Fair Value Measurements Narrative (Details)	12 Months Ended
Dec. 31, 2014
Fair Value Disclosures [Abstract]
Impaired loans discount rate	10.00%mbrg_ImpairedLoansDiscountRate
Percentage at which new appraisals are discounted	10.00%

Percentage at which new appraisals discounted for selling cost.

No definition available.

Name:	mbrg_PercentageAtWhichNewAppraisalsDiscounted
Namespace Prefix:	mbrg_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant