EARNINGS PER SHARE (Computation of Basic and Diluted Earnings per Share) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
Mar. 31, 2021	Mar. 31, 2020
Basic
Net income per consolidated statements of income	$ 12,117	$ 6,097
Less: Earnings allocated to participating securities	(55)	(65)
Net income available to common stockholder	$ 12,062	$ 6,032
Weighted average common shares outstanding including participating securities	8,313,660	8,304,205
Less: Weighted average participating securities	(37,486)	(88,246)
Weighted average common shares outstanding	8,276,174	8,215,959
Basic earnings per common share (in dollars per share)	$ 1.46	$ 0.73
Diluted
Net income allocated to common shareholders	$ 12,062	$ 6,032
Weighted average common shares outstanding for basic earnings per common share	8,276,174	8,215,959
Average shares and dilutive potential common shares	8,417,319	8,412,782
Diluted earnings per common share (in dollars per share)	$ 1.43	$ 0.72
Stock Option
Diluted
Add: Dilutive effects of assumed exercise of stock options	141,145	131,159
Restricted stock
Calculations of basic and diluted earnings per share
Number of antidilutive shares not considered in computing diluted earnings per share	108,178	108,178
Diluted
Dilutive effects of assumed exercise of stock options/vesting of performance based restricted stock		65,664

Weighted Average Number Of Shares Participating Securities

No definition available.

Name:	mcb_WeightedAverageNumberOfSharesParticipatingSecurities
Namespace Prefix:	mcb_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

- Definition

Securities (including those issuable pursuant to contingent stock agreements) that could potentially dilute basic earnings per share (EPS) or earnings per unit (EPU) in the future that were not included in the computation of diluted EPS or EPU because to do so would increase EPS or EPU amounts or decrease loss per share or unit amounts for the period presented.