Inventory - Additional Information (Detail) - USD ($) $ in Thousands	9 Months Ended
Sep. 30, 2020	Sep. 28, 2019
Inventory Disclosure [Abstract]
Inventory transfer to property plant and equipment	$ 705	$ 1,904

Value of inventory transferred to the entity's property plant and equipment in noncash transactions.

No definition available.

Name:	tmdx_InventoryTransferToPropertyPlantAndEquipment
Namespace Prefix:	tmdx_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration