Name:	mack_DebtInstrumentPercentageOfPrincipalAmountForComputationOfRedemptionPrice
Namespace Prefix:	mack_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

Long term debt issuance costs.

No definition available.

Name:	mack_LongTermDebtIssuanceCosts
Namespace Prefix:	mack_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

Face (par) amount of debt instrument at time of issuance.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 55
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=64930739&loc=d3e28878-108400

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=64930785&loc=d3e28551-108399

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

Effective interest rate for the funds borrowed under the debt agreement considering interest compounding and original issue discount or premium.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22(a)(1))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=64930785&loc=d3e28551-108399

Name:	us-gaap_DebtInstrumentInterestRateEffectivePercentage
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

Contractual interest rate for funds borrowed, under the debt agreement.

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Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

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

Date when the debt instrument is scheduled to be fully repaid, in CCYY-MM-DD format.

Name:	us-gaap_DebtInstrumentMaturityDate
Namespace Prefix:	us-gaap_
Data Type:	xbrli:dateItemType
Balance Type:	na
Period Type:	duration

Amount of the required periodic payments applied to principal.

Name:	us-gaap_DebtInstrumentPeriodicPaymentPrincipal
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

Amount of the cost of borrowed funds accounted for as interest expense.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 20
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6450988&loc=d3e26243-108391

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=64930785&loc=d3e28555-108399

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 225
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-04.9)
-URI http://asc.fasb.org/extlink&oid=6879574&loc=d3e536633-122882

Name:	us-gaap_InterestExpense
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

The cash inflow from additional borrowings, net of cash paid to third parties in connection with debt origination.

No definition available.

Name:	us-gaap_ProceedsFromDebtNetOfIssuanceCosts
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

Name:	us-gaap_DebtSecurityAxis=mack_ChangeOfControlEventMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_DebtSecurityAxis=mack_AssetSaleEventMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_LongtermDebtTypeAxis=mack_SeniorNotesDueTwoThousandTwentyTwoMember
Namespace Prefix:
Data Type:	na
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Period Type: