Cover Page	3 Months Ended
	Aug. 31, 2019 shares
Cover [Abstract]
Amendment Flag	false
Document Type	10-Q
Document Period End Date	Aug. 31, 2019
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	Q1
Current Fiscal Year End Date	--05-31
Entity Interactive Data Current	Yes
Entity Current Reporting Status	Yes
Entity Registrant Name	NEOGEN CORP
Entity Central Index Key	0000711377
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Document Quarterly Report	true
Document Transition Report	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding	52,422,942
Entity File Number	0-17988
Entity Incorporation, State or Country Code	MI
Entity Tax Identification Number	38-2367843
Entity Address, Address Line One	620 Lesher Place
Local Phone Number	372-9200
Entity Address, State or Province	MI
Entity Address, City or Town	Lansing
City Area Code	517
Entity Address, Postal Zip Code	48912