The minimum annual aggregate royalty payment due for the first five years after the first commercial sale.

No definition available.

Name:	tmdx_GuaranteedMinimumAnnualRoyaltyPayment
Namespace Prefix:	tmdx_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Lease base rent annual increase.

+ References

No definition available.

+ Details

Name:	tmdx_LeaseBaseRentAnnualIncrease
Namespace Prefix:	tmdx_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Lease expiration month and year.

+ References

No definition available.

+ Details

Name:	tmdx_LeaseExpirationMonthAndYear
Namespace Prefix:	tmdx_
Data Type:	xbrli:gYearMonthItemType
Balance Type:	na
Period Type:	duration

- Definition

The monetary allowance granted by the landlord to a tenant to entice tenant to move into landlords building which will enable the tenant to prepare the leased premises for tenants occupancy.

+ References

No definition available.

+ Details

Name:	tmdx_LeaseholdImprovementsLandlordAllowance
Namespace Prefix:	tmdx_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Carrying amount as of the balance sheet date of amounts due from the landlord as part of an allowance granted by the landlord to a tenant to entice tenant to move into landlords building which will enable the tenant to prepare the leased premises for tenants occupancy.

+ References

No definition available.

+ Details

Name:	tmdx_TenantImprovementsAllowanceReceivable
Namespace Prefix:	tmdx_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Area of a real estate property.

+ References

No definition available.

+ Details

Name:	us-gaap_AreaOfRealEstateProperty
Namespace Prefix:	us-gaap_
Data Type:	num:areaItemType
Balance Type:	na
Period Type:	instant

- Definition

Date which lease or group of leases is set to expire, in CCYY-MM-DD format.

+ References

No definition available.

+ Details

Name:	us-gaap_LeaseExpirationDate1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:dateItemType
Balance Type:	na
Period Type:	duration

- Definition

Indicates (true false) whether lessee has option to extend operating lease.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 842
-SubTopic 20
-Section 50
-Paragraph 3
-Subparagraph (a)(3)
-URI http://asc.fasb.org/extlink&oid=121609121&loc=SL77918673-209980

+ Details

Name:	us-gaap_LesseeOperatingLeaseExistenceOfOptionToExtend
Namespace Prefix:	us-gaap_
Data Type:	xbrli:booleanItemType
Balance Type:	na
Period Type:	duration

- Definition

Term of lessee's operating lease renewal, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 842
-SubTopic 20
-Section 50
-Paragraph 3
-Subparagraph (a)(3)
-URI http://asc.fasb.org/extlink&oid=121609121&loc=SL77918673-209980

+ Details

Name:	us-gaap_LesseeOperatingLeaseRenewalTerm
Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	instant

- Definition

Description of lessor's operating lease.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 842
-SubTopic 30
-Section 50
-Paragraph 3
-Subparagraph (a)(1)
-URI http://asc.fasb.org/extlink&oid=121576215&loc=SL77919359-209981

+ Details

Name:	us-gaap_LessorOperatingLeaseDescription
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

This element represents the payments that the lessee is obligated to make or can be required to make in connection with a property under the terms of an agreement classified as an operating lease, excluding contingent rentals and a guarantee by the lessee of the lessor's debt and the lessee's obligation to pay (apart from the rental payments) executory costs such as insurance, maintenance, and taxes.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/otherTransitionRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 840
-SubTopic 10
-Section 25
-Paragraph 5
-URI http://asc.fasb.org/extlink&oid=121595440&loc=d3e34039-112682

Reference 2: http://fasb.org/us-gaap/role/ref/otherTransitionRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 840
-SubTopic 10
-Section 55
-Paragraph 40
-Subparagraph (Note 3)
-URI http://asc.fasb.org/extlink&oid=121580752&loc=d3e38371-112697

Reference 3: http://fasb.org/us-gaap/role/ref/otherTransitionRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 840
-SubTopic 20
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=121573735&loc=d3e41499-112717

+ Details

Name:	us-gaap_OperatingLeasesRentExpenseMinimumRentals
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Rental expense for the reporting period incurred under operating leases, including minimum and any contingent rent expense, net of related sublease income.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/otherTransitionRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 840
-SubTopic 20
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=121573735&loc=d3e41499-112717

+ Details

Name:	us-gaap_OperatingLeasesRentExpenseNet
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Details

Name:	srt_RangeAxis=srt_MaximumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LeaseContractualTermAxis=tmdx_OmnibusAmendment1Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RelatedPartyTransactionAxis=tmdx_AnnualRentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	dei_LegalEntityAxis=tmdx_AdditionalOfficeUseMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	dei_LegalEntityAxis=tmdx_AdditionalOperationalUseMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LeaseContractualTermAxis=tmdx_OmnibusAmendment2Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RelatedPartyTransactionAxis=tmdx_AnnualRentAdditionalLeaseYearMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Commitments and Contingencies - Additional Information (Detail) $ in Millions			3 Months Ended		9 Months Ended
	Jun. 02, 2020 USD ($)	Jan. 09, 2020 USD ($) ft²	Sep. 30, 2020 USD ($)	Sep. 28, 2019 USD ($)	Sep. 30, 2020 USD ($)	Sep. 28, 2019 USD ($)
Rent expense			$ 0.4	$ 0.3	$ 1.4	$ 1.0
Tenant improvements allowance receivable			$ 0.2		0.2
Maximum [Member]
Guaranteed minimum annual royalty payment					$ 0.1
Omnibus Amendment 1 [Member]
Lease expiration month and year		2026-12
Extended lease term		5 years
Leasehold improvements landlord allowance		$ 3.4
Lease existence of option to extend		true
Lease base rent annual increase		2.50%
Omnibus Amendment 1 [Member] \| Annual Rent [Member]
Lease annual base rent		$ 1.9
Omnibus Amendment 1 [Member] \| Additional Office Use [Member]
Area of office space \| ft²		39,744
Omnibus Amendment 1 [Member] \| Additional Operational Use [Member]
Area of office space \| ft²		11,735
Omnibus Amendment 2 [Member]
Lease existence of option to extend	true
Operating Lease, Description	(i) extending each of the existing lease terms for an additional year through December 31, 2027, (ii) delaying to October 23, 2020 the commencement of the Company’s occupation of the Extension Premises, and (iii) extending to December 23, 2021 the Company’s ability to utilize the contribution from the landlord toward the Company’s work on improvements of the premises
Lease expiration month and year	Dec. 31, 2027
Omnibus Amendment 2 [Member] \| Annual Rent Additional Lease Year [Member]
Lease annual base rent	$ 2.0