INVESTMENT SECURITIES (Narrative) (Details)	9 Months Ended
Sep. 30, 2016 USD ($)
INVESTMENT SECURITIES [Abstract]
Tax provision on net realized gains on securities and calls	$ 17,000

Other comprehensive income unrealized holding gains loss on securities and calls arising during the period tax.

No definition available.

Name:	mcb_OtherComprehensiveIncomeUnrealizedHoldingGainsLossOnSecuritiesAndCallsArisingDuringPeriodTax
Namespace Prefix:	mcb_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration