Document and Entity Information	3 Months Ended
	Mar. 31, 2015	May 01, 2015
Document Information [Line Items]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Mar. 31, 2015
Document Fiscal Year Focus	2015
Document Fiscal Period Focus	Q1
Trading Symbol	ZIOP
Entity Registrant Name	ZIOPHARM ONCOLOGY INC
Entity Central Index Key	0001107421
Current Fiscal Year End Date	--12-31
Entity Filer Category	Accelerated Filer
Entity Common Stock, Shares Outstanding		128,232,537