| Document and Entity Information | Jun. 07, 2021 |
| Cover [Abstract] | |
| Amendment Flag | false |
| Entity Central Index Key | 0001055726 |
| Document Type | 8-K |
| Document Period End Date | Jun. 7, 2021 |
| Entity Registrant Name | Inovio Pharmaceuticals, Inc. |
| Entity Incorporation State Country Code | DE |
| Entity File Number | 001-14888 |
| Entity Tax Identification Number | 33-0969592 |
| Entity Address, Address Line One | 660 W. Germantown Pike |
| Entity Address, Address Line Two | Suite 110 |
| Entity Address, City or Town | Plymouth Meeting |
| Entity Address, State or Province | PA |
| Entity Address, Postal Zip Code | 19462 |
| City Area Code | (267) |
| Local Phone Number | 440-4200 |
| Written Communications | false |
| Soliciting Material | false |
| Pre Commencement Tender Offer | false |
| Pre Commencement Issuer Tender Offer | false |
| Security 12b Title | Common Stock, $0.001 par value |
| Trading Symbol | INO |
| Security Exchange Name | NASDAQ |
| Entity Emerging Growth Company | false |
