Document and Entity Information - shares	3 Months Ended
	Sep. 30, 2018	Oct. 31, 2018
Document and Entity Information
Entity Registrant Name	LANNETT CO INC
Entity Central Index Key	0000057725
Document Type	10-Q
Document Period End Date	Sep. 30, 2018
Amendment Flag	false
Current Fiscal Year End Date	--06-30
Entity Current Reporting Status	Yes
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding		38,952,752
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	Q1