Note 7 - Derivatives and Hedging Activities - Summary of Interest Rate Cap Derivatives (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2020	Dec. 31, 2019
Derivative Assets	$ 222,757	$ 87,827
Interest rate swap
Derivative Assets	222,431	84,679
Interest rate cap
Derivative Assets	67
Cash Flow Hedging \| Interest rate cap
Derivative Assets	259	3,148
Designated as Hedging Instrument \| Other Assets \| Cash Flow Hedging \| Derivative Instrument One Maturing 2023 [Member]
Notional Amount	25,000
Fair Value - Asset	$ 3	112
Designated as Hedging Instrument \| Other Assets \| Cash Flow Hedging \| Derivative Instrument One Maturing 2023 [Member] \| London Interbank Offered Rate (LIBOR)
Derivative, Basis Spread on Variable Rate	1.75%
Designated as Hedging Instrument \| Other Assets \| Cash Flow Hedging \| Derivative Instrument Two Maturing 2023 [Member]
Notional Amount	$ 50,000
Fair Value - Asset	$ 5	218
Designated as Hedging Instrument \| Other Assets \| Cash Flow Hedging \| Derivative Instrument Two Maturing 2023 [Member] \| London Interbank Offered Rate (LIBOR)
Derivative, Basis Spread on Variable Rate	1.57%
Designated as Hedging Instrument \| Other Assets \| Cash Flow Hedging \| Derivative Instrument Four Maturing 2023 [Member]
Notional Amount	$ 25,000
Fair Value - Asset	$ 3	109
Designated as Hedging Instrument \| Other Assets \| Cash Flow Hedging \| Derivative Instrument Four Maturing 2023 [Member] \| London Interbank Offered Rate (LIBOR)
Derivative, Basis Spread on Variable Rate	1.80%
Designated as Hedging Instrument \| Other Assets \| Cash Flow Hedging \| Derivative Instrument One Maturing 2024 [Member]
Notional Amount	$ 25,000
Fair Value - Asset	$ 15	214
Designated as Hedging Instrument \| Other Assets \| Cash Flow Hedging \| Derivative Instrument One Maturing 2024 [Member] \| London Interbank Offered Rate (LIBOR)
Derivative, Basis Spread on Variable Rate	1.75%
Designated as Hedging Instrument \| Other Assets \| Cash Flow Hedging \| Derivative Instrument Two Maturing 2024 [Member]
Notional Amount	$ 50,000
Fair Value - Asset	$ 31	401
Designated as Hedging Instrument \| Other Assets \| Cash Flow Hedging \| Derivative Instrument Two Maturing 2024 [Member] \| London Interbank Offered Rate (LIBOR)
Derivative, Basis Spread on Variable Rate	1.57%
Designated as Hedging Instrument \| Other Assets \| Cash Flow Hedging \| Derivative Instrument Four Maturing 2024 [Member]
Notional Amount	$ 25,000
Fair Value - Asset	$ 15	201
Designated as Hedging Instrument \| Other Assets \| Cash Flow Hedging \| Derivative Instrument Four Maturing 2024 [Member] \| London Interbank Offered Rate (LIBOR)
Derivative, Basis Spread on Variable Rate	1.80%
Designated as Hedging Instrument \| Other Assets \| Cash Flow Hedging \| Derivative Instrument One Maturing 2025 [Member]
Notional Amount	$ 25,000
Fair Value - Asset	$ 46	337
Designated as Hedging Instrument \| Other Assets \| Cash Flow Hedging \| Derivative Instrument One Maturing 2025 [Member] \| London Interbank Offered Rate (LIBOR)
Derivative, Basis Spread on Variable Rate	1.75%
Designated as Hedging Instrument \| Other Assets \| Cash Flow Hedging \| Derivative Instrument Two Maturing 2025 [Member]
Notional Amount	$ 50,000
Fair Value - Asset	$ 94	617
Designated as Hedging Instrument \| Other Assets \| Cash Flow Hedging \| Derivative Instrument Two Maturing 2025 [Member] \| London Interbank Offered Rate (LIBOR)
Derivative, Basis Spread on Variable Rate	1.57%
Designated as Hedging Instrument \| Other Assets \| Cash Flow Hedging \| Derivative Instrument Four Maturing 2025 [Member]
Notional Amount	$ 25,000
Fair Value - Asset	$ 47	309
Designated as Hedging Instrument \| Other Assets \| Cash Flow Hedging \| Derivative Instrument Four Maturing 2025 [Member] \| London Interbank Offered Rate (LIBOR)
Derivative, Basis Spread on Variable Rate	1.80%
Designated as Hedging Instrument \| Other Assets \| Cash Flow Hedging \| Interest rate cap
Notional Amount	$ 300,000
Fair Value - Asset	259	2,518
Designated as Hedging Instrument \| Other Liabilities. \| Cash Flow Hedging \| Interest rate swap
Notional Amount	39,000
Fair Value - Liability	$ (6,839)	(3,758)
Receive Rate	2.48%
Pay Rate	5.24%
Designated as Hedging Instrument \| Other Liabilities. \| Cash Flow Hedging \| QCR Holdings Statutory Trust II
Notional Amount	$ 10,000
Fair Value - Liability	$ (1,767)	(971)
Receive Rate	3.10%
Pay Rate	5.85%
Designated as Hedging Instrument \| Other Liabilities. \| Cash Flow Hedging \| QCR Holdings Statutory Trust III
Notional Amount	$ 8,000
Fair Value - Liability	$ (1,414)	(777)
Receive Rate	3.10%
Pay Rate	5.85%
Designated as Hedging Instrument \| Other Liabilities. \| Cash Flow Hedging \| QCR Holdings Statutory Trust V
Notional Amount	$ 10,000
Fair Value - Liability	$ (1,721)	(944)
Receive Rate	1.79%
Pay Rate	4.54%
Designated as Hedging Instrument \| Other Liabilities. \| Cash Flow Hedging \| Community National Statutory Trust II
Notional Amount	$ 3,000
Fair Value - Liability	$ (529)	(291)
Receive Rate	2.41%
Pay Rate	5.17%
Designated as Hedging Instrument \| Other Liabilities. \| Cash Flow Hedging \| Community National Statutory Trust III
Notional Amount	$ 3,500
Fair Value - Liability	$ (616)	(339)
Receive Rate	1.97%
Pay Rate	4.75%
Designated as Hedging Instrument \| Other Liabilities. \| Cash Flow Hedging \| Guaranty Bankshares Statutory Trust I
Notional Amount	$ 4,500
Fair Value - Liability	$ (792)	(436)
Receive Rate	1.97%
Pay Rate	4.75%
Not Designated as Hedging Instrument \| Interest rate swap
Derivative Assets	$ 222,431	84,679
Not Designated as Hedging Instrument \| Other Assets
Notional Amount	75,000
Derivative Assets	67	630
Not Designated as Hedging Instrument \| Other Assets \| Derivative Instrument One Maturing 2023 [Member]
Notional Amount	25,000
Derivative Assets	$ 2	96
Not Designated as Hedging Instrument \| Other Assets \| Derivative Instrument One Maturing 2023 [Member] \| London Interbank Offered Rate (LIBOR)
Derivative, Basis Spread on Variable Rate	1.90%
Not Designated as Hedging Instrument \| Other Assets \| Derivative Instrument One Maturing 2024 [Member]
Notional Amount	$ 25,000
Derivative Assets	$ 15	202
Not Designated as Hedging Instrument \| Other Assets \| Derivative Instrument One Maturing 2024 [Member] \| London Interbank Offered Rate (LIBOR)
Derivative, Basis Spread on Variable Rate	1.90%
Not Designated as Hedging Instrument \| Other Assets \| Derivative Instrument One Maturing 2025 [Member]
Notional Amount	$ 25,000
Derivative Assets	$ 50	$ 332
Not Designated as Hedging Instrument \| Other Assets \| Derivative Instrument One Maturing 2025 [Member] \| London Interbank Offered Rate (LIBOR)
Derivative, Basis Spread on Variable Rate	1.90%

Represents the pay rate of the derivative instrument.

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Represents the receive rate of the derivative instrument.

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No definition available.

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- Definition

Fair value, after the effects of master netting arrangements, of a financial asset or other contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes assets not subject to a master netting arrangement and not elected to be offset.

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- Definition

The percentage points added to the reference rate to compute the variable rate on the interest rate derivative.

+ References

No definition available.

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- Definition

Nominal or face amount used to calculate payment on derivative.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
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-Name Accounting Standards Codification
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- Definition

Fair value as of the balance sheet date of all interest rate derivative assets designated as cash flow hedging instruments.

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- Definition

Fair value as of the balance sheet date of all interest rate derivative liabilities designated as cash flow hedging instruments.

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