| Document And Entity Information | Feb. 03, 2021 |
| Document Information [Line Items] | |
| Entity, Registrant Name | SENECA FOODS CORPORATION |
| Document, Type | 8-K |
| Document, Period End Date | Feb. 3, 2021 |
| Entity, Incorporation, State or Country Code | NY |
| Entity, File Number | 0-01989 |
| Entity, Tax Identification Number | 16-0733425 |
| Entity, Address, Address Line One | 3736 South Main Street |
| Entity, Address, City or Town | Marion |
| Entity, Address, State or Province | NY |
| Entity, Address, Postal Zip Code | 14505-9751 |
| City Area Code | 315 |
| Local Phone Number | 926-8100 |
| Written Communications | false |
| Soliciting Material | false |
| Pre-commencement Tender Offer | false |
| Pre-commencement Issuer Tender Offer | false |
| Entity, Emerging Growth Company | false |
| Amendment Flag | false |
| Entity, Central Index Key | 0000088948 |
| CommonStockClassA Custom [Member] | |
| Document Information [Line Items] | |
| Title of 12(b) Security | Common Stock Class A |
| Trading Symbol | SENEA |
| Security Exchange Name | NASDAQ |
| CommonStockClassB Custom [Member] | |
| Document Information [Line Items] | |
| Title of 12(b) Security | Common Stock Class B |
| Trading Symbol | SENEB |
| Security Exchange Name | NASDAQ |
