XML 90 R74.htm IDEA: XBRL DOCUMENT
v3.25.2

Borrowings - FHLB Advances (Details) | 12 Months Ended
--- | ---
Jun. 30, 2025 USD ($) item | Jun. 30, 2024 USD ($) item
Federal Home Loan Bank, Advances [Line Items] |  |
Borrowings from Federal Home Loan Bank | $ 15,000,000 | $ 13,000,000
Federal Home Loan Bank, Advances, Activity for Year [Abstract] |  |
Balance at end of year | 15,000,000 | 13,000,000
Maximum outstanding at any month end | $ 15,000,000 | $ 23,000,000
Weighted average interest rate at end of year | 3.66% | 4.19%
Average interest rate during year | 3.86% | 3.84%
Borrowings, Available Borrowing Capacity | $ 54,800,000 |
Federal Funds Purchased | 5,000,000 |
Term Advance Maturing August 21, 2024 |  |
Federal Home Loan Bank, Advances [Line Items] |  |
Borrowings from Federal Home Loan Bank |  | $ 3,000,000
Term of borrowings |  | 6 months
Five Year Term Callable Putable Advances |  |
Federal Home Loan Bank, Advances [Line Items] |  |
Borrowings from Federal Home Loan Bank | $ 5,000,000 | $ 5,000,000
Term of borrowings | 5 years | 5 years
Number Of Puttable Advances | item | 3 | 2
Asset Pledged as Collateral with Right |  |
Federal Home Loan Bank, Advances, Activity for Year [Abstract] |  |
Pledged amount | $ 1,329,413 | $ 1,329,413
Borrowings, Available Borrowing Capacity | 17,487,584,000,000 |
Short-term Debt | 0 |
Asset Not Pledged as Collateral and Asset Pledged as Collateral without Right |  |
Federal Home Loan Bank, Advances, Activity for Year [Abstract] |  |
Eligible collateral | $ 70,573,734 | $ 92,177,419
Minimum |  |
Federal Home Loan Bank, Advances, Activity for Year [Abstract] |  |
Discount factor | 24.00% |
Maximum |  |
Federal Home Loan Bank, Advances, Activity for Year [Abstract] |  |
Discount factor | 38.00% |

X
- Definition Amount of available borrowing capacity from Federal Reserve Bank considering any current restrictions on the amount that could be borrowed. + References No definition available. + Details
Name: | mara_BorrowingsAvailableBorrowingCapacity
Namespace Prefix: | mara_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Number of puttable advances of the company. + References No definition available. + Details
Name: | mara_NumberOfPuttableAdvances
Namespace Prefix: | mara_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | instant

X
- Definition Percent discount factor for aggregate amount of loans required for pledge agreement + References No definition available. + Details
Name: | mara_PercentDiscountFactorForAggregateAmountOfLoansRequiredForPledgeAgreement
Namespace Prefix: | mara_
Data Type: | dtr-types:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Amount of borrowings as of the balance sheet date from the Federal Home Loan Bank, which are primarily used to cover shortages in the required reserve balance and liquidity shortages. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Topic 942 -SubTopic 470 -Name Accounting Standards Codification -Section 45 -Paragraph 1 -Publisher FASB -URI https://asc.fasb.org/1943274/2147478878/942-470-45-1 + Details
Name: | us-gaap_AdvancesFromFederalHomeLoanBanks
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Period of time between issuance and maturity of debt instrument, in PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. + References No definition available. + Details
Name: | us-gaap_DebtInstrumentTerm
Namespace Prefix: | us-gaap_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- Definition Amount, after allowance for credit loss, of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), investment in debt security measured at amortized cost (held-to-maturity), and investment in debt security measured at fair value with change in fair value recognized in net income (trading). + References Reference 1: http://www.xbrl.org/2003/role/exampleRef -Topic 944 -SubTopic 80 -Name Accounting Standards Codification -Section 55 -Paragraph 14 -Publisher FASB -URI https://asc.fasb.org/1943274/2147480078/944-80-55-14 Reference 2: http://www.xbrl.org/2003/role/exampleRef -Topic 944 -SubTopic 80 -Name Accounting Standards Codification -Section 55 -Paragraph 9 -Publisher FASB -URI https://asc.fasb.org/1943274/2147480078/944-80-55-9 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Topic 944 -SubTopic 210 -Name Accounting Standards Codification -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-03(a)(1)(a)) -Publisher FASB -URI https://asc.fasb.org/1943274/2147478777/944-210-S99-1 Reference 4: http://www.xbrl.org/2003/role/disclosureRef -Topic 320 -SubTopic 10 -Name Accounting Standards Codification -Section 45 -Paragraph 1 -Subparagraph (a) -Publisher FASB -URI https://asc.fasb.org/1943274/2147481830/320-10-45-1 Reference 5: http://www.xbrl.org/2003/role/disclosureRef -Topic 944 -SubTopic 210 -Name Accounting Standards Codification -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-03(a)(1)(6)) -Publisher FASB -URI https://asc.fasb.org/1943274/2147478777/944-210-S99-1 + Details
Name: | us-gaap_DebtSecurities
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amount of short term borrowing where a bank borrows, at the federal funds rate, from another bank. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Topic 942 -SubTopic 210 -Name Accounting Standards Codification -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-03(13)(1)) -Publisher FASB -URI https://asc.fasb.org/1943274/2147478546/942-210-S99-1 + Details
Name: | us-gaap_FederalFundsPurchased
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- References No definition available. + Details
Name: | us-gaap_FederalHomeLoanBankAdvancesActivityForYearAbstract
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition The calculated average balance outstanding for the year for all Federal Home Loan Bank advances as of the Balance Sheet date. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Topic 942 -SubTopic 210 -Name Accounting Standards Codification -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-03(13)(3)(a)) -Publisher FASB -URI https://asc.fasb.org/1943274/2147478546/942-210-S99-1 + Details
Name: | us-gaap_FederalHomeLoanBankAdvancesActivityForYearAverageBalanceOfAgreementsOutstanding
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition The calculated weighted average interest rate for Federal Home Loan Bank advances outstanding as of the Balance Sheet date. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Topic 942 -SubTopic 210 -Name Accounting Standards Codification -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-03(13)(3)(a)) -Publisher FASB -URI https://asc.fasb.org/1943274/2147478546/942-210-S99-1 + Details
Name: | us-gaap_FederalHomeLoanBankAdvancesActivityForYearAverageInterestRateAtPeriodEnd
Namespace Prefix: | us-gaap_
Data Type: | dtr-types:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition The calculated weighted average interest rate for Federal Home Loan Bank advances for the period ended as of the Balance Sheet date. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Topic 942 -SubTopic 210 -Name Accounting Standards Codification -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-03(13)(3)(a)) -Publisher FASB -URI https://asc.fasb.org/1943274/2147478546/942-210-S99-1 + Details
Name: | us-gaap_FederalHomeLoanBankAdvancesActivityForYearAverageInterestRateForYear
Namespace Prefix: | us-gaap_
Data Type: | dtr-types:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition The maximum balance outstanding at any month end during the period as of the Balance Sheet date. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Topic 942 -SubTopic 210 -Name Accounting Standards Codification -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-03(13)(3)(a)) -Publisher FASB -URI https://asc.fasb.org/1943274/2147478546/942-210-S99-1 + Details
Name: | us-gaap_FederalHomeLoanBankAdvancesActivityForYearMaximumOutstandingAtAnyMonthEnd
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. + References No definition available. + Details
Name: | us-gaap_FederalHomeLoanBankAdvancesLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition The aggregate fair value as of the balance sheet date of financial instruments and other positions owned by the entity including: (1) mortgages, mortgage-backed and asset backed securities; (2) US government and agency obligations; (3) state and municipal government obligations; (4) other sovereign government debt; (5) corporate obligations; (6) corporate equities; (7) principal investments; (8) derivative contracts; and (9) physical commodities. Includes both pledged and unpledged holdings. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 940 -SubTopic 320 -Name Accounting Standards Codification -Section 45 -Paragraph 2 -Publisher FASB -URI https://asc.fasb.org/1943274/2147479035/940-320-45-2 + Details
Name: | us-gaap_FinancialInstrumentsOwnedAtFairValue
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Reflects the total carrying amount as of the balance sheet date of debt having initial terms less than one year or the normal operating cycle, if longer. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Topic 210 -SubTopic 10 -Name Accounting Standards Codification -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02(19)(a)) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480566/210-10-S99-1 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Topic 942 -SubTopic 210 -Name Accounting Standards Codification -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-03(13)) -Publisher FASB -URI https://asc.fasb.org/1943274/2147478546/942-210-S99-1 Reference 3: http://www.xbrl.org/2003/role/exampleRef -Topic 852 -SubTopic 10 -Name Accounting Standards Codification -Section 55 -Paragraph 10 -Publisher FASB -URI https://asc.fasb.org/1943274/2147481372/852-10-55-10 Reference 4: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 944 -SubTopic 210 -Name Accounting Standards Codification -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-03(a)(16)(a)(1)) -Publisher FASB -URI https://asc.fasb.org/1943274/2147478777/944-210-S99-1 + Details
Name: | us-gaap_ShortTermBorrowings
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Details
Name: | us-gaap_FederalHomeLoanBankAdvancesOptionAxis=mara_TermAdvanceMaturingAugust212024Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FederalHomeLoanBankAdvancesOptionAxis=mara_FiveYearTermCallablePutableAdvancesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_PledgedStatusAxis=us-gaap_AssetPledgedAsCollateralWithRightMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_PledgedStatusAxis=us-gaap_AssetNotPledgedAsCollateralAndAssetPledgedAsCollateralWithoutRightMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_RangeAxis=srt_MinimumMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_RangeAxis=srt_MaximumMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |