| Document and Entity Information | 12 Months Ended |
| Dec. 31, 2022 | |
| Cover [Abstract] | |
| Document Type | DEF 14A |
| Amendment Flag | false |
| Entity Registrant Name | MERCER INTERNATIONAL INC. |
| Entity Central Index Key | 0001333274 |
| Pay vs Performance Disclosure - USD ($) | 12 Months Ended | ||
| Dec. 31, 2022 | Dec. 31, 2021 | Dec. 31, 2020 | |
| Pay vs Performance Disclosure [Table] | |||
| Pay vs Performance [Table Text Block] | We are required by SEC rules to disclose the following information regarding compensation paid to our NEOs. The amounts set forth below under the headings "Compensation Actually Paid to CEO" and "Average Compensation Actually Paid for NEOs" have been calculated in a manner consistent with Item 402(v) of Regulation S-K. Footnote (9) below sets forth the adjustments from the Total Compensation for each NEO reported in the Summary Compensation Table above. The following table sets forth additional compensation information of our CEO and our non-CEO NEOs along with total shareholder return, net income, and Operating EBITDA performance results for fiscal years 2020, 2021 and 2022: Year Summary Compensation Table Total for CEO ($) Compensation Actually Paid to CEO ($) Average Summary Compensation Table Total for Non-CEO NEOs (2) ($) Average Compensation Actually Paid to Non-CEO NEOs (2) ($) Value of Initial Fixed $100 Investment Based On: Net Income (Loss) ($) Operating EBITDA (in 000s) (8) ($) Juan Carlos Bueno (1) David Gandossi (1) Juan Carlos Bueno (1) David Gandossi (1) Total Shareholder Return (7) ($) Peer Group Total Shareholder Return (7) ($) (a) (b) (c) (d) (e) (f) (g) (h) (i) 2022 4,945,342 1,518,538 3,016,641 805,552 1,447,598 1,172,474 103.55 129.84 247,039 536,521 2021 - 3,152,658 - 2,192,172 1,372,425 1,062,311 104.19 132.54 170,988 478,782 2020 - 2,647,401 - 1,837,807 1,147,195 788,328 87.24 122.03 ( 17,235 ) 192,650 (1) Mr. Gandossi stepped down as Chief Executive Officer and President on May 1, 2022 and retired as a director effective May 31, 2022. Mr. Bueno was appointed as Chief Executive Officer and President on May 1, 2022, and was elected as a director effective May 31, 2022. In connection with Mr. Bueno's appointment, he was provided with a one-time moving cost allowance and was granted: (i) 50,000 RSUs; (ii) 96,530 PSUs that have a performance period ending on December 31, 2023; and (iii) 96,530 PSUs that have a performance period ending on December 31, 2024. Such one-time RSU and PSU grants were made to attract Mr. Bueno as well as allow Mr. Bueno to enter into the same pay for performance cycle as our other NEOs. PSU grants for the CEO in 2023 have returned to previous levels. (2) The CEOs and NEOs in the above compensation columns reflect the following: Year CEO NEOs 2022 David Gandossi (to May 1, 2022) Juan Carlos Bueno (from May 1, 2022) Jimmy S.H. Lee, David Ure, Adolf Koppensteiner, Guy Arguin 2021 David Gandossi Jimmy S.H. Lee, David Ure, Adolf Koppensteiner, Wolfram Ridder 2020 David Gandossi Jimmy S.H. Lee, David Ure, Adolf Koppensteiner, Wolfram Ridder (3) Fair value or change in fair value, as applicable, of equity awards in the "Compensation Actually Paid" columns was determined by reference to (1) for PSU awards (excluding TSR awards), closing price on applicable year-end dates or, in the case of vesting dates, the actual vesting price multiplied by the probability of achievement as of each such date, (2) for TSR-based PSU awards, the fair value calculated by a Monte Carlo simulation model as of the applicable year-end date(s) or, in the case of vesting date, the actual vesting price and probability of achievement, and in all cases based on volatility, dividend rates and risk free rates determined as of the revaluation date. (4) 2022 "Compensation Actually Paid" to the CEO and the average "Compensation Actually Paid" to the NEOs reflect the adjustments set forth in the table below in Note (9) from Total Compensation reported in the Summary Compensation Table. (5) 2021 "Compensation Actually Paid" to the CEO and the average "Compensation Actually Paid" to the NEOs reflect the adjustments set forth in the table below in Note (9) from Total Compensation reported in the Summary Compensation Table. (6) 2020 "Compensation Actually Paid" to the CEO and the average "Compensation Actually Paid" to the NEOs reflect the adjustments set forth in the table below in Note (9) from Total Compensation reported in the Summary Compensation Table. (7) For the relevant fiscal year, represents the cumulative total shareholder return (TSR) of Mercer International Inc. and the TSR Peer Group as set forth under the Fiscal 2022 Shareholder Returns section of this proxy. Each year reflects what the cumulative value of $100 would be, including the reinvestment of dividends, adjusted for stock splits and spinoffs, if such amount were invested by the market close on the last trading day before the beginning of the Company’s third preceding fiscal year. (8) EBITDA was selected as our Company Selected Measure for evaluating Pay versus Performance because it is a key metric in our PSU Plans as well as being a performance metric in our Annual Incentive Plans. (9) "Compensation Actually Paid" to the CEO and the average "Compensation Actually Paid" to the NEOs reflect the following adjustment from Total Compensation reported in the Summary Compensation Table: 2022 2021 2020 CEO (Gandossi) ($) CEO (Bueno) ($) Average of NEOs ($) CEO ($) Average of NEOs ($) CEO ($) Average of NEOs ($) Total Reported in 2022 Summary Compensation Table (SCT) 1,518,538 4,945,342 1,447,598 3,152,658 1,372,425 2,647,401 1,147,195 Less, total fair value of stock and option awards reported in SCT 314,028 3,757,708 454,575 1,375,183 415,925 1,299,232 372,768 Plus, fair value (at end of fiscal year) of awards granted in 2022 fiscal year that are unvested and outstanding 159,817 1,829,007 231,345 702,431 212,451 990,495 284,187 Plus, change in fair (at end of fiscal year) value of prior year awards that are outstanding and unvested ( 35,048 ) - ( 16,682 ) ( 208,265 ) ( 59,754 ) ( 213,615 ) ( 126,039 ) Plus, fair value (at vesting date) of awards granted and vested in 2022 fiscal year - - - - - - - Plus, change in fair value (at vesting date) of prior year awards that vested in 2022 fiscal year ( 53,439 ) - ( 15,101 ) 15,537 9,167 ( 46,132 ) ( 23,167 ) Less, fair value (at end of prior fiscal year) of prior year awards that failed to vest in 2022 fiscal year (i.e. forfeited) 470,288 - 20,111 95,006 56,053 241,110 121,079 Less, change in actuarial present value of all defined benefit and actuarial pension plans - - - - - - - Plus, pension value attributable to current year's service and any change in pension value attributable to plan amendments made in the current year - - - - - - - Compensation Actually Paid ($) 805,552 3,016,641 1,172,474 2,192,172 1,062,311 1,837,807 788,328 | ||
| Company Selected Measure Name | Operating EBITDA | ||
| Named Executive Officers, Footnote [Text Block] | (1) Mr. Gandossi stepped down as Chief Executive Officer and President on May 1, 2022 and retired as a director effective May 31, 2022. Mr. Bueno was appointed as Chief Executive Officer and President on May 1, 2022, and was elected as a director effective May 31, 2022. In connection with Mr. Bueno's appointment, he was provided with a one-time moving cost allowance and was granted: (i) 50,000 RSUs; (ii) 96,530 PSUs that have a performance period ending on December 31, 2023; and (iii) 96,530 PSUs that have a performance period ending on December 31, 2024. Such one-time RSU and PSU grants were made to attract Mr. Bueno as well as allow Mr. Bueno to enter into the same pay for performance cycle as our other NEOs. PSU grants for the CEO in 2023 have returned to previous levels. | ||
| Peer Group Issuers, Footnote [Text Block] | (7) For the relevant fiscal year, represents the cumulative total shareholder return (TSR) of Mercer International Inc. and the TSR Peer Group as set forth under the Fiscal 2022 Shareholder Returns section of this proxy. Each year reflects what the cumulative value of $100 would be, including the reinvestment of dividends, adjusted for stock splits and spinoffs, if such amount were invested by the market close on the last trading day before the beginning of the Company’s third preceding fiscal year. | ||
| Adjustment To PEO Compensation, Footnote [Text Block] | (9) "Compensation Actually Paid" to the CEO and the average "Compensation Actually Paid" to the NEOs reflect the following adjustment from Total Compensation reported in the Summary Compensation Table: 2022 2021 2020 CEO (Gandossi) ($) CEO (Bueno) ($) Average of NEOs ($) CEO ($) Average of NEOs ($) CEO ($) Average of NEOs ($) Total Reported in 2022 Summary Compensation Table (SCT) 1,518,538 4,945,342 1,447,598 3,152,658 1,372,425 2,647,401 1,147,195 Less, total fair value of stock and option awards reported in SCT 314,028 3,757,708 454,575 1,375,183 415,925 1,299,232 372,768 Plus, fair value (at end of fiscal year) of awards granted in 2022 fiscal year that are unvested and outstanding 159,817 1,829,007 231,345 702,431 212,451 990,495 284,187 Plus, change in fair (at end of fiscal year) value of prior year awards that are outstanding and unvested ( 35,048 ) - ( 16,682 ) ( 208,265 ) ( 59,754 ) ( 213,615 ) ( 126,039 ) Plus, fair value (at vesting date) of awards granted and vested in 2022 fiscal year - - - - - - - Plus, change in fair value (at vesting date) of prior year awards that vested in 2022 fiscal year ( 53,439 ) - ( 15,101 ) 15,537 9,167 ( 46,132 ) ( 23,167 ) Less, fair value (at end of prior fiscal year) of prior year awards that failed to vest in 2022 fiscal year (i.e. forfeited) 470,288 - 20,111 95,006 56,053 241,110 121,079 Less, change in actuarial present value of all defined benefit and actuarial pension plans - - - - - - - Plus, pension value attributable to current year's service and any change in pension value attributable to plan amendments made in the current year - - - - - - - Compensation Actually Paid ($) 805,552 3,016,641 1,172,474 2,192,172 1,062,311 1,837,807 788,328 | ||
| Non-PEO NEO Average Total Compensation Amount | $ 1,447,598 | $ 1,372,425 | $ 1,147,195 |
| Non-PEO NEO Average Compensation Actually Paid Amount | $ 1,172,474 | 1,062,311 | 788,328 |
| Adjustment to Non-PEO NEO Compensation Footnote [Text Block] | (9) "Compensation Actually Paid" to the CEO and the average "Compensation Actually Paid" to the NEOs reflect the following adjustment from Total Compensation reported in the Summary Compensation Table: 2022 2021 2020 CEO (Gandossi) ($) CEO (Bueno) ($) Average of NEOs ($) CEO ($) Average of NEOs ($) CEO ($) Average of NEOs ($) Total Reported in 2022 Summary Compensation Table (SCT) 1,518,538 4,945,342 1,447,598 3,152,658 1,372,425 2,647,401 1,147,195 Less, total fair value of stock and option awards reported in SCT 314,028 3,757,708 454,575 1,375,183 415,925 1,299,232 372,768 Plus, fair value (at end of fiscal year) of awards granted in 2022 fiscal year that are unvested and outstanding 159,817 1,829,007 231,345 702,431 212,451 990,495 284,187 Plus, change in fair (at end of fiscal year) value of prior year awards that are outstanding and unvested ( 35,048 ) - ( 16,682 ) ( 208,265 ) ( 59,754 ) ( 213,615 ) ( 126,039 ) Plus, fair value (at vesting date) of awards granted and vested in 2022 fiscal year - - - - - - - Plus, change in fair value (at vesting date) of prior year awards that vested in 2022 fiscal year ( 53,439 ) - ( 15,101 ) 15,537 9,167 ( 46,132 ) ( 23,167 ) Less, fair value (at end of prior fiscal year) of prior year awards that failed to vest in 2022 fiscal year (i.e. forfeited) 470,288 - 20,111 95,006 56,053 241,110 121,079 Less, change in actuarial present value of all defined benefit and actuarial pension plans - - - - - - - Plus, pension value attributable to current year's service and any change in pension value attributable to plan amendments made in the current year - - - - - - - Compensation Actually Paid ($) 805,552 3,016,641 1,172,474 2,192,172 1,062,311 1,837,807 788,328 | ||
| Compensation Actually Paid vs. Total Shareholder Return [Text Block] | CompensationactuallypaidvsNet Income Compensation actually paid vs TSR Compensation actually paid ($000) 500 1,000 1,500 2,000 2,500 3,000 3,500 TSR value of $100 investment in 2019 140 120 100 80 60 40 20 0 2020 2021 2022 CEO NEOs MERC TSR Peer TSR | ||
| Compensation Actually Paid vs. Net Income [Text Block] | Compensation actually paid vs Net Income Compensation actually paid ($000) 500 1,000 1,500 2,000 2,500 3,000 3,500 300 250 200 150 100 50 - 50 Net Income ($ millions) CEO NEOs Net Income | ||
| Compensation Actually Paid vs. Company Selected Measure [Text Block] | Compensation actually paid vs Operating EBITDA Compensation actually paid ($000) 500 1,000 1,500 2,000 2,500 3,000 3,500 2020 2021 2022 600 500 400 300 200 100 Operationg EBITDA ($ millions) CEO NEOs Operating EBITDA | ||
| Tabular List [Table Text Block] | Tabular List Listed below are the financial and non-financial performance measures which we believe to be our most important measures to link compensation actually paid to our NEOs to Company performance, for fiscal 2022. Measure Explanation Net Income Net income in accordance with GAAP. Operating EBITDA A non-GAAP financial measure comprised of Net Income before Income tax provision, Interest expense, Other income and Depreciation and amortization. Total Recordable Incident Rate (TRIR) Total recordable incident rate; the rate of recordable workplace injuries per 200,000 working hours. Return on Average Assets (ROAA) Return on average assets; the ratio of Net income in accordance with GAAP to the average Total Assets of the Company in the year. Revenues Revenues for the year in accordance with GAAP. Other Other non-financial measures including advancement of strategic priorities related to acquisitions, capital expenditures, productivity, carbon emissions reduction, environmental performance, employee and community engagement, and equity and diversity initiatives. | ||
| Total Shareholder Return Amount | $ 103.55 | 104.19 | 87.24 |
| Peer Group Total Shareholder Return Amount | 129.84 | 132.54 | 122.03 |
| Net Income (Loss) | $ 247,039 | $ 170,988 | $ (17,235) |
| Company Selected Measure Amount | 536,521,000 | 478,782,000 | 192,650,000 |
| PEO Name | David Gandossi | David Gandossi | David Gandossi |
| Measure [Axis]: 1 | |||
| Pay vs Performance Disclosure [Table] | |||
| Measure Name | Net Income | ||
| Measure [Axis]: 2 | |||
| Pay vs Performance Disclosure [Table] | |||
| Measure Name | Operating EBITDA | ||
| Measure [Axis]: 3 | |||
| Pay vs Performance Disclosure [Table] | |||
| Measure Name | Total Recordable Incident Rate (TRIR) | ||
| Measure [Axis]: 4 | |||
| Pay vs Performance Disclosure [Table] | |||
| Measure Name | Return on Average Assets (ROAA) | ||
| Measure [Axis]: 5 | |||
| Pay vs Performance Disclosure [Table] | |||
| Measure Name | Revenues | ||
| Measure [Axis]: 6 | |||
| Pay vs Performance Disclosure [Table] | |||
| Measure Name | Other | ||
| Less, Total Fair Value of Stock and Option Awards Reported in SCT | |||
| Pay vs Performance Disclosure [Table] | |||
| Adjustment to Compensation Amount | $ 454,575 | $ 415,925 | $ 372,768 |
| Plus, Fair Value (at End of Fiscal Year) of Awards Granted in 2022 Fiscal Year That Are Unvested and Outstanding | |||
| Pay vs Performance Disclosure [Table] | |||
| Adjustment to Compensation Amount | 231,345 | 212,451 | 284,187 |
| Plus, Change in Fair (at End of Fiscal Year) Value of Prior Year Awards That Are Outstanding and Unvested | |||
| Pay vs Performance Disclosure [Table] | |||
| Adjustment to Compensation Amount | (16,682) | (59,754) | (126,039) |
| Plus, Change in Fair Value (at Vesting Date) of Prior Year Awards That Vested in 2022 Fiscal Year | |||
| Pay vs Performance Disclosure [Table] | |||
| Adjustment to Compensation Amount | (15,101) | 9,167 | (23,167) |
| Less, Fair Value (at End of Prior Fiscal Year) of Prior Year Awards That Failed to Vest In 2022 Fiscal Year (I.e. Forfeited) | |||
| Pay vs Performance Disclosure [Table] | |||
| Adjustment to Compensation Amount | 20,111 | 56,053 | 121,079 |
| Juan Carlos Bueno | |||
| Pay vs Performance Disclosure [Table] | |||
| PEO Total Compensation Amount | 4,945,342 | ||
| PEO Actually Paid Compensation Amount | 3,016,641 | ||
| Juan Carlos Bueno | Less, Total Fair Value of Stock and Option Awards Reported in SCT | |||
| Pay vs Performance Disclosure [Table] | |||
| Adjustment to Compensation Amount | 3,757,708 | ||
| Juan Carlos Bueno | Plus, Fair Value (at End of Fiscal Year) of Awards Granted in 2022 Fiscal Year That Are Unvested and Outstanding | |||
| Pay vs Performance Disclosure [Table] | |||
| Adjustment to Compensation Amount | 1,829,007 | ||
| David Gandossi | |||
| Pay vs Performance Disclosure [Table] | |||
| PEO Total Compensation Amount | 1,518,538 | 3,152,658 | 2,647,401 |
| PEO Actually Paid Compensation Amount | 805,552 | 2,192,172 | 1,837,807 |
| David Gandossi | Less, Total Fair Value of Stock and Option Awards Reported in SCT | |||
| Pay vs Performance Disclosure [Table] | |||
| Adjustment to Compensation Amount | 314,028 | 1,375,183 | 1,299,232 |
| David Gandossi | Plus, Fair Value (at End of Fiscal Year) of Awards Granted in 2022 Fiscal Year That Are Unvested and Outstanding | |||
| Pay vs Performance Disclosure [Table] | |||
| Adjustment to Compensation Amount | 159,817 | 702,431 | 990,495 |
| David Gandossi | Plus, Change in Fair (at End of Fiscal Year) Value of Prior Year Awards That Are Outstanding and Unvested | |||
| Pay vs Performance Disclosure [Table] | |||
| Adjustment to Compensation Amount | (35,048) | (208,265) | (213,615) |
| David Gandossi | Plus, Change in Fair Value (at Vesting Date) of Prior Year Awards That Vested in 2022 Fiscal Year | |||
| Pay vs Performance Disclosure [Table] | |||
| Adjustment to Compensation Amount | (53,439) | 15,537 | (46,132) |
| David Gandossi | Less, Fair Value (at End of Prior Fiscal Year) of Prior Year Awards That Failed to Vest In 2022 Fiscal Year (I.e. Forfeited) | |||
| Pay vs Performance Disclosure [Table] | |||
| Adjustment to Compensation Amount | $ 470,288 | $ 95,006 | $ 241,110 |
