Loans, Net - Loans modified in TDR by class of loan (Details) $ in Thousands	3 Months Ended
Mar. 31, 2016 USD ($) loan	Mar. 31, 2015 USD ($) loan
Loans modified in a TDR by class of loan [Abstract]
Number of Contracts \| loan	1	0
Pre-Modification Outstanding Recorded Investment	$ 368	$ 0
Post-Modification Outstanding Recorded Investment	$ 367	$ 0
Real Estate Loans [Member]
Loans modified in a TDR by class of loan [Abstract]
Number of Contracts \| loan	1	0
Pre-Modification Outstanding Recorded Investment	$ 368	$ 0
Post-Modification Outstanding Recorded Investment	$ 367	$ 0
Construction [Member]
Loans modified in a TDR by class of loan [Abstract]
Number of Contracts \| loan	0	0
Pre-Modification Outstanding Recorded Investment	$ 0	$ 0
Post-Modification Outstanding Recorded Investment	$ 0	$ 0
Secured by farmland [Member]
Loans modified in a TDR by class of loan [Abstract]
Number of Contracts \| loan	0	0
Pre-Modification Outstanding Recorded Investment	$ 0	$ 0
Post-Modification Outstanding Recorded Investment	$ 0
Secured by 1-4 family residential [Member]
Loans modified in a TDR by class of loan [Abstract]
Number of Contracts \| loan	0	0
Pre-Modification Outstanding Recorded Investment	$ 0	$ 0
Post-Modification Outstanding Recorded Investment	$ 0
Other real estate loans [Member]
Loans modified in a TDR by class of loan [Abstract]
Number of Contracts \| loan	1	0
Pre-Modification Outstanding Recorded Investment	$ 368	$ 0
Post-Modification Outstanding Recorded Investment	$ 367
Commercial loans [Member]
Loans modified in a TDR by class of loan [Abstract]
Number of Contracts \| loan	0	0
Pre-Modification Outstanding Recorded Investment	$ 0	$ 0
Post-Modification Outstanding Recorded Investment	$ 0
Consumer loans [Member]
Loans modified in a TDR by class of loan [Abstract]
Number of Contracts \| loan	0	0
Pre-Modification Outstanding Recorded Investment	$ 0	$ 0
Post-Modification Outstanding Recorded Investment	$ 0

-- None. No documentation exists for this element. --

No definition available.

Name:	mbrg_LoansModifiedInTdrByClassOfLoanAbstract
Namespace Prefix:	mbrg_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Number of financing receivables that have been modified by troubled debt restructurings.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 33
-URI http://asc.fasb.org/extlink&oid=49124121&loc=SL6953676-111524

+ Details

Name:	us-gaap_FinancingReceivableModificationsNumberOfContracts2
Namespace Prefix:	us-gaap_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

Post-modification amount of investment in financing receivables modified by troubled debt restructurings.

+ References

+ Details

Name:	us-gaap_FinancingReceivableModificationsPostModificationRecordedInvestment2
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Pre-modification amount of investment in financing receivables modified by troubled debt restructurings.

+ References

+ Details

Name:	us-gaap_FinancingReceivableModificationsPreModificationRecordedInvestment2
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Details

Name:	us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=mbrg_RealEstateFinancingReceivableMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=us-gaap_ConstructionLoansMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=mbrg_SecuredByFarmlandMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=us-gaap_ResidentialMortgageMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=us-gaap_RealEstateLoanMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=us-gaap_CommercialLoanMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=us-gaap_ConsumerLoanMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: