loss) from discontinued operations for the former Harsco Industrial Segment is as follows: Three Months Ended Nine Months Ended September 30 September 30 (In millions) 2021 2020 2021 2020 Amounts for the former Harsco Industrial Segment: Total revenues $ — $ — $ — $ 10,203 Cost of products sold — — — 8,082 Gain on sale from discontinued business — — — 18,371 Income (loss) from discontinued business (856) (716) (2,859) (593) Additional amounts allocated to the former Harsco Industrial Segment: Selling, general and administrative expenses (b) $ 856 $ 521 $ 2,859 $ 1,710 (b) The Company has allocated directly attributable transaction costs to discontinued operations. In addition, this caption includes costs directly attributable to retained contingent liabilities of the Harsco Industrial Segment.

Accounts Receivable (Notes)

Accounts Receivable (Notes)	9 Months Ended
	Sep. 30, 2021
Receivables [Abstract]
Accounts and Nontrade Receivable [Text Block]	Accounts Receivable and Note Receivable Accounts receivable consist of the following: (In thousands) September 30 December 31 Trade accounts receivable $ 434,295 $ 414,891 Less: Allowance for expected credit losses (8,398) (7,501) Trade accounts receivable, net $ 425,897 $ 407,390 Other receivables (a) $ 39,454 $ 34,253 (a) Other receivables include employee receivables, insurance receivable, tax claims and refunds and other miscellaneous items not included in Trade accounts receivable, net. The provision for doubtful accounts related to trade accounts receivable was as follows: Three Months Ended Nine Months Ended September 30 September 30 (In thousands) 2021 2020 2021 2020 (Benefit) provision for expected credit losses and doubtful accounts related to trade accounts receivable $ (145) $ 861 $ 1,087 $ 1,098 At September 30, 2021 approximately $12.0 million of the Company's trade accounts receivable were past due by twelve months or more. Approximately $7.2 million of this amount is effectively reserved, and collection of the remaining balance is still ultimately expected. In January 2020 the Company sold IKG for $85.0 million including cash and a note receivable, subject to post-closing adjustments. The note receivable from the buyer has a face value of $40.0 million, bearing interest at 2.50%, that is paid in kind and matures on January 31, 2027. Any unpaid principal, along with any accrued but unpaid interest is payable at maturity. Prepayment is required in case of a change in control or a percentage of excess cash flow, as defined in the note receivable agreement. Because there are no scheduled payments under the terms of the note receivable, the balance is not classified as current as of September 30, 2021 and is included in the caption Other assets on the Condensed Consolidated Balance Sheet. The initial fair value of the note receivable was $34.3 million which was calculated using an average of various discounted cash flow scenarios based on anticipated timing of repayments (Level 3) and was a non-cash transaction. The note receivable is subsequently measured at amortized cost. Key inputs into the valuation model include: projected timing and amount of cash flows, pro forma debt rating, option-adjusted spread and U.S. Treasury spot rate. During the nine months ended September 30, 2021, the Company received a payment of $6.4 million related to excess cash flow. At September 30, 2021 the amortized cost of the note receivable was $30.6 million, compared with a fair value of $31.8 million. (In thousands) September 30 December 31 Note receivable $ 30,631 $ 35,806

Inventories

Inventories	9 Months Ended
	Sep. 30, 2021
Inventory Disclosure [Abstract]
Inventories	Inventories Inventories consist of the following: (In thousands) September 30 December 31 Finished goods $ 9,052 $ 8,505 Work-in-process 23,793 29,005 Raw materials and purchased parts 95,156 105,306 Stores and supplies 35,071 30,197 Total inventories $ 163,072 $ 173,013

Property, Plant and Equipment

Property, Plant and Equipment	9 Months Ended
	Sep. 30, 2021
Property, Plant and Equipment [Abstract]
Property, Plant and Equipment	Property, Plant and Equipment Property, plant and equipment consisted of the following: (In thousands) September 30 December 31 Land $ 75,469 $ 75,559 Land improvements 19,730 20,166 Buildings and improvements 253,659 249,954 Machinery and equipment 1,564,936 1,597,592 Uncompleted construction 69,206 42,185 Gross property, plant and equipment 1,983,000 1,985,456 Less: Accumulated depreciation (1,304,675) (1,317,247) Property, plant and equipment, net $ 678,325 $ 668,209

Leases

Leases	9 Months Ended
	Sep. 30, 2021
Leases [Abstract]
Leases	Leases The components of lease expense were as follows: Three Months Ended Nine Months Ended September 30 September 30 (In thousands) 2021 2020 2021 2020 Finance leases: Amortization expense $ 743 $ 377 $ 1,692 $ 1,115 Interest on lease liabilities 129 43 340 139 Operating leases 8,554 8,558 25,296 21,745 Variable and short-term lease expense 12,756 11,572 38,952 29,169 Sublease income (1) (51) (52) (150) Total lease expense from continuing operations $ 22,181 $ 20,499 $ 66,228 $ 52,018 Supplemental cash flow information related to leases was as follows: Nine Months Ended September 30 (In thousands) 2021 2020 Cash paid for amounts included in the measurement of lease liabilities: Cash flows from operating activities - Operating leases $ 24,747 $ 20,512 Cash flows from financing activities - Finance leases 1,978 997 ROU assets obtained in exchange for lease obligations: Operating leases $ 29,190 $ 62,507 Finance leases 5,911 1,613 Supplemental balance sheet information related to leases was as follows: (In thousands) September 30 December 31 Operating Leases: Operating lease ROU assets $ 98,841 $ 96,849 Current portion of operating lease liabilities 25,112 24,862 Operating lease liabilities 72,090 69,860 Finance Leases: Property, plant and equipment, net $ 12,508 $ 8,434 Current maturities of long-term debt 2,724 1,683 Long-term debt 10,011 6,867 Supplemental additional information related to leases was as follows: September 30 December 31 Other information: Weighted average remaining lease term - Operating leases (in years) 7.44 8.00 Weighted average remaining lease term - Finance leases (in years) 6.41 8.20 Weighted average discount rate - Operating leases 5.9 % 6.1 % Weighted average discount rate - Finance leases 4.9 % 5.1 % Maturities of lease liabilities were as follows: (In thousands) Operating Finance Year Ending December 31: 2021 (excluding the nine months ended September 30, 2021) $ 8,027 $ 849 2022 28,602 3,220 2023 22,897 3,001 2024 16,537 2,615 2025 11,284 1,576 After 2025 36,936 3,754 Total lease payments 124,283 15,015 Less: Imputed interest (27,081) (2,280) Total $ 97,202 $ 12,735
Leases	Leases The components of lease expense were as follows: Three Months Ended Nine Months Ended September 30 September 30 (In thousands) 2021 2020 2021 2020 Finance leases: Amortization expense $ 743 $ 377 $ 1,692 $ 1,115 Interest on lease liabilities 129 43 340 139 Operating leases 8,554 8,558 25,296 21,745 Variable and short-term lease expense 12,756 11,572 38,952 29,169 Sublease income (1) (51) (52) (150) Total lease expense from continuing operations $ 22,181 $ 20,499 $ 66,228 $ 52,018 Supplemental cash flow information related to leases was as follows: Nine Months Ended September 30 (In thousands) 2021 2020 Cash paid for amounts included in the measurement of lease liabilities: Cash flows from operating activities - Operating leases $ 24,747 $ 20,512 Cash flows from financing activities - Finance leases 1,978 997 ROU assets obtained in exchange for lease obligations: Operating leases $ 29,190 $ 62,507 Finance leases 5,911 1,613 Supplemental balance sheet information related to leases was as follows: (In thousands) September 30 December 31 Operating Leases: Operating lease ROU assets $ 98,841 $ 96,849 Current portion of operating lease liabilities 25,112 24,862 Operating lease liabilities 72,090 69,860 Finance Leases: Property, plant and equipment, net $ 12,508 $ 8,434 Current maturities of long-term debt 2,724 1,683 Long-term debt 10,011 6,867 Supplemental additional information related to leases was as follows: September 30 December 31 Other information: Weighted average remaining lease term - Operating leases (in years) 7.44 8.00 Weighted average remaining lease term - Finance leases (in years) 6.41 8.20 Weighted average discount rate - Operating leases 5.9 % 6.1 % Weighted average discount rate - Finance leases 4.9 % 5.1 % Maturities of lease liabilities were as follows: (In thousands) Operating Finance Year Ending December 31: 2021 (excluding the nine months ended September 30, 2021) $ 8,027 $ 849 2022 28,602 3,220 2023 22,897 3,001 2024 16,537 2,615 2025 11,284 1,576 After 2025 36,936 3,754 Total lease payments 124,283 15,015 Less: Imputed interest (27,081) (2,280) Total $ 97,202 $ 12,735

Goodwill and Other Intangible A

Goodwill and Other Intangible Assets	9 Months Ended
	Sep. 30, 2021
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill and Other Intangible Assets	Goodwill and Other Intangible Assets The following table reflects the changes in carrying amounts of goodwill by segment for the nine months ended September 30, 2021: (In thousands) Harsco Environmental Segment Harsco Harsco Rail Consolidated Balance at December 31, 2020 $ 406,401 $ 482,647 $ 13,026 $ 902,074 Changes to goodwill (a) — 1,232 — 1,232 Foreign currency translation (6,578) — — (6,578) Balance at September 30, 2021 $ 399,823 $ 483,879 $ 13,026 $ 896,728 (a) The changes to goodwill relate to the measurement period adjustments for the ESOL acquisition in the Harsco Clean Earth Segment. See Note 3, Acquisitions and Dispositions. The Company tests for goodwill impairment annually, or more frequently if indicators of impairment exist, or if a decision is made to dispose of a business. The Company performs its annual goodwill impairment test as of October 1 and monitors for triggering events on an ongoing basis. The Company determined that, as of September 30, 2021, no interim goodwill impairment testing was necessary. The Company has concluded that no triggering event occurred during the three months ended September 30, 2021. However, an economic downturn could impact the Company's future projected cash flows used to estimate fair value, and/or result in a sustained decrease in the Company's share price, which could indicate an impairment. Intangible assets, net, on the Company's Condensed Consolidated Balance Sheets consist of the following: September 30, 2021 December 31, 2020 (In thousands) Gross Carrying Accumulated Gross Carrying Accumulated Customer related $ 108,226 $ 53,757 $ 109,378 $ 48,057 Permits 308,998 30,856 308,705 18,955 Technology related 39,604 12,363 40,274 9,654 Trade names 31,876 6,797 31,949 4,834 Air rights 26,139 1,561 26,139 1,044 Patents 185 140 192 139 Non-compete Agreement 2,500 937 2,500 469 Other 3,896 1,475 3,911 1,331 Total $ 521,424 $ 107,886 $ 523,048 $ 84,483 Amortization expense for intangible assets was as follows: Three Months Ended Nine Months Ended September 30 September 30 (In thousands) 2021 2020 2021 2020 Amortization expense for intangible assets $ 8,115 $ 8,272 $ 24,514 $ 22,542 The estimated amortization expense for the next five fiscal years based on current intangible assets is as follows: (In thousands) 2021 2022 2023 2024 2025 Estimated amortization expense (b) $ 32,900 $ 32,400 $ 32,300 $ 31,800 $ 31,600 (b) These estimated amortization expense amounts do not reflect the potential effect of future foreign currency exchange fluctuations.

Debt and Credit Agreements

Debt and Credit Agreements	9 Months Ended
	Sep. 30, 2021
Debt Disclosure [Abstract]
Debt and Credit Agreements	Debt and Credit Agreements On March 10, 2021, the Company amended its Senior Secured Credit Facilities to, among other things, extend the maturity date of the Revolving Credit Facility to March 10, 2026, and to modify aspects of its total net leverage ratio covenant. The interest rate applicable to the Revolving Credit Facility bears interest at a rate, depending on total net leverage, ranging from 50 to 150 basis points over base rate or 150 to 250 basis points over LIBOR, subject to a zero floor. Under the amended agreement, the net debt to consolidated adjusted EBITDA ratio covenant is 5.75 through the end of 2021 and then decreases quarterly until reaching 4.0 in March 2023. In addition, the Company issued New Term Loans, as an additional tranche, under the Senior Secured Credit Facilities in an aggregate principal amount of $500 million. The New Term Loans bear interest at a rate per annum of 1.25% over base rate, subject to a zero floor, or 2.25% over LIBOR, subject to a 0.50% floor. The New Term Loans are subject to quarterly amortization of principal of 0.25%, beginning September 30, 2021. The proceeds of the New Term Loans were used to repay in full the outstanding Term Loan A and Term Loan B under the Senior Secured Credit Facilities, which were due on June 28, 2024 and December 8, 2024, respectively. The New Term Loans mature on March 10, 2028, or earlier, on the date that is 91 days prior to the maturity date of the Company’s 5.75% Senior Notes due 2027 if such Senior Notes are outstanding or have not been refinanced at such time. During the three and nine months ended September 30, 2021, the Company recognized total expenses of $0.2 million and $5.5 million related to the amended Senior Secured Credit Facilities in the caption Unused debt commitment fees, amendment fees and loss on extinguishment of debt on the Condensed Consolidated Statements of Operations, including a write-off of $2.7 million of previously recorded deferred financing costs. The Company has capitalized fees of $7.8 million related to the amendment of the Senior Secured Credit Facilities, all of which were paid as of September 30, 2021. Long-term debt consists of the following: (In thousands) September 30 December 31 Senior Secured Credit Facilities: New Term Loan $ 498,750 $ — Term Loan A — 280,000 Term Loan B — 218,188 Revolving Credit Facility 338,486 281,000 5.75% Notes, due July 31, 2027 500,000 500,000 Other financing payable (including finance leases) in varying amounts 24,406 21,344 Total debt obligations 1,361,642 1,300,532 Less: deferred financing costs (18,887) (15,767) Total debt obligations, net of deferred financing costs 1,342,755 1,284,765 Less: current maturities of long-term debt (9,181) (13,576) Long-term debt $ 1,333,574 $ 1,271,189

Employee Benefit Plans

Employee Benefit Plans	9 Months Ended
	Sep. 30, 2021
Retirement Benefits [Abstract]
Employee Benefit Plans	Employee Benefit Plans Three Months Ended September 30 Defined Benefit Pension Plans Net Periodic Pension Cost (Benefit) U.S. Plans International Plans (In thousands) 2021 2020 2021 2020 Service costs $ — $ — $ 489 $ 448 Interest costs 1,203 1,845 3,184 4,474 Expected return on plan assets (3,050) (2,842) (11,303) (10,405) Recognized prior service costs — — 125 113 Recognized loss 1,384 1,225 4,538 3,737 Defined benefit pension plans net periodic pension cost (benefit) $ (463) $ 228 $ (2,967) $ (1,633) Nine Months Ended September 30 Defined Benefit Pension Plans Net Periodic Pension Cost (Benefit) U.S. Plans International Plans (In thousands) 2021 2020 2021 2020 Service costs $ — $ — $ 1,482 $ 1,303 Interest costs 3,609 5,535 9,619 13,104 Expected return on plan assets (9,150) (8,526) (34,181) (30,428) Recognized prior service costs — — 381 326 Recognized loss 4,154 3,875 13,723 10,924 Defined benefit pension plans net periodic pension cost (benefit) $ (1,387) $ 884 $ (8,976) $ (4,771) Three Months Ended Nine Months Ended Company Contributions September 30 September 30 (In thousands) 2021 2020 2021 2020 Defined benefit pension plans (U.S.) $ 451 $ 453 $ 3,768 $ 2,940 Defined benefit pension plans (International) 4,549 2,682 21,472 14,235 Multiemployer pension plans 429 390 1,311 1,178 Defined contribution pension plans 2,974 2,870 9,507 7,936

Income Taxes

Income Taxes	9 Months Ended
	Sep. 30, 2021
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes Income tax expense from continuing operations for the three and nine months ended September 30, 2021 was $7.0 million and $19.8 million, respectively. Income tax benefit from continuing operations for the three and nine months ended September 30, 2020 was $1.7 million and $4.6 million, respectively. The change in the income tax expense for the three and nine months ended September 30, 2021 compared with the income tax benefit for the three and nine months ended September 30, 2020 is the result of higher pre-tax income, primarily due to an improvement in operations, acquisition and integration costs in 2020 not recurring in 2021, and a $2.8 million favorable income tax adjustment in connection with an increase in estimated usage of assumed net operating losses related to the Clean Earth acquisition in 2020 not recurring in 2021.The reserve for uncertain tax positions at September 30, 2021 was $4.3 million, including interest and penalties.  Within the next twelve months, it is reasonably possible that $0.3 million unrecognized income tax benefits will be recognized upon settlement of tax examinations and the expiration of various statutes of limitations.

Commitments and Contingencies

Commitments and Contingencies	1 Months Ended
	Dec. 31, 2018
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies Environmental The Company is involved in a number of environmental remediation investigations and cleanups and, along with other companies, has been identified as a “potentially responsible party” for certain byproduct disposal sites. While each of these matters is subject to various uncertainties, it is probable that the Company will agree to make payments toward funding certain of these activities, and it is possible that some of these matters will be decided unfavorably to the Company. The Company has evaluated its potential liability and its financial exposure is dependent upon such factors as the continuing evolution of environmental laws and regulatory requirements, the availability and application of technology, the allocation of cost among potentially responsible parties, the years of remedial activity required and the remediation methods selected. The Company evaluates its liability for future environmental remediation costs on a quarterly basis. Although actual costs to be incurred at identified sites in future periods may vary from the estimates (given inherent uncertainties in evaluating environmental exposures), the Company does not expect that any costs that are reasonably possible to be incurred by the Company in connection with environmental matters in excess of the amounts accrued would have a material adverse effect on the Company's financial condition, results of operations or cash flows. The following table summarizes information related to the location and undiscounted amount of the Company's environmental liabilities: (In thousands) September 30 December 31 Current portion of environmental liabilities (a) $ 7,005 $ 6,933 Long-term environmental liabilities 28,589 29,424 Total environmental liabilities $ 35,594 $ 36,357 (a) The current portion of environmental liabilities is included in the caption Other current liabilities on the Company's Condensed Consolidated Balance Sheets. Environmental liabilities relate primarily to the ESOL business which was acquired on April 6, 2020. As part of the ESOL acquisition, the Company assumed control of certain closed sites that were being monitored as part of ongoing environmental remediation plans. See Note 3, Acquisitions and Dispositions, for additional details. Legal Proceedings In the ordinary course of business, the company is a defendant or party to various claims and lawsuits, including those discussed below. On January 27, 2020, the U.S. EPA issued a Notice of Potential Liability to the Company, along with several other companies, concerning the Newtown Creek Superfund Site located in Kings and Queens Counties in New York. The Notice alleges certain facilities formerly owned or operated by subsidiaries of the Company may have resulted in the discharge of hazardous substances into Newtown Creek or its Dutch Kills tributary. The site has been subject to CERCLA response activities since approximately 2011. The U.S. EPA expects to propose a sitewide cleanup plan no sooner than 2024 and announced in July 2021 that it would defer its decision on a potential early action response for the lower two miles of the Creek until the sitewide studies are completed. The Company is one of approximately twenty (20) Potentially Responsible Parties that have received notices, though it is believed other PRPs may exist. The Company vigorously contests the allegations of the Notice and currently does not believe that this matter will have a material effect on the Company’s financial position. On June 25 and 26, 2018, the DTSC conducted a compliance enforcement inspection of ESOL’s facility in Rancho Cordova, California, which was then owned by Stericycle, Inc. On February 14, 2020, the DTSC filed an action in the Superior Court for the State of California, Sacramento Division, alleging violations of California’s Hazardous Waste Control Law and the facility’s hazardous waste permit arising from the inspection. On August 27, 2020 the DTSC issued a Notice of Denial of Hazardous Waste Facility Permit Application. On September 25, 2020, the Company filed an administrative appeal. On September 28, 2021, DTSC scheduled a public hearing on October 28, 2021 as part of its Violation Scoring Procedure (VSP) program to hear testimony on the compliance tier assignment assigned to the facility. The Company would have the ability to judicially challenge any adverse permit actions resulting from this process. The DTSC investigation and compliance issues leading to the compliance tier assignment were ongoing well before the Company's acquisition of the ESOL business, and the Company was aware of the investigation and many of the issues raised in the investigation at the time of the purchase. Accordingly, the Company is indemnified for certain fines and other costs and expenses associated with this matter by Stericycle, Inc. As a result, the administrative appeal and public hearing process will be led by Stericycle, Inc. The Company has not accrued any amounts in respect of these alleged violations and cannot estimate the reasonably possible loss or the range of reasonably possible losses that it may incur. As previously disclosed, the Company has had ongoing meetings with the SCE over processing salt cakes, a processing byproduct, stored at the Al Hafeerah site. The Company’s Bahrain operations that produced the salt cakes has ceased operations. An Environmental Impact Assessment and Technical Feasibility Study for facilities to process the salt cakes was approved by the SCE during the first quarter of 2018. Commissioning of the facilities was completed during the third quarter of 2021 and the processing of the salt cakes has commenced. The Company has previously established a reserve of $7.0 million, which represents the Company's best estimate of the ultimate costs to be incurred to resolve this matter. The Company continues to evaluate this reserve and any future change in estimated costs could be material to the Company’s results of operations in any one period. On July 27, 2018 Brazil’s Federal and Rio de Janeiro State Public Prosecution Offices (MPF and MPE) filed a Civil Public Action against one of the Company's customers (CSN), the Company’s Brazilian subsidiary, the Municipality of Volta Redonda, Brazil, and the Instituto Estadual do Ambiente (local environmental protection agency) seeking the implementation of various measures to limit and reduce the accumulation of customer-owned slag at the site in Brazil. On August 6, 2018 the 3rd Federal Court in Volta Redonda granted the MPF and MPE an injunction against the same parties requiring, among other things, CSN and the Company’s Brazilian subsidiary to limit the volume of slag sent to the site. Because the customer owns the site and the slag located on the site, the Company believes that complying with this injunction is the steel producer’s responsibility. On March 18, 2019 the Court issued an order fining the Company 5,000 Brazilian reais per day (or approximately $1 thousand per day) and CSN 20,000 Brazilian reais per day (or approximately $4 thousand per day) until the requirements of the injunction are met. On November 1, 2019 the Court issued an additional order increasing the fines assessed to the Company to 25,000 Brazilian reais per day (or approximately $5 thousand per day) and raising the fines assessed to CSN to 100,000 Brazilian reais per day (or approximately $18 thousand per day). The Court also assessed an additional fine of 10,000,000 Brazilian reais (or approximately $2 million) against CSN and the Company jointly. The Company is appealing the fines and the underlying injunction. Both the Company and CSN continue to have discussions with the governmental authorities on the injunction and the possible resolution of the underlying case. The Company does not believe that a loss relating to this matter is probable or estimable at this point. On October 19, 2018, local environmental authorities issued an enforcement action against the Company concerning the Company’s operations at a customer site in Ijmuiden, Netherlands. The enforcement action alleges violations of the Company’s environmental permit at the site, which restricts the release of any visible dust emissions. The enforcement action ordered the Company to cease all violations of the permit by October 31, 2018. The authorities have issued three additional enforcement actions since that time and have asserted fines of approximately $0.7 million which the Company has recorded, with the possibility of additional fines for any future violations. On or about October 14, 2021, the Company received a subpoena and two indictments on this matter before the Amsterdam District Court in the Netherlands. The Amsterdam Public Prosecutor’s Office issued the two indictments against the Company, alleging violations of Dutch environmental and criminal law in connection with dust releases and/or events alleged to have occurred in 2018 through May 2020 at the site. The indictments cite provisions which permit fines for the alleged infractions, although no specific fine is listed in the indictment. The Company is vigorously contesting the enforcement action and criminal charges and is also working with its customer to ensure the control of emissions. The Company has contractual indemnity rights from its customer that it believes will substantially cover any fines or penalties. DEA Investigation Prior to the Company’s acquisition of ESOL, Stericycle, Inc notified the Company that the DEA had served an administrative subpoena on Stericycle, Inc. and executed a search warrant at a facility in Rancho Cordova, California and an administrative inspection warrant at a facility in Indianapolis, Indiana. The Company has determined that the DEA and the DTSC have launched investigations involving, at least in part, the ESOL business of collecting, transporting, and destroying controlled substances from retail customers that transferred from Stericycle, Inc. to the Company. In connection with these investigations, the DEA also executed a search warrant on an ESOL facility in Austin Texas on July 2, 2020. The Company is cooperating with these inquiries, which relate primarily to the period before the Company owned the ESOL business. Since the acquisition of the ESOL business, the Company has performed a vigorous review of ESOL’s compliance program related to controlled substances and has made material changes to the manner in which controlled substances are transported from retail customers to DEA-registered facilities for destruction. The Company has not accrued any amounts in respect of these investigations and cannot estimate the reasonably possible loss or the range of reasonably possible losses that it may incur, if any. Investigations of this type are, by their nature, uncertain and unpredictable. While it is the Company’s position that it has recourse for some or all liabilities, if any, that arise from these matters under the ESOL purchase agreement and representations and warranties insurance policies purchased by the Company, there can be no assurances that the Company’s position will ultimately prevail. Brazilian Tax Disputes The Company is involved in a number of tax disputes with federal, state and municipal tax authorities in Brazil. These disputes are at various stages of the legal process, including the administrative review phase and the collection action phase, and include assessments of fixed amounts of principal and penalties, plus interest charges that increase at statutorily determined amounts per month and are assessed on the aggregate amount of the principal and penalties. In addition, the losing party, at the collection action or court of appeals phase, could be subject to a charge to cover statutorily mandated legal fees, which are generally calculated as a percentage of the total assessed amounts due, inclusive of penalty and interest. Many of the claims relate to ICMS, services and social security tax disputes. The largest proportion of the assessed amounts relate to ICMS claims filed by the SPRA, encompassing the period from January 2002 to May 2005. In October 2009, the Company received notification of the SPRA’s final administrative decision regarding the levying of ICMS in the State of São Paulo in relation to services provided to a customer in the State between January 2004 and May 2005. As of September 30, 2021 the principal amount of the tax assessment from the SPRA with regard to this case is approximately $1.1 million, with penalty, interest and fees assessed to date increasing such amount by an additional $15.8 million. On June 4, 2018 the Appellate Court of the State of Sao Paulo ruled in favor of the SPRA but ruled that the assessed penalty should be reduced to approximately $1.1 million. After calculating the interest accrued on the penalty, the Company estimates that this ruling reduces the current overall potential liability for this case to approximately $6.7 million. All such amounts include the effect of foreign currency translation. The Company has appealed the ruling in favor of the SPRA to the Superior Court of Justice. Due to multiple court precedents in the Company’s favor, as well as the Company’s ability to appeal, the Company does not believe a loss is probable. Another ICMS tax case involving the SPRA refers to the tax period from January 2002 to December 2003. In December 2018 the administrative tribunal hearing the case upheld the Company's liability. The Company has appealed to the judicial phase. The aggregate amount assessed by the tax authorities in August 2005 was $4.7 million (the amounts with regard to this claim are valued as of the date of the assessment since it has not yet reached the collection phase), composed of a principal amount of $1.1 million, with penalty and interest assessed through that date increasing such amount by an additional $3.6 million. On December 6, 2018 the administrative tribunal reduced the applicable penalties to $0.8 million. After calculating the interest accrued on the current penalty, the Company estimates that the current overall liability for this case to be approximately $5.2 million. All such amounts include the effect of foreign currency translation. Due to multiple court precedents in the Company's favor, the Company does not believe a loss is probable. The Company continues to believe that sufficient coverage for these claims exists as a result of the indemnification obligations of the Company's customer and such customer’s pledge of assets in connection with the October 2009 notice, as required by Brazilian law. On December 30, 2020, the Company received an assessment from the municipal authority in Ipatinga, Brazil alleging approximately $2.0 million in unpaid service taxes from the period 2015 to 2020. After calculating the interest and penalties accrued, the Company estimates that the current overall potential liability for this case to be approximately $3.3 million. On January 18, 2021, the Company filed a challenge to the assessment. Due to the multiple defenses that are available, the Company does not believe a loss is probable. The Company intends to continue its practice of vigorously defending itself against these tax claims under various alternatives, including judicial appeal. The Company will continue to evaluate its potential liability with regard to these claims on a quarterly basis; however, it is not possible to predict the ultimate outcome of these tax-related disputes in Brazil. No loss provision has been recorded in the Company's condensed consolidated financial statements for the disputes described above because the loss contingency is not deemed probable, and the Company does not expect that any costs that are reasonably possible to be incurred by the Company in connection with Brazilian tax disputes would have a material adverse effect on the Company's financial condition, results of operations or cash flows. Brazilian Labor Disputes The Company is subject to ongoing collective bargaining and individual labor claims in Brazil through the Harsco Environmental Segment which allege, among other things, the Company's failure to pay required amounts for overtime and vacation at certain sites. The Company is vigorously defending itself against these claims; however, litigation is inherently unpredictable, particularly in foreign jurisdictions. While the Company does not currently expect that the ultimate resolution of these claims will have a material adverse effect on the Company’s financial condition, results of operations or cash flows, it is not possible to predict the ultimate outcome of these labor-related disputes. As of September 30, 2021 and December 31, 2020 the Company has established reserves of $3.5 million and $4.3 million, respectively, on the Company's Condensed Consolidated Balance Sheets for amounts considered to be probable and estimable. Other The Company is named as one of many defendants (approximately 90 or more in most cases) in legal actions in the U.S. alleging personal injury from exposure to airborne asbestos over the past several decades. In their suits, the plaintiffs have named as defendants, among others, many manufacturers, distributors and installers of numerous types of equipment or products that allegedly contained asbestos. The Company believes that the claims against it are without merit. The Company has never been a producer, manufacturer or processor of asbestos fibers. Any asbestos-containing part of a Company product used in the past was purchased from a supplier and the asbestos encapsulated in other materials such that airborne exposure, if it occurred, was not harmful and is not associated with the types of injuries alleged in the pending actions. At September 30, 2021 there were approximately 17,200 pending asbestos personal injury actions filed against the Company. Of those actions, approximately 16,610 were filed in the New York Supreme Court (New York County), approximately 120 were filed in other New York State Supreme Court Counties and approximately 470 were filed in courts located in other states. The complaints in most of those actions generally follow a form that contains a standard damages demand of $20 million or $25 million, regardless of the individual plaintiff’s alleged medical condition, and without identifying any specific Company product. At September 30, 2021 approximately 16,550 of the actions filed in New York Supreme Court (New York County) were on the Deferred/Inactive Docket created by the court in December 2002 for all pending and future asbestos actions filed by persons who cannot demonstrate that they have a malignant condition or discernible physical impairment. The remaining approximately 60 cases in New York County are pending on the Active or In Extremis Docket created for plaintiffs who can demonstrate a malignant condition or physical impairment. The Company has liability insurance coverage under various primary and excess policies that the Company believes will be available, if necessary, to substantially cover any liability that might ultimately be incurred in the asbestos actions referred to above. The costs and expenses of the asbestos actions are being paid by the Company's insurers. In view of the persistence of asbestos litigation in the U.S., the Company expects to continue to receive additional claims in the future. The Company intends to continue its practice of vigorously defending these claims and cases. At September 30, 2021 the Company has obtained dismissal in approximately 28,350 cases by stipulation or summary judgment prior to trial. It is not possible to predict the ultimate outcome of asbestos-related actions in the U.S. due to the unpredictable nature of this litigation, and no loss provision has been recorded in the Company's condensed consolidated financial statements because a loss contingency is not deemed probable or estimable. Despite this uncertainty, and although results of operations and cash flows for a given period could be adversely affected by asbestos-related actions, the Company does not expect that any costs that are reasonably possible to be incurred by the Company in connection with asbestos litigation would have a material adverse effect on the Company's financial condition, results of operations or cash flows. The Company is subject to various other claims and legal proceedings covering a wide range of matters that arose in the ordinary course of business. In the opinion of management, all such matters are adequately covered by insurance or by established reserves, and, if not so covered, are without merit or are of such kind, or involve such amounts, as would not have a material adverse effect on the financial position, results of operations or cash flows of the Company. Insurance liabilities are recorded when it is probable that a liability has been incurred for a particular event and the amount of loss associated with the event can be reasonably estimated. Insurance reserves have been estimated based primarily upon actuarial calculations and reflect the undiscounted estimated liabilities for ultimate losses, including claims incurred but not reported. Inherent in these estimates are assumptions that are based on the Company's history of claims and losses, a detailed analysis of existing claims with respect to potential value, and current legal and legislative trends. If actual claims differ from those projected by management, changes (either increases or decreases) to insurance reserves may be required and would be recorded through income in the period the change was determined. When a recognized liability is covered by third-party insurance, the Company records an insurance claim receivable to reflect the covered liability. Insurance claim receivables are included in Other receivables on the Company's Condensed Consolidated Balance Sheets. See Note 1, Summary of Significant Accounting Policies, to the consolidated financial statements included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2020 for additional information on Accrued insurance and loss reserves.

Reconciliation of Basic and Dil

Reconciliation of Basic and Diluted Shares	9 Months Ended
	Sep. 30, 2021
Earnings Per Share [Abstract]
Reconciliation of Basic and Diluted Shares	Reconciliation of Basic and Diluted Shares Three Months Ended Nine Months Ended September 30 September 30 (In thousands, except per share amounts) 2021 2020 2021 2020 Income (loss) from continuing operations attributable to Harsco Corporation common stockholders $ 8,696 $ (7,843) $ 24,621 $ (27,375) Weighted-average shares outstanding: Weighted-average shares outstanding - basic 79,287 79,000 79,214 78,916 Dilutive effect of stock-based compensation 988 — 1,142 — Weighted-average shares outstanding - diluted 80,275 79,000 80,356 78,916 Earnings (loss) from continuing operations per common share, attributable to Harsco Corporation common stockholders: Basic $ 0.11 $ (0.10) $ 0.31 $ (0.35) Diluted $ 0.11 $ (0.10) $ 0.31 $ (0.35) The following average outstanding stock-based compensation units were not included in the computation of diluted earnings per share because the effect was either antidilutive or the market conditions for the performance share units were not met: Three Months Ended Nine Months Ended September 30 September 30 (In thousands) 2021 2020 2021 2020 Restricted stock units — 691 — 723 Stock appreciation rights 842 2,383 719 2,499 Performance share units 1,004 857 902 894

Derivative Instruments, Hedging

Derivative Instruments, Hedging Activities and Fair Value	9 Months Ended
	Sep. 30, 2021
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Derivative Instruments, Hedging Activities and Fair Value	Derivative Instruments, Hedging Activities and Fair Value Derivative Instruments and Hedging Activities The Company uses derivative instruments, including foreign currency exchange forward contracts, interest rate swaps and CCIRs, to manage certain foreign currency and interest rate exposures. Derivative instruments are viewed as risk management tools by the Company and are not used for trading or speculative purposes. All derivative instruments are recorded on the Company's Condensed Consolidated Balance Sheets at fair value. The accounting for changes in the fair value of derivatives depends on the intended use of the derivative, whether the Company has elected to designate a derivative in a hedging relationship and apply hedge accounting and whether the hedging relationship has satisfied the criteria necessary to apply hedge accounting. Derivatives designated and qualifying as a hedge of the exposure to variability in expected future cash flows, or other types of forecasted transactions, are considered cash flow hedges. Hedge accounting generally provides for the matching of the timing of gain or loss recognition on the hedging instrument with the recognition of the earnings effect of the hedged forecasted transactions in a cash flow hedge. The Company may enter into derivative contracts that are intended to economically hedge certain of its risks, even though hedge accounting does not apply or the Company elects not to apply hedge accounting. The Company primarily applies the market approach for recurring fair value measurements and endeavors to utilize the best available information. Accordingly, the Company utilizes valuation techniques that maximize the use of observable inputs, such as forward rates, interest rates, the Company’s credit risk and counterparties’ credit risks, and which minimize the use of unobservable inputs. The Company is able to classify fair value balances based on the ability to observe those inputs. Foreign currency exchange forward contracts, interest rate swaps and CCIRs are based upon pricing models using market-based inputs (Level 2). Model inputs can be verified and valuation techniques do not involve significant management judgment. The fair value of outstanding derivative contracts recorded as assets and liabilities on the Company's Condensed Consolidated Balance Sheets was as follows: (In thousands) Balance Sheet Location Fair Value of Derivatives Designated as Hedging Instruments Fair Value of Derivatives Not Designated as Hedging Instruments Total Fair Value September 30, 2021 Asset derivatives (Level 2): Foreign currency exchange forward contracts Other current assets $ 930 $ 8,718 $ 9,648 Total $ 930 $ 8,718 $ 9,648 (In thousands) Balance Sheet Location Fair Value of Derivatives Designated as Hedging Instruments Fair Value of Derivatives Not Designated as Hedging Instruments Total Fair Value Liability derivatives (Level 2): Foreign currency exchange forward contracts Other current liabilities $ 851 $ 866 $ 1,717 Interest rate swaps Other current liabilities 4,068 — 4,068 Interest rate swaps Other liabilities 1,053 — 1,053 Total $ 5,972 $ 866 $ 6,838 December 31, 2020 Asset derivatives (Level 2): Foreign currency exchange forward contracts Other current assets $ 900 $ 2,777 $ 3,677 Total $ 900 $ 2,777 $ 3,677 Liability derivatives (Level 2): Foreign currency exchange forward contracts Other current liabilities $ 950 $ 4,098 $ 5,048 Interest rate swaps Other current liabilities 3,959 — 3,959 Interest rate swaps Other liabilities 3,718 — 3,718 Total $ 8,627 $ 4,098 $ 12,725 All of the Company's derivatives are recorded on the Condensed Consolidated Balance Sheets at gross amounts and not offset. All of the Company's interest rate swaps, CCIRs and certain foreign currency exchange forward contracts are transacted under ISDA documentation. Each ISDA master agreement permits the net settlement of amounts owed in the event of default. The Company's derivative assets and liabilities subject to enforceable master netting arrangements, if offset, would have resulted in a $1.3 million net liability at September 30, 2021 and at December 31, 2020 would not have resulted in a net asset or liability. The effect of derivative instruments on the Company's Condensed Consolidated Statements of Operations and Condensed Consolidated Statements of Comprehensive Income (Loss) was as follows: Derivatives Designated as Hedging Instruments Amount Recognized in Location of Amount Reclassified from Amount Reclassified from Three Months Ended Three Months Ended September 30 September 30 (In thousands) 2021 2020 2021 2020 Foreign currency exchange forward contracts $ 611 $ (1,244) Product revenues $ (418) $ 174 Interest rate swaps (27) (95) Interest expense 872 739 CCIRs (a) — (24) Interest expense — 312 $ 584 $ (1,363) $ 454 $ 1,225 Amount Recognized in Location of Amount Reclassified from AOCI into Income Amount Reclassified from Nine Months Ended Nine Months Ended September 30 September 30 (In thousands) 2021 2020 2021 2020 Foreign currency exchange forward contracts $ 170 $ 834 Product revenues $ (465) $ (1,562) Interest rate swaps (41) (3,835) Interest expense 2,599 1,849 CCIRs (a) — 39 Interest expense — 912 $ 129 $ (2,962) $ 2,134 $ 1,199 (a) Amounts represent changes in foreign currency translation related to balances in AOCI. The location and amount of gain (loss) recognized on the Company's Condensed Consolidated Statements of Operations was as follows: Three Months Ended September 30 2021 2020 (in thousands) Product Revenues Interest Expense Product Revenues Interest Expense Total amounts of line items presented in the Condensed Consolidated Statement of Operations in which the effects of cash flow hedges are recorded $ 105,677 $ (16,004) $ 124,892 $ (15,794) Interest rate swaps: Gain or (loss) reclassified from AOCI into income — (872) — (739) Foreign exchange contracts: Gain or (loss) reclassified from AOCI into income 418 — (174) — Amount excluded from effectiveness testing recognized in earnings based on changes in fair value 24 — 12 — Amount excluded from the effectiveness testing recognized in earnings based on an amortization approach (1) — 3 — CCIRs: Loss reclassified from AOCI into income — — — (312) Nine Months Ended September 30 2021 2020 (in thousands) Product Revenues Interest Expense Product Revenues Interest Expense Total amounts of line items presented in the Condensed Consolidated Statement of Operations in which the effects of cash flow hedges are recorded $ 343,171 $ (48,854) $ 333,782 $ (43,396) Interest rate swaps: Gain or (loss) reclassified from AOCI into income — (2,599) — (1,849) Foreign exchange contracts: Gain or (loss) reclassified from AOCI into income 465 — 1,562 — Amount excluded from effectiveness testing recognized in earnings based on changes in fair value 62 — 208 — Amount excluded from the effectiveness testing recognized in earnings based on an amortization approach (1) — 24 — CCIRs: Loss reclassified from AOCI into income — — — (912) Derivatives Not Designated as Hedging Instruments Location of Gain (Loss) Recognized in Income on Derivatives Amount of Gain (Loss) Recognized in Income on Derivatives (b) Three Months Ended Nine Months Ended September 30 September 30 (In thousands) 2021 2020 2021 2020 Foreign currency exchange forward contracts Cost of services and products sold $ 4,105 $ (12,279) $ 8,109 $ (5,001) (b) These gains (losses) offset amounts recognized in cost of services and products sold principally as a result of intercompany or third party foreign currency exposures. Foreign Currency Exchange Forward Contracts The Company conducts business in multiple currencies and, accordingly, is subject to the inherent risks associated with foreign exchange rate movements. Foreign currency-denominated assets and liabilities are translated into U.S. dollars at the exchange rates existing at the respective consolidated balance sheet dates, and income and expense items are translated at the average exchange rates during the respective periods. The Company uses derivative instruments to hedge cash flows related to foreign currency fluctuations. Foreign currency exchange forward contracts outstanding are part of a worldwide program to minimize foreign currency exchange operating income and balance sheet exposure by offsetting foreign currency exposures of certain future payments between the Company and various subsidiaries, suppliers or customers. The unsecured contracts are with major financial institutions. The Company may be exposed to credit loss in the event of non-performance by the contract counterparties. The Company evaluates the creditworthiness of the counterparties and does not expect default by them. Foreign currency exchange forward contracts are used to hedge commitments, such as foreign currency debt, firm purchase commitments and foreign currency cash flows for certain export sales transactions. Changes in the fair value of derivatives used to hedge foreign currency denominated balance sheet items are reported directly in earnings, along with offsetting transaction gains and losses on the items being hedged. Derivatives used to hedge forecasted cash flows associated with foreign currency commitments may be accounted for as cash flow hedges, as deemed appropriate, if the criteria for hedge accounting are met. Gains and losses on derivatives designated as cash flow hedges are deferred in AOCI, a separate component of equity, and reclassified to earnings in a manner that matches the timing of the earnings impact of the hedged transactions. The ineffective portion of all hedges, if any, is recognized currently in earnings. The recognized gains and losses offset amounts recognized in cost of services and products sold principally as a result of intercompany or third-party foreign currency exposures. At September 30, 2021 and December 31, 2020 the notional amounts of foreign currency exchange forward contracts were $363.2 million and $460.5 million, respectively. These contracts are primarily denominated in British Pound Sterling and Euros and mature through March 2023. In addition to foreign currency exchange forward contracts, the Company designates certain loans as hedges of net investments in international subsidiaries. The Company recorded pre-tax net losses of $3.7 million and $0.1 million for the three and nine months ended September 30, 2021, respectively and pre-tax net gains of $4.6 million and pre-tax net losses of $7.4 million for the three and nine months ended September 30, 2020, respectively, in AOCI. Interest Rate Swaps The Company uses interest rate swaps in conjunction with certain variable rate debt issuances in order to secure a fixed interest rate. Changes in the fair value attributed to the effect of the swaps’ interest spread and changes in the credit worthiness of the counter-parties are recorded in AOCI. At September 30, 2021, the Company has entered into a series of interest rate swaps that are in effect through 2022 and have the effect of converting $200.0 million of the Term Loan Facility from floating-rate to fixed-rate. The fixed rates provided by the swaps replace the adjusted LIBOR rate in the interest calculation, ranging from 2.71% for 2021 to 3.12% for 2022. Cross-Currency Interest Rate Swaps The Company may use CCIRs in conjunction with certain debt issuances in order to secure a fixed local currency interest rate. Under these CCIRs, the Company receives interest based on a fixed or floating U.S. dollar rate and pays interest on a fixed local currency rate based on the contractual amounts in dollars and the local currency, respectively. At maturity, there is also the payment of principal amounts between currencies. Changes in the fair value attributed to the effect of the swaps' interest spread and changes in the credit worthiness of the counter-parties are recorded in AOCI. Changes in value attributed to the effect of foreign currency fluctuations are recorded on the Company's Condensed Consolidated Statements of Operations and offset currency fluctuation effects on the debt principal. The Company had no outstanding CCIRs at September 30, 2021. Fair Value of Other Financial Instruments

Review of Operations by Segment

Review of Operations by Segment	9 Months Ended
	Sep. 30, 2021
Segment Reporting [Abstract]
Review of Operations by Segment	Review of Operations by Segment Three Months Ended Nine Months Ended September 30 September 30 (In thousands) 2021 2020 2021 2020 Revenues From Continuing Operations (a) Harsco Environmental $ 269,901 $ 222,507 $ 800,433 $ 668,057 Harsco Clean Earth 200,484 194,098 585,891 434,489 Harsco Rail 73,916 92,793 256,652 252,974 Total Revenues From Continuing Operations $ 544,301 $ 509,398 $ 1,642,976 $ 1,355,520 Operating Income (Loss) From Continuing Operations (a) Harsco Environmental $ 27,630 $ 12,317 $ 83,788 $ 36,400 Harsco Clean Earth 9,893 8,902 20,457 12,945 Harsco Rail 1,957 4,059 15,533 19,162 Corporate (9,560) (20,214) (28,815) (58,694) Total Operating Income From Continuing Operations $ 29,920 $ 5,064 $ 90,963 $ 9,813 Depreciation (a) Harsco Environmental $ 27,179 $ 25,588 $ 78,446 $ 75,626 Harsco Clean Earth 4,576 5,010 14,818 12,769 Harsco Rail 1,233 1,258 3,651 3,730 Corporate 491 497 1,468 1,531 Total Depreciation $ 33,479 $ 32,353 $ 98,383 $ 93,656 Amortization (a) Harsco Environmental $ 1,997 $ 1,970 $ 6,080 $ 5,827 Harsco Clean Earth 6,033 6,218 18,179 16,463 Harsco Rail 84 85 254 252 Corporate (b) 657 776 2,041 2,179 Total Amortization $ 8,771 $ 9,049 $ 26,554 $ 24,721 Capital Expenditures (a) Harsco Environmental $ 34,218 $ 21,700 $ 94,630 $ 65,102 Harsco Clean Earth 5,707 2,647 12,962 7,134 Harsco Rail 529 3,474 1,329 6,310 Corporate 407 62 586 444 Total Capital Expenditures $ 40,861 $ 27,883 $ 109,507 $ 78,990 (a) The Company's acquisition of ESOL closed on April 6, 2020. See Note 3, Acquisitions and Dispositions, for additional details. (b) Amortization expense on Corporate relates to the amortization of deferred financing costs. Reconciliation of Segment Operating Income to Income (Loss) From Continuing Operations Before Income Taxes and Equity Income Three Months Ended Nine Months Ended September 30 September 30 (In thousands) 2021 2020 2021 2020 Segment operating income $ 39,480 $ 25,278 $ 119,778 $ 68,507 General Corporate expense (9,560) (20,214) (28,815) (58,694) Operating income from continuing operations 29,920 5,064 90,963 9,813 Interest income 618 604 1,841 1,613 Interest expense (16,004) (15,794) (48,854) (43,396) Unused debt commitment fees, amendment fees and loss on extinguishment of debt (198) — (5,506) (1,920) Defined benefit pension income 3,906 1,859 11,833 5,171 Income (loss) from continuing operations before income taxes and equity income $ 18,242 $ (8,267) $ 50,277 $ (28,719)

Revenue Recognition

Revenue Recognition	9 Months Ended
	Sep. 30, 2021
Revenue from Contract with Customer [Abstract]
Revenue Recognition	Revenue Recognition The Company recognizes revenues to depict the transfer of promised services and products to customers in an amount that reflects the consideration the Company expects to receive in exchange for those services or products. Service revenues include the Harsco Clean Earth Segment and the service components of the Harsco Environmental and Harsco Rail Segments. Product revenues include portions of the Harsco Environmental and Harsco Rail Segments. A summary of the Company's revenues by primary geographical markets as well as by key product and service groups is as follows: Three Months Ended September 30, 2021 (In thousands) Harsco Environmental Segment Harsco Harsco Consolidated Totals Primary Geographical Markets (a) (b) : North America $ 71,479 $ 200,484 $ 48,553 $ 320,516 Western Europe 106,859 — 16,915 123,774 Latin America (c) 35,072 — 693 35,765 Asia-Pacific 30,228 — 7,755 37,983 Middle East and Africa 20,804 — — 20,804 Eastern Europe 5,459 — — 5,459 Total Revenues $ 269,901 $ 200,484 $ 73,916 $ 544,301 Key Product and Service Groups (a) : Environmental services related to resource recovery for metals manufacturing and related logistical services $ 230,340 $ — $ — $ 230,340 Applied products 36,091 — — 36,091 Environmental systems for aluminum dross and scrap processing 3,470 — — 3,470 Railway track maintenance equipment — — 33,553 33,553 After market parts and services; safety and diagnostic technology — — 33,030 33,030 Railway contracting services — — 7,333 7,333 Waste processing, recycling, reuse and transportation solutions — 200,484 — 200,484 Total Revenues $ 269,901 $ 200,484 $ 73,916 $ 544,301 Three Months Ended September 30, 2020 (In thousands) Harsco Environmental Segment Harsco Harsco Consolidated Totals Primary Geographical Markets (a) (b) : North America $ 58,973 $ 194,098 $ 62,805 $ 315,876 Western Europe 92,506 — 21,416 113,922 Latin America (c) 29,085 — 412 29,497 Asia-Pacific 22,079 — 8,160 30,239 Middle East and Africa 15,558 — — 15,558 Eastern Europe 4,306 — — 4,306 Total Revenues $ 222,507 $ 194,098 $ 92,793 $ 509,398 Key Product and Service Groups (a) : Environmental services related to resource recovery for metals manufacturing and related logistical services $ 181,867 $ — $ — $ 181,867 Applied products 38,166 — — 38,166 Environmental systems for aluminum dross and scrap processing 2,474 — — 2,474 Railway track maintenance equipment — — 55,493 55,493 After market parts and services; safety and diagnostic technology — — 29,100 29,100 Railway contracting services — — 8,200 8,200 Three Months Ended September 30, 2020 (In thousands) Harsco Environmental Segment Harsco Harsco Consolidated Totals Waste processing, recycling, reuse and transportation solutions — 194,098 — 194,098 Total Revenues $ 222,507 $ 194,098 $ 92,793 $ 509,398 Nine Months Ended September 30, 2021 (In thousands) Harsco Environmental Segment Harsco Harsco Consolidated Totals Primary Geographical Markets (a) (b) : North America $ 208,395 $ 585,891 $ 185,812 $ 980,098 Western Europe 336,011 — 47,220 383,231 Latin America (c) 99,524 — 1,821 101,345 Asia-Pacific 80,520 — 21,799 102,319 Middle East and Africa 60,798 — — 60,798 Eastern Europe 15,185 — — 15,185 Total Revenues $ 800,433 $ 585,891 $ 256,652 $ 1,642,976 Key Product and Service Groups (a) : Environmental services related to resource recovery for metals manufacturing and related logistical services $ 688,923 $ — $ — $ 688,923 Applied products 100,706 — — 100,706 Environmental systems for aluminum dross and scrap processing 10,804 — — 10,804 Railway track maintenance equipment — — 140,116 140,116 After market parts and services; safety and diagnostic technology — — 94,470 94,470 Railway contracting services — — 22,066 22,066 Waste processing, recycling, reuse and transportation solutions — 585,891 — 585,891 Total Revenues $ 800,433 $ 585,891 $ 256,652 $ 1,642,976 Nine Months Ended September 30, 2020 (In thousands) Harsco Environmental Segment Harsco Harsco Consolidated Totals Primary Geographical Markets (a) (b) : North America $ 186,210 $ 434,489 $ 173,039 $ 793,738 Western Europe 271,795 — 56,435 328,230 Latin America (c) 87,453 — 1,592 89,045 Asia-Pacific 63,969 — 21,908 85,877 Middle East and Africa 46,240 — — 46,240 Eastern Europe 12,390 — — 12,390 Total Revenues $ 668,057 $ 434,489 $ 252,974 $ 1,355,520 Nine Months Ended September 30, 2020 (In thousands) Harsco Environmental Segment Harsco Harsco Consolidated Totals Key Product and Service Groups (a) : Environmental services related to resource recovery for metals manufacturing and related logistical services $ 563,701 $ — $ — $ 563,701 Applied products 95,019 — — 95,019 Environmental systems for aluminum dross and scrap processing 9,337 — — 9,337 Railway track maintenance equipment — — 138,519 138,519 After market parts and services; safety and diagnostic technology — — 92,800 92,800 Railway contracting services — — 21,655 21,655 Waste processing, recycling, reuse and transportation solutions — 434,489 — 434,489 Total Revenues $ 668,057 $ 434,489 $ 252,974 $ 1,355,520 (a) The Company's acquisition of ESOL closed on April 6, 2020. The results are included in the Harsco Clean Earth Segment. See Note 3, Acquisitions and Dispositions, for additional details. (b) Revenues are attributed to individual countries based on the location of the facility generating the revenue. (c) Includes Mexico. The Company may receive payments in advance of earning revenue, which are treated as Advances on contracts on the Condensed Consolidated Balance Sheets. The Company may recognize revenue in advance of being able to contractually invoice the customer, which is treated as Contract assets on the Condensed Consolidated Balance Sheets. Non-current contract assets are included in Other assets on the Condensed Consolidated Balance Sheets. Contract assets are transferred to Trade accounts receivable, net, when the right to payment becomes unconditional. Contract assets and Contract liabilities are reported as a net position, on a contract-by-contract basis, at the end of each reporting period. These instances are primarily related to the Harsco Rail Segment. The Company had Contract assets totaling $111.8 million and $60.1 million at September 30, 2021 and December 31, 2020, respectively. The increase is due principally to additional contract assets recognized in excess of the transfer of contract assets to accounts receivable, primarily in the Harsco Rail Segment. The Company had Advances on contracts totaling $67.8 million and $84.9 million at September 30, 2021 and December 31, 2020, respectively. The decrease is due principally to the recognition of revenue on previously received Advances on contracts in excess of the receipt of new advances on contracts during the period, primarily in the Harsco Rail Segment. During the three and nine months ended September 30, 2021, the Company recognized approximately $14 million and $44 million, respectively, of revenue related to amounts previously included in Advances on contracts. During the three and nine months ended September 30, 2020, the Company recognized approximately $20 million and $55 million, respectively, of revenue related to amounts previously included in Advances on contracts. At September 30, 2021 the Harsco Environmental Segment had remaining, fixed, unsatisfied performance obligations where the expected contract duration exceeds one year totaling $88.8 million. Of this amount, $20.9 million is expected to be fulfilled by September 30, 2022, $20.3 million by September 30, 2023, $19.3 million by September 30, 2024, $19.2 million by September 30, 2025 and the remainder thereafter. These amounts exclude any variable fees, fixed fees subject to indexation and any performance obligations expected to be satisfied within one year. At September 30, 2021 the Harsco Rail Segment had remaining, fixed, unsatisfied performance obligations where the remaining expected contract duration exceeds one year totaling $246.3 million. Of this amount, $117.8 million is expected to be fulfilled by September 30, 2022, $73.0 million by September 30, 2023, $37.4 million by September 30, 2024, $18.0 million by September 30, 2025 and the remainder thereafter. These amounts exclude any variable fees, fixed fees subject to indexation and any performance obligations expected to be satisfied within one year. The Company recognized an initial estimated forward loss provision related to the contracts with SBB of $45.1 million for the year ended December 31, 2016. The Company recorded an additional forward loss provision of $1.8 million for the year ended December 31, 2018. At September 30, 2021 and December 31, 2020 the remaining estimated forward loss provision of $3.8 million and $4.4 million, respectively, is included in the caption Other current liabilities on the Condensed Consolidated Balance Sheets. The estimated forward loss provision represents the Company's best estimate based on currently available information. It is possible that the Company's overall estimate of costs to complete these contracts may increase, which would result in an additional estimated forward loss provision at such time. The Company recognized $5.4 million and $11.8 million of revenues for the contracts with SBB on an over time basis, utilizing a cost-to-cost method for the three months ended September 30, 2021 and 2020, respectively and $15.4 million and $29.5 million for the nine months ended September 30, 2021 and 2020, respectively. The Company has substantially completed the first contract and is approximately 81% complete on the second contract with SBB as of September 30, 2021. The Company provides assurance type warranties primarily for product sales in the Harsco Rail Segment. These warranties are typically not priced or negotiated separately (there is no option to separately purchase the warranty) or the warranty does not provide customers with a service in addition to the assurance that the product complies with agreed-upon specifications. Accordingly, such warranties do not represent separate performance obligations.

Other (Income) Expenses, Net

Other (Income) Expenses, Net	9 Months Ended
	Sep. 30, 2021
Other Income and Expenses [Abstract]
Other (Income) Expenses	Other (Income) Expenses, Net The major components of this Condensed Consolidated Statements of Operations caption were as follows: Three Months Ended Nine Months Ended September 30 September 30 (In thousands) 2021 2020 2021 2020 Employee termination benefit costs $ (65) $ 798 $ 1,285 $ 6,694 Other costs to exit activities (27) 13 611 478 Impaired asset write-downs 41 2 203 75 Contingent consideration adjustments — 2,437 — 2,437 Net gains (1,575) (7) (8,622) (255) Other (1,209) 390 (1,287) (355) Other (income) expenses, net $ (2,835) $ 3,633 $ (7,810) $ 9,074

Components of Accumulated Other

Components of Accumulated Other Comprehensive Loss	9 Months Ended
	Sep. 30, 2021
Equity [Abstract]
Components of Accumulated Other Comprehensive Loss	Components of Accumulated Other Comprehensive Loss AOCI is included on the Condensed Consolidated Statements of Stockholders' Equity. The components of AOCI, net of the effect of income taxes, and activity for the nine months ended September 30, 2020 and 2021 was as follows: Components of AOCI, Net of Tax (In thousands) Cumulative Foreign Exchange Translation Adjustments Effective Portion of Derivatives Designated as Hedging Instruments Cumulative Unrecognized Actuarial Losses on Pension Obligations Unrealized Gain (Loss) on Marketable Securities Total Balance at December 31, 2019 $ (143,340) $ (3,717) $ (440,562) $ (3) $ (587,622) OCI before reclassifications (48,150) (a) (2,226) (b) 9,905 (a) (22) (40,493) Amounts reclassified from AOCI, net of tax 12,906 604 18,132 — 31,642 Total OCI (35,244) (1,622) 28,037 (22) (8,851) Less: OCI attributable to noncontrolling interests 579 — — — 579 OCI attributable to Harsco Corporation (35,823) (1,622) 28,037 (22) (9,430) Balance at September 30, 2020 $ (179,163) $ (5,339) $ (412,525) $ (25) $ (597,052) Components of AOCI, Net of Tax (In thousands) Cumulative Foreign Exchange Translation Adjustments Effective Portion of Derivatives Designated as Hedging Instruments Cumulative Unrecognized Actuarial Losses on Pension Obligations Unrealized Gain (Loss) on Marketable Securities Total Balance at December 31, 2020 $ (125,392) $ (5,840) $ (514,500) $ (9) $ (645,741) OCI before reclassifications (15,437) (a) 257 (b) 6,628 (a) 25 (8,527) Amounts reclassified from AOCI, net of tax — 1,488 17,184 — 18,672 Total OCI (15,437) 1,745 23,812 25 10,145 Less: OCI attributable to noncontrolling interests (837) — — — (837) OCI attributable to Harsco Corporation (14,600) 1,745 23,812 25 10,982 Balance at September 30, 2021 $ (139,992) $ (4,095) $ (490,688) $ 16 $ (634,759) (a) Principally foreign currency fluctuation. (b) Net change from periodic revaluations. Amounts reclassified from AOCI were as follows: (In thousands) Three Months Ended Nine Months Ended Location on the Condensed Consolidated Statements of Operations September 30 September 30 2021 2020 2021 2020 Recognition of cumulative foreign currency translation adjustments: Gain on substantial liquidation of subsidiaries (c) $ — $ — — 12,906 Gain on sale of discontinued businesses Amortization of cash flow hedging instruments: Foreign currency exchange forward contracts $ (418) $ 174 $ (465) $ (1,562) Product revenues CCIRs — 312 — 912 Interest expense Interest rate swaps 872 739 2,599 1,849 Interest expense Total before taxes 454 1,225 2,134 1,199 Income taxes (148) (408) (646) (595) Total reclassification of cash flow hedging instruments, net of tax $ 306 $ 817 $ 1,488 $ 604 Amortization of defined benefit pension items (d) : Actuarial losses $ 5,922 $ 4,962 $ 17,877 $ 14,799 Defined benefit pension income Prior service costs 125 113 381 326 Defined benefit pension income Pension liability transfer - discontinued business — — — 5,363 Gain on sale of discontinued businesses Total before taxes 6,047 5,075 18,258 20,488 Income taxes (358) (323) (1,074) (2,356) Total reclassification of defined benefit pension items, net of tax $ 5,689 $ 4,752 $ 17,184 $ 18,132 (c) No tax impact. (d) These AOCI components are included in the computation of net periodic pension costs. See Note 10, Employee Benefit Plans, for additional details.

Subsequent Event (Notes)

Subsequent Event (Notes)	9 Months Ended
	Sep. 30, 2021
Subsequent Events [Abstract]
Subsequent Event	Subsequent EventOn November 2, 2021 the Company announced it will explore strategic alternatives for the Rail business, with the intention to sell the business. As a result, the Rail segment will be classified as held for sale and reported as discontinued operations beginning in the fourth quarter of 2021.

Basis of Presentation (Policies

Basis of Presentation (Policies)	9 Months Ended
	Sep. 30, 2021
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of Presentation	Basis of Presentation The Company has prepared these unaudited condensed consolidated financial statements in accordance with U.S. GAAP for interim financial information and with the instructions to Form 10-Q and Rule 10-01 of Regulation S-X of the SEC. Accordingly, the unaudited condensed consolidated financial statements do not include all information and disclosure required by U.S. GAAP for annual financial statements. The December 31, 2020 Condensed Consolidated Balance Sheet information contained in this Quarterly Report on Form 10-Q was derived from the 2020 audited consolidated financial statements. The unaudited condensed consolidated financial statements should be read in conjunction with the audited consolidated financial statements, including the notes thereto, included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2020. In the opinion of management, all adjustments (all of which are of a normal recurring nature) that are necessary for a fair statement are reflected in the unaudited condensed consolidated financial statements. Restricted Cash The Company had restricted cash of $4.5 million and $3.2 million at September 30, 2021 and December 31, 2020, respectively, and the restrictions are primarily related to collateral provided for certain guarantees of the Company's performance. Impact of COVID-19 Beginning in early 2020, overall global economic conditions were significantly impacted by COVID-19. The Company operated, since the onset of the pandemic, as a provider of certain essential services in the U.S. and other countries and overall business conditions have strengthened since the second quarter of 2020. And while COVID-19 continues to impact various lines of business within the Company and certain operations including as a result of subsequent supply-chain challenges and labor-market tightness, the Company expects that business conditions will improve meaningfully in 2021 compared with 2020. The Company did not record any long-lived asset impairments, indefinite-lived asset impairments, goodwill impairments, significant inventory write-downs or incremental accounts receivable reserves for current expected credit losses during the three or nine months ended September 30, 2021. However, should economic conditions deteriorate, including as a result of COVID-19 such charges are possible in future periods, which could have an adverse effect on the Company's future results of operations, cash flows, or financial condition. Reclassifications Certain reclassifications have been made to prior year amounts to conform with current year classifications.
Recently Adopted and Recently Issued Accounting Standards	Recently Adopted and Recently Issued Accounting Standards The following accounting standards have been adopted in 2021: On January 1, 2021 the Company adopted changes issued by the FASB which are intended to reduce complexity and simplify the accounting for income taxes in accordance with U.S. GAAP by removing certain exceptions related to investments, intraperiod allocations and interim calculations and clarifying existing guidance to improve consistent application. These changes did not have a material impact on the Company's condensed consolidated financial statements. The following accounting standards have been issued and become effective for the Company at a future date: In March 2020 the FASB issued changes that provide companies with optional guidance to ease the potential accounting burden associated with transitioning from reference rates that are expected to be discontinued. In response to the concerns about risks of IBORs and, particularly, the risk of cessation of LIBOR, regulators in several jurisdictions around the world have undertaken reference rate reform initiatives to identify alternative reference rates that are more observable or transaction-based and less susceptible to manipulation. The changes provide optional expedients and exceptions for applying U.S. GAAP to contracts, hedging relationships, and other transactions affected by reference rate reform if certain criteria are met. In January 2021, the FASB issued additional clarification changes. The changes must be adopted no later than December 31, 2022 with early adoption permitted. Management does not believe these changes will have a material impact on its condensed consolidated financial statements. In August 2020, the FASB issued changes which simplified the accounting for certain financial instruments with characteristics of liabilities and equity, including convertible instruments and contracts on an entity’s own equity. The changes must be

Acquisitions and Dispositions (

Acquisitions and Dispositions (Tables)	9 Months Ended
	Sep. 30, 2021
Business Combinations [Abstract]
Summary of assets acquired and liabilities assumed	The fair value recorded for the assets acquired and liabilities assumed for ESOL is as follows: Final (In millions) April 6 Measurement Period Adjustments September 30 Cash and cash equivalents $ 0.4 $ — $ 0.4 Trade accounts receivable 124.1 (1.5) 122.6 Inventory 5.0 — 5.0 Other current assets 0.7 (0.7) — Property, plant and equipment 105.3 (3.9) 101.4 Right-of-use assets 56.0 — 56.0 Goodwill 152.0 1.3 153.3 Intangible assets 161.0 — 161.0 Other assets 0.2 — 0.2 Accounts payable (48.6) (1.5) (50.1) Accrued expenses (17.5) (1.8) (19.3) Current portion of operating lease liabilities (16.6) — (16.6) Other current liabilities (6.4) (0.2) (6.6) Environmental liabilities (24.4) — (24.4) Deferred income taxes (15.5) (1.5) (17.0) Operating lease liabilities (39.4) — (39.4) Total identifiable net assets of ESOL 436.3 (9.8) 426.5 Non-compete agreement 2.5 — 2.5 Total identifiable net assets of ESOL, including non-compete agreement $ 438.8 $ (9.8) $ 429.0
Preliminary valuation of identifiable intangible assets and amortization periods	The following table details the valuation of identifiable intangible assets and amortization periods for ESOL and the non-compete agreement entered into by the Company upon acquisition of ESOL: Final (Dollars in millions) Weighted-Average Amortization Period April 6 Measurement Period Adjustments September 30 Permits and rights 22 years $ 138.0 $ — $ 138.0 Customer relationships 10 years 23.0 — 23.0 Total identifiable intangible assets of ESOL 161.0 — 161.0 Non-compete agreement 4 years 2.5 — 2.5 Total identifiable intangible assets acquired $ 163.5 $ — $ 163.5
Pro forma information	Nine Months Ended September 30 (In millions) 2020 Pro forma revenues $ 1,486.2 Pro forma net income (loss) attributed to Harsco Corporation (including discontinued operations) (a) 1.0 (a) Pro forma net income includes the after tax gain on the sale of IKG of approximately $9 million for the nine months ended September 30, 2020.
Balance sheet positions and financial information included in net income from discontinued operations and statements of cash flows	Certain key selected financial information included in net income (loss) from discontinued operations for the former Harsco Industrial Segment is as follows: Three Months Ended Nine Months Ended September 30 September 30 (In millions) 2021 2020 2021 2020 Amounts for the former Harsco Industrial Segment: Total revenues $ — $ — $ — $ 10,203 Cost of products sold — — — 8,082 Gain on sale from discontinued business — — — 18,371 Income (loss) from discontinued business (856) (716) (2,859) (593) Additional amounts allocated to the former Harsco Industrial Segment: Selling, general and administrative expenses (b) $ 856 $ 521 $ 2,859 $ 1,710 (b) The Company has allocated directly attributable transaction costs to discontinued operations. In addition, this caption includes costs directly attributable to retained contingent liabilities of the Harsco Industrial Segment.

Accounts Receivable (Tables)

Accounts Receivable (Tables)	9 Months Ended
	Sep. 30, 2021
Receivables [Abstract]
Schedule of accounts receivable	Accounts receivable consist of the following: (In thousands) September 30 December 31 Trade accounts receivable $ 434,295 $ 414,891 Less: Allowance for expected credit losses (8,398) (7,501) Trade accounts receivable, net $ 425,897 $ 407,390 Other receivables (a) $ 39,454 $ 34,253 (a) Other receivables include employee receivables, insurance receivable, tax claims and refunds and other miscellaneous items not included in Trade accounts receivable, net. (In thousands) September 30 December 31 Note receivable $ 30,631 $ 35,806
Schedule of provision for doubtful accounts related to trade accounts receivable	The provision for doubtful accounts related to trade accounts receivable was as follows: Three Months Ended Nine Months Ended September 30 September 30 (In thousands) 2021 2020 2021 2020 (Benefit) provision for expected credit losses and doubtful accounts related to trade accounts receivable $ (145) $ 861 $ 1,087 $ 1,098

Inventories (Tables)

Inventories (Tables)	9 Months Ended
	Sep. 30, 2021
Inventory Disclosure [Abstract]
Schedule of inventories	Inventories consist of the following: (In thousands) September 30 December 31 Finished goods $ 9,052 $ 8,505 Work-in-process 23,793 29,005 Raw materials and purchased parts 95,156 105,306 Stores and supplies 35,071 30,197 Total inventories $ 163,072 $ 173,013

Property, Plant and Equipment (

Property, Plant and Equipment (Tables)	9 Months Ended
	Sep. 30, 2021
Property, Plant and Equipment [Abstract]
Schedule of property, plant and equipment	Property, plant and equipment consisted of the following: (In thousands) September 30 December 31 Land $ 75,469 $ 75,559 Land improvements 19,730 20,166 Buildings and improvements 253,659 249,954 Machinery and equipment 1,564,936 1,597,592 Uncompleted construction 69,206 42,185 Gross property, plant and equipment 1,983,000 1,985,456 Less: Accumulated depreciation (1,304,675) (1,317,247) Property, plant and equipment, net $ 678,325 $ 668,209

Leases (Tables)

Leases (Tables)	9 Months Ended
	Sep. 30, 2021
Leases [Abstract]
Components of Lease Expense and Supplemental Cash Flow and Additional Information	The components of lease expense were as follows: Three Months Ended Nine Months Ended September 30 September 30 (In thousands) 2021 2020 2021 2020 Finance leases: Amortization expense $ 743 $ 377 $ 1,692 $ 1,115 Interest on lease liabilities 129 43 340 139 Operating leases 8,554 8,558 25,296 21,745 Variable and short-term lease expense 12,756 11,572 38,952 29,169 Sublease income (1) (51) (52) (150) Total lease expense from continuing operations $ 22,181 $ 20,499 $ 66,228 $ 52,018 Supplemental cash flow information related to leases was as follows: Nine Months Ended September 30 (In thousands) 2021 2020 Cash paid for amounts included in the measurement of lease liabilities: Cash flows from operating activities - Operating leases $ 24,747 $ 20,512 Cash flows from financing activities - Finance leases 1,978 997 ROU assets obtained in exchange for lease obligations: Operating leases $ 29,190 $ 62,507 Finance leases 5,911 1,613 Supplemental additional information related to leases was as follows: September 30 December 31 Other information: Weighted average remaining lease term - Operating leases (in years) 7.44 8.00 Weighted average remaining lease term - Finance leases (in years) 6.41 8.20 Weighted average discount rate - Operating leases 5.9 % 6.1 % Weighted average discount rate - Finance leases 4.9 % 5.1 %
Supplemental Balance Sheet Information Related to Leases	Supplemental balance sheet information related to leases was as follows: (In thousands) September 30 December 31 Operating Leases: Operating lease ROU assets $ 98,841 $ 96,849 Current portion of operating lease liabilities 25,112 24,862 Operating lease liabilities 72,090 69,860 Finance Leases: Property, plant and equipment, net $ 12,508 $ 8,434 Current maturities of long-term debt 2,724 1,683 Long-term debt 10,011 6,867
Maturities of Operating Lease Liabilities	Maturities of lease liabilities were as follows: (In thousands) Operating Finance Year Ending December 31: 2021 (excluding the nine months ended September 30, 2021) $ 8,027 $ 849 2022 28,602 3,220 2023 22,897 3,001 2024 16,537 2,615 2025 11,284 1,576 After 2025 36,936 3,754 Total lease payments 124,283 15,015 Less: Imputed interest (27,081) (2,280) Total $ 97,202 $ 12,735
Maturities of Finance Lease Liabilities	Maturities of lease liabilities were as follows: (In thousands) Operating Finance Year Ending December 31: 2021 (excluding the nine months ended September 30, 2021) $ 8,027 $ 849 2022 28,602 3,220 2023 22,897 3,001 2024 16,537 2,615 2025 11,284 1,576 After 2025 36,936 3,754 Total lease payments 124,283 15,015 Less: Imputed interest (27,081) (2,280) Total $ 97,202 $ 12,735

Goodwill and Other Intangible_2

Goodwill and Other Intangible Assets (Tables)	9 Months Ended
	Sep. 30, 2021
Goodwill and Intangible Assets Disclosure [Abstract]
Schedule of changes in carrying amounts of goodwill by segment	The following table reflects the changes in carrying amounts of goodwill by segment for the nine months ended September 30, 2021: (In thousands) Harsco Environmental Segment Harsco Harsco Rail Consolidated Balance at December 31, 2020 $ 406,401 $ 482,647 $ 13,026 $ 902,074 Changes to goodwill (a) — 1,232 — 1,232 Foreign currency translation (6,578) — — (6,578) Balance at September 30, 2021 $ 399,823 $ 483,879 $ 13,026 $ 896,728 (a) The changes to goodwill relate to the measurement period adjustments for the ESOL acquisition in the Harsco Clean Earth Segment. See Note 3, Acquisitions and Dispositions.
Schedule of intangible assets by class	Intangible assets, net, on the Company's Condensed Consolidated Balance Sheets consist of the following: September 30, 2021 December 31, 2020 (In thousands) Gross Carrying Accumulated Gross Carrying Accumulated Customer related $ 108,226 $ 53,757 $ 109,378 $ 48,057 Permits 308,998 30,856 308,705 18,955 Technology related 39,604 12,363 40,274 9,654 Trade names 31,876 6,797 31,949 4,834 Air rights 26,139 1,561 26,139 1,044 Patents 185 140 192 139 Non-compete Agreement 2,500 937 2,500 469 Other 3,896 1,475 3,911 1,331 Total $ 521,424 $ 107,886 $ 523,048 $ 84,483
Schedule of amortization expense	Amortization expense for intangible assets was as follows: Three Months Ended Nine Months Ended September 30 September 30 (In thousands) 2021 2020 2021 2020 Amortization expense for intangible assets $ 8,115 $ 8,272 $ 24,514 $ 22,542
Schedule of estimated amortization expense	The estimated amortization expense for the next five fiscal years based on current intangible assets is as follows: (In thousands) 2021 2022 2023 2024 2025 Estimated amortization expense (b) $ 32,900 $ 32,400 $ 32,300 $ 31,800 $ 31,600

Debt and Credit Agreements (Tab

Debt and Credit Agreements (Tables)	9 Months Ended
	Sep. 30, 2021
Debt Disclosure [Abstract]
Schedule of Long-term Debt Instruments	Long-term debt consists of the following: (In thousands) September 30 December 31 Senior Secured Credit Facilities: New Term Loan $ 498,750 $ — Term Loan A — 280,000 Term Loan B — 218,188 Revolving Credit Facility 338,486 281,000 5.75% Notes, due July 31, 2027 500,000 500,000 Other financing payable (including finance leases) in varying amounts 24,406 21,344 Total debt obligations 1,361,642 1,300,532 Less: deferred financing costs (18,887) (15,767) Total debt obligations, net of deferred financing costs 1,342,755 1,284,765 Less: current maturities of long-term debt (9,181) (13,576) Long-term debt $ 1,333,574 $ 1,271,189

Employee Benefit Plans (Tables)

Employee Benefit Plans (Tables)	9 Months Ended
	Sep. 30, 2021
Retirement Benefits [Abstract]
Schedule of net benefit costs	Three Months Ended September 30 Defined Benefit Pension Plans Net Periodic Pension Cost (Benefit) U.S. Plans International Plans (In thousands) 2021 2020 2021 2020 Service costs $ — $ — $ 489 $ 448 Interest costs 1,203 1,845 3,184 4,474 Expected return on plan assets (3,050) (2,842) (11,303) (10,405) Recognized prior service costs — — 125 113 Recognized loss 1,384 1,225 4,538 3,737 Defined benefit pension plans net periodic pension cost (benefit) $ (463) $ 228 $ (2,967) $ (1,633) Nine Months Ended September 30 Defined Benefit Pension Plans Net Periodic Pension Cost (Benefit) U.S. Plans International Plans (In thousands) 2021 2020 2021 2020 Service costs $ — $ — $ 1,482 $ 1,303 Interest costs 3,609 5,535 9,619 13,104 Expected return on plan assets (9,150) (8,526) (34,181) (30,428) Recognized prior service costs — — 381 326 Recognized loss 4,154 3,875 13,723 10,924 Defined benefit pension plans net periodic pension cost (benefit) $ (1,387) $ 884 $ (8,976) $ (4,771)
Schedule of contributions to pension plans	Three Months Ended Nine Months Ended Company Contributions September 30 September 30 (In thousands) 2021 2020 2021 2020 Defined benefit pension plans (U.S.) $ 451 $ 453 $ 3,768 $ 2,940 Defined benefit pension plans (International) 4,549 2,682 21,472 14,235 Multiemployer pension plans 429 390 1,311 1,178 Defined contribution pension plans 2,974 2,870 9,507 7,936

Commitment and Contingencies (T

Commitment and Contingencies (Tables)	9 Months Ended
	Sep. 30, 2021
Commitments and Contingencies Disclosure [Abstract]
Schedule of Loss Contingencies by Contingency	The following table summarizes information related to the location and undiscounted amount of the Company's environmental liabilities: (In thousands) September 30 December 31 Current portion of environmental liabilities (a) $ 7,005 $ 6,933 Long-term environmental liabilities 28,589 29,424 Total environmental liabilities $ 35,594 $ 36,357 (a) The current portion of environmental liabilities is included in the caption Other current liabilities on the Company's Condensed Consolidated Balance Sheets.

Reconciliation of Basic and D_2

Reconciliation of Basic and Diluted Shares (Tables)	9 Months Ended
	Sep. 30, 2021
Earnings Per Share [Abstract]
Reconciliation of basic and diluted shares	Three Months Ended Nine Months Ended September 30 September 30 (In thousands, except per share amounts) 2021 2020 2021 2020 Income (loss) from continuing operations attributable to Harsco Corporation common stockholders $ 8,696 $ (7,843) $ 24,621 $ (27,375) Weighted-average shares outstanding: Weighted-average shares outstanding - basic 79,287 79,000 79,214 78,916 Dilutive effect of stock-based compensation 988 — 1,142 — Weighted-average shares outstanding - diluted 80,275 79,000 80,356 78,916 Earnings (loss) from continuing operations per common share, attributable to Harsco Corporation common stockholders: Basic $ 0.11 $ (0.10) $ 0.31 $ (0.35) Diluted $ 0.11 $ (0.10) $ 0.31 $ (0.35)
Schedule of antidilutive securities excluded from computation of earnings per share	The following average outstanding stock-based compensation units were not included in the computation of diluted earnings per share because the effect was either antidilutive or the market conditions for the performance share units were not met: Three Months Ended Nine Months Ended September 30 September 30 (In thousands) 2021 2020 2021 2020 Restricted stock units — 691 — 723 Stock appreciation rights 842 2,383 719 2,499 Performance share units 1,004 857 902 894

Derivative Instruments, Hedgi_2

Derivative Instruments, Hedging Activities and Fair Value (Tables)	9 Months Ended
	Sep. 30, 2021
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Schedule of fair value of outstanding derivative contracts	The fair value of outstanding derivative contracts recorded as assets and liabilities on the Company's Condensed Consolidated Balance Sheets was as follows: (In thousands) Balance Sheet Location Fair Value of Derivatives Designated as Hedging Instruments Fair Value of Derivatives Not Designated as Hedging Instruments Total Fair Value September 30, 2021 Asset derivatives (Level 2): Foreign currency exchange forward contracts Other current assets $ 930 $ 8,718 $ 9,648 Total $ 930 $ 8,718 $ 9,648 (In thousands) Balance Sheet Location Fair Value of Derivatives Designated as Hedging Instruments Fair Value of Derivatives Not Designated as Hedging Instruments Total Fair Value Liability derivatives (Level 2): Foreign currency exchange forward contracts Other current liabilities $ 851 $ 866 $ 1,717 Interest rate swaps Other current liabilities 4,068 — 4,068 Interest rate swaps Other liabilities 1,053 — 1,053 Total $ 5,972 $ 866 $ 6,838 December 31, 2020 Asset derivatives (Level 2): Foreign currency exchange forward contracts Other current assets $ 900 $ 2,777 $ 3,677 Total $ 900 $ 2,777 $ 3,677 Liability derivatives (Level 2): Foreign currency exchange forward contracts Other current liabilities $ 950 $ 4,098 $ 5,048 Interest rate swaps Other current liabilities 3,959 — 3,959 Interest rate swaps Other liabilities 3,718 — 3,718 Total $ 8,627 $ 4,098 $ 12,725
Schedule of effect of derivative instruments	Derivatives Designated as Hedging Instruments Amount Recognized in Location of Amount Reclassified from Amount Reclassified from Three Months Ended Three Months Ended September 30 September 30 (In thousands) 2021 2020 2021 2020 Foreign currency exchange forward contracts $ 611 $ (1,244) Product revenues $ (418) $ 174 Interest rate swaps (27) (95) Interest expense 872 739 CCIRs (a) — (24) Interest expense — 312 $ 584 $ (1,363) $ 454 $ 1,225 Amount Recognized in Location of Amount Reclassified from AOCI into Income Amount Reclassified from Nine Months Ended Nine Months Ended September 30 September 30 (In thousands) 2021 2020 2021 2020 Foreign currency exchange forward contracts $ 170 $ 834 Product revenues $ (465) $ (1,562) Interest rate swaps (41) (3,835) Interest expense 2,599 1,849 CCIRs (a) — 39 Interest expense — 912 $ 129 $ (2,962) $ 2,134 $ 1,199 (a) Amounts represent changes in foreign currency translation related to balances in AOCI. The location and amount of gain (loss) recognized on the Company's Condensed Consolidated Statements of Operations was as follows: Three Months Ended September 30 2021 2020 (in thousands) Product Revenues Interest Expense Product Revenues Interest Expense Total amounts of line items presented in the Condensed Consolidated Statement of Operations in which the effects of cash flow hedges are recorded $ 105,677 $ (16,004) $ 124,892 $ (15,794) Interest rate swaps: Gain or (loss) reclassified from AOCI into income — (872) — (739) Foreign exchange contracts: Gain or (loss) reclassified from AOCI into income 418 — (174) — Amount excluded from effectiveness testing recognized in earnings based on changes in fair value 24 — 12 — Amount excluded from the effectiveness testing recognized in earnings based on an amortization approach (1) — 3 — CCIRs: Loss reclassified from AOCI into income — — — (312) Nine Months Ended September 30 2021 2020 (in thousands) Product Revenues Interest Expense Product Revenues Interest Expense Total amounts of line items presented in the Condensed Consolidated Statement of Operations in which the effects of cash flow hedges are recorded $ 343,171 $ (48,854) $ 333,782 $ (43,396) Interest rate swaps: Gain or (loss) reclassified from AOCI into income — (2,599) — (1,849) Foreign exchange contracts: Gain or (loss) reclassified from AOCI into income 465 — 1,562 — Amount excluded from effectiveness testing recognized in earnings based on changes in fair value 62 — 208 — Amount excluded from the effectiveness testing recognized in earnings based on an amortization approach (1) — 24 — CCIRs: Loss reclassified from AOCI into income — — — (912) Derivatives Not Designated as Hedging Instruments Location of Gain (Loss) Recognized in Income on Derivatives Amount of Gain (Loss) Recognized in Income on Derivatives (b) Three Months Ended Nine Months Ended September 30 September 30 (In thousands) 2021 2020 2021 2020 Foreign currency exchange forward contracts Cost of services and products sold $ 4,105 $ (12,279) $ 8,109 $ (5,001) (b) These gains (losses) offset amounts recognized in cost of services and products sold principally as a result of intercompany or third party foreign currency exposures.

Review of Operations by Segme_2

Review of Operations by Segment (Tables)	9 Months Ended
	Sep. 30, 2021
Segment Reporting [Abstract]
Schedule of operations by segment	Three Months Ended Nine Months Ended September 30 September 30 (In thousands) 2021 2020 2021 2020 Revenues From Continuing Operations (a) Harsco Environmental $ 269,901 $ 222,507 $ 800,433 $ 668,057 Harsco Clean Earth 200,484 194,098 585,891 434,489 Harsco Rail 73,916 92,793 256,652 252,974 Total Revenues From Continuing Operations $ 544,301 $ 509,398 $ 1,642,976 $ 1,355,520 Operating Income (Loss) From Continuing Operations (a) Harsco Environmental $ 27,630 $ 12,317 $ 83,788 $ 36,400 Harsco Clean Earth 9,893 8,902 20,457 12,945 Harsco Rail 1,957 4,059 15,533 19,162 Corporate (9,560) (20,214) (28,815) (58,694) Total Operating Income From Continuing Operations $ 29,920 $ 5,064 $ 90,963 $ 9,813 Depreciation (a) Harsco Environmental $ 27,179 $ 25,588 $ 78,446 $ 75,626 Harsco Clean Earth 4,576 5,010 14,818 12,769 Harsco Rail 1,233 1,258 3,651 3,730 Corporate 491 497 1,468 1,531 Total Depreciation $ 33,479 $ 32,353 $ 98,383 $ 93,656 Amortization (a) Harsco Environmental $ 1,997 $ 1,970 $ 6,080 $ 5,827 Harsco Clean Earth 6,033 6,218 18,179 16,463 Harsco Rail 84 85 254 252 Corporate (b) 657 776 2,041 2,179 Total Amortization $ 8,771 $ 9,049 $ 26,554 $ 24,721 Capital Expenditures (a) Harsco Environmental $ 34,218 $ 21,700 $ 94,630 $ 65,102 Harsco Clean Earth 5,707 2,647 12,962 7,134 Harsco Rail 529 3,474 1,329 6,310 Corporate 407 62 586 444 Total Capital Expenditures $ 40,861 $ 27,883 $ 109,507 $ 78,990 (a) The Company's acquisition of ESOL closed on April 6, 2020. See Note 3, Acquisitions and Dispositions, for additional details. (b) Amortization expense on Corporate relates to the amortization of deferred financing costs.
Reconciliation of segment operating income to income from continuing operations before income taxes and equity income	Reconciliation of Segment Operating Income to Income (Loss) From Continuing Operations Before Income Taxes and Equity Income Three Months Ended Nine Months Ended September 30 September 30 (In thousands) 2021 2020 2021 2020 Segment operating income $ 39,480 $ 25,278 $ 119,778 $ 68,507 General Corporate expense (9,560) (20,214) (28,815) (58,694) Operating income from continuing operations 29,920 5,064 90,963 9,813 Interest income 618 604 1,841 1,613 Interest expense (16,004) (15,794) (48,854) (43,396) Unused debt commitment fees, amendment fees and loss on extinguishment of debt (198) — (5,506) (1,920) Defined benefit pension income 3,906 1,859 11,833 5,171 Income (loss) from continuing operations before income taxes and equity income $ 18,242 $ (8,267) $ 50,277 $ (28,719)

Revenue Recognition (Tables)

Revenue Recognition (Tables)	9 Months Ended
	Sep. 30, 2021
Revenue from Contract with Customer [Abstract]
Summary of revenues by primary geographical markets	A summary of the Company's revenues by primary geographical markets as well as by key product and service groups is as follows: Three Months Ended September 30, 2021 (In thousands) Harsco Environmental Segment Harsco Harsco Consolidated Totals Primary Geographical Markets (a) (b) : North America $ 71,479 $ 200,484 $ 48,553 $ 320,516 Western Europe 106,859 — 16,915 123,774 Latin America (c) 35,072 — 693 35,765 Asia-Pacific 30,228 — 7,755 37,983 Middle East and Africa 20,804 — — 20,804 Eastern Europe 5,459 — — 5,459 Total Revenues $ 269,901 $ 200,484 $ 73,916 $ 544,301 Key Product and Service Groups (a) : Environmental services related to resource recovery for metals manufacturing and related logistical services $ 230,340 $ — $ — $ 230,340 Applied products 36,091 — — 36,091 Environmental systems for aluminum dross and scrap processing 3,470 — — 3,470 Railway track maintenance equipment — — 33,553 33,553 After market parts and services; safety and diagnostic technology — — 33,030 33,030 Railway contracting services — — 7,333 7,333 Waste processing, recycling, reuse and transportation solutions — 200,484 — 200,484 Total Revenues $ 269,901 $ 200,484 $ 73,916 $ 544,301 Three Months Ended September 30, 2020 (In thousands) Harsco Environmental Segment Harsco Harsco Consolidated Totals Primary Geographical Markets (a) (b) : North America $ 58,973 $ 194,098 $ 62,805 $ 315,876 Western Europe 92,506 — 21,416 113,922 Latin America (c) 29,085 — 412 29,497 Asia-Pacific 22,079 — 8,160 30,239 Middle East and Africa 15,558 — — 15,558 Eastern Europe 4,306 — — 4,306 Total Revenues $ 222,507 $ 194,098 $ 92,793 $ 509,398 Key Product and Service Groups (a) : Environmental services related to resource recovery for metals manufacturing and related logistical services $ 181,867 $ — $ — $ 181,867 Applied products 38,166 — — 38,166 Environmental systems for aluminum dross and scrap processing 2,474 — — 2,474 Railway track maintenance equipment — — 55,493 55,493 After market parts and services; safety and diagnostic technology — — 29,100 29,100 Railway contracting services — — 8,200 8,200 Three Months Ended September 30, 2020 (In thousands) Harsco Environmental Segment Harsco Harsco Consolidated Totals Waste processing, recycling, reuse and transportation solutions — 194,098 — 194,098 Total Revenues $ 222,507 $ 194,098 $ 92,793 $ 509,398 Nine Months Ended September 30, 2021 (In thousands) Harsco Environmental Segment Harsco Harsco Consolidated Totals Primary Geographical Markets (a) (b) : North America $ 208,395 $ 585,891 $ 185,812 $ 980,098 Western Europe 336,011 — 47,220 383,231 Latin America (c) 99,524 — 1,821 101,345 Asia-Pacific 80,520 — 21,799 102,319 Middle East and Africa 60,798 — — 60,798 Eastern Europe 15,185 — — 15,185 Total Revenues $ 800,433 $ 585,891 $ 256,652 $ 1,642,976 Key Product and Service Groups (a) : Environmental services related to resource recovery for metals manufacturing and related logistical services $ 688,923 $ — $ — $ 688,923 Applied products 100,706 — — 100,706 Environmental systems for aluminum dross and scrap processing 10,804 — — 10,804 Railway track maintenance equipment — — 140,116 140,116 After market parts and services; safety and diagnostic technology — — 94,470 94,470 Railway contracting services — — 22,066 22,066 Waste processing, recycling, reuse and transportation solutions — 585,891 — 585,891 Total Revenues $ 800,433 $ 585,891 $ 256,652 $ 1,642,976 Nine Months Ended September 30, 2020 (In thousands) Harsco Environmental Segment Harsco Harsco Consolidated Totals Primary Geographical Markets (a) (b) : North America $ 186,210 $ 434,489 $ 173,039 $ 793,738 Western Europe 271,795 — 56,435 328,230 Latin America (c) 87,453 — 1,592 89,045 Asia-Pacific 63,969 — 21,908 85,877 Middle East and Africa 46,240 — — 46,240 Eastern Europe 12,390 — — 12,390 Total Revenues $ 668,057 $ 434,489 $ 252,974 $ 1,355,520 Nine Months Ended September 30, 2020 (In thousands) Harsco Environmental Segment Harsco Harsco Consolidated Totals Key Product and Service Groups (a) : Environmental services related to resource recovery for metals manufacturing and related logistical services $ 563,701 $ — $ — $ 563,701 Applied products 95,019 — — 95,019 Environmental systems for aluminum dross and scrap processing 9,337 — — 9,337 Railway track maintenance equipment — — 138,519 138,519 After market parts and services; safety and diagnostic technology — — 92,800 92,800 Railway contracting services — — 21,655 21,655 Waste processing, recycling, reuse and transportation solutions — 434,489 — 434,489 Total Revenues $ 668,057 $ 434,489 $ 252,974 $ 1,355,520 (a) The Company's acquisition of ESOL closed on April 6, 2020. The results are included in the Harsco Clean Earth Segment. See Note 3, Acquisitions and Dispositions, for additional details. (b) Revenues are attributed to individual countries based on the location of the facility generating the revenue. (c) Includes Mexico.

Other (Income) Expenses, Net (T

Other (Income) Expenses, Net (Tables)	9 Months Ended
	Sep. 30, 2021
Other Income and Expenses [Abstract]
Schedule of other (income) expenses	The major components of this Condensed Consolidated Statements of Operations caption were as follows: Three Months Ended Nine Months Ended September 30 September 30 (In thousands) 2021 2020 2021 2020 Employee termination benefit costs $ (65) $ 798 $ 1,285 $ 6,694 Other costs to exit activities (27) 13 611 478 Impaired asset write-downs 41 2 203 75 Contingent consideration adjustments — 2,437 — 2,437 Net gains (1,575) (7) (8,622) (255) Other (1,209) 390 (1,287) (355) Other (income) expenses, net $ (2,835) $ 3,633 $ (7,810) $ 9,074

Components of Accumulated Oth_2

Components of Accumulated Other Comprehensive Loss (Tables)	9 Months Ended
	Sep. 30, 2021
Equity [Abstract]
Schedule of accumulated other comprehensive loss	The components of AOCI, net of the effect of income taxes, and activity for the nine months ended September 30, 2020 and 2021 was as follows: Components of AOCI, Net of Tax (In thousands) Cumulative Foreign Exchange Translation Adjustments Effective Portion of Derivatives Designated as Hedging Instruments Cumulative Unrecognized Actuarial Losses on Pension Obligations Unrealized Gain (Loss) on Marketable Securities Total Balance at December 31, 2019 $ (143,340) $ (3,717) $ (440,562) $ (3) $ (587,622) OCI before reclassifications (48,150) (a) (2,226) (b) 9,905 (a) (22) (40,493) Amounts reclassified from AOCI, net of tax 12,906 604 18,132 — 31,642 Total OCI (35,244) (1,622) 28,037 (22) (8,851) Less: OCI attributable to noncontrolling interests 579 — — — 579 OCI attributable to Harsco Corporation (35,823) (1,622) 28,037 (22) (9,430) Balance at September 30, 2020 $ (179,163) $ (5,339) $ (412,525) $ (25) $ (597,052) Components of AOCI, Net of Tax (In thousands) Cumulative Foreign Exchange Translation Adjustments Effective Portion of Derivatives Designated as Hedging Instruments Cumulative Unrecognized Actuarial Losses on Pension Obligations Unrealized Gain (Loss) on Marketable Securities Total Balance at December 31, 2020 $ (125,392) $ (5,840) $ (514,500) $ (9) $ (645,741) OCI before reclassifications (15,437) (a) 257 (b) 6,628 (a) 25 (8,527) Amounts reclassified from AOCI, net of tax — 1,488 17,184 — 18,672 Total OCI (15,437) 1,745 23,812 25 10,145 Less: OCI attributable to noncontrolling interests (837) — — — (837) OCI attributable to Harsco Corporation (14,600) 1,745 23,812 25 10,982 Balance at September 30, 2021 $ (139,992) $ (4,095) $ (490,688) $ 16 $ (634,759) (a) Principally foreign currency fluctuation. (b) Net change from periodic revaluations.
Reclassification out of accumulated other comprehensive income	Amounts reclassified from AOCI were as follows: (In thousands) Three Months Ended Nine Months Ended Location on the Condensed Consolidated Statements of Operations September 30 September 30 2021 2020 2021 2020 Recognition of cumulative foreign currency translation adjustments: Gain on substantial liquidation of subsidiaries (c) $ — $ — — 12,906 Gain on sale of discontinued businesses Amortization of cash flow hedging instruments: Foreign currency exchange forward contracts $ (418) $ 174 $ (465) $ (1,562) Product revenues CCIRs — 312 — 912 Interest expense Interest rate swaps 872 739 2,599 1,849 Interest expense Total before taxes 454 1,225 2,134 1,199 Income taxes (148) (408) (646) (595) Total reclassification of cash flow hedging instruments, net of tax $ 306 $ 817 $ 1,488 $ 604 Amortization of defined benefit pension items (d) : Actuarial losses $ 5,922 $ 4,962 $ 17,877 $ 14,799 Defined benefit pension income Prior service costs 125 113 381 326 Defined benefit pension income Pension liability transfer - discontinued business — — — 5,363 Gain on sale of discontinued businesses Total before taxes 6,047 5,075 18,258 20,488 Income taxes (358) (323) (1,074) (2,356) Total reclassification of defined benefit pension items, net of tax $ 5,689 $ 4,752 $ 17,184 $ 18,132 (c) No tax impact. (d) These AOCI components are included in the computation of net periodic pension costs. See Note 10, Employee Benefit Plans, for additional details.

Basis of Presentation (Details)

Basis of Presentation (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Restricted cash	$ 4,525	$ 3,215

Acquisitions and Dispositions -

Acquisitions and Dispositions - Acquisitions Narrative (Details) - USD ($)	Apr. 06, 2020	Jun. 28, 2019	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Business Acquisition [Line Items]
Additional interest expense			$ 16,004,000	$ 15,794,000	$ 48,854,000	$ 43,396,000
Gain (loss) on sale of discontinued business			$ 0	0	$ 0	18,371,000
Stericycle
Business Acquisition [Line Items]
Corporate charge						8,900,000
ESOL
Business Acquisition [Line Items]
Percentage of interests acquired	100.00%
Cash consideration	$ 429,000,000
Goodwill to be deductible for income tax purposes	$ 36,800,000
Direct acquisition costs				$ 10,600,000		41,000,000
Harsco Clean Earth Segment
Business Acquisition [Line Items]
Percentage of interests acquired		100.00%
Cash consideration		$ 628,000,000
Business Acquisition, Purchased Enterprise Valuation		$ 625,000,000
Clean Earth and ESOL
Business Acquisition [Line Items]
Additional interest expense						$ 4,700,000

Acquisitions and Dispositions_2

Acquisitions and Dispositions - Assets Acquired and Liabilities Assumed (Details) - USD ($) $ in Thousands	18 Months Ended
	Sep. 30, 2021	Dec. 31, 2020	Apr. 06, 2020
Business Acquisition [Line Items]
Goodwill	$ 896,728	$ 902,074
Gross Carrying Amount	521,424	523,048
Non-compete agreement
Business Acquisition [Line Items]
Gross Carrying Amount	2,500	2,500
Harsco Clean Earth Segment
Business Acquisition [Line Items]
Goodwill	483,879	$ 482,647
Harsco Clean Earth Segment | ESOL
Business Acquisition [Line Items]
Cash and cash equivalents	400		$ 400
Trade accounts receivable	122,600		124,100
Inventory	5,000		5,000
Other current assets	0		700
Property, plant and equipment	101,400		105,300
Right-of-use assets	56,000		56,000
Goodwill	153,300		152,000
Intangible assets	161,000		161,000
Other assets	200		200
Accounts payable	(50,100)		(48,600)
Accrued expenses	(19,300)		(17,500)
Current portion of operating lease liabilities	(16,600)		(16,600)
Other current liabilities	(6,600)		(6,400)
Environmental liabilities	(24,400)		(24,400)
Deferred income taxes	(17,000)		(15,500)
Operating lease liabilities	(39,400)		(39,400)
Total identifiable net assets of ESOL	426,500		436,300
Gross Carrying Amount	2,500		2,500
Business Acquisitions, Purchase Price Allocation	429,000		$ 438,800
Measurement Period Adjustments
Cash and cash equivalents	0
Trade accounts receivable	(1,500)
Inventory	0
Other current assets	(700)
Property, plant and equipment	(3,900)
Right-of-use assets	0
Goodwill	1,300
Intangible assets	0
Other assets	0
Accounts payable	(1,500)
Current portion of operating lease liabilities	(1,800)
Current portion of operating lease liabilities	0
Other current liabilities	(200)
Environmental liabilities	0
Deferred income taxes	(1,500)
Operating lease liabilities	0
Total identifiable net assets of ESOL	(9,800)
Total identifiable net assets of ESOL, including non-compete agreement	(9,800)
Harsco Clean Earth Segment | ESOL | Non-compete agreement
Measurement Period Adjustments
Intangible assets	$ 0

Acquisitions and Dispositions_3

Acquisitions and Dispositions - Preliminary Valuation of Identifiable Intangible Assets and Amortization Periods (Details) - USD ($) $ in Thousands	Apr. 06, 2020	Sep. 30, 2021	Dec. 31, 2020
Acquired Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount		$ 521,424	$ 523,048
Permits and rights
Acquired Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount		308,998	308,705
Non-compete agreement
Acquired Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount		2,500	$ 2,500
ESOL | Permits and rights
Acquired Finite-Lived Intangible Assets [Line Items]
Weighted-Average Amortization Period	22 years
Preliminary Valuation	$ 138,000	138,000
ESOL | Customer relationships
Acquired Finite-Lived Intangible Assets [Line Items]
Weighted-Average Amortization Period	10 years
Preliminary Valuation	$ 23,000	23,000
ESOL | Non-compete agreement
Acquired Finite-Lived Intangible Assets [Line Items]
Weighted-Average Amortization Period	4 years
Harsco Clean Earth Segment | ESOL
Acquired Finite-Lived Intangible Assets [Line Items]
Preliminary Valuation	$ 161,000	161,000
Gross Carrying Amount	2,500	2,500
Total identifiable intangible assets acquired	$ 163,500	163,500
Measurement Period Adjustments
Intangible assets		0
Harsco Clean Earth Segment | ESOL | Non-compete agreement
Measurement Period Adjustments
Permits and rights		0
Customer relationships		0
Intangible assets		0
Total identifiable intangible assets acquired		$ 0

Acquisitions and Dispositions_4

Acquisitions and Dispositions - Pro Forma Information (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2020	Jan. 31, 2020
Disposal Group, Disposed of by Sale, Not Discontinued Operations | Harsco Industrial IKG
Business Acquisition [Line Items]
Disposal Group, Net Gain on Disposal		$ 9
Clean Earth and ESOL
Business Acquisition [Line Items]
Pro forma revenues	$ 1,486.2
Pro forma net income (loss) attributed to Harsco Corporation (including discontinued operations) (a)	$ 1

Acquisitions and Dispositions_5

Acquisitions and Dispositions - Financial Information Included in Net Income from Discontinued Operations (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Amounts for the former Harsco Industrial Segment:
Gain (loss) on sale of discontinued business	$ 0	$ 0	$ 0	$ 18,371
Harsco Industrial | Discontinued Operations, Held-for-sale
Amounts for the former Harsco Industrial Segment:
Total revenues	0	0	0	10,203
Cost of products sold	0	0	0	8,082
Gain (loss) on sale of discontinued business	0	0	0	18,371
Income (loss) from discontinued business	(856)	(716)	(2,859)	(593)
Additional amounts allocated to the former Harsco Industrial Segment:
Selling, general and administrative expenses	$ 856	$ 521	$ 2,859	$ 1,710

Accounts Receivable (Details)

Accounts Receivable (Details) - USD ($)	9 Months Ended
	Sep. 30, 2021	Dec. 31, 2020	Jan. 01, 2020
Accounts, Notes, Loans and Financing Receivable [Line Items]
Trade accounts receivable	$ 434,295,000	$ 414,891,000
Accounts Receivable Greater than 12 Months Reserved	7,200,000
Receivable with Imputed Interest, Face Amount	$ 40,000,000
Note Receivable; Interest Rate; Stated percentage	2.50%
Receivables, Fair Value Disclosure	$ 31,800,000		$ 34,300,000
Proceeds from Collection of Notes Receivable	6,400,000
Greater than 12 months
Accounts, Notes, Loans and Financing Receivable [Line Items]
Trade accounts receivable	$ 12,000,000
Harsco Industrial IKG | Disposal Group, Disposed of by Sale, Not Discontinued Operations
Accounts, Notes, Loans and Financing Receivable [Line Items]
Selling price			$ 85,000,000

Accounts Receivable - Schedule

Accounts Receivable - Schedule of Receivables (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Accounts, Notes, Loans and Financing Receivable [Line Items]
Trade accounts receivable	$ 434,295	$ 414,891
Less: Allowance for expected credit losses	(8,398)	(7,501)
Trade accounts receivable, net	425,897	407,390
Other receivables	$ 39,454	$ 34,253

Accounts Receivable - Schedul_2

Accounts Receivable - Schedule of Changes in Provisions For Allowance For Credit Loss (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Receivables [Abstract]
(Benefit) provision for expected credit losses and doubtful accounts related to trade accounts receivable	$ (145)	$ 861	$ 1,087	$ 1,098

Accounts Receivable - Schedul_3

Accounts Receivable - Schedule of Fair Value of Notes Receivable (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020	Jan. 01, 2020
Receivables [Abstract]
Receivable with Imputed Interest, Net Amount	$ 30,631	$ 35,806
Receivables, Fair Value Disclosure	$ 31,800		$ 34,300

Inventories - Schedule of Inven

Inventories - Schedule of Inventory (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Inventory Disclosure [Abstract]
Finished goods	$ 9,052	$ 8,505
Work-in-process	23,793	29,005
Raw materials and purchased parts	95,156	105,306
Stores and supplies	35,071	30,197
Total inventories	$ 163,072	$ 173,013

Property, Plant and Equipment_2

Property, Plant and Equipment (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Property, Plant and Equipment
Gross property, plant and equipment	$ 1,983,000	$ 1,985,456
Less: Accumulated depreciation	(1,304,675)	(1,317,247)
Property, plant and equipment, net	678,325	668,209
Land
Property, Plant and Equipment
Gross property, plant and equipment	75,469	75,559
Land improvements
Property, Plant and Equipment
Gross property, plant and equipment	19,730	20,166
Buildings and improvements
Property, Plant and Equipment
Gross property, plant and equipment	253,659	249,954
Machinery and equipment
Property, Plant and Equipment
Gross property, plant and equipment	1,564,936	1,597,592
Construction in progress
Property, Plant and Equipment
Gross property, plant and equipment	$ 69,206	$ 42,185

Property, Plant and Equipment -

Property, Plant and Equipment - Narrative (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Property, Plant and Equipment
Property, plant and equipment, net	$ 678,325	$ 668,209
CHINA | Harsco Environmental Segment
Property, Plant and Equipment
Property, plant and equipment, net	$ 20,000

Leases - Narrative (Details)

Leases - Narrative (Details) $ in Thousands	9 Months Ended
	Sep. 30, 2021USD ($)
Lessee, Lease, Description [Line Items]
Operating And Finance Leases, Excluding Short Term Leases, Renewal Option	10 years
Operating And Finance Leases, Excluding Short Term Leases, Termination Option	1 year
Estimated ROU Assets And Lease Liabilities To Be Recognized	$ 11,800
Minimum
Lessee, Lease, Description [Line Items]
Operating And Finance Leases, Excluding Short Term Leases, Weighted-Average Remaining Lease Term	1 year
Maximum
Lessee, Lease, Description [Line Items]
Operating And Finance Leases, Excluding Short Term Leases, Weighted-Average Remaining Lease Term	29 years

Leases - Components of Lease Ex

Leases - Components of Lease Expense (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Finance leases:
Amortization expense	$ 743	$ 377	$ 1,692	$ 1,115
Interest on lease liabilities	129	43	340	139
Operating leases	8,554	8,558	25,296	21,745
Variable and short-term lease expense	12,756	11,572	38,952	29,169
Sublease Income	(1)	(51)	(52)	(150)
Total lease expense from continuing operations	$ 22,181	$ 20,499	$ 66,228	$ 52,018

Leases - Supplemental Cash Flow

Leases - Supplemental Cash Flow Information Related to Leases (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020
Cash paid for amounts included in the measurement of lease liabilities:
Cash flows from operating activities - Operating leases	$ 24,747	$ 20,512
Finance Lease, Interest Payment on Liability	1,978	997
ROU assets obtained in exchange for lease obligations:
Operating leases	29,190	62,507
Finance leases	$ 5,911	$ 1,613

Leases - Supplemental Balance S

Leases - Supplemental Balance Sheet Information Related to Leases (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Operating Leases:
Right-of-use assets, net	$ 98,841	$ 96,849
Current portion of operating lease liabilities	25,112	24,862
Operating lease liabilities	72,090	69,860
Finance Leases:
Property, plant and equipment, net	12,508	8,434
Current maturities of long-term debt	2,724	1,683
Long-term debt	$ 10,011	$ 6,867

Leases - Supplemental Additiona

Leases - Supplemental Additional Information (Details)	Sep. 30, 2021	Dec. 31, 2020
Other information:
Weighted average remaining lease term - Operating leases (in years)	7 years 5 months 8 days	8 years
Weighted average remaining lease term - Finance leases (in years)	6 years 4 months 28 days	8 years 2 months 12 days
Weighted average discount rate - Operating leases	5.90%	6.10%
Weighted average discount rate - Finance leases	4.90%	5.10%

Leases - Maturities of Lease Li

Leases - Maturities of Lease Liabilities (Details) $ in Thousands	Sep. 30, 2021USD ($)
Operating Leases
2021 (excluding the nine months ended September 30, 2021)	$ 8,027
2022	28,602
2023	22,897
2024	16,537
2025	11,284
After 2025	36,936
Total lease payments	124,283
Less: Imputed interest	(27,081)
Total	97,202
Finance Leases
2021 (excluding the nine months ended September 30, 2021)	849
2022	3,220
2023	3,001
2024	2,615
2025	1,576
After 2025	3,754
Total lease payments	15,015
Less: Imputed interest	(2,280)
Total	$ 12,735

Goodwill and Other Intangible_3

Goodwill and Other Intangible Assets - Changes in Carrying Amounts of Goodwill by Segment (Details) $ in Thousands	9 Months Ended
	Sep. 30, 2021USD ($)
Changes in carrying amounts of goodwill
Balance at December 31, 2020	$ 902,074
Goodwill, Other Increase (Decrease)	1,232
Foreign currency translation	(6,578)
Balance at September 30, 2021	896,728
Harsco Environmental Segment
Changes in carrying amounts of goodwill
Balance at December 31, 2020	406,401
Goodwill, Other Increase (Decrease)	0
Foreign currency translation	(6,578)
Balance at September 30, 2021	399,823
Harsco Clean Earth Segment
Changes in carrying amounts of goodwill
Balance at December 31, 2020	482,647
Goodwill, Other Increase (Decrease)	1,232
Foreign currency translation	0
Balance at September 30, 2021	483,879
Harsco Rail Segment
Changes in carrying amounts of goodwill
Balance at December 31, 2020	13,026
Goodwill, Other Increase (Decrease)	0
Foreign currency translation	0
Balance at September 30, 2021	$ 13,026

Goodwill and Other Intangible_4

Goodwill and Other Intangible Assets - Other Intangible Assets (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020
Intangible Assets, by category
Gross Carrying Amount	$ 521,424		$ 521,424		$ 523,048
Accumulated Amortization	107,886		107,886		84,483
Amortization expense for intangible assets	8,115	$ 8,272	24,514	$ 22,542
Estimated amortization expense for next 5 years
2021	32,900		32,900
2022	32,400		32,400
2023	32,300		32,300
2024	31,800		31,800
2025	31,600		31,600
Customer related
Intangible Assets, by category
Gross Carrying Amount	108,226		108,226		109,378
Accumulated Amortization	53,757		53,757		48,057
Permits and rights
Intangible Assets, by category
Gross Carrying Amount	308,998		308,998		308,705
Accumulated Amortization	30,856		30,856		18,955
Patents
Intangible Assets, by category
Gross Carrying Amount	185		185		192
Accumulated Amortization	140		140		139
Technology related
Intangible Assets, by category
Gross Carrying Amount	39,604		39,604		40,274
Accumulated Amortization	12,363		12,363		9,654
Trade Names [Member]
Intangible Assets, by category
Gross Carrying Amount	31,876		31,876		31,949
Accumulated Amortization	6,797		6,797		4,834
Air Rights [Member]
Intangible Assets, by category
Gross Carrying Amount	26,139		26,139		26,139
Accumulated Amortization	1,561		1,561		1,044
Other
Intangible Assets, by category
Gross Carrying Amount	3,896		3,896		3,911
Accumulated Amortization	1,475		1,475		1,331
Non-compete agreement
Intangible Assets, by category
Gross Carrying Amount	2,500		2,500		2,500
Accumulated Amortization	$ 937		$ 937		$ 469

Debt and Credit Agreements - Na

Debt and Credit Agreements - Narrative (Details)	3 Months Ended	9 Months Ended
	Sep. 30, 2021USD ($)	Sep. 30, 2021USD ($)	Mar. 31, 2023	Dec. 31, 2021	Mar. 10, 2021USD ($)
Revolving Credit Facility
Debt Instrument [Line Items]
Debt issuance expense	$ 200,000	$ 5,500,000
Write off of deferred debt issuance cost		2,700,000
Capitalized debt issuance cost	$ 7,800,000	$ 7,800,000
Revolving Credit Facility | Forecast
Debt Instrument [Line Items]
Net debt to consolidated adjusted EBITDA ratio			4	5.75
Base Rate | Minimum | Revolving Credit Facility
Debt Instrument [Line Items]
Variable rate basis spread		0.50%
Base Rate | Maximum | Revolving Credit Facility
Debt Instrument [Line Items]
Variable rate basis spread		1.50%
LIBOR | Minimum | Revolving Credit Facility
Debt Instrument [Line Items]
Variable rate basis spread		1.50%
LIBOR | Maximum | Revolving Credit Facility
Debt Instrument [Line Items]
Variable rate basis spread		2.50%
Term Loan Facility | New Term Loan
Debt Instrument [Line Items]
Principal amount					$ 500,000,000
Floor rate		0.50%
Quarterly amortization rate	0.0025	0.0025
Term Loan Facility | Base Rate | New Term Loan
Debt Instrument [Line Items]
Variable rate basis spread		1.25%
Term Loan Facility | LIBOR | New Term Loan
Debt Instrument [Line Items]
Variable rate basis spread		2.25%
Senior Notes | 5.75% Notes, due July 31, 2027
Debt Instrument [Line Items]
Interest rate	5.75%	5.75%

Debt and Credit Agreements - Sc

Debt and Credit Agreements - Schedule of Long-term Debt (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Debt Instrument [Line Items]
Debt Obligation	$ 1,361,642	$ 1,300,532
Less: deferred financing costs	(18,887)	(15,767)
Total debt obligations, net of deferred financing costs	1,342,755	1,284,765
Current maturities of long-term debt	(9,181)	(13,576)
Long-term debt	1,333,574	1,271,189
Other financing payable (including finance leases) in varying amounts
Debt Instrument [Line Items]
Debt Obligation	24,406	21,344
Term Loan Facility | New Term Loan
Debt Instrument [Line Items]
Debt Obligation	498,750	0
Term Loan Facility | Term Loan A
Debt Instrument [Line Items]
Debt Obligation	0	280,000
Term Loan Facility | Term Loan B
Debt Instrument [Line Items]
Debt Obligation	0	218,188
Line of Credit | Revolving Credit Facility
Debt Instrument [Line Items]
Debt Obligation	338,486	281,000
Senior Notes | 5.75% Notes, due July 31, 2027
Debt Instrument [Line Items]
Debt Obligation	$ 500,000	$ 500,000

Employee Benefit Plans (Details

Employee Benefit Plans (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Defined benefit plans:
Multiemployer pension plans	$ 429	$ 390	$ 1,311	$ 1,178
Defined contribution pension plans	2,974	2,870	9,507	7,936
Pension Plan | U.S. Plans
Defined benefit plans:
Service cost	0	0	0	0
Interest cost	1,203	1,845	3,609	5,535
Expected return on plan assets	(3,050)	(2,842)	(9,150)	(8,526)
Recognized prior service costs	0	0	0	0
Recognized loss	1,384	1,225	4,154	3,875
Defined benefit pension plans net periodic pension cost (benefit)	(463)	228	(1,387)	884
Defined benefit pension plan	451	453	3,768	2,940
Anticipated contributions to defined benefit pension plans during the remainder of the fiscal year	500		500
Pension Plan | International Plans
Defined benefit plans:
Service cost	489	448	1,482	1,303
Interest cost	3,184	4,474	9,619	13,104
Expected return on plan assets	(11,303)	(10,405)	(34,181)	(30,428)
Recognized prior service costs	125	113	381	326
Recognized loss	4,538	3,737	13,723	10,924
Defined benefit pension plans net periodic pension cost (benefit)	(2,967)	(1,633)	(8,976)	(4,771)
Defined benefit pension plan	4,549	$ 2,682	21,472	$ 14,235
Anticipated contributions to defined benefit pension plans during the remainder of the fiscal year	$ 3,300		$ 3,300

Income Taxes (Details)

Income Taxes (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Income Tax Disclosure [Abstract]
Income tax expense (benefit)	$ 6,989	$ (1,654)	$ 19,782	$ (4,640)
Unrecognized income tax benefits including interest and penalties	4,300		4,300
Significant Change in Unrecognized Tax Benefits is Reasonably Possible, Amount of Unrecorded Benefit	$ 300		$ 300
Harsco Clean Earth Segment
Operating Loss Carryforwards [Line Items]
Operating Loss Carryforwards		$ 2,800		$ 2,800

Commitments and Contingencies (

Commitments and Contingencies (Details)	Jun. 04, 2018USD ($)	Dec. 31, 2018USD ($)	Aug. 31, 2005USD ($)	Sep. 30, 2021USD ($)enforcementActioncasedefendantclaim	Dec. 31, 2020USD ($)	Dec. 30, 2020USD ($)	Jan. 27, 2020party	Nov. 01, 2019USD ($)	Nov. 01, 2019BRL (R$)	Mar. 18, 2019USD ($)	Mar. 18, 2019BRL (R$)
Commitments and Contingencies
Number Of Potentially Related Parties | party							20
Reserve for loss contingencies				$ 7,000,000
Penalties per day								$ 5,000	R$ 25000	$ 1,000	R$ 5000
Penalties								2,000,000	10,000,000
Current Portion of Environmental Liabilities				7,005,000	$ 6,933,000
Environmental liabilities				28,589,000	29,424,000
Total environmental liabilities				$ 35,594,000	36,357,000
Enforcement Actions | enforcementAction				3
Netherlands
Commitments and Contingencies
Damages sought - interest, penalties and fees				$ 700,000
BRAZIL
Commitments and Contingencies
Loss Contingencies, Unpaid Service Taxes						$ 2,000,000
Loss Contingencies, Overall Liability				3,300,000
Brazilian Tax Disputes - Jan 2004 through May 2005 | Sao Paulo State Revenue Authority
Commitments and Contingencies
Damages sought - interest, penalties and fees				15,800,000
Damages sought - principal				1,100,000
Loss contingency, reduced penalty	$ 1,100,000
Amount of damages sought	$ 6,700,000
Brazilian Tax Disputes - Jan 2002 through Dec 2003 | Sao Paulo State Revenue Authority
Commitments and Contingencies
Damages sought - interest, penalties and fees			$ 3,600,000
Damages sought - principal			1,100,000
Loss contingency, reduced penalty		$ 800,000
Amount of damages sought			$ 4,700,000
Loss contingency, reduced penalty, including interest		$ 5,200,000
Brazilian Labor Claims
Commitments and Contingencies
Loss contingency reserves				$ 3,500,000	$ 4,300,000
Other
Commitments and Contingencies
Approximate number of defendants that includes the company named in legal actions | defendant				90
Number of pending claims | claim				17,200
Number of claims dismissed to date by stipulation or summary judgment prior to trial | case				28,350
Other | Active or In Extremis docket
Commitments and Contingencies
Number of pending claims | claim				60
Other | Minimum
Commitments and Contingencies
Amount of damages sought				$ 20,000,000
Other | Maximum
Commitments and Contingencies
Amount of damages sought				$ 25,000,000
Other | New York County as managed by the New York Supreme Court
Commitments and Contingencies
Number of pending claims | case				16,610
Other | New York County as managed by the New York Supreme Court | Pending And Future Litigation, Deferred Or Inactive Docket
Commitments and Contingencies
Number of pending claims | claim				16,550
Other | New York State Supreme Court, Counties Excluding New York County
Commitments and Contingencies
Number of pending claims | case				120
Other | Courts Located In States Other Than New York
Commitments and Contingencies
Number of pending claims | case				470
CSN
Commitments and Contingencies
Penalties per day								$ 18,000	R$ 100000	$ 4,000	R$ 20000

Commitments and Contingencies -

Commitments and Contingencies - Schedule of Loss Contingencies by Contingency (Details) - USD ($)	Sep. 30, 2021	Dec. 31, 2020
Commitments and Contingencies Disclosure [Abstract]
Current Portion of Environmental Liabilities	$ 7,005,000	$ 6,933,000
Long-term environmental liabilities	28,589,000	29,424,000
Total environmental liabilities	$ 35,594,000	$ 36,357,000

Reconciliation of Basic and D_3

Reconciliation of Basic and Diluted Shares - Reconciliation of Basic and Diluted Shares (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Earnings Per Share [Abstract]
Income (loss) from continuing operations, net of tax	$ 8,696	$ (7,843)	$ 24,621	$ (27,375)
Weighted-average shares outstanding - basic (in shares)	79,287	79,000	79,214	78,916
Dilutive effect of stock-based compensation (in shares)	988	0	1,142	0
Weighted-average shares outstanding - diluted (in shares)	80,275	79,000	80,356	78,916
Earnings (loss) from continuing operations per common share, attributable to Harsco Corporation common stockholders:
Basic (in dollars per share)	$ 0.11	$ (0.10)	$ 0.31	$ (0.35)
Diluted (in dollars per share)	$ 0.11	$ (0.10)	$ 0.31	$ (0.35)

Reconciliation of Basic and D_4

Reconciliation of Basic and Diluted Shares - Antidilutive Securities Excluded from Computation of Earnings per Share (Details) - shares shares in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Restricted Stock Units (RSUs) [Member]
Antidilutive securities
Number of securities not included in computation of diluted earnings per share (in shares)	0	691	0	723
Stock appreciation rights
Antidilutive securities
Number of securities not included in computation of diluted earnings per share (in shares)	842	2,383	719	2,499
Performance share units
Antidilutive securities
Number of securities not included in computation of diluted earnings per share (in shares)	1,004	857	902	894

Derivative Instruments, Hedgi_3

Derivative Instruments, Hedging Activities and Fair Value - Fair Value of Outstanding Derivative Contracts (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Derivative contracts
Asset derivatives	$ 9,648	$ 3,677
Liability derivatives	6,838	12,725
Foreign currency exchange forward contracts | Other current assets
Derivative contracts
Asset derivatives	9,648	3,677
Foreign currency exchange forward contracts | Other current liabilities
Derivative contracts
Liability derivatives	1,717	5,048
Interest rate swaps | Other current liabilities
Derivative contracts
Liability derivatives	4,068	3,959
Interest rate swaps | Other liabilities
Derivative contracts
Liability derivatives	1,053	3,718
Fair Value of Derivatives Designated as Hedging Instruments
Derivative contracts
Asset derivatives	930	900
Liability derivatives	5,972	8,627
Fair Value of Derivatives Designated as Hedging Instruments | Foreign currency exchange forward contracts | Other current assets
Derivative contracts
Asset derivatives	930	900
Fair Value of Derivatives Designated as Hedging Instruments | Foreign currency exchange forward contracts | Other current liabilities
Derivative contracts
Liability derivatives	851	950
Fair Value of Derivatives Designated as Hedging Instruments | Interest rate swaps | Other current liabilities
Derivative contracts
Liability derivatives	4,068	3,959
Fair Value of Derivatives Designated as Hedging Instruments | Interest rate swaps | Other liabilities
Derivative contracts
Liability derivatives	1,053	3,718
Fair Value of Derivatives Not Designated as Hedging Instruments
Derivative contracts
Asset derivatives	8,718	2,777
Liability derivatives	866	4,098
Fair Value of Derivatives Not Designated as Hedging Instruments | Foreign currency exchange forward contracts | Other current assets
Derivative contracts
Asset derivatives	8,718	2,777
Fair Value of Derivatives Not Designated as Hedging Instruments | Foreign currency exchange forward contracts | Other current liabilities
Derivative contracts
Liability derivatives	866	4,098
Fair Value of Derivatives Not Designated as Hedging Instruments | Interest rate swaps | Other current liabilities
Derivative contracts
Liability derivatives	0	0
Fair Value of Derivatives Not Designated as Hedging Instruments | Interest rate swaps | Other liabilities
Derivative contracts
Liability derivatives	$ 0	$ 0

Derivative Instruments, Hedgi_4

Derivative Instruments, Hedging Activities and Fair Value - Narrative (Details) - USD ($)	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2022	Dec. 31, 2020
Foreign Currency Derivatives
Derivative Liability, Fair Value, Amount Not Offset Against Collateral	$ 1,300,000		$ 1,300,000
Pre-tax net gains (losses) on certain loans designated as hedges of net investments in foreign subsidiaries	(3,700,000)	$ 4,600,000	(100,000)	$ (7,400,000)
Long-term debt	1,378,500,000		1,378,500,000			$ 1,324,900,000
Foreign currency exchange forward contracts
Foreign Currency Derivatives
Derivative, Notional Amount	363,200,000		363,200,000			460,500,000
Term Loan Facility, Fixed-Rate | Term Loan
Foreign Currency Derivatives
Principal amount	200,000,000		$ 200,000,000
LIBOR | Term Loan Facility, Fixed-Rate | Term Loan
Foreign Currency Derivatives
Variable rate basis spread			2.71%
LIBOR | Forecast | Term Loan Facility, Fixed-Rate | Term Loan
Foreign Currency Derivatives
Variable rate basis spread					3.12%
Reported Value Measurement
Foreign Currency Derivatives
Long-term debt	$ 1,361,600,000		$ 1,361,600,000			$ 1,300,500,000

Derivative Instruments, Hedgi_5

Derivative Instruments, Hedging Activities and Fair Value - Effect of Derivative Instruments (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Effect of derivative instruments
Amount Recognized in OCI on Derivatives	$ 584	$ (1,363)	$ 129	$ (2,962)
Amount Reclassified from AOCI into Income - Effective Portion or Equity	454	1,225	2,134	1,199
Foreign currency exchange forward contracts
Effect of derivative instruments
Amount Recognized in OCI on Derivatives	611	(1,244)	170	834
Foreign currency exchange forward contracts | Cost of services and products sold
Effect of derivative instruments
Amount Reclassified from AOCI into Income - Effective Portion or Equity	(418)	174	(465)	(1,562)
Interest rate swaps
Effect of derivative instruments
Amount Recognized in OCI on Derivatives	(27)	(95)	(41)	(3,835)
Interest rate swaps | Interest Expense
Effect of derivative instruments
Amount Reclassified from AOCI into Income - Effective Portion or Equity	872	739	2,599	1,849
Cross currency interest rate swaps
Effect of derivative instruments
Amount Recognized in OCI on Derivatives	0	(24)	0	39
Cross currency interest rate swaps | Interest Expense
Effect of derivative instruments
Amount Reclassified from AOCI into Income - Effective Portion or Equity	$ 0	$ 312	$ 0	$ 912

Derivative Instruments, Hedgi_6

Derivative Instruments, Hedging Activities and Fair Value - Derivatives Designated as Hedging Instruments (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Derivative [Line Items]
Product Revenues	$ 544,301	$ 509,398	$ 1,642,976	$ 1,355,520
Interest Expense	(16,004)	(15,794)	(48,854)	(43,396)
Gain or (loss) reclassified from AOCI into income	(454)	(1,225)	(2,134)	(1,199)
Product Revenues | Interest rate swaps
Derivative [Line Items]
Gain or (loss) reclassified from AOCI into income	0	0
Product Revenues | Foreign exchange contracts
Derivative [Line Items]
Gain or (loss) reclassified from AOCI into income	418	(174)	465	1,562
Amount excluded from effectiveness testing recognized in earnings	24	12	62	208
Derivative Instruments, Loss Recognized in Income, Ineffective Portion and Amount Excluded from Effectiveness Testing	(1)	3	(1)	24
Product Revenues | Cross-currency interest rate swaps
Derivative [Line Items]
Gain or (loss) reclassified from AOCI into income	0	0
Interest Expense | Interest rate swaps
Derivative [Line Items]
Gain or (loss) reclassified from AOCI into income	(872)	(739)	(2,599)	(1,849)
Interest Expense | Foreign exchange contracts
Derivative [Line Items]
Gain or (loss) reclassified from AOCI into income	0	0
Amount excluded from effectiveness testing recognized in earnings	0	0
Interest Expense | Cross-currency interest rate swaps
Derivative [Line Items]
Gain or (loss) reclassified from AOCI into income	0	(312)	0	(912)
Cost of services and products sold | Foreign currency exchange forward contracts
Derivative [Line Items]
Gain or (loss) reclassified from AOCI into income	418	(174)	465	1,562
Amount of Gain Recognized in Income on Derivatives	4,105	(12,279)	8,109	(5,001)
Product Revenues
Derivative [Line Items]
Product Revenues	$ 105,677	$ 124,892	$ 343,171	$ 333,782

Review of Operations by Segme_3

Review of Operations by Segment (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2019
Operations by segment
Revenues	$ 544,301	$ 509,398	$ 1,642,976	$ 1,355,520
Operating income from continuing operations	29,920	5,064	90,963	9,813	$ 9,813
Interest income	618	604	1,841	1,613
Interest expense	(16,004)	(15,794)	(48,854)	(43,396)
Unused debt commitment fees, amendment fees and loss on extinguishment of debt	(198)	0	(5,506)	(1,920)
Defined benefit pension income (expense)	(3,906)	(1,859)	(11,833)	(5,171)
Income (loss) from continuing operations before income taxes and equity income	18,242	(8,267)	50,277	(28,719)
Capital Expenditures	40,861	27,883	109,507	78,990
Depreciation	33,479		98,383	93,864
Depreciation Excluding Industrial Segment		32,353		93,656
Amortization	8,771	9,049	26,554	24,721
Operating Segments
Operations by segment
Operating income from continuing operations	39,480	25,278	119,778	68,507
Corporate
Operations by segment
Operating income from continuing operations	(9,560)	(20,214)	(28,815)	(58,694)
Capital Expenditures	407	62	586	444
Depreciation	491	497	1,468	1,531
Amortization	657	776	2,041	2,179
Harsco Environmental Segment | Operating Segments
Operations by segment
Revenues	269,901	222,507	800,433	668,057
Operating income from continuing operations	27,630	12,317	83,788	36,400
Capital Expenditures	34,218	21,700	94,630	65,102
Depreciation	27,179	25,588	78,446	75,626
Amortization	1,997	1,970	6,080	5,827
Harsco Clean Earth Segment | Operating Segments
Operations by segment
Revenues	200,484	194,098	585,891	434,489
Operating income from continuing operations	9,893	8,902	20,457	12,945
Capital Expenditures	5,707	2,647	12,962	7,134
Depreciation	4,576	5,010	14,818	12,769
Amortization	6,033	6,218	18,179	16,463
Harsco Rail Segment | Operating Segments
Operations by segment
Revenues	73,916	92,793	256,652	252,974
Operating income from continuing operations	1,957	4,059	15,533	19,162
Capital Expenditures	529	3,474	1,329	6,310
Depreciation	1,233	1,258	3,651	3,730
Amortization	$ 84	$ 85	$ 254	$ 252

Revenue Recognition - Revenues

Revenue Recognition - Revenues by Primary Geographical Markets (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Disaggregation of Revenue [Line Items]
Total revenues	$ 544,301	$ 509,398	$ 1,642,976	$ 1,355,520
Waste Processing and Reuse Solutions
Disaggregation of Revenue [Line Items]
Total revenues	200,484	194,098	585,891	434,489
Environmental services related to resource recovery for metals manufacturing and related logistical services
Disaggregation of Revenue [Line Items]
Total revenues	230,340	181,867	688,923	563,701
Applied Products
Disaggregation of Revenue [Line Items]
Total revenues	36,091	38,166	100,706	95,019
Aluminum Dross and Scrap Processing Systems
Disaggregation of Revenue [Line Items]
Total revenues	3,470	2,474	10,804	9,337
Railway Track Maintenance Equipment
Disaggregation of Revenue [Line Items]
Total revenues	33,553	55,493	140,116	138,519
After-market Parts and Services; Safety and Diagnostic Technology
Disaggregation of Revenue [Line Items]
Total revenues	33,030	29,100	94,470	92,800
Railway Contracting Services
Disaggregation of Revenue [Line Items]
Total revenues	7,333	8,200	22,066	21,655
North America
Disaggregation of Revenue [Line Items]
Total revenues	320,516	315,876	980,098	793,738
Western Europe
Disaggregation of Revenue [Line Items]
Total revenues	123,774	113,922	383,231	328,230
Latin America
Disaggregation of Revenue [Line Items]
Total revenues	35,765	29,497	101,345	89,045
Asia-Pacific
Disaggregation of Revenue [Line Items]
Total revenues	37,983	30,239	102,319	85,877
Middle East and Africa
Disaggregation of Revenue [Line Items]
Total revenues	20,804	15,558	60,798	46,240
Eastern Europe
Disaggregation of Revenue [Line Items]
Total revenues	5,459	4,306	15,185	12,390
Operating Segments | Harsco Environmental Segment
Disaggregation of Revenue [Line Items]
Total revenues	269,901	222,507	800,433	668,057
Operating Segments | Harsco Environmental Segment | Waste Processing and Reuse Solutions
Disaggregation of Revenue [Line Items]
Total revenues	0	0	0	0
Operating Segments | Harsco Environmental Segment | Environmental services related to resource recovery for metals manufacturing and related logistical services
Disaggregation of Revenue [Line Items]
Total revenues	230,340	181,867	688,923	563,701
Operating Segments | Harsco Environmental Segment | Applied Products
Disaggregation of Revenue [Line Items]
Total revenues	36,091	38,166	100,706	95,019
Operating Segments | Harsco Environmental Segment | Aluminum Dross and Scrap Processing Systems
Disaggregation of Revenue [Line Items]
Total revenues	3,470	2,474	10,804	9,337
Operating Segments | Harsco Environmental Segment | Railway Track Maintenance Equipment
Disaggregation of Revenue [Line Items]
Total revenues	0	0	0	0
Operating Segments | Harsco Environmental Segment | After-market Parts and Services; Safety and Diagnostic Technology
Disaggregation of Revenue [Line Items]
Total revenues	0	0	0	0
Operating Segments | Harsco Environmental Segment | Railway Contracting Services
Disaggregation of Revenue [Line Items]
Total revenues	0	0	0	0
Operating Segments | Harsco Environmental Segment | North America
Disaggregation of Revenue [Line Items]
Total revenues	71,479	58,973	208,395	186,210
Operating Segments | Harsco Environmental Segment | Western Europe
Disaggregation of Revenue [Line Items]
Total revenues	106,859	92,506	336,011	271,795
Operating Segments | Harsco Environmental Segment | Latin America
Disaggregation of Revenue [Line Items]
Total revenues	35,072	29,085	99,524	87,453
Operating Segments | Harsco Environmental Segment | Asia-Pacific
Disaggregation of Revenue [Line Items]
Total revenues	30,228	22,079	80,520	63,969
Operating Segments | Harsco Environmental Segment | Middle East and Africa
Disaggregation of Revenue [Line Items]
Total revenues	20,804	15,558	60,798	46,240
Operating Segments | Harsco Environmental Segment | Eastern Europe
Disaggregation of Revenue [Line Items]
Total revenues	5,459	4,306	15,185	12,390
Operating Segments | Harsco Clean Earth Segment
Disaggregation of Revenue [Line Items]
Total revenues	200,484	194,098	585,891	434,489
Operating Segments | Harsco Clean Earth Segment | Waste Processing and Reuse Solutions
Disaggregation of Revenue [Line Items]
Total revenues	200,484	194,098	585,891	434,489
Operating Segments | Harsco Clean Earth Segment | Environmental services related to resource recovery for metals manufacturing and related logistical services
Disaggregation of Revenue [Line Items]
Total revenues	0	0	0	0
Operating Segments | Harsco Clean Earth Segment | Applied Products
Disaggregation of Revenue [Line Items]
Total revenues	0	0	0	0
Operating Segments | Harsco Clean Earth Segment | Aluminum Dross and Scrap Processing Systems
Disaggregation of Revenue [Line Items]
Total revenues	0	0	0	0
Operating Segments | Harsco Clean Earth Segment | Railway Track Maintenance Equipment
Disaggregation of Revenue [Line Items]
Total revenues	0	0	0	0
Operating Segments | Harsco Clean Earth Segment | After-market Parts and Services; Safety and Diagnostic Technology
Disaggregation of Revenue [Line Items]
Total revenues	0	0	0	0
Operating Segments | Harsco Clean Earth Segment | Railway Contracting Services
Disaggregation of Revenue [Line Items]
Total revenues	0	0	0	0
Operating Segments | Harsco Clean Earth Segment | North America
Disaggregation of Revenue [Line Items]
Total revenues	200,484	194,098	585,891	434,489
Operating Segments | Harsco Clean Earth Segment | Western Europe
Disaggregation of Revenue [Line Items]
Total revenues	0	0	0	0
Operating Segments | Harsco Clean Earth Segment | Latin America
Disaggregation of Revenue [Line Items]
Total revenues	0	0	0	0
Operating Segments | Harsco Clean Earth Segment | Asia-Pacific
Disaggregation of Revenue [Line Items]
Total revenues	0	0	0	0
Operating Segments | Harsco Clean Earth Segment | Middle East and Africa
Disaggregation of Revenue [Line Items]
Total revenues	0	0	0	0
Operating Segments | Harsco Clean Earth Segment | Eastern Europe
Disaggregation of Revenue [Line Items]
Total revenues	0	0	0	0
Operating Segments | Harsco Rail Segment
Disaggregation of Revenue [Line Items]
Total revenues	73,916	92,793	256,652	252,974
Operating Segments | Harsco Rail Segment | Waste Processing and Reuse Solutions
Disaggregation of Revenue [Line Items]
Total revenues	0	0	0	0
Operating Segments | Harsco Rail Segment | Environmental services related to resource recovery for metals manufacturing and related logistical services
Disaggregation of Revenue [Line Items]
Total revenues	0	0	0	0
Operating Segments | Harsco Rail Segment | Applied Products
Disaggregation of Revenue [Line Items]
Total revenues	0	0	0	0
Operating Segments | Harsco Rail Segment | Aluminum Dross and Scrap Processing Systems
Disaggregation of Revenue [Line Items]
Total revenues	0	0	0	0
Operating Segments | Harsco Rail Segment | Railway Track Maintenance Equipment
Disaggregation of Revenue [Line Items]
Total revenues	33,553	55,493	140,116	138,519
Operating Segments | Harsco Rail Segment | After-market Parts and Services; Safety and Diagnostic Technology
Disaggregation of Revenue [Line Items]
Total revenues	33,030	29,100	94,470	92,800
Operating Segments | Harsco Rail Segment | Railway Contracting Services
Disaggregation of Revenue [Line Items]
Total revenues	7,333	8,200	22,066	21,655
Operating Segments | Harsco Rail Segment | North America
Disaggregation of Revenue [Line Items]
Total revenues	48,553	62,805	185,812	173,039
Operating Segments | Harsco Rail Segment | Western Europe
Disaggregation of Revenue [Line Items]
Total revenues	16,915	21,416	47,220	56,435
Operating Segments | Harsco Rail Segment | Latin America
Disaggregation of Revenue [Line Items]
Total revenues	693	412	1,821	1,592
Operating Segments | Harsco Rail Segment | Asia-Pacific
Disaggregation of Revenue [Line Items]
Total revenues	7,755	8,160	21,799	21,908
Operating Segments | Harsco Rail Segment | Middle East and Africa
Disaggregation of Revenue [Line Items]
Total revenues	0	0	0	0
Operating Segments | Harsco Rail Segment | Eastern Europe
Disaggregation of Revenue [Line Items]
Total revenues	$ 0	$ 0	$ 0	$ 0

Revenue Recognition - Narrative

Revenue Recognition - Narrative (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2018	Dec. 31, 2016	Dec. 31, 2020
Disaggregation of Revenue [Line Items]
Total contract assets	$ 111,800		$ 111,800				$ 60,100
Total advances on contracts	67,800		67,800				84,900
Revenue recognized	14,000	$ 20,000	44,000	$ 55,000
Contract with Customer, Liability, Revenue Recognized	14,000	20,000	44,000	55,000
Contract estimated forward loss provision for Harsco Rail Segment					$ 1,800	$ 45,100
Loss provision that exceeds accumulated contract costs	3,800		3,800				$ 4,400
Revenues	544,301	509,398	1,642,976	1,355,520
SBB [Member]
Disaggregation of Revenue [Line Items]
Revenues	$ 5,400	$ 11,800	$ 15,400	$ 29,500
Contract 2 [Member] | SBB [Member]
Disaggregation of Revenue [Line Items]
Percentage complete	81.00%		81.00%

Revenue Recognition - Remaining

Revenue Recognition - Remaining Performance Obligation (Details) $ in Millions	Sep. 30, 2021USD ($)
Harsco Environmental Segment
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligation	$ 88.8
Harsco Environmental Segment | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2021-10-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligation	$ 20.9
Period of expected timing of satisfaction	1 year
Harsco Environmental Segment | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2022-10-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligation	$ 20.3
Period of expected timing of satisfaction	1 year
Harsco Environmental Segment | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2023-10-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligation	$ 19.3
Period of expected timing of satisfaction	1 year
Harsco Environmental Segment | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2024-10-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligation	$ 19.2
Period of expected timing of satisfaction	1 year
Harsco Environmental Segment | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2025-10-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Period of expected timing of satisfaction
Harsco Rail Segment
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligation	$ 246.3
Harsco Rail Segment | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2021-10-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligation	$ 117.8
Period of expected timing of satisfaction	1 year
Harsco Rail Segment | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2022-10-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligation	$ 73
Period of expected timing of satisfaction	1 year
Harsco Rail Segment | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2023-10-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligation	$ 37.4
Period of expected timing of satisfaction	1 year
Harsco Rail Segment | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2024-10-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligation	$ 18
Period of expected timing of satisfaction	1 year
Harsco Rail Segment | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2025-10-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Period of expected timing of satisfaction

Other (Income) Expenses, Net (D

Other (Income) Expenses, Net (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Other Income and Expenses [Abstract]
Employee termination benefit costs	$ (65)	$ 798	$ 1,285	$ 6,694
Net gains	(1,575)	(7)	(8,622)	(255)
Other costs to exit activities	(27)	13	611	478
Impaired asset write-downs	41	2	203	75
Business Combination, Contingent Consideration Arrangements, Change in Amount of Contingent Consideration, Liability	0	2,437	0	2,437
Other	(1,209)	390	(1,287)	(355)
Other (income) expenses, net	$ (2,835)	$ 3,633	$ (7,810)	$ 9,074

Components of Accumulated Oth_3

Components of Accumulated Other Comprehensive Loss - Accumulated Other Comprehensive Income Loss (Details) - USD ($) $ in Thousands	3 Months Ended						9 Months Ended
	Sep. 30, 2021	Jun. 30, 2021	Mar. 31, 2021	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Sep. 30, 2021	Sep. 30, 2020
Components of Accumulated Other Comprehensive Income [Roll Forward]
Beginning balance	$ 749,383	$ 716,583	$ 713,399	$ 764,516	$ 758,870	$ 789,659	$ 713,399	$ 789,659
Other comprehensive income (loss) before reclassifications							(8,527)	(40,493)
Amounts reclassified from accumulated other comprehensive loss							18,672	31,642
Total other comprehensive income (loss)	(8,997)	17,913	1,229	8,120	13,031	(30,002)	10,145	(8,851)
Less: OCI attributable to noncontrolling interests							(837)	579
Other comprehensive income (loss) attributable to Harsco Corporation							10,982	(9,430)
Ending balance	753,227	749,383	716,583	766,414	764,516	758,870	753,227	766,414
Accumulated Foreign Currency Adjustment Attributable to Parent [Member]
Components of Accumulated Other Comprehensive Income [Roll Forward]
Beginning balance			(125,392)			(143,340)	(125,392)	(143,340)
Other comprehensive income (loss) before reclassifications							(15,437)	(48,150)
Amounts reclassified from accumulated other comprehensive loss							0	12,906
Total other comprehensive income (loss)							(15,437)	(35,244)
Less: OCI attributable to noncontrolling interests							(837)	579
Other comprehensive income (loss) attributable to Harsco Corporation							(14,600)	(35,823)
Ending balance	(139,992)			(179,163)			(139,992)	(179,163)
Effective Portion of Deriviatives Designated as Hedging Instruments
Components of Accumulated Other Comprehensive Income [Roll Forward]
Beginning balance			(5,840)			(3,717)	(5,840)	(3,717)
Other comprehensive income (loss) before reclassifications							257	(2,226)
Amounts reclassified from accumulated other comprehensive loss							1,488	604
Total other comprehensive income (loss)							1,745	(1,622)
Less: OCI attributable to noncontrolling interests							0	0
Other comprehensive income (loss) attributable to Harsco Corporation							1,745	(1,622)
Ending balance	(4,095)			(5,339)			(4,095)	(5,339)
Cumulative Unrecognized Actuarial Losses on Pension Obligations
Components of Accumulated Other Comprehensive Income [Roll Forward]
Beginning balance			(514,500)			(440,562)	(514,500)	(440,562)
Other comprehensive income (loss) before reclassifications							6,628	9,905
Amounts reclassified from accumulated other comprehensive loss							17,184	18,132
Total other comprehensive income (loss)							23,812	28,037
Less: OCI attributable to noncontrolling interests							0	0
Other comprehensive income (loss) attributable to Harsco Corporation							23,812	28,037
Ending balance	(490,688)			(412,525)			(490,688)	(412,525)
Unrealized Loss on Marketable Securities
Components of Accumulated Other Comprehensive Income [Roll Forward]
Beginning balance			(9)			(3)	(9)	(3)
Other comprehensive income (loss) before reclassifications							25	(22)
Amounts reclassified from accumulated other comprehensive loss							0	0
Total other comprehensive income (loss)							25	(22)
Less: OCI attributable to noncontrolling interests							0	0
Other comprehensive income (loss) attributable to Harsco Corporation							25	(22)
Ending balance	16			(25)			16	(25)
Accumulated Other Comprehensive Loss
Components of Accumulated Other Comprehensive Income [Roll Forward]
Beginning balance	(626,206)	(643,446)	(645,741)	(603,618)	(616,476)	(587,622)	(645,741)	(587,622)
Total other comprehensive income (loss)	(8,553)	17,240	2,295	6,566	12,858	(28,854)
Ending balance	$ (634,759)	$ (626,206)	$ (643,446)	$ (597,052)	$ (603,618)	$ (616,476)	$ (634,759)	$ (597,052)

Components of Accumulated Oth_4

Components of Accumulated Other Comprehensive Loss - Reclassification out of Accumulated Other Comprehensive Income (Details) - USD ($) $ in Thousands	3 Months Ended						9 Months Ended
	Sep. 30, 2021	Jun. 30, 2021	Mar. 31, 2021	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Sep. 30, 2021	Sep. 30, 2020
Reclassification out of Accumulated Other Comprehensive Income [Line Items]
Product revenues	$ 544,301			$ 509,398			$ 1,642,976	$ 1,355,520
Interest expense	16,004			15,794			48,854	43,396
Income from continuing operations before income taxes	18,242			(8,267)			50,277	(28,719)
Income tax expense (benefit)	6,989			(1,654)			19,782	(4,640)
Net income (loss)	9,828	$ 15,080	$ 1,565	(8,339)	$ (9,455)	$ 1,227	26,473	(16,567)
Amount Reclassified from Accumulated Other Comprehensive Loss | Cumulative Unrecognized Actuarial Losses on Pension Obligations
Reclassification out of Accumulated Other Comprehensive Income [Line Items]
Income from continuing operations before income taxes	6,047			5,075			18,258	20,488
Income tax expense (benefit)	(358)			(323)			(1,074)	(2,356)
Net income (loss)	5,689			4,752			17,184	18,132
Amount Reclassified from Accumulated Other Comprehensive Loss | Effective Portion of Deriviatives Designated as Hedging Instruments
Reclassification out of Accumulated Other Comprehensive Income [Line Items]
Income from continuing operations before income taxes	454			1,225			2,134	1,199
Income tax expense (benefit)	(148)			(408)			(646)	(595)
Net income (loss)	306			817			1,488	604
Amount Reclassified from Accumulated Other Comprehensive Loss | Effective Portion of Deriviatives Designated as Hedging Instruments | Foreign currency exchange forward contracts
Reclassification out of Accumulated Other Comprehensive Income [Line Items]
Discontinued Operation, Gain From Disposal Of Discontinued Operation, Before Income Tax	0			0			0	12,906
Product revenues	(418)			174			(465)	(1,562)
Amount Reclassified from Accumulated Other Comprehensive Loss | Effective Portion of Deriviatives Designated as Hedging Instruments | Cross currency interest rate swaps
Reclassification out of Accumulated Other Comprehensive Income [Line Items]
Interest expense	0			312			0	912
Amount Reclassified from Accumulated Other Comprehensive Loss | Effective Portion of Deriviatives Designated as Hedging Instruments | Interest rate swaps
Reclassification out of Accumulated Other Comprehensive Income [Line Items]
Interest expense	872			739			2,599	1,849
Amount Reclassified from Accumulated Other Comprehensive Loss | Actuarial losses
Reclassification out of Accumulated Other Comprehensive Income [Line Items]
Defined benefit pension income	5,922			4,962			17,877	14,799
Amount Reclassified from Accumulated Other Comprehensive Loss | Prior service costs
Reclassification out of Accumulated Other Comprehensive Income [Line Items]
Defined benefit pension income	125			113			381	326
Amount Reclassified from Accumulated Other Comprehensive Loss | Pension liability transfer - discontinued business
Reclassification out of Accumulated Other Comprehensive Income [Line Items]
Defined benefit pension income	$ 0			$ 0			$ 0	$ 5,363

Subsequent Events (Details)

Subsequent Events (Details) $ in Millions	Apr. 06, 2020USD ($)
ESOL
Subsequent Event [Line Items]
Cash consideration	$ 429