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

Contingent Liabilities and Commitments (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Feb. 06, 2015
Property, Plant and Equipment [Line Items]
Daily average required reserves	$ 2.3	$ 2.1
Subsequent Event [Member] \| Building [Member]
Property, Plant and Equipment [Line Items]
Building purchase agreement, purchase price			$ 2.2