XML 129 R97.htm IDEA: XBRL DOCUMENT
v3.22.4

Note 17 - Regulatory Capital - Capital Ratios (Details) | Dec. 31, 2022 | Dec. 31, 2021
--- | --- | ---
Leverage capital, adequately capitalized, ratio | 0.0400 | 0.0400
Tier 1 risk based capital, adequately capitalized, ratio | 0.0600 | 0.0600
Common equity tier 1 capital, adequately capitalized, ratio | 4.50% | 4.50%
Total risk based capital, adequately capitalized, ratio | 0.0800 | 0.0800
Leverage capital, adequately capitalized plus capital conservation buffer, ratio | 4.00% | 4.00%
Tier 1 risk based capital, adequately capitalized plus capital conservation buffer, ratio | 8.50% | 8.50%
Common equity tier 1 capital, adequately capitalized plus capital conservation buffer, ratio | 7.00% | 7.00%
Total risk based capital, adequately capitalized plus capital conservation buffer, ratio | 10.50% | 10.50%
Middlefield Banking Company [Member] |  |
Leverage capital, actual, ratio | 0.1116 | 0.0980
Tier 1 risk based capital, actual, ratio | 0.1263 | 0.1272
Common equity tier 1 capital, actual, ratio | 12.63% | 12.72%
Total risk based capital, actual, ratio | 0.1361 | 0.1397
Leverage capital, well-capitalized, ratio (bank only) | 0.0500 | 0.0500
Tier 1 risk based capital, well-capitalized, ratio (bank only) | 0.0800 | 0.0800
Common equity tier 1 capital, well-capitalized, ratio (bank only) | 6.50% | 6.50%
Total risk based capital, well-capitalized, ratio (bank only) | 0.1000 | 0.1000
Middlefield Banc Corp [Member] |  |
Leverage capital, actual, ratio | 0.1130 | 0.1002
Tier 1 risk based capital, actual, ratio | 0.1280 | 0.1296
Common equity tier 1 capital, actual, ratio | 12.25% | 12.18%
Total risk based capital, actual, ratio | 0.1378 | 0.1421

X
- Definition The minimum Total risk based capital ratio (total capital divided by risk weighted assets) required for capital adequacy purposes plus capital conservation buffer under the regulatory framework for prompt corrective action. + References No definition available. + Details
Name: | mbcn_CapitalRequiredForCapitalAdequacyPlusCapitalConservationBufferToRiskWeightedAssets
Namespace Prefix: | mbcn_
Data Type: | dtr-types:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition The minimum common equity tier 1 risk based capital ratio (common equity tier 1 capital divided by risk weighted assets) required for capital adequacy purposes plus capital conservation buffer under the regulatory framework for prompt corrective action. + References No definition available. + Details
Name: | mbcn_CommonEquityTier1CapitalRequiredForCapitalAdequacyPlusCapitalConservationBuffer
Namespace Prefix: | mbcn_
Data Type: | dtr-types:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition The minimum common equity tier 1 risk based capital ratio (common equity tier 1 capital divided by risk weighted assets) required for capital adequacy purposes under the regulatory framework for prompt corrective action. + References No definition available. + Details
Name: | mbcn_CommonEquityTier1CapitalRequiredForCapitalAdequacyToRiskWeightedAssets
Namespace Prefix: | mbcn_
Data Type: | dtr-types:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition The common equity tier 1 risk based capital ratio (common equity tier 1 capital divided by risk weighted assets) required to be categorized as "well capitalized", in the regulatory framework for prompt corrective action. + References No definition available. + Details
Name: | mbcn_CommonEquityTier1CapitalRequiredToBeWellCapitalizedToRiskWeightedAssets
Namespace Prefix: | mbcn_
Data Type: | dtr-types:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition Common equity tier 1 capital divided by risk weighted assets as defined in the regulations. + References No definition available. + Details
Name: | mbcn_CommonEquityTier1CapitalToRiskWeightedAssets
Namespace Prefix: | mbcn_
Data Type: | dtr-types:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition The minimum amount of Tier 1 Leverage Capital for capital adequacy plus conservation buffer purposes divided by average assets as defined in the regulations. + References No definition available. + Details
Name: | mbcn_TierOneLeverageCapitalRequiredForCapitalAdequacyPlusConservationBufferToAverageAssets
Namespace Prefix: | mbcn_
Data Type: | dtr-types:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition The minimum Tier One Capital Ratio (Tier one capital divided by risk-weighted assets) required for capital adequacy purposes plus capital conservation buffer under the regulatory framework for prompt corrective action. + References No definition available. + Details
Name: | mbcn_TierOneRiskBasedCapitalRequiredForCapitalAdequacyPlusCapitalConservationBufferToRiskWeightedAssets
Namespace Prefix: | mbcn_
Data Type: | dtr-types:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition Ratio of minimum total risk-based capital to risk-weighted assets required for capital adequacy as defined by regulatory framework. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 505 -Section 50 -Paragraph 1B -URI https://asc.fasb.org/extlink&oid=117337116&loc=SL5958570-112826 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 505 -Section 50 -Paragraph 1 -Subparagraph (c)(1) -URI https://asc.fasb.org/extlink&oid=117337116&loc=SL5958568-112826 + Details
Name: | us-gaap_CapitalRequiredForCapitalAdequacyToRiskWeightedAssets
Namespace Prefix: | us-gaap_
Data Type: | xbrli:pureItemType
Balance Type: | na
Period Type: | instant

X
- Definition Ratio of minimum total risk-based capital to risk-weighted assets categorized as well capitalized as defined by regulatory framework for prompt corrective action. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 505 -Section 50 -Paragraph 1 -Subparagraph (c)(1) -URI https://asc.fasb.org/extlink&oid=117337116&loc=SL5958568-112826 + Details
Name: | us-gaap_CapitalRequiredToBeWellCapitalizedToRiskWeightedAssets
Namespace Prefix: | us-gaap_
Data Type: | xbrli:pureItemType
Balance Type: | na
Period Type: | instant

X
- Definition Ratio of total risk-based capital to risk-weighted assets as defined by regulatory framework. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 505 -Section 50 -Paragraph 1 -Subparagraph (c)(1) -URI https://asc.fasb.org/extlink&oid=117337116&loc=SL5958568-112826 + Details
Name: | us-gaap_CapitalToRiskWeightedAssets
Namespace Prefix: | us-gaap_
Data Type: | xbrli:pureItemType
Balance Type: | na
Period Type: | instant

X
- Definition Ratio of minimum Tier 1 leverage capital to average assets required for capital adequacy as defined by regulatory framework. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 505 -Section 50 -Paragraph 1B -URI https://asc.fasb.org/extlink&oid=117337116&loc=SL5958570-112826 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 505 -Section 50 -Paragraph 1 -Subparagraph (c)(1) -URI https://asc.fasb.org/extlink&oid=117337116&loc=SL5958568-112826 + Details
Name: | us-gaap_TierOneLeverageCapitalRequiredForCapitalAdequacyToAverageAssets
Namespace Prefix: | us-gaap_
Data Type: | xbrli:pureItemType
Balance Type: | na
Period Type: | instant

X
- Definition Ratio of minimum Tier 1 leverage capital to average assets categorized as well capitalized as defined by regulatory framework for prompt corrective action. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 505 -Section 50 -Paragraph 1 -Subparagraph (c)(1) -URI https://asc.fasb.org/extlink&oid=117337116&loc=SL5958568-112826 + Details
Name: | us-gaap_TierOneLeverageCapitalRequiredToBeWellCapitalizedToAverageAssets
Namespace Prefix: | us-gaap_
Data Type: | xbrli:pureItemType
Balance Type: | na
Period Type: | instant

X
- Definition Ratio of Tier 1 capital to average assets as defined by regulatory framework. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 505 -Section 50 -Paragraph 1 -Subparagraph (c)(1) -URI https://asc.fasb.org/extlink&oid=117337116&loc=SL5958568-112826 + Details
Name: | us-gaap_TierOneLeverageCapitalToAverageAssets
Namespace Prefix: | us-gaap_
Data Type: | xbrli:pureItemType
Balance Type: | na
Period Type: | instant

X
- Definition Ratio of minimum Tier 1 risk-based capital to risk-weighted assets required for capital adequacy as defined by regulatory framework. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 505 -Section 50 -Paragraph 1B -URI https://asc.fasb.org/extlink&oid=117337116&loc=SL5958570-112826 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 505 -Section 50 -Paragraph 1 -Subparagraph (c)(1) -URI https://asc.fasb.org/extlink&oid=117337116&loc=SL5958568-112826 + Details
Name: | us-gaap_TierOneRiskBasedCapitalRequiredForCapitalAdequacyToRiskWeightedAssets
Namespace Prefix: | us-gaap_
Data Type: | xbrli:pureItemType
Balance Type: | na
Period Type: | instant

X
- Definition Ratio of minimum Tier 1 risk-based capital to risk-weighted assets categorized as well capitalized as defined by regulatory framework for prompt corrective action. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 505 -Section 50 -Paragraph 1 -Subparagraph (c)(1) -URI https://asc.fasb.org/extlink&oid=117337116&loc=SL5958568-112826 + Details
Name: | us-gaap_TierOneRiskBasedCapitalRequiredToBeWellCapitalizedToRiskWeightedAssets
Namespace Prefix: | us-gaap_
Data Type: | xbrli:pureItemType
Balance Type: | na
Period Type: | instant

X
- Definition Ratio of Tier 1 risk-based capital to risk-weighted assets as defined by regulatory framework. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 505 -Section 50 -Paragraph 1 -Subparagraph (c)(1) -URI https://asc.fasb.org/extlink&oid=117337116&loc=SL5958568-112826 + Details
Name: | us-gaap_TierOneRiskBasedCapitalToRiskWeightedAssets
Namespace Prefix: | us-gaap_
Data Type: | xbrli:pureItemType
Balance Type: | na
Period Type: | instant

X
- Details
Name: | dei_LegalEntityAxis=mbcn_MiddlefieldBankingCompanyMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | dei_LegalEntityAxis=mbcn_MiddlefieldBancCorpMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |