Contingent Liabilities and Commitments (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
Dec. 31, 2012	Dec. 31, 2011
Contingent Liabilities and Commitments [Abstract]
Daily average required reserves	$ 9.1	$ 5.5

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:	na
Period Type:	duration