XML 129 R97.htm IDEA: XBRL DOCUMENT
v3.5.0.2

Fair Value Measurements - Assets Measured on a Recurring Basis (Detail) - USD ($) $ in Thousands | Sep. 30, 2016 | Dec. 31, 2015 | Dec. 31, 2014
--- | --- | --- | ---
Available-for-sale Securities | $ 123,054 | $ 146,520 | $ 154,334
US Government Agencies Debt Securities [Member] |  |  |
Available-for-sale Securities | 10,863 | 21,629 | 22,896
Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member] |  |  |
Available-for-sale Securities | 21,380 | 24,524 | 29,391
Mortgage-backed Securities, Issued by Private Enterprises [Member] |  |  |
Available-for-sale Securities | 2,068 | 2,263 | 2,919
Debt Securities [Member] |  |  |
Available-for-sale Securities | 121,836 | 145,706 | 153,551
Equity Securities In Financial Institutions [Member] |  |  |
Available-for-sale Securities | 1,218 | 814 | 783
Fair Value, Measurements, Recurring [Member] | US Government Agencies Debt Securities [Member] |  |  |
Available-for-sale Securities | 10,863 | 21,629 | 22,896
Fair Value, Measurements, Recurring [Member] | US States and Political Subdivisions Debt Securities [Member] |  |  |
Available-for-sale Securities | 87,525 | 97,290 | 98,345
Fair Value, Measurements, Recurring [Member] | Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member] |  |  |
Available-for-sale Securities | 21,380 | 24,524 | 29,391
Fair Value, Measurements, Recurring [Member] | Mortgage-backed Securities, Issued by Private Enterprises [Member] |  |  |
Available-for-sale Securities | 2,068 | 2,263 | 2,919
Fair Value, Measurements, Recurring [Member] | Debt Securities [Member] |  |  |
Available-for-sale Securities | 121,836 | 145,706 | 153,551
Fair Value, Measurements, Recurring [Member] | Equity Securities In Financial Institutions [Member] |  |  |
Available-for-sale Securities | 1,218 | 814 | 783
Fair Value, Inputs, Level 1 [Member] |  |  |
Available-for-sale Securities | 5 | 5 |
Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Equity Securities In Financial Institutions [Member] |  |  |
Available-for-sale Securities | 5 | 5 |
Fair Value, Inputs, Level 2 [Member] |  |  |
Available-for-sale Securities | 123,049 | 146,515 | 154,334
Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | US Government Agencies Debt Securities [Member] |  |  |
Available-for-sale Securities | 10,863 | 21,629 | 22,896
Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | US States and Political Subdivisions Debt Securities [Member] |  |  |
Available-for-sale Securities | 87,525 | 97,290 | 98,345
Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member] |  |  |
Available-for-sale Securities | 21,380 | 24,524 | 29,391
Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Mortgage-backed Securities, Issued by Private Enterprises [Member] |  |  |
Available-for-sale Securities | 2,068 | 2,263 | 2,919
Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Debt Securities [Member] |  |  |
Available-for-sale Securities | 121,836 | 145,706 | 153,551
Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Equity Securities In Financial Institutions [Member] |  |  |
Available-for-sale Securities | $ 1,213 | 809 | $ 783
Scenario, Previously Reported [Member] |  |  |
Available-for-sale Securities |  | 146,520 |
Scenario, Previously Reported [Member] | Fair Value, Inputs, Level 2 [Member] |  |  |
Available-for-sale Securities |  | 146,520 |
Scenario, Previously Reported [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Equity Securities In Financial Institutions [Member] |  |  |
Available-for-sale Securities |  | $ 814 |

X
- Definition Amount of investment in debt and equity securities categorized neither as held-to-maturity nor trading. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 25 -Paragraph 1 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=65884222&loc=d3e22054-111558 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 5 -Subparagraph (aa) -URI http://asc.fasb.org/extlink&oid=73527792&loc=d3e27232-111563 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 45 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=66010992&loc=d3e26610-111562 + Details
Name: | us-gaap_AvailableForSaleSecurities
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Details
Name: | us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis=us-gaap_USGovernmentAgenciesDebtSecuritiesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis=us-gaap_MortgageBackedSecuritiesIssuedByUSGovernmentSponsoredEnterprisesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis=us-gaap_MortgageBackedSecuritiesIssuedByPrivateEnterprisesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis=us-gaap_DebtSecuritiesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis=mbcn_EquitySecuritiesInFinancialInstitutionsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FairValueByMeasurementFrequencyAxis=us-gaap_FairValueMeasurementsRecurringMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis=us-gaap_USStatesAndPoliticalSubdivisionsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FairValueByFairValueHierarchyLevelAxis=us-gaap_FairValueInputsLevel1Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FairValueByFairValueHierarchyLevelAxis=us-gaap_FairValueInputsLevel2Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

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