XML 48 R38.htm IDEA: XBRL DOCUMENT
v3.24.3

Collaboration agreements - Contract Assets and Liabilities (Details) - USD ($) $ in Thousands | 3 Months Ended | 9 Months Ended
--- | --- | ---
Sep. 30, 2024 | Sep. 30, 2023 | Sep. 30, 2024 | Sep. 30, 2023
Contract liabilities |  |  |  |
Balance at Beginning of Period |  |  | $ 125,314 | $ 147,653
Additions |  |  | 5,860 | 1,710
Deductions |  |  | 15,937 | 16,267
Balance at End of Period | $ 115,237 | $ 133,096 | 115,237 | 133,096
Amounts included in the contract liability at the beginning of the period | $ 4,388 | $ 4,503 | $ 14,875 | $ 17,963

X
- Definition Change In Contract Assets And Liabilities + References No definition available. + Details
Name: | mrsn_ChangeInContractAssetsAndLiabilitiesRollForward
Namespace Prefix: | mrsn_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Amount of decrease in obligation to transfer good or service to customer for which consideration has been received or is receivable. + References No definition available. + Details
Name: | mrsn_ContractWithCustomerLiabilityDecrease
Namespace Prefix: | mrsn_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Amount of increase in obligation to transfer good or service to customer for which consideration has been received or is receivable. + References No definition available. + Details
Name: | mrsn_ContractWithCustomerLiabilityIncrease
Namespace Prefix: | mrsn_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Amount of obligation to transfer good or service to customer for which consideration has been received or is receivable. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 606 -SubTopic 10 -Name Accounting Standards Codification -Section 45 -Paragraph 1 -Publisher FASB -URI https://asc.fasb.org/1943274/2147479837/606-10-45-1 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Topic 606 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 8 -Subparagraph (a) -Publisher FASB -URI https://asc.fasb.org/1943274/2147479806/606-10-50-8 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Topic 606 -SubTopic 10 -Name Accounting Standards Codification -Section 45 -Paragraph 2 -Publisher FASB -URI https://asc.fasb.org/1943274/2147479837/606-10-45-2 + Details
Name: | us-gaap_ContractWithCustomerLiability
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Amount of revenue recognized that was previously included in balance of obligation to transfer good or service to customer for which consideration from customer has been received or is due. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 606 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 8 -Subparagraph (b) -Publisher FASB -URI https://asc.fasb.org/1943274/2147479806/606-10-50-8 + Details
Name: | us-gaap_ContractWithCustomerLiabilityRevenueRecognized
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration