The aggregate depreciation from amortized cost basis as a percent.

No definition available.

Name:	qcrh_AggregateDepreciationFromAmortizedCostBasisPercent
Namespace Prefix:	qcrh_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Number of issuers of debt securities.

+ References

No definition available.

+ Details

Name:	qcrh_NumberOfIssuers
Namespace Prefix:	qcrh_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- Definition

Number of securities.

+ References

No definition available.

+ Details

Name:	qcrh_NumberOfSecurities
Namespace Prefix:	qcrh_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- Definition

Represents the number of states investments are held in.

+ References

No definition available.

+ Details

Name:	qcrh_NumberOfStatesInvestmentsHeldIn
Namespace Prefix:	qcrh_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- Definition

Percentage threshhold of stockholders' equity which general obligation or revenue bonds market value of any single issuer does not exceed.

+ References

No definition available.

+ Details

Name:	qcrh_ThreshholdForBondsHeldBySingleIssuerMarketValueAsPercentageOfStockholdersEquity
Namespace Prefix:	qcrh_
Data Type:	xbrli:pureItemType
Balance Type:	na
Period Type:	instant

- Definition

Number of investment positions in available-for-sale investments in a continuous unrealized loss position for which an other-than-temporary impairment (OTTI) has not been recognized in the income statement.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 6
-Subparagraph (b)(3)
-URI http://asc.fasb.org/extlink&oid=82897076&loc=d3e27290-111563

+ Details

Name:	us-gaap_AvailableforsaleSecuritiesInUnrealizedLossPositionsQualitativeDisclosureNumberOfPositions1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- Definition

Number of investment positions in available-for-sale investments that have been in a continuous unrealized loss position for greater than or equal to a year for which an other-than-temporary impairment (OTTI) has not been recognized in the income statement.

+ References

No definition available.

+ Details

Name:	us-gaap_AvailableforsaleSecuritiesInUnrealizedLossPositionsQualitativeDisclosureNumberOfPositionsGreaterThanOrEqualToOneYear
Namespace Prefix:	us-gaap_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- Definition

For an entity that discloses a concentration risk in relation to quantitative amount, which serves as the "benchmark" (or denominator) in the equation, this concept represents the concentration percentage derived from the division.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 275
-SubTopic 10
-Section 50
-Paragraph 18
-URI http://asc.fasb.org/extlink&oid=99393423&loc=d3e6351-108592

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 50
-Paragraph 20
-URI http://asc.fasb.org/extlink&oid=109250915&loc=d3e13531-108611

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 50
-Paragraph 21
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=109250915&loc=d3e13537-108611

Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 275
-SubTopic 10
-Section 50
-Paragraph 20
-URI http://asc.fasb.org/extlink&oid=99393423&loc=d3e6404-108592

+ Details

Name:	us-gaap_ConcentrationRiskPercentage1
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

The amount by which the fair value of an investment is less than the amortized cost basis or carrying amount of that investment at the balance sheet date and the decline in fair value is deemed to be other than temporary, before considering whether or not such amount is recognized in earnings or other comprehensive income.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 45
-Paragraph 8A
-URI http://asc.fasb.org/extlink&oid=109979856&loc=SL6284422-111562

+ Details

Name:	us-gaap_ImpairmentOfInvestments
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- 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
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=99377789&loc=d3e19207-110258

+ Details

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

- Details

Name:	invest_InvestmentAxis=qcrh_GeneralObligationBondsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_ConcentrationRiskByBenchmarkAxis=us-gaap_StockholdersEquityTotalMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_ConcentrationRiskByTypeAxis=us-gaap_CreditConcentrationRiskMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	invest_InvestmentAxis=qcrh_RevenueBondsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_InvestmentTypeAxis=us-gaap_MunicipalBondsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_RangeAxis=srt_MinimumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_StatementScenarioAxis=qcrh_AggregateFairValueExceeding5MillionMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Note 3 - Investment Securities (Details) $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
Note 3 - Investment Securities (Details) $ in Thousands	Sep. 30, 2018 USD ($) state item	Sep. 30, 2017 USD ($)	Sep. 30, 2018 USD ($) state item	Sep. 30, 2017 USD ($)	Dec. 31, 2017 USD ($) state item
Number of securities \| item	613		613
Available-for-sale, unrealized loss positions, qualitative disclosure, number of positions \| item	434		434
Aggregate losses of securities (as a percent)	3.20%		3.20%
Available-for-sale, unrealized loss positions, qualitative disclosure, number of positions, greater than or equal to one year \| item	171		171
Other than temporary impairment losses, investments	$ 0	$ 0	$ 0	$ 0
Percentage threshhold	5		5
General Obligation Bonds \| Stockholders' Equity, Total [Member] \| Credit Concentration Risk [Member]
Concentration risk percentage (as a percent)			0.00%		0.00%
Revenue Bonds \| Stockholders' Equity, Total [Member] \| Credit Concentration Risk [Member]
Concentration risk percentage (as a percent)			0.00%		0.00%
Municipal Bonds \| General Obligation Bonds
Number of issuers \| item	113		113		131
Other investments	$ 86,200		$ 86,200		$ 108,000
Number of states holding investments \| state	27		27		26
Municipal Bonds \| General Obligation Bonds \| Minimum
Other investments	$ 5,000		$ 5,000		$ 5,000
Municipal Bonds \| General Obligation Bonds \| Aggregate Fair Value Exceeding 5 Million [Member]
Number of states holding investments \| state	6		6		9
Municipal Bonds \| Revenue Bonds
Number of issuers \| item	163		163		145
Other investments	$ 360,200		$ 360,200		$ 337,300
Number of states holding investments	19		19		16
Municipal Bonds \| Revenue Bonds \| Minimum
Other investments					$ 5,000
Municipal Bonds \| Revenue Bonds \| Aggregate Fair Value Exceeding 5 Million [Member]
Other investments	$ 5,000		$ 5,000
Number of states holding investments	7		7		7