Retirement Plan (Details) - USD ($)	9 Months Ended
Sep. 30, 2021	Sep. 30, 2020
Retirement Plan [Abstract]
Allocated contributions	$ (10,667)
Allocated contributions and expense		$ 13,309

Amount of increase (decrease) in discretionary contributions made by an employer to a defined contribution plan.

No definition available.

Name:	mghl_IncreaseDecreaseInDefinedContributionPlanEmployerDiscretionaryContributionAmount
Namespace Prefix:	mghl_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration