| Cover | Jul. 26, 2021 |
| Cover [Abstract] | |
| Document Type | 8-K |
| Amendment Flag | false |
| Document Period End Date | Jul. 26, 2021 |
| Entity File Number | 0-22208 |
| Entity Registrant Name | QCR Holdings, Inc. |
| Entity Central Index Key | 0000906465 |
| Entity Tax Identification Number | 42-1397595 |
| Entity Incorporation, State or Country Code | DE |
| Entity Address, Address Line One | 3551 Seventh Street |
| Entity Address, City or Town | Moline |
| Entity Address, State or Province | IL |
| Entity Address, Postal Zip Code | 61265 |
| City Area Code | 309 |
| Local Phone Number | 736-3584 |
| Written Communications | false |
| Soliciting Material | false |
| Pre-commencement Tender Offer | false |
| Pre-commencement Issuer Tender Offer | false |
| Title of 12(b) Security | Common Stock, $1.00 Par Value |
| Trading Symbol | QCRH |
| Security Exchange Name | NASDAQ |
| Entity Emerging Growth Company | false |
