XML 50 R38.htm IDEA: XBRL DOCUMENT v3.23.1

Note 5 - Fair Value Measurements - Assets Measured on a Recurring Basis (Details) - USD ($)	Mar. 31, 2023	Dec. 31, 2022
Total debt securities	$ 169,605,000	$ 164,967,000
Equity securities in financial institutions	777,000	915,000
Investment securities available for sale, at fair value	169,605,000	164,967,000
Subordinated Debt Securities [Member]
Total debt securities	32,513,000	30,164,000
Investment securities available for sale, at fair value	32,513,000	30,164,000
Mortgage-Backed Securities, Issued by US Government Sponsored Enterprises [Member]
Total debt securities	7,333,000	7,469,000
Investment securities available for sale, at fair value	7,333,000	7,469,000
Fair Value, Recurring [Member]
Total debt securities	169,605,000	164,967,000
Equity securities in financial institutions	777,000	915,000
Total	170,382,000	165,882,000
Investment securities available for sale, at fair value	169,605,000	164,967,000
Fair Value, Recurring [Member] | Subordinated Debt Securities [Member]
Total debt securities	32,513,000	30,164,000
Investment securities available for sale, at fair value	32,513,000	30,164,000
Fair Value, Recurring [Member] | US States and Political Subdivisions Debt Securities [Member]
Total debt securities	129,759,000	127,334,000
Investment securities available for sale, at fair value	129,759,000	127,334,000
Fair Value, Recurring [Member] | Mortgage-Backed Securities, Issued by US Government Sponsored Enterprises [Member]
Total debt securities	7,333,000	7,469,000
Investment securities available for sale, at fair value	7,333,000	7,469,000
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 1 [Member]
Total debt securities	0	0
Equity securities in financial institutions	777,000	915,000
Total	777,000	915,000
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	160,799,000	156,230,000
Equity securities in financial institutions	0	0
Total	160,799,000	156,230,000
Investment securities available for sale, at fair value	160,799,000	156,230,000
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Subordinated Debt Securities [Member]
Total debt securities	23,707,000	21,427,000
Investment securities available for sale, at fair value	23,707,000	21,427,000
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | US States and Political Subdivisions Debt Securities [Member]
Total debt securities	129,759,000	127,334,000
Investment securities available for sale, at fair value	129,759,000	127,334,000
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Mortgage-Backed Securities, Issued by US Government Sponsored Enterprises [Member]
Total debt securities	7,333,000	7,469,000
Investment securities available for sale, at fair value	7,333,000	7,469,000
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 3 [Member]
Total debt securities	8,806,000	8,737,000
Equity securities in financial institutions	0	0
Total	8,806,000	8,737,000
Investment securities available for sale, at fair value	8,806,000	8,737,000
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | Subordinated Debt Securities [Member]
Total debt securities	8,806,000	8,737,000
Investment securities available for sale, at fair value	8,806,000	8,737,000
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
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (aa)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481800/320-10-50-2

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 45
-Paragraph 1
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481830/320-10-45-1

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 942
-SubTopic 210
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03(6))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479853/942-210-S99-1

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Topic 326
-SubTopic 30
-Name Accounting Standards Codification
-Section 45
-Paragraph 1
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479130/326-30-45-1

+ 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), classified as current.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 210
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(2))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480566/210-10-S99-1

Reference 2: http://www.xbrl.org/2003/role/exampleRef
-Topic 210
-SubTopic 10
-Name Accounting Standards Codification
-Section 45
-Paragraph 1
-Subparagraph (f)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147483467/210-10-45-1

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 825
-SubTopic 10
-Name Accounting Standards Codification
-Section 45
-Paragraph 1A
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482736/825-10-45-1A

+ 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
-Topic 820
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482106/820-10-50-2

+ Details

Name:	us-gaap_InvestmentsFairValueDisclosure
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

X

- Details

Name:	us-gaap_FinancialInstrumentAxis=mbcn_SubordinatedDebtSecuritiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_FinancialInstrumentAxis=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_FinancialInstrumentAxis=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: