| Cover | Dec. 31, 2021 |
| Cover [Abstract] | |
| Document Type | 8-K |
| Document Period End Date | Mar. 30, 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 |
| Current Fiscal Year End Date | --12-31 |
