Note 2 - INVESTMENT SECURITIES (Details)	3 Months Ended
Mar. 31, 2021 USD ($) item state issuer	Mar. 31, 2020 USD ($)	Dec. 31, 2020 USD ($) state item issuer
Number of securities \| item	644
Available-for-sale, unrealized loss positions, qualitative disclosure, number of positions \| item	101
Aggregate losses of securities (as a percent)	0.40%
Available-for-sale, unrealized loss positions, qualitative disclosure, number of positions, greater than or equal to one year	8
Sale of securities	$ 19,500,000	$ 0
Gain on sale	$ 0
Number Of Charters Owning Municipal Securities \| item	4
Revenue Bonds
Number of issuers \| issuer	2		2
Percentage threshold	5.00%		5.00%
Municipal securities \| General Obligation Bonds
Number of issuers \| item	117		117
Other investments	$ 117,600,000		$ 116,700,000
Number of states holding investments \| state	21		21
Municipal securities \| General Obligation Bonds \| Minimum
Other investments	$ 5,000,000.0		$ 5,000,000.0
Municipal securities \| General Obligation Bonds \| Aggregate Fair Value Exceeding 5 Million [Member]
Number of states holding investments \| state	8		8
Municipal securities \| Revenue Bonds
Number of issuers \| item	192		191
Other investments	$ 535,300,000		$ 555,900,000
Number of states holding investments	26		26
Municipal securities \| Revenue Bonds \| Minimum
Other investments	$ 5,000,000.0		$ 5,000,000.0
Municipal securities \| Revenue Bonds \| Aggregate Fair Value Exceeding 5 Million [Member]
Number of states holding investments	13		12

The aggregate depreciation from amortized cost basis as a percent.

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- Definition

The number of the company's that own the company's municipal securities.

+ References

No definition available.

+ Details

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- Definition

Number of issuers of debt securities.

+ References

No definition available.

+ Details

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Namespace Prefix:	qcrh_
Data Type:	xbrli:integerItemType
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- Definition

Number of securities.

+ References

No definition available.

+ Details

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- Definition

Represents the number of states investments are held in.

+ References

No definition available.

+ Details

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- Definition

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

+ References

No definition available.

+ Details

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- Definition

Number of investments in debt securities measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in continuous unrealized loss position for 12 months or longer, without an allowance for credit loss. Includes beneficial interest in securitized financial asset.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 30
-Section 50
-Paragraph 4
-Subparagraph (b)(3)
-URI http://asc.fasb.org/extlink&oid=121582814&loc=SL82922888-210455

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- Definition

Number of investments in debt securities measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in unrealized loss position, without allowance for credit loss. Includes beneficial interest in securitized financial asset.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 6
-Subparagraph (b)(3)
-URI http://asc.fasb.org/extlink&oid=121645371&loc=d3e27290-111563

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 30
-Section 50
-Paragraph 4
-Subparagraph (b)(3)
-URI http://asc.fasb.org/extlink&oid=121582814&loc=SL82922888-210455

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- Definition

The difference between the carrying value and the sale price of an investment. A gain would be recognized when the sale price of the investment is greater than the carrying value of the investment. This element refers to the Gain included in earnings and not to the cash proceeds of the sale.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 220
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-04(3)(a))
-URI http://asc.fasb.org/extlink&oid=120400993&loc=SL114874131-224263

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=121586364&loc=d3e3602-108585

Reference 3: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 220
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-04(13))
-URI http://asc.fasb.org/extlink&oid=120399700&loc=SL114874048-224260

Reference 4: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03(b)(9)(a))
-URI http://asc.fasb.org/extlink&oid=120395209&loc=SL114868664-224227

Reference 5: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03(b)(7)(c))
-URI http://asc.fasb.org/extlink&oid=120395209&loc=SL114868664-224227

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
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=117815213&loc=d3e19207-110258

+ Details

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Balance Type:	debit
Period Type:	instant

- Definition

The cash inflow associated with the aggregate amount received by the entity through sale or maturity of marketable securities (held-to-maturity or available-for-sale) during the period.

+ References

No definition available.

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
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- Details

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- Details

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