Document and Entity Information - shares	3 Months Ended
	Mar. 31, 2020	Apr. 30, 2020
Cover [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Mar. 31, 2020
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	Q1
Trading Symbol	ATNX
Entity Registrant Name	ATHENEX, INC.
Entity Central Index Key	0001300699
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Entity Shell Company	false
Entity Small Business	false
Entity Emerging Growth Company	false
Document Quarterly Report	true
Document Transition Report	false
Entity Common Stock, Shares Outstanding		81,625,343
Entity Incorporation, State or Country Code	DE
Entity File Number	001-38112
Entity Tax Identification Number	43-1985966
Entity Address, Address Line One	1001 Main Street
Entity Address, Address Line Two	Suite 600
Entity Address, City or Town	Buffalo
Entity Address, State or Province	NY
Entity Address, Postal Zip Code	14203
City Area Code	716
Local Phone Number	427-2950
Title of 12(b) Security	Common Stock, par value $0.001 per share
Security Exchange Name	NASDAQ