Note 12 - Junior Subordinated Debentures (Details Textual) - USD ($)		12 Months Ended
	Sep. 27, 2017	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Oct. 01, 2017	Feb. 29, 2004
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Noncurrent Liabilities, Long-term Debt		$ 3,857,275
Debt Instrument, Face Amount		40,210,000	35,570,000
Gain (Loss) on Extinguishment of Debt			$ (4,577,668)	(7,185,601)
Debt Instrument, Interest Rate, Effective Percentage		3.82%	3.26%
Junior Subordinated Debt [Member]
Debt Instrument, Term		30 years
Note Payable to QCR Holdings Capital Trust II [Member]
Debt Instrument, Face Amount						$ 12,372,000
Note Payable to QCR Holdings Capital Trust II [Member] | Junior Subordinated Debt [Member]
Extinguishment of Debt, Amount				2,100,000
Gain (Loss) on Extinguishment of Debt				$ 300,000
Debt Instrument, Interest Rate, Effective Percentage				3.18%
Note Payable to QCR Holdings Capital Trust IV [Member] | Junior Subordinated Debt [Member]
Extinguishment of Debt, Amount			$ 5,100,000
Gain (Loss) on Extinguishment of Debt			$ 1,200,000
Debt Instrument, Interest Rate, Effective Percentage			2.42%
Note Payable to QCR Holdings Capital Trust IV [Member] | Junior Subordinated Debt [Member] | London Interbank Offered Rate (LIBOR) [Member]
Debt Instrument, Basis Spread on Variable Rate			1.80%	2.85%
Guaranty Bank and Trust Company [Member]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Noncurrent Liabilities, Long-term Debt					$ 3,857,275
Debt Instrument, Face Amount	$ 7,000,000
Debt Instrument, Term	4 years