Note 11 - Capital Ratios and Regulatory Minimum Requirements (Details) $ in Thousands	Sep. 30, 2020 USD ($)	Dec. 31, 2019 USD ($)
The Company [Member]
Compliance With Regulatory Capital Requirements Under Banking Regulations [Line Items]
Capital	$ 136,502	$ 130,412
Tier 1 capital	125,652	120,452
Common equity tier 1 capital	125,652	120,452
Tier 1 leverage capital	$ 125,652	$ 120,452
Capital to risk-weighted assets	0.1423	0.1382
Tier 1 capital to risk-weighted assets	0.1310	0.1276
Common equity tier 1 capital to risk-weighted assets	13.10%	12.76%
Tier 1 leverage capital to average assets	0.0890	0.0978
Capital required for capital adequacy	$ 76,745	$ 75,498
Tier 1 capital required for capital adequacy	57,558	56,624
Common equity tier 1 capital required for capital adequacy	43,169	42,468
Tier 1 leverage capital required for capital adequacy	$ 56,459	$ 49,283
Capital required for capital adequacy to risk-weighted assets	0.0800	0.0800
Tier 1 capital required for capital adequacy to risk-weighted assets	0.0600	0.0600
Common equity tier 1 capital required for capital adequacy to risk-weighted assets	4.50%	4.50%
Tier 1 leverage capital required for capital adequacy to average assets	0.0400	0.0400
Capital required to be well capitalized	$ 95,931	$ 94,373
Tier 1 capital required to be well capitalized	$ 57,558	$ 56,624
Capital required to be well capitalized to risk-weighted assets	0.1000	0.1000
Tier 1 capital required to be well capitalized to risk-weighted assets	0.0600	0.0600
Bank [Member]
Compliance With Regulatory Capital Requirements Under Banking Regulations [Line Items]
Capital	$ 124,749	$ 118,389
Tier 1 capital	113,899	108,429
Common equity tier 1 capital	113,899	108,429
Tier 1 leverage capital	$ 113,899	$ 108,429
Capital to risk-weighted assets	0.1351	0.1293
Tier 1 capital to risk-weighted assets	0.1233	0.1184
Common equity tier 1 capital to risk-weighted assets	12.33%	11.84%
Tier 1 leverage capital to average assets	0.0814	0.0889
Capital required for capital adequacy	$ 73,892	$ 73,270
Tier 1 capital required for capital adequacy	55,419	54,952
Common equity tier 1 capital required for capital adequacy	41,564	41,241
Tier 1 leverage capital required for capital adequacy	$ 55,947	$ 48,804
Capital required for capital adequacy to risk-weighted assets	0.0800	0.0800
Tier 1 capital required for capital adequacy to risk-weighted assets	0.0600	0.0600
Common equity tier 1 capital required for capital adequacy to risk-weighted assets	4.50%	4.50%
Tier 1 leverage capital required for capital adequacy to average assets	0.0400	0.0400
Capital required to be well capitalized	$ 92,365	$ 91,587
Tier 1 capital required to be well capitalized	73,892	73,270
Common equity tier 1 capital required to be well capitalized	60,037	59,532
Tier 1 leverage capital required to be well capitalized	$ 69,933	$ 61,005
Capital required to be well capitalized to risk-weighted assets	0.1000	0.1000
Tier 1 capital required to be well capitalized to risk-weighted assets	0.0800	0.0800
Common equity tier 1 capital required to be well capitalized to risk-weighted assets	6.50%	6.50%
Tier 1 leverage capital required to be well capitalized to average assets	0.0500	0.0500

Common equity tier 1 capital as defined in the regulations.

No definition available.

Name:	qnbc_CommonEquityTier1Capital
Namespace Prefix:	qnbc_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Common equity tier 1 capital to risk-weighted assets as defined in regulations.

+ References

No definition available.

+ Details

Name:	qnbc_CommonEquityTier1CapitalToRiskWeightedAssets
Namespace Prefix:	qnbc_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

The minimum amount of common equity tier 1 capital required for capital adequacy purposes under the regulatory framework for prompt corrective action.

+ References

No definition available.

+ Details

Name:	qnbc_CommonEquityTier1CapitalToRiskWeightedAssetsAdequatelyCapitalizedAmount
Namespace Prefix:	qnbc_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The minimum common equity tier 1 capital (common equity divided by risk weighted assets) required for capital adequacy purposes under the regulatory framework for prompt corrective action.

+ References

No definition available.

+ Details

Name:	qnbc_CommonEquityTier1CapitalToRiskWeightedAssetsAdequatelyCapitalizedRatio
Namespace Prefix:	qnbc_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

The amount of common equity tier 1 capital required to be categorized as well capitalized under the regulatory framework for prompt corrective action.

+ References

No definition available.

+ Details

Name:	qnbc_CommonEquityTier1CapitalToRiskWeightedAssetsWellCapitalizedAmount
Namespace Prefix:	qnbc_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

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

+ References

No definition available.

+ Details

Name:	qnbc_CommonEquityTier1CapitalToRiskWeightedAssetsWellCapitalizedRatio
Namespace Prefix:	qnbc_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Amount of total capital as defined by regulatory framework.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 948
-SubTopic 10
-Section 50
-Paragraph 5
-URI http://asc.fasb.org/extlink&oid=6490092&loc=d3e47304-110998

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 http://asc.fasb.org/extlink&oid=117337116&loc=SL5958568-112826

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 948
-SubTopic 10
-Section 50
-Paragraph 3
-Subparagraph (c)(1)
-URI http://asc.fasb.org/extlink&oid=6490092&loc=d3e47080-110998

+ Details

Name:	us-gaap_Capital
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of minimum total risk-based capital 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 1
-Subparagraph (c)(1)
-URI http://asc.fasb.org/extlink&oid=117337116&loc=SL5958568-112826

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 505
-Section 50
-Paragraph 1B
-URI http://asc.fasb.org/extlink&oid=117337116&loc=SL5958570-112826

+ Details

Name:	us-gaap_CapitalRequiredForCapitalAdequacy
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- 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 http://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 http://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

- Definition

Amount of minimum total risk-based capital categorized as well capitalized as defined by regulatory framework for prompt corrective action.

+ References

+ Details

Name:	us-gaap_CapitalRequiredToBeWellCapitalized
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- 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

+ Details

Name:	us-gaap_CapitalRequiredToBeWellCapitalizedToRiskWeightedAssets
Namespace Prefix:	us-gaap_
Data Type:	xbrli:pureItemType
Balance Type:	na
Period Type:	instant

- Definition

Ratio of total risk-based capital to risk-weighted assets as defined by regulatory framework.

+ References

+ Details

Name:	us-gaap_CapitalToRiskWeightedAssets
Namespace Prefix:	us-gaap_
Data Type:	xbrli:pureItemType
Balance Type:	na
Period Type:	instant

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

Name:	us-gaap_ComplianceWithRegulatoryCapitalRequirementsUnderBankingRegulationsLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of Tier 1 leverage capital as defined by regulatory framework.

+ References

+ Details

Name:	us-gaap_TierOneLeverageCapital
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of minimum Tier 1 leverage capital required for capital adequacy as defined by regulatory framework.

+ References

+ Details

Name:	us-gaap_TierOneLeverageCapitalRequiredForCapitalAdequacy
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Ratio of minimum Tier 1 leverage capital to average assets required for capital adequacy as defined by regulatory framework.

+ References

+ Details

Name:	us-gaap_TierOneLeverageCapitalRequiredForCapitalAdequacyToAverageAssets
Namespace Prefix:	us-gaap_
Data Type:	xbrli:pureItemType
Balance Type:	na
Period Type:	instant

- Definition

Amount of minimum Tier 1 leverage capital categorized as well capitalized as defined by regulatory framework for prompt corrective action.

+ References

+ Details

Name:	us-gaap_TierOneLeverageCapitalRequiredToBeWellCapitalized
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- 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

+ Details

Name:	us-gaap_TierOneLeverageCapitalRequiredToBeWellCapitalizedToAverageAssets
Namespace Prefix:	us-gaap_
Data Type:	xbrli:pureItemType
Balance Type:	na
Period Type:	instant

- Definition

Ratio of Tier 1 capital to average assets as defined by regulatory framework.

+ References

+ Details

Name:	us-gaap_TierOneLeverageCapitalToAverageAssets
Namespace Prefix:	us-gaap_
Data Type:	xbrli:pureItemType
Balance Type:	na
Period Type:	instant

- Definition

Amount of Tier 1 risk-based capital as defined by regulatory framework.

+ References

+ Details

Name:	us-gaap_TierOneRiskBasedCapital
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of minimum Tier 1 risk-based capital required for capital adequacy as defined by regulatory framework.

+ References

+ Details

Name:	us-gaap_TierOneRiskBasedCapitalRequiredForCapitalAdequacy
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Ratio of minimum Tier 1 risk-based capital to risk-weighted assets required for capital adequacy as defined by regulatory framework.

+ References

+ Details

Name:	us-gaap_TierOneRiskBasedCapitalRequiredForCapitalAdequacyToRiskWeightedAssets
Namespace Prefix:	us-gaap_
Data Type:	xbrli:pureItemType
Balance Type:	na
Period Type:	instant

- Definition

Amount of minimum Tier 1 risk-based capital categorized as well capitalized as defined by regulatory framework for prompt corrective action.

+ References

+ Details

Name:	us-gaap_TierOneRiskBasedCapitalRequiredToBeWellCapitalized
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- 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

+ Details

Name:	us-gaap_TierOneRiskBasedCapitalRequiredToBeWellCapitalizedToRiskWeightedAssets
Namespace Prefix:	us-gaap_
Data Type:	xbrli:pureItemType
Balance Type:	na
Period Type:	instant

- Definition

Ratio of Tier 1 risk-based capital to risk-weighted assets as defined by regulatory framework.

+ References

+ Details

Name:	us-gaap_TierOneRiskBasedCapitalToRiskWeightedAssets
Namespace Prefix:	us-gaap_
Data Type:	xbrli:pureItemType
Balance Type:	na
Period Type:	instant

- Details

Name:	srt_ConsolidatedEntitiesAxis=us-gaap_ConsolidatedEntitiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_ConsolidatedEntitiesAxis=qnbc_BankMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: