Employee Benefit Plans - 401(k) Plan Narrative (Details) - 401(k) Plan [Member] - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Defined Benefit Plan Disclosure [Line Items]
Employees contribution, maximum	100.00%
Matching contribution	50.00%
Percentage of employer matching contribution to employees compensation	6.00%
Matching contributions vesting period	5 years
Expense attributable to the plan	$ 364	$ 351	$ 340

Percentage of employer matching contribution on first specified percentage contributed to the plan by the employee.

No definition available.

Name:	mbrg_DefinedContributionPlanEmployerMatchingContributionMaximum
Namespace Prefix:	mbrg_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Period over which matching contributions vest to the employee.

+ References

No definition available.

+ Details

Name:	mbrg_DefinedContributionPlanEmployersMatchingContributionVestingPeriod
Namespace Prefix:	mbrg_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Maximum percentage of gross pay, by the terms of the plan, that the employee may contribute to a defined contribution plan.

+ References

No definition available.

+ Details

Name:	mbrg_DefinedContributionPlanMaximumAnnualContributionByEmployeePercent
Namespace Prefix:	mbrg_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

Name:	us-gaap_DefinedBenefitPlanDisclosureLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

The amount of the cost recognized during the period for defined contribution plans.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 70
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=49170846&loc=d3e28014-114942

+ Details

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

- Definition

Percentage of employees' gross pay for which the employer contributes a matching contribution to a defined contribution plan.

+ References

No definition available.

+ Details

Name:	us-gaap_DefinedContributionPlanEmployerMatchingContributionPercent
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	us-gaap_PlanNameAxis=mbrg_KPlanMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: