Document and Entity Information - shares	9 Months Ended
	Sep. 30, 2019	Nov. 11, 2019
Document And Entity Information
Entity Registrant Name	SPHERIX INC
Entity Central Index Key	0000012239
Document Type	10-Q
Current Fiscal Year End Date	--12-31
Amendment Flag	false
Document Period End Date	Sep. 30, 2019
Entity File Number	000-05576
Entity Incorporation, State or Country Code	DE
Entity Reporting Status Current	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Non-accelerated Filer
Entity Small Business	true
Entity Emerging Growth Company	false
Entity Ex Transition Period	false
Entity Shell Company	false
Title of 12(g) Security	Common Stock, $0.0001 par value
Trading Symbol	SPEX
Security Exchange Name	NASDAQ
Entity Common Stock, Shares Outstanding		2,886,491
Document Fiscal Period Focus	Q3
Document Fiscal Year Focus	2019