v3.19.2
Cover Page - shares
6 Months Ended
Jun. 30, 2019
Jul. 26, 2019
Cover page.    
Document Type 10-Q  
Document Quarterly Report true  
Document Transition Report false  
Document Period End Date Jun. 30, 2019  
Entity File Number 001-36112  
Document Fiscal Year Focus 2019  
Document Fiscal Period Focus Q2  
Entity Registrant Name MACROGENICS, INC.  
Entity Central Index Key 0001125345  
Current Fiscal Year End Date --12-31  
Entity Interactive Data Current Yes  
Entity Filer Category Large Accelerated Filer  
Entity Emerging Growth Company false  
Entity Current Reporting Status Yes  
Title of 12(b) Security Common Stock, par value $0.01 per share  
Entity Small Business false  
Local Phone Number 251-5172  
City Area Code 301  
Trading Symbol MGNX  
Security Exchange Name NASDAQ  
Entity Address, Postal Zip Code 20850  
Entity Tax Identification Number 06-1591613  
Entity Incorporation, State or Country Code DE  
Entity Common Stock, Shares Outstanding   48,893,451
Entity Address, Address Line One 9704 Medical Center Drive  
Entity Address, City or Town Rockville  
Entity Address, State or Province MD  
Amendment Flag false  
Entity Shell Company false