XML 56 R44.htm IDEA: XBRL DOCUMENT
v3.24.3

Note 6 - Investments and Equity Securities - Gross Unrealized Losses and Fair Value (Details) - USD ($) $ in Thousands | Sep. 30, 2024 | Dec. 31, 2023
--- | --- | ---
Less than Twelve Months, Fair Value | $ 9,193 | $ 2,575
Less than Twelve Months, Gross Unrealized Losses | (392) | (17)
Twelve Months or Greater, Fair Value | 137,681 | 141,556
Twelve Months or Greater, Gross Unrealized Losses | (20,690) | (20,573)
Total, Fair Value | 146,874 | 144,131
Total, Gross Unrealized Losses | (21,082) | (20,590)
Less than Twelve Months, Fair Value | 9,193 | 2,575
Less than Twelve Months, Gross Unrealized Losses | (392) | (17)
Twelve Months or Greater, Fair Value | 137,681 | 141,556
Twelve Months or Greater, Gross Unrealized Losses | (20,690) | (20,573)
Total, Fair Value | 146,874 | 144,131
Total, Gross Unrealized Losses | (21,082) | (20,590)
Subordinated Debt Securities [Member] |  |
Less than Twelve Months, Fair Value | 2,812 | 994
Less than Twelve Months, Gross Unrealized Losses | (238) | (6)
Twelve Months or Greater, Fair Value | 27,105 | 29,356
Twelve Months or Greater, Gross Unrealized Losses | (1,645) | (2,445)
Total, Fair Value | 29,917 | 30,350
Total, Gross Unrealized Losses | (1,883) | (2,451)
Less than Twelve Months, Fair Value | 2,812 | 994
Less than Twelve Months, Gross Unrealized Losses | (238) | (6)
Twelve Months or Greater, Fair Value | 27,105 | 29,356
Twelve Months or Greater, Gross Unrealized Losses | (1,645) | (2,445)
Total, Fair Value | 29,917 | 30,350
Total, Gross Unrealized Losses | (1,883) | (2,451)
Nontaxable Municipal Bonds [Member] |  |
Less than Twelve Months, Fair Value | 6,381 | 1,386
Less than Twelve Months, Gross Unrealized Losses | (154) | (10)
Twelve Months or Greater, Fair Value | 105,040 | 106,078
Twelve Months or Greater, Gross Unrealized Losses | (18,550) | (17,482)
Total, Fair Value | 111,421 | 107,464
Total, Gross Unrealized Losses | (18,704) | (17,492)
Less than Twelve Months, Fair Value | 6,381 | 1,386
Less than Twelve Months, Gross Unrealized Losses | (154) | (10)
Twelve Months or Greater, Fair Value | 105,040 | 106,078
Twelve Months or Greater, Gross Unrealized Losses | (18,550) | (17,482)
Total, Fair Value | 111,421 | 107,464
Total, Gross Unrealized Losses | (18,704) | (17,492)
Mortgage-Backed Security, Issued by US Government-Sponsored Enterprise [Member] |  |
Less than Twelve Months, Fair Value | 0 | 195
Less than Twelve Months, Gross Unrealized Losses | 0 | (1)
Twelve Months or Greater, Fair Value | 5,536 | 6,122
Twelve Months or Greater, Gross Unrealized Losses | (495) | (646)
Total, Fair Value | 5,536 | 6,317
Total, Gross Unrealized Losses | (495) | (647)
Less than Twelve Months, Fair Value | 0 | 195
Less than Twelve Months, Gross Unrealized Losses | 0 | (1)
Twelve Months or Greater, Fair Value | 5,536 | 6,122
Twelve Months or Greater, Gross Unrealized Losses | (495) | (646)
Total, Fair Value | 5,536 | 6,317
Total, Gross Unrealized Losses | $ (495) | $ (647)

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), in continuous unrealized loss position for more than 12 months, without allowance for credit loss. Includes beneficial interest in securitized financial asset. + References Reference 1: http://www.xbrl.org/2003/role/exampleRef -Topic 326 -SubTopic 30 -Name Accounting Standards Codification -Section 55 -Paragraph 8 -Publisher FASB -URI https://asc.fasb.org/1943274/2147479081/326-30-55-8 Reference 2: http://fasb.org/us-gaap/role/ref/otherTransitionRef -Topic 320 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 7 -Publisher FASB -URI https://asc.fasb.org/1943274/2147481800/320-10-50-7 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Topic 326 -SubTopic 30 -Name Accounting Standards Codification -Section 50 -Paragraph 5 -Publisher FASB -URI https://asc.fasb.org/1943274/2147479106/326-30-50-5 + Details
Name: | us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLonger
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amount of accumulated unrealized loss on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in continuous unrealized loss position for 12 months or longer, without allowance for credit loss. Includes beneficial interest in securitized financial asset. + References Reference 1: http://fasb.org/us-gaap/role/ref/otherTransitionRef -Topic 320 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 7 -Publisher FASB -URI https://asc.fasb.org/1943274/2147481800/320-10-50-7 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Topic 326 -SubTopic 30 -Name Accounting Standards Codification -Section 50 -Paragraph 5 -Publisher FASB -URI https://asc.fasb.org/1943274/2147479106/326-30-50-5 + Details
Name: | us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLongerAccumulatedLoss
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

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), in continuous unrealized loss position for less than 12 months, without allowance for credit loss. Includes beneficial interest in securitized financial asset. + References Reference 1: http://www.xbrl.org/2003/role/exampleRef -Topic 326 -SubTopic 30 -Name Accounting Standards Codification -Section 55 -Paragraph 8 -Publisher FASB -URI https://asc.fasb.org/1943274/2147479081/326-30-55-8 Reference 2: http://fasb.org/us-gaap/role/ref/otherTransitionRef -Topic 320 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 7 -Publisher FASB -URI https://asc.fasb.org/1943274/2147481800/320-10-50-7 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Topic 326 -SubTopic 30 -Name Accounting Standards Codification -Section 50 -Paragraph 5 -Publisher FASB -URI https://asc.fasb.org/1943274/2147479106/326-30-50-5 + Details
Name: | us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12Months
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amount of accumulated unrealized loss on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in continuous unrealized loss position for less than 12 months, without allowance for credit loss. Includes beneficial interest in securitized financial asset. + References Reference 1: http://fasb.org/us-gaap/role/ref/otherTransitionRef -Topic 320 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 7 -Publisher FASB -URI https://asc.fasb.org/1943274/2147481800/320-10-50-7 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Topic 326 -SubTopic 30 -Name Accounting Standards Codification -Section 50 -Paragraph 5 -Publisher FASB -URI https://asc.fasb.org/1943274/2147479106/326-30-50-5 + Details
Name: | us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12MonthsAccumulatedLoss
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

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), in unrealized loss position without allowance for credit loss. + References Reference 1: http://www.xbrl.org/2003/role/exampleRef -Topic 326 -SubTopic 30 -Name Accounting Standards Codification -Section 55 -Paragraph 8 -Publisher FASB -URI https://asc.fasb.org/1943274/2147479081/326-30-55-8 Reference 2: http://fasb.org/us-gaap/role/ref/otherTransitionRef -Topic 320 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 6 -Subparagraph (a)(1) -Publisher FASB -URI https://asc.fasb.org/1943274/2147481800/320-10-50-6 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Topic 326 -SubTopic 30 -Name Accounting Standards Codification -Section 50 -Paragraph 4 -Subparagraph (a)(1) -Publisher FASB -URI https://asc.fasb.org/1943274/2147479106/326-30-50-4 + Details
Name: | us-gaap_DebtSecuritiesAvailableForSaleUnrealizedLossPosition
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amount of accumulated unrealized loss on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in unrealized loss position, without allowance for credit loss. Includes beneficial interest in securitized financial asset. + References Reference 1: http://fasb.org/us-gaap/role/ref/otherTransitionRef -Topic 320 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 6 -Subparagraph (a)(2) -Publisher FASB -URI https://asc.fasb.org/1943274/2147481800/320-10-50-6 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Topic 326 -SubTopic 30 -Name Accounting Standards Codification -Section 50 -Paragraph 4 -Subparagraph (a)(2) -Publisher FASB -URI https://asc.fasb.org/1943274/2147479106/326-30-50-4 + Details
Name: | us-gaap_DebtSecuritiesAvailableForSaleUnrealizedLossPositionAccumulatedLoss
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_NontaxableMunicipalBondsMember
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: |