Document and Entity Information	9 Months Ended
	Sep. 30, 2017 shares
Document and Entity Information
Entity Registrant Name	MAGELLAN HEALTH INC
Entity Central Index Key	0000019411
Document Type	10-Q
Document Period End Date	Sep. 30, 2017
Amendment Flag	false
Current Fiscal Year End Date	--12-31
Entity Current Reporting Status	Yes
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding	24,042,290
Document Fiscal Year Focus	2017
Document Fiscal Period Focus	Q3