Commitments and Contingencies - Summary of Total Restructuring Costs (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2026	Sep. 30, 2025	Sep. 30, 2026	Sep. 30, 2025
Restructuring Cost and Reserve [Line Items]
Total restructuring charges	$ 1,370	$ (92)	$ 1,340	$ 1,464
Restructuring Incurred Cost Statement Of Income Or Comprehensive Income Extensible Enumeration Not Disclosed [Flag]	true	true	true	true
Employee Termination Benefits
Restructuring Cost and Reserve [Line Items]
Total restructuring charges	$ 1,370	$ (92)	$ 1,340	$ 1,464
Location, Statement of Income, Balance [Axis]: us-gaap:GeneralAndAdministrativeExpense \| Employee Termination Benefits
Restructuring Cost and Reserve [Line Items]
Total restructuring charges	20	32	(14)	174
Location, Statement of Income, Balance [Axis]: us-gaap:ResearchAndDevelopmentExpense \| Employee Termination Benefits
Restructuring Cost and Reserve [Line Items]
Total restructuring charges	731	11	733	510
Location, Statement of Income, Balance [Axis]: us-gaap:SellingAndMarketingExpense \| Employee Termination Benefits
Restructuring Cost and Reserve [Line Items]
Total restructuring charges	190	(27)	190	62
Location, Statement of Income, Balance [Axis]: xmtr:OperationsAndSupportExpense \| Employee Termination Benefits
Restructuring Cost and Reserve [Line Items]
Total restructuring charges	$ 429	$ (108)	$ 431	$ 718

- Definition

Amount of expenses associated with exit or disposal activities pursuant to an authorized plan. Excludes expenses related to a discontinued operation or an asset retirement obligation.

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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.

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