| Cover Page | Jan. 14, 2020 |
| Cover page. | |
| Document Type | 8-K |
| Document Period End Date | Jan. 14, 2020 |
| Entity Registrant Name | HALOZYME THERAPEUTICS, INC. |
| Entity File Number | 001-32335 |
| Entity Incorporation, State or Country Code | DE |
| Entity Tax Identification Number | 88-0488686 |
| Entity Address, Address Line One | 11388 Sorrento Valley Road |
| Entity Address, City or Town | San Diego |
| Entity Address, State or Province | CA |
| Entity Address, Postal Zip Code | 92121 |
| City Area Code | 858 |
| Local Phone Number | 794-8889 |
| Written Communications | false |
| Soliciting Material | false |
| Pre-commencement Tender Offer | false |
| Pre-commencement Issuer Tender Offer | false |
| Title of 12(b) Security | Common Stock, $0.001 par value |
| Trading Symbol | HALO |
| Security Exchange Name | NASDAQ |
| Entity Emerging Growth Company | false |
| Amendment Flag | false |
| Entity Central Index Key | 0001159036 |
