Document And Entity Information - shares	6 Months Ended
	Jun. 30, 2018	Aug. 01, 2018
Document And Entity Information [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Jun. 30, 2018
Document Fiscal Year Focus	2018
Document Fiscal Period Focus	Q2
Entity Registrant Name	CARRIZO OIL & GAS INC
Entity Central Index Key	0001040593
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding		82,114,492