Document and Entity Information - USD ($)	12 Months Ended
	Dec. 31, 2018	Feb. 28, 2019	Jun. 30, 2018
Document and Entity Information [Abstract]
Entity Registrant Name	QCR HOLDINGS INC
Entity Central Index Key	0000906465
Document Type	10-K
Document Period End Date	Dec. 31, 2018
Amendment Flag	false
Current Fiscal Year End Date	--12-31
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Filer Category	Accelerated Filer
Entity Small Business	false
Entity Shell Company	false
Entity Emerging Growth Company	false
Entity Public Float			$ 624,586,534
Entity Common Stock, Shares Outstanding (in shares)		15,738,761
Document Fiscal Year Focus	2018
Document Fiscal Period Focus	FY
Entity Well-known Seasoned Issuer	No