| Segment Information (Schedule Of Revenue Percentage By Product) (Details) | 3 Months Ended | |
|---|---|---|
| Mar. 28, 2020 | Mar. 30, 2019 | |
| USANA Nutritionals [Member] | ||
| Revenue from External Customer [Line Items] | ||
| Percentage of product revenue | 86.00% | 84.00% | 
| USANA Foods [Member] | ||
| Revenue from External Customer [Line Items] | ||
| Percentage of product revenue | 8.00% | 8.00% | 
| Personal Care and Skincare [Member] | ||
| Revenue from External Customer [Line Items] | ||
| Percentage of product revenue | 5.00% | 7.00% | 
| All Other [Member] | ||
| Revenue from External Customer [Line Items] | ||
| Percentage of product revenue | 1.00% | 1.00% | 
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