v3.25.3

Property and equipment sale - Narrative (Details) - USD ($) $ in Thousands	1 Months Ended		9 Months Ended
	Jul. 31, 2025	Jun. 30, 2025	Sep. 30, 2025	Sep. 30, 2024
Property, Plant and Equipment [Line Items]
Sale of laboratory equipment			$ 767	$ 0
Loss on sale of assets and asset impairment charges			(588)	$ 0
Laboratory equipment
Property, Plant and Equipment [Line Items]
Sale of laboratory equipment	$ 400	$ 400
Sale of property plant and equipment (as a percent)	50.00%	50.00%
Loss on sale of assets and asset impairment charges			$ 600

The cash inflow from the sale of long-lived, physical assets, as a percent of the total sale price

+ References

No definition available.

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- Definition

Amount of gain (loss) from the difference between the sale price or salvage price and the book value of an asset that was sold or retired, and gain (loss) from the write down of assets from their carrying value to fair value.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 230
-SubTopic 10
-Name Accounting Standards Codification
-Section 45
-Paragraph 28
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482740/230-10-45-28

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- Definition

The cash inflow from the sale of long-lived, physical assets that are used in the normal conduct of business to produce goods and services and not intended for resale.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Topic 230
-SubTopic 10
-Name Accounting Standards Codification
-Section 45
-Paragraph 12
-Subparagraph (c)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482740/230-10-45-12

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- Definition

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.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 842
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 7A
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147478964/842-20-50-7A

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Mersana Therapeutics, Inc. 10-Q