XML 53 R36.htm IDEA: XBRL DOCUMENT
v3.19.3

Note 5 - Fair Value Measurements - Assets Measured on a Recurring Basis (Details) - Fair Value, Recurring [Member] - USD ($) $ in Thousands | Sep. 30, 2019 | Dec. 31, 2018
--- | --- | ---
Assets measured on a recurring basis | $ 105,669 | $ 98,938
US Government Agencies Debt Securities [Member] |  |
Assets measured on a recurring basis | 1,999 | 7,471
Subordinated Debt Securities [Member] |  |
Assets measured on a recurring basis | 4,150 |
US States and Political Subdivisions Debt Securities [Member] |  |
Assets measured on a recurring basis | 79,641 | 73,093
Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member] |  |
Assets measured on a recurring basis | 19,251 | 17,758
Debt Securities [Member] |  |
Assets measured on a recurring basis | 105,041 | 98,322
Equity Securities [Member] |  |
Assets measured on a recurring basis | 628 | 616
Fair Value, Inputs, Level 1 [Member] |  |
Assets measured on a recurring basis | 628 | 616
Fair Value, Inputs, Level 1 [Member] | US Government Agencies Debt Securities [Member] |  |
Assets measured on a recurring basis |  |
Fair Value, Inputs, Level 1 [Member] | Subordinated Debt Securities [Member] |  |
Assets measured on a recurring basis |  |
Fair Value, Inputs, Level 1 [Member] | US States and Political Subdivisions Debt Securities [Member] |  |
Assets measured on a recurring basis |  |
Fair Value, Inputs, Level 1 [Member] | Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member] |  |
Assets measured on a recurring basis |  |
Fair Value, Inputs, Level 1 [Member] | Debt Securities [Member] |  |
Assets measured on a recurring basis |  |
Fair Value, Inputs, Level 1 [Member] | Equity Securities [Member] |  |
Assets measured on a recurring basis | 628 | 616
Fair Value, Inputs, Level 2 [Member] |  |
Assets measured on a recurring basis | 105,041 | 98,322
Fair Value, Inputs, Level 2 [Member] | US Government Agencies Debt Securities [Member] |  |
Assets measured on a recurring basis | 1,999 | 7,471
Fair Value, Inputs, Level 2 [Member] | Subordinated Debt Securities [Member] |  |
Assets measured on a recurring basis | 4,150 |
Fair Value, Inputs, Level 2 [Member] | US States and Political Subdivisions Debt Securities [Member] |  |
Assets measured on a recurring basis | 79,641 | 73,093
Fair Value, Inputs, Level 2 [Member] | Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member] |  |
Assets measured on a recurring basis | 19,251 | 17,758
Fair Value, Inputs, Level 2 [Member] | Debt Securities [Member] |  |
Assets measured on a recurring basis | 105,041 | 98,322
Fair Value, Inputs, Level 2 [Member] | Equity Securities [Member] |  |
Assets measured on a recurring basis |  |
Fair Value, Inputs, Level 3 [Member] |  |
Assets measured on a recurring basis |  |
Fair Value, Inputs, Level 3 [Member] | US Government Agencies Debt Securities [Member] |  |
Assets measured on a recurring basis |  |
Fair Value, Inputs, Level 3 [Member] | Subordinated Debt Securities [Member] |  |
Assets measured on a recurring basis |  |
Fair Value, Inputs, Level 3 [Member] | US States and Political Subdivisions Debt Securities [Member] |  |
Assets measured on a recurring basis |  |
Fair Value, Inputs, Level 3 [Member] | Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member] |  |
Assets measured on a recurring basis |  |
Fair Value, Inputs, Level 3 [Member] | Debt Securities [Member] |  |
Assets measured on a recurring basis |  |
Fair Value, Inputs, Level 3 [Member] | Equity Securities [Member] |  |
Assets measured on a recurring basis |  |

X
- Definition Amount of investment in debt and equity securities categorized neither as held-to-maturity nor trading. + References No definition available. + Details
Name: | us-gaap_AvailableForSaleSecurities
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

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

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

X
- Details
Name: | us-gaap_InvestmentTypeAxis=mbcn_SubordinatedDebtSecuritiesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

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

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

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

X
- Details
Name: | us-gaap_InvestmentTypeAxis=us-gaap_EquitySecuritiesMember
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_FairValueByFairValueHierarchyLevelAxis=us-gaap_FairValueInputsLevel3Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |