Cover
| Cover | Sep. 23, 2021 | Sep. 16, 2021 | May 13, 2021 |
| Cover [Abstract] | |||
| Document Type | 8-K | ||
| Document Period End Date | Sep. 23, 2021 | ||
| Entity Registrant Name | MACROGENICS, INC. | ||
| Entity Incorporation, State or Country Code | DE | ||
| Entity File Number | 001-36112 | ||
| Entity Tax Identification Number | 06-1591613 | ||
| Entity Address, Address Line One | 9704 Medical Center Drive | ||
| Entity Address, City or Town | Rockville, | ||
| Entity Address, State or Province | MD | ||
| Entity Address, Postal Zip Code | 20850 | ||
| City Area Code | 301 | ||
| Local Phone Number | 251-5172 | ||
| Title of 12(b) Security | Common Stock, par value $0.01 per share | ||
| Trading Symbol | MGNX | ||
| Security Exchange Name | NASDAQ | ||
| Written Communications | false | ||
| Soliciting Material | false | ||
| Pre-commencement Tender Offer | false | ||
| Pre-commencement Issuer Tender Offer | false | ||
| Entity Emerging Growth Company | false | ||
| Entity Central Index Key | 0001125345 | ||
| Amendment Flag | false |