Segment Information (Schedule Of Revenue Percentage By Product) (Details)	12 Months Ended
	Dec. 28, 2019	Dec. 29, 2018	Dec. 30, 2017
USANA Nutritionals [Member]
Revenue from External Customer [Line Items]
Percentage of product revenue	83.00%	82.00%	83.00%
USANA Foods [Member]
Revenue from External Customer [Line Items]
Percentage of product revenue	8.00%	9.00%	9.00%
Personal Care and Skincare [Member]
Revenue from External Customer [Line Items]
Percentage of product revenue	8.00%	8.00%	6.00%
All Other [Member]
Revenue from External Customer [Line Items]
Percentage of product revenue	1.00%	1.00%	2.00%