Leases - Schedule of Consolidated Balance Sheets for Leases (Details) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023
Operating leases
Right-of-use asset	$ 14,835	$ 15,910
Capitalized lease obligations	$ 15,984	$ 17,145
Operating Lease, Liability, Statement of Financial Position [Extensible List]	mgtx:LeaseObligationsNonCurrent	mgtx:LeaseObligationsNonCurrent
Finance leases
Right-of-use asset	$ 23,687	$ 24,432
Weighted-average remaining lease term
Operating leases	4 years 1 month 6 days	4 years 3 months 18 days
Finance leases	174 years 7 months 6 days	174 years 9 months 18 days
Weighted-average discount rate
Operating leases	8.80%	8.80%
Finance leases	8.00%	8.00%