| Cover Page | May 11, 2021 | Nov. 04, 2020 |
| Cover [Abstract] | ||
| Document Type | 8-K | |
| Document Period End Date | May 11, 2021 | |
| Entity Registrant Name | PROTHENA CORPORATION PUBLIC LIMITED COMPANY | |
| Entity Incorporation, State or Country Code | L2 | |
| Entity File Number | 001-35676 | |
| Entity Tax Identification Number | 98-1111119 | |
| Entity Address, Address Line One | 77 Sir John Rogerson's Quay, Block C | |
| Entity Address, Address Line Two | Grand Canal Docklands | |
| Entity Address, City or Town | Dublin 2, | |
| Entity Address, Postal Zip Code | D02 VK60, | |
| Entity Address, Country | IE | |
| Country Region | 353 | |
| City Area Code | 1 | |
| Local Phone Number | 236-2500 | |
| Written Communications | false | |
| Soliciting Material | false | |
| Pre-commencement Tender Offer | false | |
| Pre-commencement Issuer Tender Offer | false | |
| Title of 12(b) Security | Ordinary Shares, par value $0.01 per share | |
| Trading Symbol | PRTA | |
| Security Exchange Name | NASDAQ | |
| Entity Emerging Growth Company | false | |
| Entity Central Index Key | 0001559053 | |
| Amendment Flag | false |
