Document and Entity Information - USD ($)	12 Months Ended
	Dec. 31, 2019	May 08, 2020	Jun. 28, 2019
Document And Entity Information
Entity Registrant Name	MATEON THERAPEUTICS INC
Entity Central Index Key	0000908259
Document Type	10-K
Document Period End Date	Dec. 31, 2019
Amendment Flag	false
Current Fiscal Year End Date	--12-31
Entity Well-Known Seasoned Issuer	No
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Non-accelerated Filer
Entity Small Business Flag	true
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Public Float			$ 11,546,000
Entity Common Stock, Shares Outstanding		87,012,809
Document Fiscal Period Focus	FY
Document Fiscal Year Focus	2019