Name:	mrns_MinimumCashAndCashEquivalentsRequiredToBeMaintainedInDepositsAfterRepaymentOfLoans
Namespace Prefix:	mrns_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

The minimum amount of cash and cash equivalents required to be maintained in deposit accounts until the repayment of loans under the credit agreement.

No definition available.

Name:	mrns_MinimumCashAndCashEquivalentsRequiredToBeMaintainedInDepositsUntilRepaymentOfLoans
Namespace Prefix:	mrns_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

The annual Product Revenue threshold used in the calculation of payments due under the revenue interest financing agreement.

No definition available.

Name:	mrns_RevenueInterestFinancingAgreementAnnualProductRevenueThreshold
Namespace Prefix:	mrns_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

The estimated effective annual interest rate related to the revenue interest financing agreement.

No definition available.

Name:	mrns_RevenueInterestFinancingAgreementEstimatedEffectiveAnnualInterestRate
Namespace Prefix:	mrns_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

Represents the value of hard cap based on which payments made.

No definition available.

Name:	mrns_RevenueInterestFinancingAgreementHardCapAmount
Namespace Prefix:	mrns_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

The Hard Cap expressed as a percentage of the Investment Amount.

No definition available.

Name:	mrns_RevenueInterestFinancingAgreementHardCapPercentage
Namespace Prefix:	mrns_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

The investment amount received upfront under the revenue interest financing agreement.

No definition available.

Name:	mrns_RevenueInterestFinancingAgreementInvestmentAmount
Namespace Prefix:	mrns_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

Issuance costs related to the revenue interest financing agreement.

No definition available.

Name:	mrns_RevenueInterestFinancingAgreementIssuanceCosts
Namespace Prefix:	mrns_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

The Minimum Amount expressed as a percentage of the Investment Amount.

No definition available.

Name:	mrns_RevenueInterestFinancingAgreementMinimumAmountPercentage
Namespace Prefix:	mrns_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

The quarterly payments due, expressed as a percentage of the annual Product Revenue of the Included Products in excess of $100 million.

No definition available.

Name:	mrns_RevenueInterestFinancingAgreementPaymentsPercentageOfAnnualProductRevenueInExcessOfSpecifiedDollarAmount
Namespace Prefix:	mrns_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

he quarterly payments due, expressed as a percentage of the first $100 million in annual Product Revenue of the Included Products.

No definition available.

Name:	mrns_RevenueInterestFinancingAgreementPaymentsPercentageOfAnnualProductRevenueSpecifiedDollarAmount
Namespace Prefix:	mrns_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

The quarterly payments expressed as a percentage of the U.S. net sales of Ztalmy and all other pharmaceutical products that contain ganaxolene, required under the revenue interest financing agreement.

No definition available.

Name:	mrns_RevenueInterestFinancingAgreementQuarterlyPaymentsAsPercentageOfNetSales
Namespace Prefix:	mrns_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

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.

No definition available.

Name:	mrns_RevenueInterestFinancingPayableLineItems
Namespace Prefix:	mrns_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

Carrying value as of the balance sheet date of obligations incurred through that date and payable for professional fees, such as for legal and accounting services received. Used to reflect the current portion of the liabilities (due within one year or within the normal operating cycle if longer).

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.20)
-URI https://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

Name:	us-gaap_AccruedProfessionalFeesCurrent
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

Percentage price of original principal amount of debt at which debt can be redeemed by the issuer.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 470
-Section 50
-Paragraph 3
-Subparagraph e
-URI https://asc.fasb.org/extlink&oid=123599511&loc=d3e64711-112823

Name:	us-gaap_DebtInstrumentRedemptionPricePercentage
Namespace Prefix:	us-gaap_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

Name:	srt_StatementScenarioAxis=mrns_EachCalendarQuarterFromAndAfterClosingDateThroughJune302026Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	srt_CounterpartyNameAxis=mrns_SagardHealthcarePartnersMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_TypeOfArrangementAxis=mrns_RevenueInterestFinancingAgreementMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_LineOfCreditFacilityAxis=mrns_OaktreeCapitalManagementLpCreditAgreementMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	srt_StatementScenarioAxis=mrns_PeriodEndingDecember312027Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	srt_StatementScenarioAxis=mrns_PeriodEndingDecember312032Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	srt_StatementScenarioAxis=mrns_OnOrBeforeThirdAnniversaryMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	srt_StatementScenarioAxis=mrns_AfterThirdAnniversaryMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_TypeOfArrangementAxis=mrns_RoyaltyMonetizationAgreementMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: