| Document and Entity Information | Feb. 04, 2020 |
| Cover [Abstract] | |
| Document Type | 8-K |
| Amendment Flag | false |
| Document Period End Date | Feb. 4, 2020 |
| Entity Registrant Name | USANA HEALTH SCIENCES, INC. |
| Entity Incorporation, State or Country Code | UT |
| Entity File Number | 001-35024 |
| Entity Tax Identification Number | 87-0500306 |
| Entity Address, Address Line One | 3838 West Parkway Boulevard |
| Entity Address, City or Town | Salt Lake City |
| Entity Address, State or Province | UT |
| Entity Address, Postal Zip Code | 84120 |
| City Area Code | 801 |
| Local Phone Number | 954-7100 |
| 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 | 0000896264 |
| Title of 12(b) Security | Common Stock, $0.001 per value per share |
| Trading Symbol | USNA |
| Security Exchange Name | NYSE |
