XML 141 R109.htm IDEA: XBRL DOCUMENT
v3.5.0.2

Subsequent Event (Textual) (Detail) - Merger of Liberty Bank, N.A. into The Middlefield Banking Company [member] - USD ($) $ / shares in Units, $ in Thousands | 2 Months Ended |
--- | --- | ---
Dec. 31, 2016 | Jul. 28, 2016
Liberty Bank, N.A. [Member] |  |
Business Combination, Merger Agreement, Special Dividend to Be Paid to Entity's Shareholders Before Merger |  | $ 3,000
Business Combination, Merger Agreement, Percentage of Merger Consideration to Be Paid in Common Stock |  | 45.00%
Business Combination, Merger Agreement, Cash Per Share of Reporting Entity Common Stock |  | $ 37.96
Business Combination, Merger Agreement, Ratio of Shares of Reporting Entity's Common Stock for Each Share of Acquired Entity's Common Stock |  | 1.1934
Business Combination, Shares in Acquired Entity Owned Prior to Merger |  | 23,218
Business Combination, Ownership Percentage in Acquired Entity Prior to Merger |  | 2.40%
Scenario, Forecast [Member] |  |
Payments to Acquire Businesses, Gross | $ 1,147 |

X
- Definition Represents the cash paid, or to be paid, per share of the reporting entity's common stock. + References No definition available. + Details
Name: | mbcn_BusinessCombinationMergerAgreementConsiderationCashPerShareOfReportingEntityCommonStock
Namespace Prefix: | mbcn_
Data Type: | num:perShareItemType
Balance Type: | na
Period Type: | instant

X
- Definition Represents the percentage of the total merger consideration that is to be paid in the form of common stock. + References No definition available. + Details
Name: | mbcn_BusinessCombinationMergerAgreementPercentageOfMergerConsiderationToBePaidInCommonStock
Namespace Prefix: | mbcn_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition Represents the ratio of the shares of the reporting entity's common stock for each share of the acquired entity's common stock. + References No definition available. + Details
Name: | mbcn_BusinessCombinationMergerAgreementRatioOfSharesOfReportingEntitysCommonStockForEachShareOfAcquiredEntitysCommonStock
Namespace Prefix: | mbcn_
Data Type: | xbrli:sharesItemType
Balance Type: | na
Period Type: | instant

X
- Definition Represents the amount of a special dividend to be paid by the specified entity to its shareholders prior to the merger, in accordance with the merger agreement. + References No definition available. + Details
Name: | mbcn_BusinessCombinationMergerAgreementSpecialDividendToBePaidToEntitysShareholdersBeforeMerger
Namespace Prefix: | mbcn_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Represents the percentage of the acquired entity's stock owned by the reporting entity prior to a merger. + References No definition available. + Details
Name: | mbcn_BusinessCombinationOwnershipPercentageInAcquiredEntityPriorToMerger
Namespace Prefix: | mbcn_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition Represents the number of shares of the acquired entity's stock owned by the reporting entity prior to a merger. + References No definition available. + Details
Name: | mbcn_BusinessCombinationSharesInAcquiredEntityOwnedPriorToMerger
Namespace Prefix: | mbcn_
Data Type: | xbrli:sharesItemType
Balance Type: | na
Period Type: | instant

X
- Definition The cash outflow associated with the acquisition of business during the period. The cash portion only of the acquisition price. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Glossary Investing Activities -URI http://asc.fasb.org/extlink&oid=6516133 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 13 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=66902209&loc=d3e3213-108585 + Details
Name: | us-gaap_PaymentsToAcquireBusinessesGross
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Details
Name: | us-gaap_BusinessAcquisitionAxis=mbcn_MergerOfLibertyBankNaIntoTheMiddlefieldBankingCompanyMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | dei_LegalEntityAxis=mbcn_LibertyBankNaMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_StatementScenarioAxis=us-gaap_ScenarioForecastMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |