v3.25.4

Income Taxes (Tables)

12 Months Ended

Dec. 31, 2025

Income Tax Disclosure [Abstract]

Components of Loss Before Income Taxes

The components of loss before income taxes for the years ended December 31, 2025, 2024 and 2023 were as follows:

	For the Year Ended December 31,
	2025				2024				2023
U.S.	$	(120,255	)		$	(80,257	)		$	(69,116	)
Foreign		(390,956	)			(6,658	)			(200,707	)
	$	(511,211	)		$	(86,915	)		$	(269,823	)

Schedule of Income Tax Recovery Recognized in Consolidated Statements of Operations

Income tax recovery recognized in the Consolidated Statements of Operations for the years ended December 31, 2025, 2024 and 2023 was comprised of the following:

	For the Year Ended December 31,
	2025				2024				2023
Current income tax recovery (provision)
U.S. Federal	$	(21	)
U.S. State		(30	)
U.S.		(51	)		$	(640	)		$	1,564
Foreign		2,055				(33,307	)			(10,189	)
Total current income tax recovery (provision)	$	2,004			$	(33,947	)		$	(8,625	)
Deferred income tax recovery (provision)
Foreign	$	11,318			$	35,721			$	36,392
Total income tax recovery (provision)
U.S. Federal	$	(21	)
U.S. State		(30	)
U.S.		(51	)		$	(640	)		$	1,564
Foreign		13,373				2,414				26,203
Total income tax recovery	$	13,322			$	1,774			$	27,767

Reconciliation of Effective Tax Rate

The difference between the U.S. Federal statutory and the Company’s effective rate for the year ended December 31, 2025 was as follows:

	For the Year Ended December 31,
	Amount			%
Income tax recovery using U.S. Federal statutory rate on loss before income taxes	$	107,354		21.0%
U.S. Federal
Changes in valuation allowances		(20,435	)	(4.0%)
Other (a)		(4,424	)	(0.9%)
U.S. state income taxes, net of federal income tax effect (b)		(30	)	(0.0%)
Foreign tax effects
Germany
Trade taxes		10,689		2.1%
Changes in valuation allowances		(13,515	)	(2.6%)
Other (a)		(223	)	(0.0%)
Canada
Statutory income tax rate differential		(18,365	)	(3.6%)
Provincial taxes		25,989		5.1%
Changes in valuation allowances		(72,747	)	(14.2%)
Other (a)		(557	)	(0.1%)
Australia
Changes in valuation allowances		(7,201	)	(1.4%)
Prior year true-up: Non-capital loss and others		6,610		1.3%
Other (a)		177		0.0%
Income tax recovery and effective tax rate	$	13,322		2.6%

(a)Primarily includes return-to-provision adjustments, non-taxable government subsidies, tax benefit of partnership structure and the effect of statutory tax rate changes enacted during the period.

(b)In 2025, state income taxes in Maryland and Louisiana comprise the majority of the U.S. state income taxes, net of federal income tax effect category.

Differences between the U.S. Federal statutory and the Company’s effective rates for the years ended December 31, 2024 and 2023 were as follows:

	For the Year Ended December 31,
	2024				2023
U.S. Federal statutory rate	21%				21%
Income tax recovery using U.S. Federal statutory rate on loss before income taxes	$	18,252			$	56,663
Tax differential on foreign income (loss)		(1,243	)			9,049
Effect of foreign earnings (a)		(5,169	)			—
Valuation allowance		(2,392	)			(39,810	)
Tax benefit of partnership structure		1,479				3,132
Non-taxable foreign subsidies		2,332				3,297
Non-deductible goodwill impairment		(10,039	)			—
True-up of prior year taxes		(363	)			(4,553	)
Other		(1,083	)			(11	)
Income tax recovery	$	1,774			$	27,767

(a)Primarily due to the impact of the global intangible low-taxed income provision in the Tax Cuts and Jobs Act of 2017.

Deferred Tax Assets and Liabilities

Deferred income tax assets and liabilities as of December 31, 2025 and December 31, 2024 were comprised of the following:

	December 31,
	2025				2024
German tax loss carryforwards	$	20,090			$	18,843
U.S. tax loss carryforwards and credits		88,205				61,318
Canadian tax loss carryforwards		56,886				34,758
Australian tax loss carryforwards		9,047				5,544
Basis difference between income tax and financial reporting with respect to operating sites		(51,025	)			(109,550	)
Amortizable intangible assets		(822	)			(6,973	)
Accounts payable and accrued expenses		4,020				3,100
Finance leases		9,883				10,799
Scientific research and experimental development investment tax credit and expenditure pool		8,076				6,390
Other		3,958				575
		148,318				24,804
Valuation allowance		(198,777	)			(81,798	)
Net deferred income tax liability	$	(50,459	)		$	(56,994	)
Comprised of:
Deferred income tax asset	$	7,839			$	17,778
Deferred income tax liability		(58,298	)			(74,772	)
Net deferred income tax liability	$	(50,459	)		$	(56,994	)

Summary of Investment Tax Credit and Other Tax Attributes Carryforwards

The following table details the scheduled expiration dates of the Company’s net operating loss, interest, investment tax credit and other tax attributes carryforwards as of December 31, 2025:

	Amount				Expiration
U.S.
Net operating loss	$	76,800			Indefinite
Interest	$	343,200			Indefinite
Germany
Corporate and trade tax loss	$	101,300			Indefinite
Interest	$	24,800			Indefinite
Canada
Net operating loss	$	174,100			2036 – 2044
Interest	$	51,500			Indefinite
Scientific research and experimental development investment tax credit	$	6,800			2030 – 2044
Australia
Net operating loss	$	30,200			Indefinite

Summary of Changes in Valuation Allowance

Changes in valuation allowances related to net deferred tax assets for the years ended December 31, 2025 and 2024 were as follows:

	December 31,
	2025				2024
Beginning of year balance	$	81,798			$	78,689
Additions (reversals)
U.S.		20,435				8,727
Germany		13,515				—
Canada		72,747				(7,815	)
Australia		7,201				610
The impact of changes in foreign exchange rates		3,081				1,587
End of year balance	$	198,777			$	81,798

Income Tax Payments (Net of Refunds) by Jurisdiction

Income tax payments (net of refunds) by jurisdiction for the year ended December 31, 2025 were as follows:

	For the Year Ended
	December 31, 2025
U.S. state	$	548
Foreign
Germany Federal		2,828
Germany state and local
Thuringia		6,610
Saalburg-Ebersdorf		6,478
Arneburg		3,753
Rosenthal		3,576
Torgau		1,482
Other		743
Total	$	26,018

X

- Definition

Income tax payments (net of refunds) by jurisdiction.

+ References

No definition available.

+ Details

Name:	merc_IncomeTaxPaymentsNetOfRefundsByJurisdictionTableTextBlock
Namespace Prefix:	merc_
Data Type:	dtr-types:textBlockItemType
Balance Type:	na
Period Type:	duration

X

- Definition

Summary of operating loss carryforwards and tax credit carryforwards.

+ References

No definition available.

+ Details

Name:	merc_SummaryOfOperatingLossCarryforwardsAndTaxCreditCarryforwardsTextBlock
Namespace Prefix:	merc_
Data Type:	dtr-types:textBlockItemType
Balance Type:	na
Period Type:	duration

X

- References

No definition available.

+ Details

Name:	us-gaap_IncomeTaxDisclosureAbstract
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

X

- Definition

Tabular disclosure of the components of income tax expense attributable to continuing operations for each year presented including, but not limited to: current tax expense (benefit), deferred tax expense (benefit), investment tax credits, government grants, the benefits of operating loss carryforwards, tax expense that results from allocating certain tax benefits either directly to contributed capital or to reduce goodwill or other noncurrent intangible assets of an acquired entity, adjustments of a deferred tax liability or asset for enacted changes in tax laws or rates or a change in the tax status of the entity, and adjustments of the beginning-of-the-year balances of a valuation allowance because of a change in circumstances that causes a change in judgment about the realizability of the related deferred tax asset in future years.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 740
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 9
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482685/740-10-50-9

+ Details

Name:	us-gaap_ScheduleOfComponentsOfIncomeTaxExpenseBenefitTableTextBlock
Namespace Prefix:	us-gaap_
Data Type:	dtr-types:textBlockItemType
Balance Type:	na
Period Type:	duration

X

- Definition

Tabular disclosure of the components of net deferred tax asset or liability recognized in an entity's statement of financial position, including the following: the total of all deferred tax liabilities, the total of all deferred tax assets, the total valuation allowance recognized for deferred tax assets.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 740
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482685/740-10-50-2

+ Details

Name:	us-gaap_ScheduleOfDeferredTaxAssetsAndLiabilitiesTableTextBlock
Namespace Prefix:	us-gaap_
Data Type:	dtr-types:textBlockItemType
Balance Type:	na
Period Type:	duration

X

- Definition

Tabular disclosure of the reconciliation using percentage or dollar amounts of the reported amount of income tax expense attributable to continuing operations for the year to the amount of income tax expense that would result from applying domestic federal statutory tax rates to pretax income from continuing operations.

+ References

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Topic 740
-SubTopic 10
-Name Accounting Standards Codification
-Section 55
-Paragraph 231
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482663/740-10-55-231

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 740
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 12A
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482685/740-10-50-12A

Reference 3: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 740
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 12
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482685/740-10-50-12

+ Details

Name:	us-gaap_ScheduleOfEffectiveIncomeTaxRateReconciliationTableTextBlock
Namespace Prefix:	us-gaap_
Data Type:	dtr-types:textBlockItemType
Balance Type:	na
Period Type:	duration

X

- Definition

Tabular disclosure of income before income tax between domestic and foreign jurisdictions.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 235
-SubTopic 10
-Name Accounting Standards Codification
-Section S50
-Paragraph 1
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480738/235-10-S50-1

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 235
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08(h)(1)(Note 1))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480678/235-10-S99-1

+ Details

Name:	us-gaap_ScheduleOfIncomeBeforeIncomeTaxDomesticAndForeignTableTextBlock
Namespace Prefix:	us-gaap_
Data Type:	dtr-types:textBlockItemType
Balance Type:	na
Period Type:	duration

X

- Definition

Tabular disclosure of valuation allowances to reduce deferred tax assets to net realizable value, including identification of the deferred tax asset more likely than not will not be fully realized and the corresponding amount of the valuation allowance.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 740
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (c)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482685/740-10-50-2

+ Details

Name:	us-gaap_SummaryOfValuationAllowanceTextBlock
Namespace Prefix:	us-gaap_
Data Type:	dtr-types:textBlockItemType
Balance Type:	na
Period Type:	duration