XML 49 R37.htm IDEA: XBRL DOCUMENT
v3.20.2

Note 5 - Fair Value Measurements - Assets Measured on a Recurring Basis (Details) - USD ($) $ in Thousands | Jun. 30, 2020 | Dec. 31, 2019
--- | --- | ---
Total debt securities | $ 112,529 | $ 105,733
Equity securities in financial institutions | 581 | 710
Investment securities available for sale, at fair value | 112,529 | 105,733
Subordinated Debt Securities [Member] |  |
Total debt securities | 11,289 | 4,126
Investment securities available for sale, at fair value | 11,289 | 4,126
Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member] |  |
Total debt securities | 16,700 | 18,630
Investment securities available for sale, at fair value | 16,700 | 18,630
Fair Value, Recurring [Member] |  |
Total debt securities | 112,529 | 105,733
Equity securities in financial institutions | 581 | 710
Total | 113,110 | 106,443
Investment securities available for sale, at fair value | 112,529 | 105,733
Fair Value, Recurring [Member] | Subordinated Debt Securities [Member] |  |
Total debt securities | 11,289 | 4,126
Investment securities available for sale, at fair value | 11,289 | 4,126
Fair Value, Recurring [Member] | US States and Political Subdivisions Debt Securities [Member] |  |
Total debt securities | 84,540 | 82,977
Investment securities available for sale, at fair value | 84,540 | 82,977
Fair Value, Recurring [Member] | Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member] |  |
Total debt securities | 16,700 | 18,630
Investment securities available for sale, at fair value | 16,700 | 18,630
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] |  |
Total debt securities | 0 | 0
Equity securities in financial institutions | 581 | 710
Total | 581 | 710
Investment securities available for sale, at fair value | 0 | 0
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | Subordinated Debt Securities [Member] |  |
Total debt securities | 0 | 0
Investment securities available for sale, at fair value | 0 | 0
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | US States and Political Subdivisions Debt Securities [Member] |  |
Total debt securities | 0 | 0
Investment securities available for sale, at fair value | 0 | 0
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member] |  |
Total debt securities | 0 | 0
Investment securities available for sale, at fair value | 0 | 0
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] |  |
Total debt securities | 112,529 | 105,733
Equity securities in financial institutions | 0 | 0
Total | 112,529 | 105,733
Investment securities available for sale, at fair value | 112,529 | 105,733
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Subordinated Debt Securities [Member] |  |
Total debt securities | 11,289 | 4,126
Investment securities available for sale, at fair value | 11,289 | 4,126
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | US States and Political Subdivisions Debt Securities [Member] |  |
Total debt securities | 84,540 | 82,977
Investment securities available for sale, at fair value | 84,540 | 82,977
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member] |  |
Total debt securities | 16,700 | 18,630
Investment securities available for sale, at fair value | 16,700 | 18,630
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] |  |
Total debt securities | 0 | 0
Equity securities in financial institutions | 0 | 0
Total | 0 | 0
Investment securities available for sale, at fair value | 0 | 0
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | Subordinated Debt Securities [Member] |  |
Total debt securities | 0 | 0
Investment securities available for sale, at fair value | 0 | 0
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | US States and Political Subdivisions Debt Securities [Member] |  |
Total debt securities | 0 | 0
Investment securities available for sale, at fair value | 0 | 0
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member] |  |
Total debt securities | 0 | 0
Investment securities available for sale, at fair value | $ 0 | $ 0

X
- Definition Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale). + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-03(6)) -URI http://asc.fasb.org/extlink&oid=120398452&loc=d3e534808-122878 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 30 -Section 45 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=121558606&loc=SL82898722-210454 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 45 -Paragraph 1 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=121553693&loc=d3e26610-111562 Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (aa) -URI http://asc.fasb.org/extlink&oid=121645371&loc=d3e27161-111563 + Details
Name: | us-gaap_AvailableForSaleSecuritiesDebtSecurities
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amount of investment in equity security measured at fair value with change in fair value recognized in net income (FV-NI). + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 825 -SubTopic 10 -Section 45 -Paragraph 1A -URI http://asc.fasb.org/extlink&oid=99377092&loc=SL75136599-209740 + Details
Name: | us-gaap_EquitySecuritiesFvNi
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Fair value portion of investment securities, including, but not limited to, marketable securities, derivative financial instruments, and investments accounted for under the equity method. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=117815213&loc=d3e19207-110258 + Details
Name: | us-gaap_InvestmentsFairValueDisclosure
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

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_MortgageBackedSecuritiesIssuedByUSGovernmentSponsoredEnterprisesMember
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_InvestmentTypeAxis=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_FairValueByFairValueHierarchyLevelAxis=us-gaap_FairValueInputsLevel3Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |