NOTE 4 - DERIVATIVES AND HEDGING ACTIVITIES - Summary of Interest Rate Swaps Derivatives (Details) - Designated as Hedging Instrument [Member] - Cash Flow Hedging [Member] - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2020	Dec. 31, 2019
Derivative Instrument One Maturing 2023 [Member] | London Interbank Offered Rate (LIBOR)
Derivative, Basis Spread on Variable Rate	1.75%
Derivative Instrument Two Maturing 2023 [Member] | London Interbank Offered Rate (LIBOR)
Derivative, Basis Spread on Variable Rate	1.57%
Derivative Instrument Three Maturing 2023 [Member] | London Interbank Offered Rate (LIBOR)
Derivative, Basis Spread on Variable Rate	1.90%
Derivative Instrument Four Maturing 2023 [Member] | London Interbank Offered Rate (LIBOR)
Derivative, Basis Spread on Variable Rate	1.80%
Derivative Instrument One Maturing 2024 [Member] | London Interbank Offered Rate (LIBOR)
Derivative, Basis Spread on Variable Rate	1.75%
Derivative Instrument Two Maturing 2024 [Member] | London Interbank Offered Rate (LIBOR)
Derivative, Basis Spread on Variable Rate	1.57%
Derivative Instrument Three Maturing 2024 [Member] | London Interbank Offered Rate (LIBOR)
Derivative, Basis Spread on Variable Rate	1.90%
Derivative Instrument Four Maturing 2024 [Member] | London Interbank Offered Rate (LIBOR)
Derivative, Basis Spread on Variable Rate	1.80%
Derivative Instrument One Maturing 2025 [Member] | London Interbank Offered Rate (LIBOR)
Derivative, Basis Spread on Variable Rate	1.75%
Derivative Instrument Two Maturing 2025 [Member] | London Interbank Offered Rate (LIBOR)
Derivative, Basis Spread on Variable Rate	1.57%
Derivative Instrument Three Maturing 2025 [Member] | London Interbank Offered Rate (LIBOR)
Derivative, Basis Spread on Variable Rate	1.90%
Derivative Instrument Four Maturing 2025 [Member] | London Interbank Offered Rate (LIBOR)
Derivative, Basis Spread on Variable Rate	1.80%
Interest rate swap
Receive Rate	1.34%
Pay Rate	5.24%
CRBT - FHLB Advances or Brokered CDs [Member]
Receive Rate	0.23%
Pay Rate	1.12%
SFCB - FHLB Advances or Brokered CDs [Member]
Receive Rate	0.24%
Pay Rate	0.95%
QCR Holdings Statutory Trust II
Receive Rate	3.07%
Pay Rate	5.85%
QCR Holdings Statutory Trust III
Receive Rate	3.07%
Pay Rate	5.85%
QCR Holdings Statutory Trust V
Receive Rate	1.83%
Pay Rate	4.54%
Community National Statutory Trust II
Receive Rate	2.40%
Pay Rate	5.17%
Community National Statutory Trust III
Receive Rate	2.00%
Pay Rate	4.75%
Guaranty Bankshares Statutory Trust I
Receive Rate	2.00%
Pay Rate	4.75%
Other Assets | Derivative Instrument One Maturing 2023 [Member]
Notional Amount	$ 25,000
Fair Value - Asset	6	$ 112
Other Assets | Derivative Instrument Two Maturing 2023 [Member]
Notional Amount	50,000
Fair Value - Asset	11	218
Other Assets | Derivative Instrument Three Maturing 2023 [Member]
Notional Amount	25,000
Fair Value - Asset	5	96
Other Assets | Derivative Instrument Four Maturing 2023 [Member]
Notional Amount	25,000
Fair Value - Asset	6	109
Other Assets | Derivative Instrument One Maturing 2024 [Member]
Notional Amount	25,000
Fair Value - Asset	17	214
Other Assets | Derivative Instrument Two Maturing 2024 [Member]
Notional Amount	50,000
Fair Value - Asset	35	401
Other Assets | Derivative Instrument Three Maturing 2024 [Member]
Notional Amount	25,000
Fair Value - Asset	17	202
Other Assets | Derivative Instrument Four Maturing 2024 [Member]
Notional Amount	25,000
Fair Value - Asset	17	201
Other Assets | Derivative Instrument One Maturing 2025 [Member]
Notional Amount	25,000
Fair Value - Asset	37	337
Other Assets | Derivative Instrument Two Maturing 2025 [Member]
Notional Amount	50,000
Fair Value - Asset	75	617
Other Assets | Derivative Instrument Three Maturing 2025 [Member]
Notional Amount	25,000
Fair Value - Asset	40	332
Other Assets | Derivative Instrument Four Maturing 2025 [Member]
Notional Amount	25,000
Fair Value - Asset	38	309
Other Assets | Interest rate swap
Notional Amount	375,000
Fair Value - Asset	304	3,148
Derivative Liabilities | Interest rate swap
Notional Amount	79,000
Fair Value - Liability	(8,433)	(3,758)
Derivative Liabilities | CRBT - FHLB Advances or Brokered CDs [Member]
Notional Amount	30,000
Fair Value - Liability	(660)
Derivative Liabilities | SFCB - FHLB Advances or Brokered CDs [Member]
Notional Amount	10,000
Fair Value - Liability	(181)
Derivative Liabilities | QCR Holdings Statutory Trust II
Notional Amount	10,000
Fair Value - Liability	(1,963)	(971)
Derivative Liabilities | QCR Holdings Statutory Trust III
Notional Amount	8,000
Fair Value - Liability	(1,570)	(777)
Derivative Liabilities | QCR Holdings Statutory Trust V
Notional Amount	10,000
Fair Value - Liability	(1,909)	(944)
Derivative Liabilities | Community National Statutory Trust II
Notional Amount	3,000
Fair Value - Liability	(587)	(291)
Derivative Liabilities | Community National Statutory Trust III
Notional Amount	3,500
Fair Value - Liability	(684)	(339)
Derivative Liabilities | Guaranty Bankshares Statutory Trust I
Notional Amount	4,500
Fair Value - Liability	$ (879)	$ (436)