| Document and Entity Information | Nov. 02, 2020 |
| Cover [Abstract] | |
| Document Type | 8-K |
| Document Period End Date | Nov. 2, 2020 |
| Entity Registrant Name | WEIS MARKETS, INC. |
| Entity Incorporation, State or Country Code | PA |
| Entity File Number | 1-5039 |
| Entity Tax Identification Number | 24-0755415 |
| Entity Address, Address Line One | 1000 South Second Street |
| Entity Address, City or Town | Sunbury |
| Entity Address, State or Province | PA |
| Entity Address, Postal Zip Code | 17801 |
| City Area Code | 570 |
| Local Phone Number | 286-4571 |
| Written Communications | false |
| Soliciting Material | false |
| Pre-commencement Tender Offer | false |
| Pre-commencement Issuer Tender Offer | false |
| Title of 12(b) Security | Common stock, no par value |
| Trading Symbol | WMK |
| Security Exchange Name | NYSE |
| Entity Emerging Growth Company | false |
| Amendment Flag | false |
| Entity Central Index Key | 0000105418 |
