REVENUE RECOGNITION (Details)	12 Months Ended
Dec. 31, 2019	Dec. 31, 2018
Maximum
Percentage of all services charges on deposit accounts to total revenue	1.00%	1.00%

The percentage of all services charges on deposit accounts to total revenue

No definition available.

Name:	mcbs_PercentageOfServiceChargesOnDepositAccountsToTotalRevenue
Namespace Prefix:	mcbs_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration