XML 54 R45.htm IDEA: XBRL DOCUMENT
v3.19.2

Shareholders' Equity - Summary of Inputs Used in the Measurement of the Fair Values and the Related Fair Values at the Grant Dates (Detail) | 6 Months Ended
--- | ---
Jun. 30, 2019 yr € / shares
Key management personnel [member] |
Disclosure of terms and conditions of share-based payment arrangement [line items] |
Expected volatility (weighted-average) | 87.58%
Contractual life | yr | 10
Expected dividends | 0.00%
Key management personnel [member] | Bottom of range [member] |
Disclosure of terms and conditions of share-based payment arrangement [line items] |
Fair value at grant date | € 6.07
Share price at grant date | 9.83
Exercise price | € 9.83
Expected dividends | 0.00%
Risk-free interest rate (based on government bonds) | 2.13%
Key management personnel [member] | Top of range [member] |
Disclosure of terms and conditions of share-based payment arrangement [line items] |
Fair value at grant date | € 7.60
Share price at grant date | 12.49
Exercise price | € 12.49
Expected dividends | 0.00%
Risk-free interest rate (based on government bonds) | 2.74%
All other employees [member] |
Disclosure of terms and conditions of share-based payment arrangement [line items] |
Expected volatility (weighted-average) | 87.11%
Contractual life | yr | 10
Expected dividends | 0.00%
All other employees [member] | Bottom of range [member] |
Disclosure of terms and conditions of share-based payment arrangement [line items] |
Fair value at grant date | € 6.15
Share price at grant date | 9.83
Exercise price | € 9.83
Expected dividends | 0.00%
Risk-free interest rate (based on government bonds) | 2.02%
All other employees [member] | Top of range [member] |
Disclosure of terms and conditions of share-based payment arrangement [line items] |
Fair value at grant date | € 8.62
Share price at grant date | 14.19
Exercise price | € 14.19
Expected dividends | 0.00%
Risk-free interest rate (based on government bonds) | 2.65%

X
- Definition The expected volatility of the share price used to calculate the fair value of the share options granted. Expected volatility is a measure of the amount by which a price is expected to fluctuate during a period. The measure of volatility used in option pricing models is the annualised standard deviation of the continuously compounded rates of return on the share over a period of time. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Name IFRS -Number 2 -IssueDate 2018-01-01 -Paragraph 47 -Subparagraph a -Clause i -URI http://eifrs.ifrs.org/eifrs/XBRL?type=IFRS&num=2&date=2018-03-01&anchor=para_47_a_i&doctype=Standard -URIDate 2018-03-16 + Details
Name: | ifrs-full_DescriptionOfExpectedVolatilityShareOptionsGranted
Namespace Prefix: | ifrs-full_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition The option life of share options granted. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Name IFRS -Number 2 -IssueDate 2018-01-01 -Paragraph 47 -Subparagraph a -Clause i -URI http://eifrs.ifrs.org/eifrs/XBRL?type=IFRS&num=2&date=2018-03-01&anchor=para_47_a_i&doctype=Standard -URIDate 2018-03-16 + Details
Name: | ifrs-full_DescriptionOfOptionLifeShareOptionsGranted
Namespace Prefix: | ifrs-full_
Data Type: | xbrli:decimalItemType
Balance Type: | na
Period Type: | duration

X
- Definition The implied yield currently available on zero-coupon government issues of the country in whose currency the exercise price for share options granted is expressed, with a remaining term equal to the expected term of the option being valued (based on the option's remaining contractual life and taking into account the effects of expected early exercise). [Refer: Government [member]] + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Name IFRS -Number 2 -IssueDate 2018-01-01 -Paragraph 47 -Subparagraph a -Clause i -URI http://eifrs.ifrs.org/eifrs/XBRL?type=IFRS&num=2&date=2018-03-01&anchor=para_47_a_i&doctype=Standard -URIDate 2018-03-16 + Details
Name: | ifrs-full_DescriptionOfRiskFreeInterestRateShareOptionsGranted
Namespace Prefix: | ifrs-full_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Line items represent concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes of the table. + References No definition available. + Details
Name: | ifrs-full_DisclosureOfTermsAndConditionsOfSharebasedPaymentArrangementLineItems
Namespace Prefix: | ifrs-full_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition The percentage of an expected dividend used to calculate the fair value of share options granted. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Name IFRS -Number 2 -IssueDate 2018-01-01 -Paragraph 47 -Subparagraph a -Clause i -URI http://eifrs.ifrs.org/eifrs/XBRL?type=IFRS&num=2&date=2018-03-01&anchor=para_47_a_i&doctype=Standard -URIDate 2018-03-16 + Details
Name: | ifrs-full_ExpectedDividendAsPercentageShareOptionsGranted
Namespace Prefix: | ifrs-full_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Employee option exercised price per share + References No definition available. + Details
Name: | mrus_EmployeeOptionExercisedPricePerShare
Namespace Prefix: | mrus_
Data Type: | num:perShareItemType
Balance Type: | na
Period Type: | duration

X
- Definition Fair value assumptions grant date share price. + References No definition available. + Details
Name: | mrus_FairValueAssumptionsGrantDateSharePrice
Namespace Prefix: | mrus_
Data Type: | num:perShareItemType
Balance Type: | na
Period Type: | duration

X
- Definition Share purchased price per share. + References No definition available. + Details
Name: | mrus_SharePurchasedPricePerShare
Namespace Prefix: | mrus_
Data Type: | num:perShareItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | ifrs-full_CategoriesOfRelatedPartiesAxis=ifrs-full_KeyManagementPersonnelOfEntityOrParentMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | ifrs-full_RangeAxis=ifrs-full_BottomOfRangeMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | ifrs-full_RangeAxis=ifrs-full_TopOfRangeMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | ifrs-full_CategoriesOfRelatedPartiesAxis=mrus_AllOtherEmployeesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |