| Cover Page | Sep. 29, 2020 |
| Cover [Abstract] | |
| Document Type | 8-K |
| Document Period End Date | Sep. 29, 2020 |
| Entity Registrant Name | SILK ROAD MEDICAL, INC. |
| Entity Incorporation, State or Country Code | DE |
| Entity File Number | 001-38847 |
| Entity Tax Identification Number | 20-8777622 |
| Entity Address, Address Line One | 1213 Innsbruck Drive |
| Entity Address, City or Town | Sunnyvale |
| Entity Address, State or Province | CA |
| Entity Address, Postal Zip Code | 94089 |
| City Area Code | 408 |
| Local Phone Number | 720-9002 |
| 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 | 0001397702 |
| Amendment Flag | false |
