Fair Value of Assets and Liabilities - Non Recurring Basis (Details) - Level 3 - Non Recurring	Dec. 31, 2025 USD ($)	Jun. 30, 2025 USD ($)
Foreclosed assets (OREO), net
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Alternative investment	$ 996,373	$ 996,373
Alternative Investment, Valuation Technique [Extensible Enumeration]	mara:CollateralValuationMember	mara:CollateralValuationMember
Alternative Investment, Measurement Input [Extensible Enumeration]	us-gaap:MeasurementInputDiscountRateMember	us-gaap:MeasurementInputDiscountRateMember
Collateral dependent financial assets
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Alternative investment	$ 190,013	$ 66,645
Alternative Investment, Valuation Technique [Extensible Enumeration]	mara:AppraisalValuationMember	mara:AppraisalValuationMember
Alternative investment, measurement input	0	0
Alternative Investment, Measurement Input [Extensible Enumeration]	us-gaap:MeasurementInputDiscountRateMember	us-gaap:MeasurementInputDiscountRateMember
Minimum \| Foreclosed assets (OREO), net
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Alternative investment, measurement input	0.10	0.10
Maximum \| Foreclosed assets (OREO), net
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Alternative investment, measurement input	0.75	0.75