Earnings (Loss) Per Share - Additional Information (Details) - shares shares in Millions	3 Months Ended	6 Months Ended
Jun. 30, 2025	Jun. 30, 2024	Jun. 30, 2025	Jun. 30, 2024
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Shares assumed issued	1.7	2.4	1.8	2.2
Shares assumed purchased with potential proceeds	1.0	1.3	1.0	1.0
Underwater Options
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive securities excluded from calculation of computation of diluted earnings (loss) per share	1.1	0.1	0.8	0.5
Equity-based Awards
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive securities excluded from calculation of computation of diluted earnings (loss) per share	2.8	2.5	2.6	2.7

Incremental common Shares attributable to share based payment arrangements shares assumed Issued.

No definition available.

Name:	mtus_IncrementalCommonSharesAttributableToShareBasedPaymentArrangementsSharesAssumedIssued
Namespace Prefix:	mtus_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

- Definition

Incremental common shares attributable to share based payment arrangements shares assumed purchased with potential proceeds.

+ References

No definition available.

+ Details

Name:	mtus_IncrementalCommonSharesAttributableToShareBasedPaymentArrangementsSharesAssumedPurchasedWithPotentialProceeds
Namespace Prefix:	mtus_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

- Definition

Securities (including those issuable pursuant to contingent stock agreements) that could potentially dilute basic earnings per share (EPS) or earnings per unit (EPU) in the future that were not included in the computation of diluted EPS or EPU because to do so would increase EPS or EPU amounts or decrease loss per share or unit amounts for the period presented.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 260
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (c)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482662/260-10-50-1

+ Details

Name:	us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

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

- Details

Name:	us-gaap_AwardTypeAxis=us-gaap_EmployeeStockMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis=us-gaap_StockCompensationPlanMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: