Note 12 - Junior Subordinated Debentures - Junior Subordinated Debentures (Details) - USD ($)	Dec. 31, 2018	Dec. 31, 2017
Junior subordinated debentures	$ 37,670,043	$ 37,486,487
Junior subordinated debentures	(2,539,957)	(2,723,513)
Note Payable to QCR Holdings Capital Trust II [Member]
Junior subordinated debentures	10,310,000	10,310,000
Note Payable to Trust III [Member]
Junior subordinated debentures	8,248,000	8,248,000
Note Payable to Trust V [Member]
Junior subordinated debentures	10,310,000	10,310,000
Community National Trust II [Member]
Junior subordinated debentures	3,093,000	3,093,000
Community National Trust III [Member]
Junior subordinated debentures	3,609,000	3,609,000
Note Payable to Guaranty Bankshares Statutory Trust I [Member]
Junior subordinated debentures	$ 4,640,000	$ 4,640,000