Document and Entity Information - USD ($) $ in Millions |
12 Months Ended | ||
|---|---|---|---|
Dec. 31, 2025 |
Feb. 10, 2026 |
Jun. 30, 2025 |
|
| Cover [Abstract] | |||
| Entity Registrant Name | MERCER INTERNATIONAL INC. | ||
| Entity Central Index Key | 0001333274 | ||
| Document Type | 10-K | ||
| Document Period End Date | Dec. 31, 2025 | ||
| Trading Symbol | MERC | ||
| Amendment Flag | false | ||
| Document Fiscal Year Focus | 2025 | ||
| Document Fiscal Period Focus | FY | ||
| Current Fiscal Year End Date | --12-31 | ||
| Entity Filer Category | Accelerated Filer | ||
| Entity Common Stock, Shares Outstanding | 66,982,506 | ||
| Entity Shell Company | false | ||
| Entity Current Reporting Status | Yes | ||
| Entity Interactive Data Current | Yes | ||
| Entity Emerging Growth Company | false | ||
| Entity Small Business | false | ||
| Entity File Number | 000-51826 | ||
| Entity Incorporation, State or Country Code | WA | ||
| Entity Tax Identification Number | 47-0956945 | ||
| Entity Address, Address Line One | Suite 1120 | ||
| Entity Address, Address Line Two | 700 West Pender Street | ||
| Entity Address, City or Town | Vancouver | ||
| Entity Address, State or Province | BC | ||
| Entity Address, Country | CA | ||
| Entity Address, Postal Zip Code | V6C 1G8 | ||
| City Area Code | 604 | ||
| Local Phone Number | 684-1099 | ||
| Title of 12(b) Security | Common Stock, par value $1.00 per share | ||
| Security Exchange Name | NASDAQ | ||
| Document Annual Report | true | ||
| Document Transition Report | false | ||
| Entity Well-known Seasoned Issuer | No | ||
| Entity Voluntary Filers | No | ||
| Entity Public Float | $ 231.7 | ||
| ICFR Auditor Attestation Flag | true | ||
| Auditor Name | PricewaterhouseCoopers LLP | ||
| Auditor Firm ID | 271 | ||
| Auditor Location | Vancouver, Canada | ||
| Documents Incorporated by Reference | Portions of the Registrant’s definitive Proxy Statement to be filed with the Securities and Exchange Commission in connection with its annual meeting of shareholders to be held in 2026 are incorporated by reference into Part III hereof. |
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| Document Financial Statement Error Correction [Flag] | false | ||
| Auditor Opinion [Text Block] | Opinions on the Financial Statements and Internal Control over Financial Reporting We have audited the accompanying consolidated balance sheets of Mercer International Inc. and its subsidiaries (the Company) as of December 31, 2025 and 2024, and the related consolidated statements of operations, of comprehensive loss, of changes in shareholders’ equity and of cash flows for each of the three years in the period ended December 31, 2025, including the related notes (collectively referred to as the consolidated financial statements). We also have audited the Company’s internal control over financial reporting as of December 31, 2025, based on criteria established in Internal Control ‒ Integrated Framework(2013) issued by the Committee of Sponsoring Organizations of the Treadway Commission (COSO). In our opinion, the consolidated financial statements referred to above present fairly, in all material respects, the financial position of the Company as of December 31, 2025 and 2024, and the results of its operations and its cash flows for each of the three years in the period ended December 31, 2025 in conformity with accounting principles generally accepted in the United States of America. Also in our opinion, the Company maintained, in all material respects, effective internal control over financial reporting as of December 31, 2025, based on criteria established in Internal Control ‒ Integrated Framework(2013) issued by the COSO.
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