CONSOLIDATED STATEMENTS OF CONVERTIBLE PREFERRED STOCK AND STOCKHOLDERS' EQUITY (DEFICIT) (Parenthetical) - USD ($) $ in Thousands	3 Months Ended
Jun. 30, 2020	Jun. 29, 2019
Statement Of Stockholders Equity [Abstract]
Discounts and issuance costs of stock issued	$ 628	$ 5,966

Discounts and costs incurred directly with the issuance of an equity security.

No definition available.

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