Amortized cost excluding accrued interest, of financing receivable modified during period for debtor experiencing financial difficulty.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 310
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 42
-Subparagraph (a)(1)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481962/310-10-50-42

+ Details

Name:	us-gaap_FinancingReceivableExcludingAccruedInterestModifiedPeriod
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Percentage, excluding accrued interest, of financing receivable modified during period for debtor experiencing financial difficulty to total financing receivables.

+ References

+ Details

Name:	us-gaap_FinancingReceivableModificationToTotalFinancingReceivablesExcludingAccruedInterestPercent
Namespace Prefix:	us-gaap_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

- 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_LoansAndLeasesReceivableDisclosureLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	us-gaap_FinancingReceivablePortfolioSegmentAxis=mcb_RealEstatePortfolioSegmentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=mcb_MultifamilyRealEstateMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivablePortfolioSegmentAxis=us-gaap_CommercialRealEstatePortfolioSegmentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LoanRestructuringModificationAxis=us-gaap_ExtendedMaturityMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LoanRestructuringModificationAxis=us-gaap_ExtendedMaturityAndInterestRateReductionMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LoanRestructuringModificationAxis=us-gaap_ContractualInterestRateReductionMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

LOANS AND ALLOWANCE FOR CREDIT LOSSES (Amortized Cost Basis of Loans) (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
	Sep. 30, 2025	Sep. 30, 2025	Sep. 30, 2024
Loans and Leases Receivable Disclosure [Line Items]
Loans modified	$ 13,937	$ 58,334	$ 62,925
Real Estate \| Multi-family
Loans and Leases Receivable Disclosure [Line Items]
Loans modified	$ 3,015	$ 47,412	$ 51,239
Modifications as a % of loan class	0.70%	11.70%	13.20%
Commercial and industrial
Loans and Leases Receivable Disclosure [Line Items]
Loans modified	$ 10,922	$ 10,922	$ 11,686
Modifications as a % of loan class	1.10%	1.10%	1.10%
Extension
Loans and Leases Receivable Disclosure [Line Items]
Loans modified	$ 13,937	$ 58,334
Extension \| Real Estate \| Multi-family
Loans and Leases Receivable Disclosure [Line Items]
Loans modified	3,015	47,412
Extension \| Commercial and industrial
Loans and Leases Receivable Disclosure [Line Items]
Loans modified	$ 10,922	$ 10,922
Combination Term Extension and Interest Rate
Loans and Leases Receivable Disclosure [Line Items]
Loans modified			$ 59,910
Combination Term Extension and Interest Rate \| Real Estate \| Multi-family
Loans and Leases Receivable Disclosure [Line Items]
Loans modified			48,224
Combination Term Extension and Interest Rate \| Commercial and industrial
Loans and Leases Receivable Disclosure [Line Items]
Loans modified			11,686
Interest Rate Reduction
Loans and Leases Receivable Disclosure [Line Items]
Loans modified			3,015
Interest Rate Reduction \| Real Estate \| Multi-family
Loans and Leases Receivable Disclosure [Line Items]
Loans modified			$ 3,015