XML 79 R57.htm IDEA: XBRL DOCUMENT v3.10.0.1

Employee Benefits - Schedule of Share-based Compensation Expenses Recognized as Employee Benefit Expenses (Detail) - EUR (€) € in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Disclosure Of Share Of Equity Investment [line items]
Stock award expense	€ 2,109	€ 3,254	€ 4,554	€ 7,880
Research and development costs [member]
Disclosure Of Share Of Equity Investment [line items]
Stock award expense	714	673	1,525	1,798
Management and administration costs [member]
Disclosure Of Share Of Equity Investment [line items]
Stock award expense	1,343	2,376	2,852	5,782
Other expenses [member]
Disclosure Of Share Of Equity Investment [line items]
Stock award expense	€ 52	€ 205	€ 177	€ 300

X

- Definition

Disclosure Of Share Of Equity Investment

+ References

No definition available.

+ Details

Name:	mrus_DisclosureOfShareOfEquityInvestmentLineItems
Namespace Prefix:	mrus_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

X

- Definition

Stock award expense.

+ References

No definition available.

+ Details

Name:	mrus_StockAwardExpense
Namespace Prefix:	mrus_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

X

- Details

Name:	mrus_IncomeStatementLineItemLocationAxis=mrus_ResearchAndDevelopmentCostsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	mrus_IncomeStatementLineItemLocationAxis=mrus_ManagementAndAdministrationCostsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	mrus_IncomeStatementLineItemLocationAxis=mrus_OtherExpensesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: