Summary of Significant Accounting Policies and Recent Accounting Pronouncements - Additional Information (Details)	Jun. 30, 2023
Janssen Pharmaceuticals Inc
Percentage of research and development costs covered by Janssen	100.00%

Percentage of research and development costs incurred by the Company and covered by Janssen.

No definition available.

Name:	mgtx_PercentageOfResearchAndDevelopmentCostsCoveredByJanssen
Namespace Prefix:	mgtx_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	instant