| Document and Entity Information | Nov. 04, 2019 |
| Cover [Abstract] | |
| Entity Registrant Name | CARRIZO OIL & GAS INC |
| Amendment Flag | false |
| Entity Central Index Key | 0001040593 |
| Document Type | 8-K |
| Document Period End Date | Nov. 4, 2019 |
| Entity Incorporation State Country Code | TX |
| Entity File Number | 000-29187-87 |
| Entity Tax Identification Number | 76-0415919 |
| Entity Address, Address Line One | 500 Dallas Street |
| Entity Address, Address Line Two | Suite 2300 |
| Entity Address, City or Town | Houston |
| Entity Address, State or Province | TX |
| Entity Address, Postal Zip Code | 77002 |
| City Area Code | (713) |
| Local Phone Number | 328-1000 |
| Written Communications | false |
| Soliciting Material | false |
| Pre Commencement Tender Offer | false |
| Pre Commencement Issuer Tender Offer | false |
| Security 12b Title | Common Stock, $0.01 par value |
| Trading Symbol | CRZO |
| Security Exchange Name | NASDAQ |
| Entity Emerging Growth Company | false |
