Note 18 - Regulatory Capital - Regulatory Capital Requirements (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Common Equity Tier One Risk Based Capital Capital Required for Capital Adequacy to Risk Weighted Assets	4.50%
Subtotal Bank of Commerce Holdings [Member]
Common Equity Tier One Risk Based Capital	$ 139,488	$ 125,745
Common Equity Tier One Risk Based Capital to Risk Weighted Assets	12.79%	12.26%
Common Equity Tier One Risk Based Capital Required for Capital Adequacy	$ 49,072	$ 46,169
Common Equity Tier One Risk Based Capital Capital Required for Capital Adequacy to Risk Weighted Assets	4.50%	4.50%
Applicable capital conservation buffer, common equity tier 1 capital	1.875%	1.25%
Common Equity Tier One, Capital Adequacy Plus Capital Conservation Buffer	$ 69,519	$ 58,994
Common Equity Tier One Capital Adequacy Plus Capital Conservation Buffer to Risk Weighted Assets	6.375%	5.75%
Tier 1 capital ratio	$ 149,488	$ 135,745
Tier One Risk Based Capital to Risk Weighted Assets	13.71%	13.23%
Tier One Risk Based Capital Required for Capital Adequacy	$ 65,429	$ 61,559
Tier One Risk Based Capital Required for Capital Adequacy to Risk Weighted Assets	6.00%	6.00%
Applicable capital conservation buffer, Tier 1 capital ratio	1.875%	1.25%
Tier One Risk Based Capital Required to be Well Capitalized, Capital Adequacy Plus Capital Conservation Buffer	$ 85,876	$ 74,384
Tier One Risk Based Capital Capital Adequacy Plus Capital Conservation Buffer to Risk Weighted Assets	7.875%	7.25%
Capital	$ 172,475	$ 158,365
Capital to Risk Weighted Assets	15.82%	15.44%
Capital Required for Capital Adequacy	$ 87,239	$ 82,079
Capital Required for Capital Adequacy to Risk Weighted Assets	8.00%	8.00%
Applicable capital conservation buffer, Total capital ratio	1.875%	1.25%
Capital Required to be Well Capitalized, Capital Adequacy Plus Capital Conservation Buffer	$ 107,686	$ 94,903
Capital Adequacy Plus Capital Conservation Buffer to Risk Weighted Assets	9.875%	9.25%
Tier One Leverage Capital	$ 149,488	$ 135,745
Tier One Leverage Capital to Average Assets	11.21%	10.86%
Tier One Leverage Capital Required for Capital Adequacy	$ 53,079	$ 50,008
Tier One Leverage Capital Required for Capital Adequacy to Average Assets	4.00%	4.00%
Tier One Leverage, Capital Adequacy Plus Capital Conservation Buffer	$ 53,079	$ 50,008
Tier One Leverage, Capital Adequacy Plus Capital Conservative Buffer to Risk Weighted Assets	4.00%	4.00%
Commercial Banking [Member]
Common Equity Tier One Risk Based Capital	$ 144,245	$ 129,139
Common Equity Tier One Risk Based Capital to Risk Weighted Assets	13.23%	12.58%
Common Equity Tier One Risk Based Capital Required for Capital Adequacy	$ 49,054	$ 46,179
Common Equity Tier One Risk Based Capital Capital Required for Capital Adequacy to Risk Weighted Assets	4.50%	4.50%
Applicable capital conservation buffer, common equity tier 1 capital	1.875%	1.25%
Common Equity Tier One, Capital Adequacy Plus Capital Conservation Buffer	$ 69,493	$ 59,006
Common Equity Tier One Capital Adequacy Plus Capital Conservation Buffer to Risk Weighted Assets	6.375%	5.75%
Tier 1 capital ratio	$ 144,245	$ 129,139
Tier One Risk Based Capital to Risk Weighted Assets	13.23%	12.58%
Tier One Risk Based Capital Required for Capital Adequacy	$ 65,405	$ 61,572
Tier One Risk Based Capital Required for Capital Adequacy to Risk Weighted Assets	6.00%	6.00%
Applicable capital conservation buffer, Tier 1 capital ratio	1.875%	1.25%
Tier One Risk Based Capital Required to be Well Capitalized, Capital Adequacy Plus Capital Conservation Buffer	$ 85,844	$ 74,399
Tier One Risk Based Capital Capital Adequacy Plus Capital Conservation Buffer to Risk Weighted Assets	7.875%	7.25%
Capital	$ 157,232	$ 141,760
Capital to Risk Weighted Assets	14.42%	13.81%
Capital Required for Capital Adequacy	$ 87,207	$ 82,096
Capital Required for Capital Adequacy to Risk Weighted Assets	8.00%	8.00%
Applicable capital conservation buffer, Total capital ratio	1.875%	1.25%
Capital Required to be Well Capitalized, Capital Adequacy Plus Capital Conservation Buffer	$ 107,646	$ 94,923
Capital Adequacy Plus Capital Conservation Buffer to Risk Weighted Assets	9.875%	9.25%
Tier One Leverage Capital	$ 144,245	$ 129,139
Tier One Leverage Capital to Average Assets	10.81%	10.33%
Tier One Leverage Capital Required for Capital Adequacy	$ 53,369	$ 49,989
Tier One Leverage Capital Required for Capital Adequacy to Average Assets	4.00%	4.00%
Tier One Leverage, Capital Adequacy Plus Capital Conservation Buffer	$ 53,369	$ 49,989
Tier One Leverage, Capital Adequacy Plus Capital Conservative Buffer to Risk Weighted Assets	4.00%	4.00%
Common Equity Tier One Risk Based Capital Required to Be Well Capitalized	$ 70,856	$ 66,703
Common Equity Tier One Risk Based Capital Required to Be Well Capitalized to Risk Weighted Assets	6.50%	6.50%
Tier One Risk Based Capital Required to be Well Capitalized	$ 87,207	$ 82,096
Tier One Risk Based Capital Required to be Well Capitalized to Risk Weighted Assets	8.00%	8.00%
Capital Required to be Well Capitalized	$ 109,009	$ 102,620
Capital Required to be Well Capitalized to Risk Weighted Assets	10.00%	10.00%
Tier One Leverage Capital Required to be Well Capitalized	$ 66,712	$ 62,486
Tier One Leverage Capital Required to be Well Capitalized to Average Assets	5.00%	5.00%

Capital adequacy plus capital conservation buffer as defined in the regulations.

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Capital, capital adequacy plus capital conservation buffer, ratio as defined in the regulations.

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An additional amount held in risk-based capital designed to ensure that banks build up capital buffers outside periods of stress which can be drawn down as losses are incurred. The requirement is based on simple capital conservation rules designed to avoid breaches of minimum capital requirements applicable to common equity tier one capital.

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Common equity tier one risk based capital, capital adequacy plus capital conservation buffer as defined in the regulations.

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Common equity tier one risk based capital, capital adequacy plus capital conservation buffer ratio as defined in the regulations.

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The minimum Common Equity Tier One Capital Ratio (Tier one capital divided by risk-weighted assets) required for capital adequacy purposes under the regulatory framework for prompt corrective action.

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The Common Equity Tier 1 capital ratio (Tier 1 capital divided by risk weighted assets) required to be categorized as "well capitalized" under the regulatory framework for prompt corrective action.

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Tier one leverage, capital adequacy plus capital conservation buffer as defined in the regulations.

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Tier one leverage, capital adequacy plus capital conservation buffer ratio as defined in the regulations.

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Tier one risk based capital, capital adequacy plus capital conservation buffer as defined in the regulations.

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Tier one risk based capital, capital adequacy plus capital conservation buffer ratio as defined in the regulations.

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The amount of total capital as defined in the regulations.

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The minimum amount of Total Capital required for capital adequacy purposes under the regulatory framework for prompt corrective action.

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The minimum Total risk based capital ratio (total capital divided by risk weighted assets) required for capital adequacy purposes under the regulatory framework for prompt corrective action.

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The amount of Total Capital required to be categorized as well as capitalized under the regulatory framework for prompt corrective action.

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The Total risk based capital ratio (total capital divided by risk weighted assets) required to be categorized as "well capitalized", in the regulatory framework for prompt corrective action.

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Total Capital divided by risk weighted assets as defined in the regulations.

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Amount of Common Equity Tier One Risk-based Capital, as defined by regulatory framework.

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Percentage of Common Equity Tier One Risk-based Capital to total risk-weighted assets, as defined by regulatory framework.

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Amount of Common Equity Tier 1 Risk-based Capital required to be categorized as adequately capitalized under regulatory framework for prompt corrective action.

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Amount of Common Equity Tier 1 Risk-based Capital required to be categorized as well-capitalized under regulatory framework for prompt corrective action.

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Tier 1 Leverage Capital as defined in the regulations. Also called Core Capital.

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The minimum amount of Tier 1 Leverage Capital required for capital adequacy purposes under the regulatory framework for prompt corrective action.

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The minimum amount of Tier 1 Leverage Capital for capital adequacy purposes divided by average assets as defined in the regulations.

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The amount of Tier 1 Leverage Capital required to be categorized as well capitalized under the regulatory framework for prompt corrective action.

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The amount of Tier 1 Leverage Capital required to be categorized as well capitalized divided by average assets as defined in the regulatory framework for prompt corrective action.

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Tier 1 Leverage Capital divided by average assets as defined in the regulations.

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Tier 1 Risk Based Capital as defined in the regulations.

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The minimum amount of Tier 1 Risk Based Capital required for capital adequacy purposes under the regulatory framework for prompt corrective action.

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The amount of Tier 1 Risk Based Capital required to be categorized as well capitalized under the regulatory framework for prompt corrective action.

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Tier 1 capital divided by risk weighted assets as defined by regulations.

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