Investment Securities - Additional Information (Detail) - Securities	Jun. 30, 2025	Dec. 31, 2024
Debt Securities, Available-for-Sale [Abstract]
Number of Securities	57	58
Percentage by which aggregate book value exceeded company's equity	10.00%	10.00%

Percentage by which aggregate book value exceeded the Company's equity.

No definition available.

Name:	mfin_AggregateBookValueExceedingCompanysEquityPercentage
Namespace Prefix:	mfin_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	instant