Document and Entity Information
3 Months Ended
Mar. 31, 2018
Document and Entity Information  
Entity Registrant Name MAGELLAN HEALTH INC
Entity Central Index Key 0000019411
Document Type 10-Q
Document Period End Date Mar. 31, 2018
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 24,627,170
Document Fiscal Year Focus 2018
Document Fiscal Period Focus Q1