v3.25.4

Net Loss Per Common Share - Reconciliation of Basic and Diluted Net Loss Per Common Share (Parenthetical) (Details) - shares | 12 Months Ended
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Dec. 31, 2025 | Dec. 31, 2024 | Dec. 31, 2023
Restricted Stock |  |  |
Net Income Per Common Share Basic And Diluted [Line Items] |  |  |
Antidilutive securities excluded from computation of basic earnings per share amount | 111,732 | 21,054 | 54,227

X
- Definition Antidilutive securities excluded from computation of basic earnings per share amount. + References No definition available. + Details
Name: | merc_AntidilutiveSecuritiesExcludedFromComputationOfBasicEarningsPerShareAmount
Namespace Prefix: | merc_
Data Type: | xbrli:sharesItemType
Balance Type: | na
Period Type: | duration

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- Definition Net Income Per Share Attributable To Common Shareholders Basic And Diluted [Line Items] + References No definition available. + Details
Name: | merc_NetIncomePerShareAttributableToCommonShareholdersBasicAndDilutedLineItems
Namespace Prefix: | merc_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

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- Details
Name: | us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis=us-gaap_RestrictedStockMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |