Note 4 - Borrowings (Details Textual) - USD ($)	3 Months Ended	6 Months Ended		12 Months Ended
	Mar. 31, 2016	Jun. 30, 2016	Jun. 30, 2015	Dec. 31, 2015
Junior Subordinated Debt [Member] | Note Payable to QCR Holdings Capital Trust IV [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%
Junior Subordinated Debt [Member] | London Interbank Offered Rate (LIBOR) [Member]
Debt Instrument, Basis Spread on Variable Rate	1.80%
London Interbank Offered Rate (LIBOR) [Member] | Revolving Credit Facility [Member]
Debt Instrument, Basis Spread on Variable Rate		2.50%		2.50%
Whole sale Repurchase Agreements [Member]
Repayments of Other Debt	$ 10,000,000
Wholesale Repurchase Agreement and FHLB Advances [Member]
Gain (Loss) on Extinguishment of Debt	$ (1,300,000)
Debt Instrument, Interest Rate, Stated Percentage	3.92%
Extinguished Debt Weighted Average Term	2 years 62 days
Long-term Debt, Maturities, Repayments of Principal, Remainder of Fiscal Year	$ 10,000,000
Long-term Debt, Maturities, Repayments of Principal in Year Two	10,000,000
Revolving Credit Facility [Member]
Debt Instrument, Interest Rate, Effective Percentage		3.13%		3.10%
Line of Credit Facility, Maximum Borrowing Capacity		$ 10,000,000		$ 40,000,000
Long-term Line of Credit		0		$ 0
Repayments of Other Debt		10,759,000	$ 29,177,000
Repayments of Federal Home Loan Bank Borrowings	$ 10,000,000	10,524,197	$ 81,192,185
Short-term Debt, Weighted Average Interest Rate	0.50%
Notes Payable		$ 30,000,000
Debt Instrument, Term		5 years