Note 2 - Sales/Mergers/Acquisitions - Purchased Loans As of the Acquisition Date (Details) - USD ($)	Jul. 01, 2018	Oct. 01, 2017
Guaranty Bank and Trust Company [Member]
Contractually required principal payments		$ 196,109
Nonaccretable discount		(1,147)
Principal cash flows expected to be collected		194,962
Accretable discount		(2,444)
Fair Value of acquired loans		192,518
Guaranty Bank and Trust Company [Member] \| Performing Loans
Contractually required principal payments		192,983
Principal cash flows expected to be collected		192,983
Accretable discount		(2,224)
Fair Value of acquired loans		190,759
Springfield Bancshares
Contractually required principal payments	$ 486,993
Nonaccretable discount	(1,563)
Principal cash flows expected to be collected	485,430
Accretable discount	(8,093)
Fair Value of acquired loans	477,337
Springfield Bancshares \| Performing Loans
Contractually required principal payments	479,440
Principal cash flows expected to be collected	479,440
Accretable discount	(7,800)
Fair Value of acquired loans	471,640
PCI Loans \| Guaranty Bank and Trust Company [Member]
Contractually required principal payments		3,126
Nonaccretable discount		(1,147)
Principal cash flows expected to be collected		1,979
Accretable discount		(220)
Fair Value of acquired loans		$ 1,759
PCI Loans \| Springfield Bancshares
Contractually required principal payments	7,553
Nonaccretable discount	(1,563)
Principal cash flows expected to be collected	5,990
Accretable discount	(293)
Fair Value of acquired loans	$ 5,697

Fair value at acquisition of acquired loans accounted for as debt securities with evidence of deterioration of credit quality.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 30
-Section 50
-Paragraph 2
-Subparagraph (a)(3)
-URI http://asc.fasb.org/extlink&oid=118939070&loc=d3e15032-111544

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 30
-Section 15
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=118938799&loc=d3e13503-111538

+ Details

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

- Definition

Amount of cash flows expected to be collected at acquisition of acquired loans accounted for as debt securities with evidence of deterioration of credit quality.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 30
-Section 15
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=118938799&loc=d3e13503-111538

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 30
-Section 50
-Paragraph 2
-Subparagraph (a)(3)
-URI http://asc.fasb.org/extlink&oid=118939070&loc=d3e15032-111544

+ Details

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

- Definition

Amount of contractually required payments receivable at acquisition of acquired loans accounted for as debt securities with evidence of deterioration of credit quality.

+ References

+ Details

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

- Definition

The aggregate excess of a loan's cash flows expected to be collected over the investor's initial investment in the loan. This relates to loans with deteriorating of credit quality since origination that were acquired by completion of a transfer for which it is probable, at acquisition, that the investor will be unable to collect all contractually required payments receivable.

+ References

No definition available.

+ Details

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

- Definition

The amount of the loan's contractually required payments receivable in excess of the amount of its cash flows expected to be collected. This relates to loans with deteriorating of credit quality since origination that were acquired by completion of a transfer for which it is probable, at acquisition, that the investor will be unable to collect all contractually required payments receivable.

+ References

No definition available.

+ Details

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

- Details

Name:	us-gaap_BusinessAcquisitionAxis=qcrh_GuarantyBankAndTrustCompanyMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancialInstrumentPerformanceStatusAxis=us-gaap_PerformingFinancingReceivableMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_BusinessAcquisitionAxis=qcrh_SpringfieldBancsharesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_CreditLossStatusAxis=us-gaap_FinancialAssetAcquiredWithCreditDeteriorationMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: