Note 2 - Revenue Recognition (Details Textual)	9 Months Ended
Sep. 30, 2022
Revenue from Interest Income and Noninterest Income, Percent	89.50%

Represents the percentage of revenue from interest income and noninterest income.

No definition available.

Name:	mbcn_RevenueFromInterestIncomeAndNoninterestIncomePercent
Namespace Prefix:	mbcn_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration