Contingent Liabilities and Commitments (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2016	Dec. 31, 2015
Commitments and Contingencies Disclosure [Abstract]
Daily average required reserves	$ 3.5	$ 3.1

Daily average required reserves against its deposits in accordance with Regulation D of the Federal Reserve Act.

No definition available.

Name:	mbrg_FederalReserveActDailyAverageRequiredReserves
Namespace Prefix:	mbrg_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration